xref: /aosp_15_r20/external/libdrm/xf86drm.c (revision 7688df22e49036ff52a766b7101da3a49edadb8c)

/**
 * \file xf86drm.c
 * User-level interface to DRM device
 *
 * \author Rickard E. (Rik) Faith <[email protected]>
 * \author Kevin E. Martin <[email protected]>
 */

/*
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <ctype.h>
#include <dirent.h>
#include <stddef.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#define stat_t struct stat
#include <sys/ioctl.h>
#include <sys/time.h>
#include <stdarg.h>
#ifdef MAJOR_IN_MKDEV
#include <sys/mkdev.h>
#endif
#ifdef MAJOR_IN_SYSMACROS
#include <sys/sysmacros.h>
#endif
#if HAVE_SYS_SYSCTL_H
#include <sys/sysctl.h>
#endif
#include <inttypes.h>

#if defined(__FreeBSD__)
#include <sys/param.h>
#include <sys/pciio.h>
#endif

#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))

/* Not all systems have MAP_FAILED defined */
#ifndef MAP_FAILED
#define MAP_FAILED ((void *)-1)
#endif

#include "xf86drm.h"
#include "libdrm_macros.h"
#include "drm_fourcc.h"

#include "util_math.h"

#ifdef __DragonFly__
#define DRM_MAJOR 145
#endif

#ifdef __NetBSD__
#define DRM_MAJOR 34
#endif

#ifdef __OpenBSD__
#ifdef __i386__
#define DRM_MAJOR 88
#else
#define DRM_MAJOR 87
#endif
#endif /* __OpenBSD__ */

#ifndef DRM_MAJOR
#define DRM_MAJOR 226 /* Linux */
#endif

#if defined(__OpenBSD__) || defined(__DragonFly__)
struct drm_pciinfo {
	uint16_t	domain;
	uint8_t		bus;
	uint8_t		dev;
	uint8_t		func;
	uint16_t	vendor_id;
	uint16_t	device_id;
	uint16_t	subvendor_id;
	uint16_t	subdevice_id;
	uint8_t		revision_id;
};

#define DRM_IOCTL_GET_PCIINFO	DRM_IOR(0x15, struct drm_pciinfo)
#endif

#define DRM_MSG_VERBOSITY 3

#define memclear(s) memset(&s, 0, sizeof(s))

static drmServerInfoPtr drm_server_info;

static bool drmNodeIsDRM(int maj, int min);
static char *drmGetMinorNameForFD(int fd, int type);

#define DRM_MODIFIER(v, f, f_name) \
       .modifier = DRM_FORMAT_MOD_##v ## _ ##f, \
       .modifier_name = #f_name

#define DRM_MODIFIER_INVALID(v, f_name) \
       .modifier = DRM_FORMAT_MOD_INVALID, .modifier_name = #f_name

#define DRM_MODIFIER_LINEAR(v, f_name) \
       .modifier = DRM_FORMAT_MOD_LINEAR, .modifier_name = #f_name

/* Intel is abit special as the format doesn't follow other vendors naming
 * scheme */
#define DRM_MODIFIER_INTEL(f, f_name) \
       .modifier = I915_FORMAT_MOD_##f, .modifier_name = #f_name

struct drmFormatModifierInfo {
    uint64_t modifier;
    const char *modifier_name;
};

struct drmFormatModifierVendorInfo {
    uint8_t vendor;
    const char *vendor_name;
};

#include "generated_static_table_fourcc.h"

struct drmVendorInfo {
    uint8_t vendor;
    char *(*vendor_cb)(uint64_t modifier);
};

struct drmFormatVendorModifierInfo {
    uint64_t modifier;
    const char *modifier_name;
};

static char *
drmGetFormatModifierNameFromArm(uint64_t modifier);

static char *
drmGetFormatModifierNameFromNvidia(uint64_t modifier);

static char *
drmGetFormatModifierNameFromAmd(uint64_t modifier);

static char *
drmGetFormatModifierNameFromAmlogic(uint64_t modifier);

static char *
drmGetFormatModifierNameFromVivante(uint64_t modifier);

static const struct drmVendorInfo modifier_format_vendor_table[] = {
    { DRM_FORMAT_MOD_VENDOR_ARM, drmGetFormatModifierNameFromArm },
    { DRM_FORMAT_MOD_VENDOR_NVIDIA, drmGetFormatModifierNameFromNvidia },
    { DRM_FORMAT_MOD_VENDOR_AMD, drmGetFormatModifierNameFromAmd },
    { DRM_FORMAT_MOD_VENDOR_AMLOGIC, drmGetFormatModifierNameFromAmlogic },
    { DRM_FORMAT_MOD_VENDOR_VIVANTE, drmGetFormatModifierNameFromVivante },
};

#ifndef AFBC_FORMAT_MOD_MODE_VALUE_MASK
#define AFBC_FORMAT_MOD_MODE_VALUE_MASK	0x000fffffffffffffULL
#endif

static const struct drmFormatVendorModifierInfo arm_mode_value_table[] = {
    { AFBC_FORMAT_MOD_YTR,          "YTR" },
    { AFBC_FORMAT_MOD_SPLIT,        "SPLIT" },
    { AFBC_FORMAT_MOD_SPARSE,       "SPARSE" },
    { AFBC_FORMAT_MOD_CBR,          "CBR" },
    { AFBC_FORMAT_MOD_TILED,        "TILED" },
    { AFBC_FORMAT_MOD_SC,           "SC" },
    { AFBC_FORMAT_MOD_DB,           "DB" },
    { AFBC_FORMAT_MOD_BCH,          "BCH" },
    { AFBC_FORMAT_MOD_USM,          "USM" },
};

static bool
drmGetAfbcFormatModifierNameFromArm(uint64_t modifier, FILE *fp)
{
    uint64_t mode_value = modifier & AFBC_FORMAT_MOD_MODE_VALUE_MASK;
    uint64_t block_size = mode_value & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK;

    const char *block = NULL;
    const char *mode = NULL;
    bool did_print_mode = false;

    /* add block, can only have a (single) block */
    switch (block_size) {
    case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
        block = "16x16";
        break;
    case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
        block = "32x8";
        break;
    case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
        block = "64x4";
        break;
    case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
        block = "32x8_64x4";
        break;
    }

    if (!block) {
        return false;
    }

    fprintf(fp, "BLOCK_SIZE=%s,", block);

    /* add mode */
    for (unsigned int i = 0; i < ARRAY_SIZE(arm_mode_value_table); i++) {
        if (arm_mode_value_table[i].modifier & mode_value) {
            mode = arm_mode_value_table[i].modifier_name;
            if (!did_print_mode) {
                fprintf(fp, "MODE=%s", mode);
                did_print_mode = true;
            } else {
                fprintf(fp, "|%s", mode);
            }
        }
    }

    return true;
}

static bool
drmGetAfrcFormatModifierNameFromArm(uint64_t modifier, FILE *fp)
{
    bool scan_layout;
    for (unsigned int i = 0; i < 2; ++i) {
        uint64_t coding_unit_block =
          (modifier >> (i * 4)) & AFRC_FORMAT_MOD_CU_SIZE_MASK;
        const char *coding_unit_size = NULL;

        switch (coding_unit_block) {
        case AFRC_FORMAT_MOD_CU_SIZE_16:
            coding_unit_size = "CU_16";
            break;
        case AFRC_FORMAT_MOD_CU_SIZE_24:
            coding_unit_size = "CU_24";
            break;
        case AFRC_FORMAT_MOD_CU_SIZE_32:
            coding_unit_size = "CU_32";
            break;
        }

        if (!coding_unit_size) {
            if (i == 0) {
                return false;
            }
            break;
        }

        if (i == 0) {
            fprintf(fp, "P0=%s,", coding_unit_size);
        } else {
            fprintf(fp, "P12=%s,", coding_unit_size);
        }
    }

    scan_layout =
        (modifier & AFRC_FORMAT_MOD_LAYOUT_SCAN) == AFRC_FORMAT_MOD_LAYOUT_SCAN;
    if (scan_layout) {
        fprintf(fp, "SCAN");
    } else {
        fprintf(fp, "ROT");
    }
    return true;
}

static char *
drmGetFormatModifierNameFromArm(uint64_t modifier)
{
    uint64_t type = (modifier >> 52) & 0xf;

    FILE *fp;
    size_t size = 0;
    char *modifier_name = NULL;
    bool result = false;

    fp = open_memstream(&modifier_name, &size);
    if (!fp)
        return NULL;

    switch (type) {
    case DRM_FORMAT_MOD_ARM_TYPE_AFBC:
        result = drmGetAfbcFormatModifierNameFromArm(modifier, fp);
        break;
    case DRM_FORMAT_MOD_ARM_TYPE_AFRC:
        result = drmGetAfrcFormatModifierNameFromArm(modifier, fp);
        break;
    /* misc type is already handled by the static table */
    case DRM_FORMAT_MOD_ARM_TYPE_MISC:
    default:
        result = false;
        break;
    }

    fclose(fp);
    if (!result) {
        free(modifier_name);
        return NULL;
    }

    return modifier_name;
}

static char *
drmGetFormatModifierNameFromNvidia(uint64_t modifier)
{
    uint64_t height, kind, gen, sector, compression;

    height = modifier & 0xf;
    kind = (modifier >> 12) & 0xff;

    gen = (modifier >> 20) & 0x3;
    sector = (modifier >> 22) & 0x1;
    compression = (modifier >> 23) & 0x7;

    /* just in case there could other simpler modifiers, not yet added, avoid
     * testing against TEGRA_TILE */
    if ((modifier & 0x10) == 0x10) {
        char *mod_nvidia;
        asprintf(&mod_nvidia, "BLOCK_LINEAR_2D,HEIGHT=%"PRIu64",KIND=%"PRIu64","
                 "GEN=%"PRIu64",SECTOR=%"PRIu64",COMPRESSION=%"PRIu64"", height,
                 kind, gen, sector, compression);
        return mod_nvidia;
    }

    return  NULL;
}

static char *
drmGetFormatModifierNameFromAmd(uint64_t modifier)
{
    static const char *gfx9_gfx11_tile_strings[32] = {
        "LINEAR",
        "256B_S",
        "256B_D",
        "256B_R",
        "4KB_Z",
        "4KB_S",
        "4KB_D",
        "4KB_R",
        "64KB_Z",
        "64KB_S",
        "64KB_D",
        "64KB_R",
        "INVALID12",
        "INVALID13",
        "INVALID14",
        "INVALID15",
        "64KB_Z_T",
        "64KB_S_T",
        "64KB_D_T",
        "64KB_R_T",
        "4KB_Z_X",
        "4KB_S_X",
        "4KB_D_X",
        "4KB_R_X",
        "64KB_Z_X",
        "64KB_S_X",
        "64KB_D_X",
        "64KB_R_X",
        "256KB_Z_X",
        "256KB_S_X",
        "256KB_D_X",
        "256KB_R_X",
    };
    static const char *gfx12_tile_strings[32] = {
        "LINEAR",
        "256B_2D",
        "4KB_2D",
        "64KB_2D",
        "256KB_2D",
        "4KB_3D",
        "64KB_3D",
        "256KB_3D",
        /* other values are unused */
    };
    uint64_t tile_version = AMD_FMT_MOD_GET(TILE_VERSION, modifier);
    FILE *fp;
    char *mod_amd = NULL;
    size_t size = 0;

    fp = open_memstream(&mod_amd, &size);
    if (!fp)
        return NULL;

    switch (tile_version) {
    case AMD_FMT_MOD_TILE_VER_GFX9:
        fprintf(fp, "GFX9");
        break;
    case AMD_FMT_MOD_TILE_VER_GFX10:
        fprintf(fp, "GFX10");
        break;
    case AMD_FMT_MOD_TILE_VER_GFX10_RBPLUS:
        fprintf(fp, "GFX10_RBPLUS");
        break;
    case AMD_FMT_MOD_TILE_VER_GFX11:
        fprintf(fp, "GFX11");
        break;
    case AMD_FMT_MOD_TILE_VER_GFX12:
        fprintf(fp, "GFX12");
        break;
    default:
        fclose(fp);
        free(mod_amd);
        return NULL;
    }

    if (tile_version >= AMD_FMT_MOD_TILE_VER_GFX12) {
        unsigned tile = AMD_FMT_MOD_GET(TILE, modifier);

        fprintf(fp, ",%s", gfx12_tile_strings[tile]);

        if (AMD_FMT_MOD_GET(DCC, modifier)) {
            fprintf(fp, ",DCC,DCC_MAX_COMPRESSED_BLOCK=%uB",
                    64 << AMD_FMT_MOD_GET(DCC_MAX_COMPRESSED_BLOCK, modifier));

            /* Other DCC fields are unused by GFX12. */
        }
    } else {
        unsigned tile = AMD_FMT_MOD_GET(TILE, modifier);

        fprintf(fp, ",%s", gfx9_gfx11_tile_strings[tile]);

        /* All *_T and *_X modes are affected by chip-specific fields. */
        if (tile >= 16) {
            fprintf(fp, ",PIPE_XOR_BITS=%u",
                    (unsigned)AMD_FMT_MOD_GET(PIPE_XOR_BITS, modifier));

            switch (tile_version) {
            case AMD_FMT_MOD_TILE_VER_GFX9:
                fprintf(fp, ",BANK_XOR_BITS=%u",
                        (unsigned)AMD_FMT_MOD_GET(BANK_XOR_BITS, modifier));
                break;

            case AMD_FMT_MOD_TILE_VER_GFX10:
                /* Nothing else for GFX10. */
                break;

            case AMD_FMT_MOD_TILE_VER_GFX10_RBPLUS:
            case AMD_FMT_MOD_TILE_VER_GFX11:
                /* This also determines the DCC layout, but DCC is only legal
                 * with tile=27 and tile=31 (*_R_X modes).
                 */
                fprintf(fp, ",PACKERS=%u",
                        (unsigned)AMD_FMT_MOD_GET(PACKERS, modifier));
                break;
            }
        }

        if (AMD_FMT_MOD_GET(DCC, modifier)) {
            if (tile_version == AMD_FMT_MOD_TILE_VER_GFX9 &&
                (AMD_FMT_MOD_GET(DCC_PIPE_ALIGN, modifier) ||
                 AMD_FMT_MOD_GET(DCC_RETILE, modifier))) {
                /* These two only determine the layout of
                 * the non-displayable DCC plane.
                 */
                fprintf(fp, ",RB=%u",
                        (unsigned)AMD_FMT_MOD_GET(RB, modifier));
                fprintf(fp, ",PIPE=%u",
                        (unsigned)AMD_FMT_MOD_GET(PIPE, modifier));
            }

            fprintf(fp, ",DCC,DCC_MAX_COMPRESSED_BLOCK=%uB",
                    64 << AMD_FMT_MOD_GET(DCC_MAX_COMPRESSED_BLOCK, modifier));

            if (AMD_FMT_MOD_GET(DCC_INDEPENDENT_64B, modifier))
                fprintf(fp, ",DCC_INDEPENDENT_64B");

            if (AMD_FMT_MOD_GET(DCC_INDEPENDENT_128B, modifier))
                fprintf(fp, ",DCC_INDEPENDENT_128B");

            if (AMD_FMT_MOD_GET(DCC_CONSTANT_ENCODE, modifier))
                fprintf(fp, ",DCC_CONSTANT_ENCODE");

            if (AMD_FMT_MOD_GET(DCC_PIPE_ALIGN, modifier))
                fprintf(fp, ",DCC_PIPE_ALIGN");

            if (AMD_FMT_MOD_GET(DCC_RETILE, modifier))
                fprintf(fp, ",DCC_RETILE");
        }
    }

    fclose(fp);
    return mod_amd;
}

static char *
drmGetFormatModifierNameFromAmlogic(uint64_t modifier)
{
    uint64_t layout = modifier & 0xff;
    uint64_t options = (modifier >> 8) & 0xff;
    char *mod_amlogic = NULL;

    const char *layout_str;
    const char *opts_str;

    switch (layout) {
    case AMLOGIC_FBC_LAYOUT_BASIC:
       layout_str = "BASIC";
       break;
    case AMLOGIC_FBC_LAYOUT_SCATTER:
       layout_str = "SCATTER";
       break;
    default:
       layout_str = "INVALID_LAYOUT";
       break;
    }

    if (options & AMLOGIC_FBC_OPTION_MEM_SAVING)
        opts_str = "MEM_SAVING";
    else
        opts_str = "0";

    asprintf(&mod_amlogic, "FBC,LAYOUT=%s,OPTIONS=%s", layout_str, opts_str);
    return mod_amlogic;
}

static char *
drmGetFormatModifierNameFromVivante(uint64_t modifier)
{
    const char *color_tiling, *tile_status, *compression;
    char *mod_vivante = NULL;

    switch (modifier & VIVANTE_MOD_TS_MASK) {
    case 0:
        tile_status = "";
        break;
    case VIVANTE_MOD_TS_64_4:
        tile_status = ",TS=64B_4";
        break;
    case VIVANTE_MOD_TS_64_2:
        tile_status = ",TS=64B_2";
        break;
    case VIVANTE_MOD_TS_128_4:
        tile_status = ",TS=128B_4";
        break;
    case VIVANTE_MOD_TS_256_4:
        tile_status = ",TS=256B_4";
        break;
    default:
        tile_status = ",TS=UNKNOWN";
        break;
    }

    switch (modifier & VIVANTE_MOD_COMP_MASK) {
    case 0:
        compression = "";
        break;
    case VIVANTE_MOD_COMP_DEC400:
        compression = ",COMP=DEC400";
        break;
    default:
        compression = ",COMP=UNKNOWN";
	break;
    }

    switch (modifier & ~VIVANTE_MOD_EXT_MASK) {
    case 0:
        color_tiling = "LINEAR";
	break;
    case DRM_FORMAT_MOD_VIVANTE_TILED:
        color_tiling = "TILED";
	break;
    case DRM_FORMAT_MOD_VIVANTE_SUPER_TILED:
        color_tiling = "SUPER_TILED";
	break;
    case DRM_FORMAT_MOD_VIVANTE_SPLIT_TILED:
        color_tiling = "SPLIT_TILED";
	break;
    case DRM_FORMAT_MOD_VIVANTE_SPLIT_SUPER_TILED:
        color_tiling = "SPLIT_SUPER_TILED";
	break;
    default:
        color_tiling = "UNKNOWN";
	break;
    }

    asprintf(&mod_vivante, "%s%s%s", color_tiling, tile_status, compression);
    return mod_vivante;
}

static unsigned log2_int(unsigned x)
{
    unsigned l;

    if (x < 2) {
        return 0;
    }
    for (l = 2; ; l++) {
        if ((unsigned)(1 << l) > x) {
            return l - 1;
        }
    }
    return 0;
}


drm_public void drmSetServerInfo(drmServerInfoPtr info)
{
    drm_server_info = info;
}

/**
 * Output a message to stderr.
 *
 * \param format printf() like format string.
 *
 * \internal
 * This function is a wrapper around vfprintf().
 */

static int DRM_PRINTFLIKE(1, 0)
drmDebugPrint(const char *format, va_list ap)
{
    return vfprintf(stderr, format, ap);
}

drm_public void
drmMsg(const char *format, ...)
{
    va_list ap;
    const char *env;
    if (((env = getenv("LIBGL_DEBUG")) && strstr(env, "verbose")) ||
        (drm_server_info && drm_server_info->debug_print))
    {
        va_start(ap, format);
        if (drm_server_info) {
            drm_server_info->debug_print(format,ap);
        } else {
            drmDebugPrint(format, ap);
        }
        va_end(ap);
    }
}

static void *drmHashTable = NULL; /* Context switch callbacks */

drm_public void *drmGetHashTable(void)
{
    return drmHashTable;
}

drm_public void *drmMalloc(int size)
{
    return calloc(1, size);
}

drm_public void drmFree(void *pt)
{
    free(pt);
}

/**
 * Call ioctl, restarting if it is interrupted
 */
drm_public int
drmIoctl(int fd, unsigned long request, void *arg)
{
    int ret;

    do {
        ret = ioctl(fd, request, arg);
    } while (ret == -1 && (errno == EINTR || errno == EAGAIN));
    return ret;
}

static unsigned long drmGetKeyFromFd(int fd)
{
    stat_t     st;

    st.st_rdev = 0;
    fstat(fd, &st);
    return st.st_rdev;
}

drm_public drmHashEntry *drmGetEntry(int fd)
{
    unsigned long key = drmGetKeyFromFd(fd);
    void          *value;
    drmHashEntry  *entry;

    if (!drmHashTable)
        drmHashTable = drmHashCreate();

    if (drmHashLookup(drmHashTable, key, &value)) {
        entry           = drmMalloc(sizeof(*entry));
        entry->fd       = fd;
        entry->f        = NULL;
        entry->tagTable = drmHashCreate();
        drmHashInsert(drmHashTable, key, entry);
    } else {
        entry = value;
    }
    return entry;
}

/**
 * Compare two busid strings
 *
 * \param first
 * \param second
 *
 * \return 1 if matched.
 *
 * \internal
 * This function compares two bus ID strings.  It understands the older
 * PCI:b:d:f format and the newer pci:oooo:bb:dd.f format.  In the format, o is
 * domain, b is bus, d is device, f is function.
 */
static int drmMatchBusID(const char *id1, const char *id2, int pci_domain_ok)
{
    /* First, check if the IDs are exactly the same */
    if (strcasecmp(id1, id2) == 0)
        return 1;

    /* Try to match old/new-style PCI bus IDs. */
    if (strncasecmp(id1, "pci", 3) == 0) {
        unsigned int o1, b1, d1, f1;
        unsigned int o2, b2, d2, f2;
        int ret;

        ret = sscanf(id1, "pci:%04x:%02x:%02x.%u", &o1, &b1, &d1, &f1);
        if (ret != 4) {
            o1 = 0;
            ret = sscanf(id1, "PCI:%u:%u:%u", &b1, &d1, &f1);
            if (ret != 3)
                return 0;
        }

        ret = sscanf(id2, "pci:%04x:%02x:%02x.%u", &o2, &b2, &d2, &f2);
        if (ret != 4) {
            o2 = 0;
            ret = sscanf(id2, "PCI:%u:%u:%u", &b2, &d2, &f2);
            if (ret != 3)
                return 0;
        }

        /* If domains aren't properly supported by the kernel interface,
         * just ignore them, which sucks less than picking a totally random
         * card with "open by name"
         */
        if (!pci_domain_ok)
            o1 = o2 = 0;

        if ((o1 != o2) || (b1 != b2) || (d1 != d2) || (f1 != f2))
            return 0;
        else
            return 1;
    }
    return 0;
}

/**
 * Handles error checking for chown call.
 *
 * \param path to file.
 * \param id of the new owner.
 * \param id of the new group.
 *
 * \return zero if success or -1 if failure.
 *
 * \internal
 * Checks for failure. If failure was caused by signal call chown again.
 * If any other failure happened then it will output error message using
 * drmMsg() call.
 */
#if !UDEV
static int chown_check_return(const char *path, uid_t owner, gid_t group)
{
        int rv;

        do {
            rv = chown(path, owner, group);
        } while (rv != 0 && errno == EINTR);

        if (rv == 0)
            return 0;

        drmMsg("Failed to change owner or group for file %s! %d: %s\n",
               path, errno, strerror(errno));
        return -1;
}
#endif

static const char *drmGetDeviceName(int type)
{
    switch (type) {
    case DRM_NODE_PRIMARY:
        return DRM_DEV_NAME;
    case DRM_NODE_RENDER:
        return DRM_RENDER_DEV_NAME;
    }
    return NULL;
}

/**
 * Open the DRM device, creating it if necessary.
 *
 * \param dev major and minor numbers of the device.
 * \param minor minor number of the device.
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * Assembles the device name from \p minor and opens it, creating the device
 * special file node with the major and minor numbers specified by \p dev and
 * parent directory if necessary and was called by root.
 */
static int drmOpenDevice(dev_t dev, int minor, int type)
{
    stat_t          st;
    const char      *dev_name = drmGetDeviceName(type);
    char            buf[DRM_NODE_NAME_MAX];
    int             fd;
    mode_t          devmode = DRM_DEV_MODE, serv_mode;
    gid_t           serv_group;
#if !UDEV
    int             isroot  = !geteuid();
    uid_t           user    = DRM_DEV_UID;
    gid_t           group   = DRM_DEV_GID;
#endif

    if (!dev_name)
        return -EINVAL;

    sprintf(buf, dev_name, DRM_DIR_NAME, minor);
    drmMsg("drmOpenDevice: node name is %s\n", buf);

    if (drm_server_info && drm_server_info->get_perms) {
        drm_server_info->get_perms(&serv_group, &serv_mode);
        devmode  = serv_mode ? serv_mode : DRM_DEV_MODE;
        devmode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
    }

#if !UDEV
    if (stat(DRM_DIR_NAME, &st)) {
        if (!isroot)
            return DRM_ERR_NOT_ROOT;
        mkdir(DRM_DIR_NAME, DRM_DEV_DIRMODE);
        chown_check_return(DRM_DIR_NAME, 0, 0); /* root:root */
        chmod(DRM_DIR_NAME, DRM_DEV_DIRMODE);
    }

    /* Check if the device node exists and create it if necessary. */
    if (stat(buf, &st)) {
        if (!isroot)
            return DRM_ERR_NOT_ROOT;
        remove(buf);
        mknod(buf, S_IFCHR | devmode, dev);
    }

    if (drm_server_info && drm_server_info->get_perms) {
        group = ((int)serv_group >= 0) ? serv_group : DRM_DEV_GID;
        chown_check_return(buf, user, group);
        chmod(buf, devmode);
    }
#else
    /* if we modprobed then wait for udev */
    {
        int udev_count = 0;
wait_for_udev:
        if (stat(DRM_DIR_NAME, &st)) {
            usleep(20);
            udev_count++;

            if (udev_count == 50)
                return -1;
            goto wait_for_udev;
        }

        if (stat(buf, &st)) {
            usleep(20);
            udev_count++;

            if (udev_count == 50)
                return -1;
            goto wait_for_udev;
        }
    }
#endif

    fd = open(buf, O_RDWR | O_CLOEXEC);
    drmMsg("drmOpenDevice: open result is %d, (%s)\n",
           fd, fd < 0 ? strerror(errno) : "OK");
    if (fd >= 0)
        return fd;

#if !UDEV
    /* Check if the device node is not what we expect it to be, and recreate it
     * and try again if so.
     */
    if (st.st_rdev != dev) {
        if (!isroot)
            return DRM_ERR_NOT_ROOT;
        remove(buf);
        mknod(buf, S_IFCHR | devmode, dev);
        if (drm_server_info && drm_server_info->get_perms) {
            chown_check_return(buf, user, group);
            chmod(buf, devmode);
        }
    }
    fd = open(buf, O_RDWR | O_CLOEXEC);
    drmMsg("drmOpenDevice: open result is %d, (%s)\n",
           fd, fd < 0 ? strerror(errno) : "OK");
    if (fd >= 0)
        return fd;

    drmMsg("drmOpenDevice: Open failed\n");
    remove(buf);
#endif
    return -errno;
}


/**
 * Open the DRM device
 *
 * \param minor device minor number.
 * \param create allow to create the device if set.
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * Calls drmOpenDevice() if \p create is set, otherwise assembles the device
 * name from \p minor and opens it.
 */
static int drmOpenMinor(int minor, int create, int type)
{
    int  fd;
    char buf[DRM_NODE_NAME_MAX];
    const char *dev_name = drmGetDeviceName(type);

    if (create)
        return drmOpenDevice(makedev(DRM_MAJOR, minor), minor, type);

    if (!dev_name)
        return -EINVAL;

    sprintf(buf, dev_name, DRM_DIR_NAME, minor);
    if ((fd = open(buf, O_RDWR | O_CLOEXEC)) >= 0)
        return fd;
    return -errno;
}


/**
 * Determine whether the DRM kernel driver has been loaded.
 *
 * \return 1 if the DRM driver is loaded, 0 otherwise.
 *
 * \internal
 * Determine the presence of the kernel driver by attempting to open the 0
 * minor and get version information.  For backward compatibility with older
 * Linux implementations, /proc/dri is also checked.
 */
drm_public int drmAvailable(void)
{
    drmVersionPtr version;
    int           retval = 0;
    int           fd;

    if ((fd = drmOpenMinor(0, 1, DRM_NODE_PRIMARY)) < 0) {
#ifdef __linux__
        /* Try proc for backward Linux compatibility */
        if (!access("/proc/dri/0", R_OK))
            return 1;
#endif
        return 0;
    }

    if ((version = drmGetVersion(fd))) {
        retval = 1;
        drmFreeVersion(version);
    }
    close(fd);

    return retval;
}

static int drmGetMinorBase(int type)
{
    switch (type) {
    case DRM_NODE_PRIMARY:
        return 0;
    case DRM_NODE_RENDER:
        return 128;
    default:
        return -1;
    };
}

static int drmGetMinorType(int major, int minor)
{
#ifdef __FreeBSD__
    char name[SPECNAMELEN];
    int id;

    if (!devname_r(makedev(major, minor), S_IFCHR, name, sizeof(name)))
        return -1;

    if (sscanf(name, "drm/%d", &id) != 1) {
        // If not in /dev/drm/ we have the type in the name
        if (sscanf(name, "dri/card%d\n", &id) >= 1)
           return DRM_NODE_PRIMARY;
        else if (sscanf(name, "dri/renderD%d\n", &id) >= 1)
           return DRM_NODE_RENDER;
        return -1;
    }

    minor = id;
#endif
    char path[DRM_NODE_NAME_MAX];
    const char *dev_name;
    int i;

    for (i = DRM_NODE_PRIMARY; i < DRM_NODE_MAX; i++) {
        dev_name = drmGetDeviceName(i);
        if (!dev_name)
           continue;
        snprintf(path, sizeof(path), dev_name, DRM_DIR_NAME, minor);
        if (!access(path, F_OK))
           return i;
    }

    return -1;
}

static const char *drmGetMinorName(int type)
{
    switch (type) {
    case DRM_NODE_PRIMARY:
        return DRM_PRIMARY_MINOR_NAME;
    case DRM_NODE_RENDER:
        return DRM_RENDER_MINOR_NAME;
    default:
        return NULL;
    }
}

/**
 * Open the device by bus ID.
 *
 * \param busid bus ID.
 * \param type device node type.
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * This function attempts to open every possible minor (up to DRM_MAX_MINOR),
 * comparing the device bus ID with the one supplied.
 *
 * \sa drmOpenMinor() and drmGetBusid().
 */
static int drmOpenByBusid(const char *busid, int type)
{
    int        i, pci_domain_ok = 1;
    int        fd;
    const char *buf;
    drmSetVersion sv;
    int        base = drmGetMinorBase(type);

    if (base < 0)
        return -1;

    drmMsg("drmOpenByBusid: Searching for BusID %s\n", busid);
    for (i = base; i < base + DRM_MAX_MINOR; i++) {
        fd = drmOpenMinor(i, 1, type);
        drmMsg("drmOpenByBusid: drmOpenMinor returns %d\n", fd);
        if (fd >= 0) {
            /* We need to try for 1.4 first for proper PCI domain support
             * and if that fails, we know the kernel is busted
             */
            sv.drm_di_major = 1;
            sv.drm_di_minor = 4;
            sv.drm_dd_major = -1;        /* Don't care */
            sv.drm_dd_minor = -1;        /* Don't care */
            if (drmSetInterfaceVersion(fd, &sv)) {
#ifndef __alpha__
                pci_domain_ok = 0;
#endif
                sv.drm_di_major = 1;
                sv.drm_di_minor = 1;
                sv.drm_dd_major = -1;       /* Don't care */
                sv.drm_dd_minor = -1;       /* Don't care */
                drmMsg("drmOpenByBusid: Interface 1.4 failed, trying 1.1\n");
                drmSetInterfaceVersion(fd, &sv);
            }
            buf = drmGetBusid(fd);
            drmMsg("drmOpenByBusid: drmGetBusid reports %s\n", buf);
            if (buf && drmMatchBusID(buf, busid, pci_domain_ok)) {
                drmFreeBusid(buf);
                return fd;
            }
            if (buf)
                drmFreeBusid(buf);
            close(fd);
        }
    }
    return -1;
}


/**
 * Open the device by name.
 *
 * \param name driver name.
 * \param type the device node type.
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * This function opens the first minor number that matches the driver name and
 * isn't already in use.  If it's in use it then it will already have a bus ID
 * assigned.
 *
 * \sa drmOpenMinor(), drmGetVersion() and drmGetBusid().
 */
static int drmOpenByName(const char *name, int type)
{
    int           i;
    int           fd;
    drmVersionPtr version;
    char *        id;
    int           base = drmGetMinorBase(type);

    if (base < 0)
        return -1;

    /*
     * Open the first minor number that matches the driver name and isn't
     * already in use.  If it's in use it will have a busid assigned already.
     */
    for (i = base; i < base + DRM_MAX_MINOR; i++) {
        if ((fd = drmOpenMinor(i, 1, type)) >= 0) {
            if ((version = drmGetVersion(fd))) {
                if (!strcmp(version->name, name)) {
                    drmFreeVersion(version);
                    id = drmGetBusid(fd);
                    drmMsg("drmGetBusid returned '%s'\n", id ? id : "NULL");
                    if (!id || !*id) {
                        if (id)
                            drmFreeBusid(id);
                        return fd;
                    } else {
                        drmFreeBusid(id);
                    }
                } else {
                    drmFreeVersion(version);
                }
            }
            close(fd);
        }
    }

#ifdef __linux__
    /* Backward-compatibility /proc support */
    for (i = 0; i < 8; i++) {
        char proc_name[64], buf[512];
        char *driver, *pt, *devstring;
        int  retcode;

        sprintf(proc_name, "/proc/dri/%d/name", i);
        if ((fd = open(proc_name, O_RDONLY)) >= 0) {
            retcode = read(fd, buf, sizeof(buf)-1);
            close(fd);
            if (retcode) {
                buf[retcode-1] = '\0';
                for (driver = pt = buf; *pt && *pt != ' '; ++pt)
                    ;
                if (*pt) { /* Device is next */
                    *pt = '\0';
                    if (!strcmp(driver, name)) { /* Match */
                        for (devstring = ++pt; *pt && *pt != ' '; ++pt)
                            ;
                        if (*pt) { /* Found busid */
                            return drmOpenByBusid(++pt, type);
                        } else { /* No busid */
                            return drmOpenDevice(strtol(devstring, NULL, 0),i, type);
                        }
                    }
                }
            }
        }
    }
#endif

    return -1;
}


/**
 * Open the DRM device.
 *
 * Looks up the specified name and bus ID, and opens the device found.  The
 * entry in /dev/dri is created if necessary and if called by root.
 *
 * \param name driver name. Not referenced if bus ID is supplied.
 * \param busid bus ID. Zero if not known.
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * It calls drmOpenByBusid() if \p busid is specified or drmOpenByName()
 * otherwise.
 */
drm_public int drmOpen(const char *name, const char *busid)
{
    return drmOpenWithType(name, busid, DRM_NODE_PRIMARY);
}

/**
 * Open the DRM device with specified type.
 *
 * Looks up the specified name and bus ID, and opens the device found.  The
 * entry in /dev/dri is created if necessary and if called by root.
 *
 * \param name driver name. Not referenced if bus ID is supplied.
 * \param busid bus ID. Zero if not known.
 * \param type the device node type to open, PRIMARY or RENDER
 *
 * \return a file descriptor on success, or a negative value on error.
 *
 * \internal
 * It calls drmOpenByBusid() if \p busid is specified or drmOpenByName()
 * otherwise.
 */
drm_public int drmOpenWithType(const char *name, const char *busid, int type)
{
    if (name != NULL && drm_server_info &&
        drm_server_info->load_module && !drmAvailable()) {
        /* try to load the kernel module */
        if (!drm_server_info->load_module(name)) {
            drmMsg("[drm] failed to load kernel module \"%s\"\n", name);
            return -1;
        }
    }

    if (busid) {
        int fd = drmOpenByBusid(busid, type);
        if (fd >= 0)
            return fd;
    }

    if (name)
        return drmOpenByName(name, type);

    return -1;
}

drm_public int drmOpenControl(int minor)
{
    return -EINVAL;
}

drm_public int drmOpenRender(int minor)
{
    return drmOpenMinor(minor, 0, DRM_NODE_RENDER);
}

/**
 * Free the version information returned by drmGetVersion().
 *
 * \param v pointer to the version information.
 *
 * \internal
 * It frees the memory pointed by \p %v as well as all the non-null strings
 * pointers in it.
 */
drm_public void drmFreeVersion(drmVersionPtr v)
{
    if (!v)
        return;
    drmFree(v->name);
    drmFree(v->date);
    drmFree(v->desc);
    drmFree(v);
}


/**
 * Free the non-public version information returned by the kernel.
 *
 * \param v pointer to the version information.
 *
 * \internal
 * Used by drmGetVersion() to free the memory pointed by \p %v as well as all
 * the non-null strings pointers in it.
 */
static void drmFreeKernelVersion(drm_version_t *v)
{
    if (!v)
        return;
    drmFree(v->name);
    drmFree(v->date);
    drmFree(v->desc);
    drmFree(v);
}


/**
 * Copy version information.
 *
 * \param d destination pointer.
 * \param s source pointer.
 *
 * \internal
 * Used by drmGetVersion() to translate the information returned by the ioctl
 * interface in a private structure into the public structure counterpart.
 */
static void drmCopyVersion(drmVersionPtr d, const drm_version_t *s)
{
    d->version_major      = s->version_major;
    d->version_minor      = s->version_minor;
    d->version_patchlevel = s->version_patchlevel;
    d->name_len           = s->name_len;
    d->name               = strdup(s->name);
    d->date_len           = s->date_len;
    d->date               = strdup(s->date);
    d->desc_len           = s->desc_len;
    d->desc               = strdup(s->desc);
}


/**
 * Query the driver version information.
 *
 * \param fd file descriptor.
 *
 * \return pointer to a drmVersion structure which should be freed with
 * drmFreeVersion().
 *
 * \note Similar information is available via /proc/dri.
 *
 * \internal
 * It gets the version information via successive DRM_IOCTL_VERSION ioctls,
 * first with zeros to get the string lengths, and then the actually strings.
 * It also null-terminates them since they might not be already.
 */
drm_public drmVersionPtr drmGetVersion(int fd)
{
    drmVersionPtr retval;
    drm_version_t *version = drmMalloc(sizeof(*version));

    if (drmIoctl(fd, DRM_IOCTL_VERSION, version)) {
        drmFreeKernelVersion(version);
        return NULL;
    }

    if (version->name_len)
        version->name    = drmMalloc(version->name_len + 1);
    if (version->date_len)
        version->date    = drmMalloc(version->date_len + 1);
    if (version->desc_len)
        version->desc    = drmMalloc(version->desc_len + 1);

    if (drmIoctl(fd, DRM_IOCTL_VERSION, version)) {
        drmMsg("DRM_IOCTL_VERSION: %s\n", strerror(errno));
        drmFreeKernelVersion(version);
        return NULL;
    }

    /* The results might not be null-terminated strings, so terminate them. */
    if (version->name_len) version->name[version->name_len] = '\0';
    if (version->date_len) version->date[version->date_len] = '\0';
    if (version->desc_len) version->desc[version->desc_len] = '\0';

    retval = drmMalloc(sizeof(*retval));
    drmCopyVersion(retval, version);
    drmFreeKernelVersion(version);
    return retval;
}


/**
 * Get version information for the DRM user space library.
 *
 * This version number is driver independent.
 *
 * \param fd file descriptor.
 *
 * \return version information.
 *
 * \internal
 * This function allocates and fills a drm_version structure with a hard coded
 * version number.
 */
drm_public drmVersionPtr drmGetLibVersion(int fd)
{
    drm_version_t *version = drmMalloc(sizeof(*version));

    /* Version history:
     *   NOTE THIS MUST NOT GO ABOVE VERSION 1.X due to drivers needing it
     *   revision 1.0.x = original DRM interface with no drmGetLibVersion
     *                    entry point and many drm<Device> extensions
     *   revision 1.1.x = added drmCommand entry points for device extensions
     *                    added drmGetLibVersion to identify libdrm.a version
     *   revision 1.2.x = added drmSetInterfaceVersion
     *                    modified drmOpen to handle both busid and name
     *   revision 1.3.x = added server + memory manager
     */
    version->version_major      = 1;
    version->version_minor      = 3;
    version->version_patchlevel = 0;

    return (drmVersionPtr)version;
}

drm_public int drmGetCap(int fd, uint64_t capability, uint64_t *value)
{
    struct drm_get_cap cap;
    int ret;

    memclear(cap);
    cap.capability = capability;

    ret = drmIoctl(fd, DRM_IOCTL_GET_CAP, &cap);
    if (ret)
        return ret;

    *value = cap.value;
    return 0;
}

drm_public int drmSetClientCap(int fd, uint64_t capability, uint64_t value)
{
    struct drm_set_client_cap cap;

    memclear(cap);
    cap.capability = capability;
    cap.value = value;

    return drmIoctl(fd, DRM_IOCTL_SET_CLIENT_CAP, &cap);
}

/**
 * Free the bus ID information.
 *
 * \param busid bus ID information string as given by drmGetBusid().
 *
 * \internal
 * This function is just frees the memory pointed by \p busid.
 */
drm_public void drmFreeBusid(const char *busid)
{
    drmFree((void *)busid);
}


/**
 * Get the bus ID of the device.
 *
 * \param fd file descriptor.
 *
 * \return bus ID string.
 *
 * \internal
 * This function gets the bus ID via successive DRM_IOCTL_GET_UNIQUE ioctls to
 * get the string length and data, passing the arguments in a drm_unique
 * structure.
 */
drm_public char *drmGetBusid(int fd)
{
    drm_unique_t u;

    memclear(u);

    if (drmIoctl(fd, DRM_IOCTL_GET_UNIQUE, &u))
        return NULL;
    u.unique = drmMalloc(u.unique_len + 1);
    if (drmIoctl(fd, DRM_IOCTL_GET_UNIQUE, &u)) {
        drmFree(u.unique);
        return NULL;
    }
    u.unique[u.unique_len] = '\0';

    return u.unique;
}


/**
 * Set the bus ID of the device.
 *
 * \param fd file descriptor.
 * \param busid bus ID string.
 *
 * \return zero on success, negative on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_SET_UNIQUE ioctl, passing
 * the arguments in a drm_unique structure.
 */
drm_public int drmSetBusid(int fd, const char *busid)
{
    drm_unique_t u;

    memclear(u);
    u.unique     = (char *)busid;
    u.unique_len = strlen(busid);

    if (drmIoctl(fd, DRM_IOCTL_SET_UNIQUE, &u)) {
        return -errno;
    }
    return 0;
}

drm_public int drmGetMagic(int fd, drm_magic_t * magic)
{
    drm_auth_t auth;

    memclear(auth);

    *magic = 0;
    if (drmIoctl(fd, DRM_IOCTL_GET_MAGIC, &auth))
        return -errno;
    *magic = auth.magic;
    return 0;
}

drm_public int drmAuthMagic(int fd, drm_magic_t magic)
{
    drm_auth_t auth;

    memclear(auth);
    auth.magic = magic;
    if (drmIoctl(fd, DRM_IOCTL_AUTH_MAGIC, &auth))
        return -errno;
    return 0;
}

/**
 * Specifies a range of memory that is available for mapping by a
 * non-root process.
 *
 * \param fd file descriptor.
 * \param offset usually the physical address. The actual meaning depends of
 * the \p type parameter. See below.
 * \param size of the memory in bytes.
 * \param type type of the memory to be mapped.
 * \param flags combination of several flags to modify the function actions.
 * \param handle will be set to a value that may be used as the offset
 * parameter for mmap().
 *
 * \return zero on success or a negative value on error.
 *
 * \par Mapping the frame buffer
 * For the frame buffer
 * - \p offset will be the physical address of the start of the frame buffer,
 * - \p size will be the size of the frame buffer in bytes, and
 * - \p type will be DRM_FRAME_BUFFER.
 *
 * \par
 * The area mapped will be uncached. If MTRR support is available in the
 * kernel, the frame buffer area will be set to write combining.
 *
 * \par Mapping the MMIO register area
 * For the MMIO register area,
 * - \p offset will be the physical address of the start of the register area,
 * - \p size will be the size of the register area bytes, and
 * - \p type will be DRM_REGISTERS.
 * \par
 * The area mapped will be uncached.
 *
 * \par Mapping the SAREA
 * For the SAREA,
 * - \p offset will be ignored and should be set to zero,
 * - \p size will be the desired size of the SAREA in bytes,
 * - \p type will be DRM_SHM.
 *
 * \par
 * A shared memory area of the requested size will be created and locked in
 * kernel memory. This area may be mapped into client-space by using the handle
 * returned.
 *
 * \note May only be called by root.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_ADD_MAP ioctl, passing
 * the arguments in a drm_map structure.
 */
drm_public int drmAddMap(int fd, drm_handle_t offset, drmSize size, drmMapType type,
                         drmMapFlags flags, drm_handle_t *handle)
{
    drm_map_t map;

    memclear(map);
    map.offset  = offset;
    map.size    = size;
    map.type    = (enum drm_map_type)type;
    map.flags   = (enum drm_map_flags)flags;
    if (drmIoctl(fd, DRM_IOCTL_ADD_MAP, &map))
        return -errno;
    if (handle)
        *handle = (drm_handle_t)(uintptr_t)map.handle;
    return 0;
}

drm_public int drmRmMap(int fd, drm_handle_t handle)
{
    drm_map_t map;

    memclear(map);
    map.handle = (void *)(uintptr_t)handle;

    if(drmIoctl(fd, DRM_IOCTL_RM_MAP, &map))
        return -errno;
    return 0;
}

/**
 * Make buffers available for DMA transfers.
 *
 * \param fd file descriptor.
 * \param count number of buffers.
 * \param size size of each buffer.
 * \param flags buffer allocation flags.
 * \param agp_offset offset in the AGP aperture
 *
 * \return number of buffers allocated, negative on error.
 *
 * \internal
 * This function is a wrapper around DRM_IOCTL_ADD_BUFS ioctl.
 *
 * \sa drm_buf_desc.
 */
drm_public int drmAddBufs(int fd, int count, int size, drmBufDescFlags flags,
                          int agp_offset)
{
    drm_buf_desc_t request;

    memclear(request);
    request.count     = count;
    request.size      = size;
    request.flags     = (int)flags;
    request.agp_start = agp_offset;

    if (drmIoctl(fd, DRM_IOCTL_ADD_BUFS, &request))
        return -errno;
    return request.count;
}

drm_public int drmMarkBufs(int fd, double low, double high)
{
    drm_buf_info_t info;
    int            i;

    memclear(info);

    if (drmIoctl(fd, DRM_IOCTL_INFO_BUFS, &info))
        return -EINVAL;

    if (!info.count)
        return -EINVAL;

    if (!(info.list = drmMalloc(info.count * sizeof(*info.list))))
        return -ENOMEM;

    if (drmIoctl(fd, DRM_IOCTL_INFO_BUFS, &info)) {
        int retval = -errno;
        drmFree(info.list);
        return retval;
    }

    for (i = 0; i < info.count; i++) {
        info.list[i].low_mark  = low  * info.list[i].count;
        info.list[i].high_mark = high * info.list[i].count;
        if (drmIoctl(fd, DRM_IOCTL_MARK_BUFS, &info.list[i])) {
            int retval = -errno;
            drmFree(info.list);
            return retval;
        }
    }
    drmFree(info.list);

    return 0;
}

/**
 * Free buffers.
 *
 * \param fd file descriptor.
 * \param count number of buffers to free.
 * \param list list of buffers to be freed.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \note This function is primarily used for debugging.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_FREE_BUFS ioctl, passing
 * the arguments in a drm_buf_free structure.
 */
drm_public int drmFreeBufs(int fd, int count, int *list)
{
    drm_buf_free_t request;

    memclear(request);
    request.count = count;
    request.list  = list;
    if (drmIoctl(fd, DRM_IOCTL_FREE_BUFS, &request))
        return -errno;
    return 0;
}


/**
 * Close the device.
 *
 * \param fd file descriptor.
 *
 * \internal
 * This function closes the file descriptor.
 */
drm_public int drmClose(int fd)
{
    unsigned long key    = drmGetKeyFromFd(fd);
    drmHashEntry  *entry = drmGetEntry(fd);

    drmHashDestroy(entry->tagTable);
    entry->fd       = 0;
    entry->f        = NULL;
    entry->tagTable = NULL;

    drmHashDelete(drmHashTable, key);
    drmFree(entry);

    return close(fd);
}


/**
 * Map a region of memory.
 *
 * \param fd file descriptor.
 * \param handle handle returned by drmAddMap().
 * \param size size in bytes. Must match the size used by drmAddMap().
 * \param address will contain the user-space virtual address where the mapping
 * begins.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper for mmap().
 */
drm_public int drmMap(int fd, drm_handle_t handle, drmSize size,
                      drmAddressPtr address)
{
    static unsigned long pagesize_mask = 0;

    if (fd < 0)
        return -EINVAL;

    if (!pagesize_mask)
        pagesize_mask = getpagesize() - 1;

    size = (size + pagesize_mask) & ~pagesize_mask;

    *address = drm_mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, handle);
    if (*address == MAP_FAILED)
        return -errno;
    return 0;
}


/**
 * Unmap mappings obtained with drmMap().
 *
 * \param address address as given by drmMap().
 * \param size size in bytes. Must match the size used by drmMap().
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper for munmap().
 */
drm_public int drmUnmap(drmAddress address, drmSize size)
{
    return drm_munmap(address, size);
}

drm_public drmBufInfoPtr drmGetBufInfo(int fd)
{
    drm_buf_info_t info;
    drmBufInfoPtr  retval;
    int            i;

    memclear(info);

    if (drmIoctl(fd, DRM_IOCTL_INFO_BUFS, &info))
        return NULL;

    if (info.count) {
        if (!(info.list = drmMalloc(info.count * sizeof(*info.list))))
            return NULL;

        if (drmIoctl(fd, DRM_IOCTL_INFO_BUFS, &info)) {
            drmFree(info.list);
            return NULL;
        }

        retval = drmMalloc(sizeof(*retval));
        retval->count = info.count;
        if (!(retval->list = drmMalloc(info.count * sizeof(*retval->list)))) {
                drmFree(retval);
                drmFree(info.list);
                return NULL;
        }

        for (i = 0; i < info.count; i++) {
            retval->list[i].count     = info.list[i].count;
            retval->list[i].size      = info.list[i].size;
            retval->list[i].low_mark  = info.list[i].low_mark;
            retval->list[i].high_mark = info.list[i].high_mark;
        }
        drmFree(info.list);
        return retval;
    }
    return NULL;
}

/**
 * Map all DMA buffers into client-virtual space.
 *
 * \param fd file descriptor.
 *
 * \return a pointer to a ::drmBufMap structure.
 *
 * \note The client may not use these buffers until obtaining buffer indices
 * with drmDMA().
 *
 * \internal
 * This function calls the DRM_IOCTL_MAP_BUFS ioctl and copies the returned
 * information about the buffers in a drm_buf_map structure into the
 * client-visible data structures.
 */
drm_public drmBufMapPtr drmMapBufs(int fd)
{
    drm_buf_map_t bufs;
    drmBufMapPtr  retval;
    int           i;

    memclear(bufs);
    if (drmIoctl(fd, DRM_IOCTL_MAP_BUFS, &bufs))
        return NULL;

    if (!bufs.count)
        return NULL;

    if (!(bufs.list = drmMalloc(bufs.count * sizeof(*bufs.list))))
        return NULL;

    if (drmIoctl(fd, DRM_IOCTL_MAP_BUFS, &bufs)) {
        drmFree(bufs.list);
        return NULL;
    }

    retval = drmMalloc(sizeof(*retval));
    retval->count = bufs.count;
    retval->list  = drmMalloc(bufs.count * sizeof(*retval->list));
    for (i = 0; i < bufs.count; i++) {
        retval->list[i].idx     = bufs.list[i].idx;
        retval->list[i].total   = bufs.list[i].total;
        retval->list[i].used    = 0;
        retval->list[i].address = bufs.list[i].address;
    }

    drmFree(bufs.list);
    return retval;
}


/**
 * Unmap buffers allocated with drmMapBufs().
 *
 * \return zero on success, or negative value on failure.
 *
 * \internal
 * Calls munmap() for every buffer stored in \p bufs and frees the
 * memory allocated by drmMapBufs().
 */
drm_public int drmUnmapBufs(drmBufMapPtr bufs)
{
    int i;

    for (i = 0; i < bufs->count; i++) {
        drm_munmap(bufs->list[i].address, bufs->list[i].total);
    }

    drmFree(bufs->list);
    drmFree(bufs);
    return 0;
}


#define DRM_DMA_RETRY  16

/**
 * Reserve DMA buffers.
 *
 * \param fd file descriptor.
 * \param request
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * Assemble the arguments into a drm_dma structure and keeps issuing the
 * DRM_IOCTL_DMA ioctl until success or until maximum number of retries.
 */
drm_public int drmDMA(int fd, drmDMAReqPtr request)
{
    drm_dma_t dma;
    int ret, i = 0;

    dma.context         = request->context;
    dma.send_count      = request->send_count;
    dma.send_indices    = request->send_list;
    dma.send_sizes      = request->send_sizes;
    dma.flags           = (enum drm_dma_flags)request->flags;
    dma.request_count   = request->request_count;
    dma.request_size    = request->request_size;
    dma.request_indices = request->request_list;
    dma.request_sizes   = request->request_sizes;
    dma.granted_count   = 0;

    do {
        ret = ioctl( fd, DRM_IOCTL_DMA, &dma );
    } while ( ret && errno == EAGAIN && i++ < DRM_DMA_RETRY );

    if ( ret == 0 ) {
        request->granted_count = dma.granted_count;
        return 0;
    } else {
        return -errno;
    }
}


/**
 * Obtain heavyweight hardware lock.
 *
 * \param fd file descriptor.
 * \param context context.
 * \param flags flags that determine the state of the hardware when the function
 * returns.
 *
 * \return always zero.
 *
 * \internal
 * This function translates the arguments into a drm_lock structure and issue
 * the DRM_IOCTL_LOCK ioctl until the lock is successfully acquired.
 */
drm_public int drmGetLock(int fd, drm_context_t context, drmLockFlags flags)
{
    drm_lock_t lock;

    memclear(lock);
    lock.context = context;
    lock.flags   = 0;
    if (flags & DRM_LOCK_READY)      lock.flags |= _DRM_LOCK_READY;
    if (flags & DRM_LOCK_QUIESCENT)  lock.flags |= _DRM_LOCK_QUIESCENT;
    if (flags & DRM_LOCK_FLUSH)      lock.flags |= _DRM_LOCK_FLUSH;
    if (flags & DRM_LOCK_FLUSH_ALL)  lock.flags |= _DRM_LOCK_FLUSH_ALL;
    if (flags & DRM_HALT_ALL_QUEUES) lock.flags |= _DRM_HALT_ALL_QUEUES;
    if (flags & DRM_HALT_CUR_QUEUES) lock.flags |= _DRM_HALT_CUR_QUEUES;

    while (drmIoctl(fd, DRM_IOCTL_LOCK, &lock))
        ;
    return 0;
}

/**
 * Release the hardware lock.
 *
 * \param fd file descriptor.
 * \param context context.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_UNLOCK ioctl, passing the
 * argument in a drm_lock structure.
 */
drm_public int drmUnlock(int fd, drm_context_t context)
{
    drm_lock_t lock;

    memclear(lock);
    lock.context = context;
    return drmIoctl(fd, DRM_IOCTL_UNLOCK, &lock);
}

drm_public drm_context_t *drmGetReservedContextList(int fd, int *count)
{
    drm_ctx_res_t res;
    drm_ctx_t     *list;
    drm_context_t * retval;
    int           i;

    memclear(res);
    if (drmIoctl(fd, DRM_IOCTL_RES_CTX, &res))
        return NULL;

    if (!res.count)
        return NULL;

    if (!(list   = drmMalloc(res.count * sizeof(*list))))
        return NULL;
    if (!(retval = drmMalloc(res.count * sizeof(*retval))))
        goto err_free_list;

    res.contexts = list;
    if (drmIoctl(fd, DRM_IOCTL_RES_CTX, &res))
        goto err_free_context;

    for (i = 0; i < res.count; i++)
        retval[i] = list[i].handle;
    drmFree(list);

    *count = res.count;
    return retval;

err_free_list:
    drmFree(list);
err_free_context:
    drmFree(retval);
    return NULL;
}

drm_public void drmFreeReservedContextList(drm_context_t *pt)
{
    drmFree(pt);
}

/**
 * Create context.
 *
 * Used by the X server during GLXContext initialization. This causes
 * per-context kernel-level resources to be allocated.
 *
 * \param fd file descriptor.
 * \param handle is set on success. To be used by the client when requesting DMA
 * dispatch with drmDMA().
 *
 * \return zero on success, or a negative value on failure.
 *
 * \note May only be called by root.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_ADD_CTX ioctl, passing the
 * argument in a drm_ctx structure.
 */
drm_public int drmCreateContext(int fd, drm_context_t *handle)
{
    drm_ctx_t ctx;

    memclear(ctx);
    if (drmIoctl(fd, DRM_IOCTL_ADD_CTX, &ctx))
        return -errno;
    *handle = ctx.handle;
    return 0;
}

drm_public int drmSwitchToContext(int fd, drm_context_t context)
{
    drm_ctx_t ctx;

    memclear(ctx);
    ctx.handle = context;
    if (drmIoctl(fd, DRM_IOCTL_SWITCH_CTX, &ctx))
        return -errno;
    return 0;
}

drm_public int drmSetContextFlags(int fd, drm_context_t context,
                                  drm_context_tFlags flags)
{
    drm_ctx_t ctx;

    /*
     * Context preserving means that no context switches are done between DMA
     * buffers from one context and the next.  This is suitable for use in the
     * X server (which promises to maintain hardware context), or in the
     * client-side library when buffers are swapped on behalf of two threads.
     */
    memclear(ctx);
    ctx.handle = context;
    if (flags & DRM_CONTEXT_PRESERVED)
        ctx.flags |= _DRM_CONTEXT_PRESERVED;
    if (flags & DRM_CONTEXT_2DONLY)
        ctx.flags |= _DRM_CONTEXT_2DONLY;
    if (drmIoctl(fd, DRM_IOCTL_MOD_CTX, &ctx))
        return -errno;
    return 0;
}

drm_public int drmGetContextFlags(int fd, drm_context_t context,
                                  drm_context_tFlagsPtr flags)
{
    drm_ctx_t ctx;

    memclear(ctx);
    ctx.handle = context;
    if (drmIoctl(fd, DRM_IOCTL_GET_CTX, &ctx))
        return -errno;
    *flags = 0;
    if (ctx.flags & _DRM_CONTEXT_PRESERVED)
        *flags |= DRM_CONTEXT_PRESERVED;
    if (ctx.flags & _DRM_CONTEXT_2DONLY)
        *flags |= DRM_CONTEXT_2DONLY;
    return 0;
}

/**
 * Destroy context.
 *
 * Free any kernel-level resources allocated with drmCreateContext() associated
 * with the context.
 *
 * \param fd file descriptor.
 * \param handle handle given by drmCreateContext().
 *
 * \return zero on success, or a negative value on failure.
 *
 * \note May only be called by root.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_RM_CTX ioctl, passing the
 * argument in a drm_ctx structure.
 */
drm_public int drmDestroyContext(int fd, drm_context_t handle)
{
    drm_ctx_t ctx;

    memclear(ctx);
    ctx.handle = handle;
    if (drmIoctl(fd, DRM_IOCTL_RM_CTX, &ctx))
        return -errno;
    return 0;
}

drm_public int drmCreateDrawable(int fd, drm_drawable_t *handle)
{
    drm_draw_t draw;

    memclear(draw);
    if (drmIoctl(fd, DRM_IOCTL_ADD_DRAW, &draw))
        return -errno;
    *handle = draw.handle;
    return 0;
}

drm_public int drmDestroyDrawable(int fd, drm_drawable_t handle)
{
    drm_draw_t draw;

    memclear(draw);
    draw.handle = handle;
    if (drmIoctl(fd, DRM_IOCTL_RM_DRAW, &draw))
        return -errno;
    return 0;
}

drm_public int drmUpdateDrawableInfo(int fd, drm_drawable_t handle,
                                     drm_drawable_info_type_t type,
                                     unsigned int num, void *data)
{
    drm_update_draw_t update;

    memclear(update);
    update.handle = handle;
    update.type = type;
    update.num = num;
    update.data = (unsigned long long)(unsigned long)data;

    if (drmIoctl(fd, DRM_IOCTL_UPDATE_DRAW, &update))
        return -errno;

    return 0;
}

drm_public int drmCrtcGetSequence(int fd, uint32_t crtcId, uint64_t *sequence,
                                  uint64_t *ns)
{
    struct drm_crtc_get_sequence get_seq;
    int ret;

    memclear(get_seq);
    get_seq.crtc_id = crtcId;
    ret = drmIoctl(fd, DRM_IOCTL_CRTC_GET_SEQUENCE, &get_seq);
    if (ret)
        return ret;

    if (sequence)
        *sequence = get_seq.sequence;
    if (ns)
        *ns = get_seq.sequence_ns;
    return 0;
}

drm_public int drmCrtcQueueSequence(int fd, uint32_t crtcId, uint32_t flags,
                                    uint64_t sequence,
                                    uint64_t *sequence_queued,
                                    uint64_t user_data)
{
    struct drm_crtc_queue_sequence queue_seq;
    int ret;

    memclear(queue_seq);
    queue_seq.crtc_id = crtcId;
    queue_seq.flags = flags;
    queue_seq.sequence = sequence;
    queue_seq.user_data = user_data;

    ret = drmIoctl(fd, DRM_IOCTL_CRTC_QUEUE_SEQUENCE, &queue_seq);
    if (ret == 0 && sequence_queued)
        *sequence_queued = queue_seq.sequence;

    return ret;
}

/**
 * Acquire the AGP device.
 *
 * Must be called before any of the other AGP related calls.
 *
 * \param fd file descriptor.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_ACQUIRE ioctl.
 */
drm_public int drmAgpAcquire(int fd)
{
    if (drmIoctl(fd, DRM_IOCTL_AGP_ACQUIRE, NULL))
        return -errno;
    return 0;
}


/**
 * Release the AGP device.
 *
 * \param fd file descriptor.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_RELEASE ioctl.
 */
drm_public int drmAgpRelease(int fd)
{
    if (drmIoctl(fd, DRM_IOCTL_AGP_RELEASE, NULL))
        return -errno;
    return 0;
}


/**
 * Set the AGP mode.
 *
 * \param fd file descriptor.
 * \param mode AGP mode.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_ENABLE ioctl, passing the
 * argument in a drm_agp_mode structure.
 */
drm_public int drmAgpEnable(int fd, unsigned long mode)
{
    drm_agp_mode_t m;

    memclear(m);
    m.mode = mode;
    if (drmIoctl(fd, DRM_IOCTL_AGP_ENABLE, &m))
        return -errno;
    return 0;
}


/**
 * Allocate a chunk of AGP memory.
 *
 * \param fd file descriptor.
 * \param size requested memory size in bytes. Will be rounded to page boundary.
 * \param type type of memory to allocate.
 * \param address if not zero, will be set to the physical address of the
 * allocated memory.
 * \param handle on success will be set to a handle of the allocated memory.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_ALLOC ioctl, passing the
 * arguments in a drm_agp_buffer structure.
 */
drm_public int drmAgpAlloc(int fd, unsigned long size, unsigned long type,
                           unsigned long *address, drm_handle_t *handle)
{
    drm_agp_buffer_t b;

    memclear(b);
    *handle = DRM_AGP_NO_HANDLE;
    b.size   = size;
    b.type   = type;
    if (drmIoctl(fd, DRM_IOCTL_AGP_ALLOC, &b))
        return -errno;
    if (address != 0UL)
        *address = b.physical;
    *handle = b.handle;
    return 0;
}


/**
 * Free a chunk of AGP memory.
 *
 * \param fd file descriptor.
 * \param handle handle to the allocated memory, as given by drmAgpAllocate().
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_FREE ioctl, passing the
 * argument in a drm_agp_buffer structure.
 */
drm_public int drmAgpFree(int fd, drm_handle_t handle)
{
    drm_agp_buffer_t b;

    memclear(b);
    b.handle = handle;
    if (drmIoctl(fd, DRM_IOCTL_AGP_FREE, &b))
        return -errno;
    return 0;
}


/**
 * Bind a chunk of AGP memory.
 *
 * \param fd file descriptor.
 * \param handle handle to the allocated memory, as given by drmAgpAllocate().
 * \param offset offset in bytes. It will round to page boundary.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_BIND ioctl, passing the
 * argument in a drm_agp_binding structure.
 */
drm_public int drmAgpBind(int fd, drm_handle_t handle, unsigned long offset)
{
    drm_agp_binding_t b;

    memclear(b);
    b.handle = handle;
    b.offset = offset;
    if (drmIoctl(fd, DRM_IOCTL_AGP_BIND, &b))
        return -errno;
    return 0;
}


/**
 * Unbind a chunk of AGP memory.
 *
 * \param fd file descriptor.
 * \param handle handle to the allocated memory, as given by drmAgpAllocate().
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_UNBIND ioctl, passing
 * the argument in a drm_agp_binding structure.
 */
drm_public int drmAgpUnbind(int fd, drm_handle_t handle)
{
    drm_agp_binding_t b;

    memclear(b);
    b.handle = handle;
    if (drmIoctl(fd, DRM_IOCTL_AGP_UNBIND, &b))
        return -errno;
    return 0;
}


/**
 * Get AGP driver major version number.
 *
 * \param fd file descriptor.
 *
 * \return major version number on success, or a negative value on failure..
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public int drmAgpVersionMajor(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return -errno;
    return i.agp_version_major;
}


/**
 * Get AGP driver minor version number.
 *
 * \param fd file descriptor.
 *
 * \return minor version number on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public int drmAgpVersionMinor(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return -errno;
    return i.agp_version_minor;
}


/**
 * Get AGP mode.
 *
 * \param fd file descriptor.
 *
 * \return mode on success, or zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned long drmAgpGetMode(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.mode;
}


/**
 * Get AGP aperture base.
 *
 * \param fd file descriptor.
 *
 * \return aperture base on success, zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned long drmAgpBase(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.aperture_base;
}


/**
 * Get AGP aperture size.
 *
 * \param fd file descriptor.
 *
 * \return aperture size on success, zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned long drmAgpSize(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.aperture_size;
}


/**
 * Get used AGP memory.
 *
 * \param fd file descriptor.
 *
 * \return memory used on success, or zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned long drmAgpMemoryUsed(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.memory_used;
}


/**
 * Get available AGP memory.
 *
 * \param fd file descriptor.
 *
 * \return memory available on success, or zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned long drmAgpMemoryAvail(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.memory_allowed;
}


/**
 * Get hardware vendor ID.
 *
 * \param fd file descriptor.
 *
 * \return vendor ID on success, or zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned int drmAgpVendorId(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.id_vendor;
}


/**
 * Get hardware device ID.
 *
 * \param fd file descriptor.
 *
 * \return zero on success, or zero on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_AGP_INFO ioctl, getting the
 * necessary information in a drm_agp_info structure.
 */
drm_public unsigned int drmAgpDeviceId(int fd)
{
    drm_agp_info_t i;

    memclear(i);

    if (drmIoctl(fd, DRM_IOCTL_AGP_INFO, &i))
        return 0;
    return i.id_device;
}

drm_public int drmScatterGatherAlloc(int fd, unsigned long size,
                                     drm_handle_t *handle)
{
    drm_scatter_gather_t sg;

    memclear(sg);

    *handle = 0;
    sg.size   = size;
    if (drmIoctl(fd, DRM_IOCTL_SG_ALLOC, &sg))
        return -errno;
    *handle = sg.handle;
    return 0;
}

drm_public int drmScatterGatherFree(int fd, drm_handle_t handle)
{
    drm_scatter_gather_t sg;

    memclear(sg);
    sg.handle = handle;
    if (drmIoctl(fd, DRM_IOCTL_SG_FREE, &sg))
        return -errno;
    return 0;
}

/**
 * Wait for VBLANK.
 *
 * \param fd file descriptor.
 * \param vbl pointer to a drmVBlank structure.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_WAIT_VBLANK ioctl.
 */
drm_public int drmWaitVBlank(int fd, drmVBlankPtr vbl)
{
    struct timespec timeout, cur;
    int ret;

    ret = clock_gettime(CLOCK_MONOTONIC, &timeout);
    if (ret < 0) {
        fprintf(stderr, "clock_gettime failed: %s\n", strerror(errno));
        goto out;
    }
    timeout.tv_sec++;

    do {
       ret = ioctl(fd, DRM_IOCTL_WAIT_VBLANK, vbl);
       vbl->request.type &= ~DRM_VBLANK_RELATIVE;
       if (ret && errno == EINTR) {
           clock_gettime(CLOCK_MONOTONIC, &cur);
           /* Timeout after 1s */
           if (cur.tv_sec > timeout.tv_sec + 1 ||
               (cur.tv_sec == timeout.tv_sec && cur.tv_nsec >=
                timeout.tv_nsec)) {
                   errno = EBUSY;
                   ret = -1;
                   break;
           }
       }
    } while (ret && errno == EINTR);

out:
    return ret;
}

drm_public int drmError(int err, const char *label)
{
    switch (err) {
    case DRM_ERR_NO_DEVICE:
        fprintf(stderr, "%s: no device\n", label);
        break;
    case DRM_ERR_NO_ACCESS:
        fprintf(stderr, "%s: no access\n", label);
        break;
    case DRM_ERR_NOT_ROOT:
        fprintf(stderr, "%s: not root\n", label);
        break;
    case DRM_ERR_INVALID:
        fprintf(stderr, "%s: invalid args\n", label);
        break;
    default:
        if (err < 0)
            err = -err;
        fprintf( stderr, "%s: error %d (%s)\n", label, err, strerror(err) );
        break;
    }

    return 1;
}

/**
 * Install IRQ handler.
 *
 * \param fd file descriptor.
 * \param irq IRQ number.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_CONTROL ioctl, passing the
 * argument in a drm_control structure.
 */
drm_public int drmCtlInstHandler(int fd, int irq)
{
    drm_control_t ctl;

    memclear(ctl);
    ctl.func  = DRM_INST_HANDLER;
    ctl.irq   = irq;
    if (drmIoctl(fd, DRM_IOCTL_CONTROL, &ctl))
        return -errno;
    return 0;
}


/**
 * Uninstall IRQ handler.
 *
 * \param fd file descriptor.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_CONTROL ioctl, passing the
 * argument in a drm_control structure.
 */
drm_public int drmCtlUninstHandler(int fd)
{
    drm_control_t ctl;

    memclear(ctl);
    ctl.func  = DRM_UNINST_HANDLER;
    ctl.irq   = 0;
    if (drmIoctl(fd, DRM_IOCTL_CONTROL, &ctl))
        return -errno;
    return 0;
}

drm_public int drmFinish(int fd, int context, drmLockFlags flags)
{
    drm_lock_t lock;

    memclear(lock);
    lock.context = context;
    if (flags & DRM_LOCK_READY)      lock.flags |= _DRM_LOCK_READY;
    if (flags & DRM_LOCK_QUIESCENT)  lock.flags |= _DRM_LOCK_QUIESCENT;
    if (flags & DRM_LOCK_FLUSH)      lock.flags |= _DRM_LOCK_FLUSH;
    if (flags & DRM_LOCK_FLUSH_ALL)  lock.flags |= _DRM_LOCK_FLUSH_ALL;
    if (flags & DRM_HALT_ALL_QUEUES) lock.flags |= _DRM_HALT_ALL_QUEUES;
    if (flags & DRM_HALT_CUR_QUEUES) lock.flags |= _DRM_HALT_CUR_QUEUES;
    if (drmIoctl(fd, DRM_IOCTL_FINISH, &lock))
        return -errno;
    return 0;
}

/**
 * Get IRQ from bus ID.
 *
 * \param fd file descriptor.
 * \param busnum bus number.
 * \param devnum device number.
 * \param funcnum function number.
 *
 * \return IRQ number on success, or a negative value on failure.
 *
 * \internal
 * This function is a wrapper around the DRM_IOCTL_IRQ_BUSID ioctl, passing the
 * arguments in a drm_irq_busid structure.
 */
drm_public int drmGetInterruptFromBusID(int fd, int busnum, int devnum,
                                        int funcnum)
{
    drm_irq_busid_t p;

    memclear(p);
    p.busnum  = busnum;
    p.devnum  = devnum;
    p.funcnum = funcnum;
    if (drmIoctl(fd, DRM_IOCTL_IRQ_BUSID, &p))
        return -errno;
    return p.irq;
}

drm_public int drmAddContextTag(int fd, drm_context_t context, void *tag)
{
    drmHashEntry  *entry = drmGetEntry(fd);

    if (drmHashInsert(entry->tagTable, context, tag)) {
        drmHashDelete(entry->tagTable, context);
        drmHashInsert(entry->tagTable, context, tag);
    }
    return 0;
}

drm_public int drmDelContextTag(int fd, drm_context_t context)
{
    drmHashEntry  *entry = drmGetEntry(fd);

    return drmHashDelete(entry->tagTable, context);
}

drm_public void *drmGetContextTag(int fd, drm_context_t context)
{
    drmHashEntry  *entry = drmGetEntry(fd);
    void          *value;

    if (drmHashLookup(entry->tagTable, context, &value))
        return NULL;

    return value;
}

drm_public int drmAddContextPrivateMapping(int fd, drm_context_t ctx_id,
                                           drm_handle_t handle)
{
    drm_ctx_priv_map_t map;

    memclear(map);
    map.ctx_id = ctx_id;
    map.handle = (void *)(uintptr_t)handle;

    if (drmIoctl(fd, DRM_IOCTL_SET_SAREA_CTX, &map))
        return -errno;
    return 0;
}

drm_public int drmGetContextPrivateMapping(int fd, drm_context_t ctx_id,
                                           drm_handle_t *handle)
{
    drm_ctx_priv_map_t map;

    memclear(map);
    map.ctx_id = ctx_id;

    if (drmIoctl(fd, DRM_IOCTL_GET_SAREA_CTX, &map))
        return -errno;
    if (handle)
        *handle = (drm_handle_t)(uintptr_t)map.handle;

    return 0;
}

drm_public int drmGetMap(int fd, int idx, drm_handle_t *offset, drmSize *size,
                         drmMapType *type, drmMapFlags *flags,
                         drm_handle_t *handle, int *mtrr)
{
    drm_map_t map;

    memclear(map);
    map.offset = idx;
    if (drmIoctl(fd, DRM_IOCTL_GET_MAP, &map))
        return -errno;
    *offset = map.offset;
    *size   = map.size;
    *type   = (drmMapType)map.type;
    *flags  = (drmMapFlags)map.flags;
    *handle = (unsigned long)map.handle;
    *mtrr   = map.mtrr;
    return 0;
}

drm_public int drmGetClient(int fd, int idx, int *auth, int *pid, int *uid,
                            unsigned long *magic, unsigned long *iocs)
{
    drm_client_t client;

    memclear(client);
    client.idx = idx;
    if (drmIoctl(fd, DRM_IOCTL_GET_CLIENT, &client))
        return -errno;
    *auth      = client.auth;
    *pid       = client.pid;
    *uid       = client.uid;
    *magic     = client.magic;
    *iocs      = client.iocs;
    return 0;
}

drm_public int drmGetStats(int fd, drmStatsT *stats)
{
    drm_stats_t s;
    unsigned    i;

    memclear(s);
    if (drmIoctl(fd, DRM_IOCTL_GET_STATS, &s))
        return -errno;

    stats->count = 0;
    memset(stats, 0, sizeof(*stats));
    if (s.count > sizeof(stats->data)/sizeof(stats->data[0]))
        return -1;

#define SET_VALUE                              \
    stats->data[i].long_format = "%-20.20s";   \
    stats->data[i].rate_format = "%8.8s";      \
    stats->data[i].isvalue     = 1;            \
    stats->data[i].verbose     = 0

#define SET_COUNT                              \
    stats->data[i].long_format = "%-20.20s";   \
    stats->data[i].rate_format = "%5.5s";      \
    stats->data[i].isvalue     = 0;            \
    stats->data[i].mult_names  = "kgm";        \
    stats->data[i].mult        = 1000;         \
    stats->data[i].verbose     = 0

#define SET_BYTE                               \
    stats->data[i].long_format = "%-20.20s";   \
    stats->data[i].rate_format = "%5.5s";      \
    stats->data[i].isvalue     = 0;            \
    stats->data[i].mult_names  = "KGM";        \
    stats->data[i].mult        = 1024;         \
    stats->data[i].verbose     = 0


    stats->count = s.count;
    for (i = 0; i < s.count; i++) {
        stats->data[i].value = s.data[i].value;
        switch (s.data[i].type) {
        case _DRM_STAT_LOCK:
            stats->data[i].long_name = "Lock";
            stats->data[i].rate_name = "Lock";
            SET_VALUE;
            break;
        case _DRM_STAT_OPENS:
            stats->data[i].long_name = "Opens";
            stats->data[i].rate_name = "O";
            SET_COUNT;
            stats->data[i].verbose   = 1;
            break;
        case _DRM_STAT_CLOSES:
            stats->data[i].long_name = "Closes";
            stats->data[i].rate_name = "Lock";
            SET_COUNT;
            stats->data[i].verbose   = 1;
            break;
        case _DRM_STAT_IOCTLS:
            stats->data[i].long_name = "Ioctls";
            stats->data[i].rate_name = "Ioc/s";
            SET_COUNT;
            break;
        case _DRM_STAT_LOCKS:
            stats->data[i].long_name = "Locks";
            stats->data[i].rate_name = "Lck/s";
            SET_COUNT;
            break;
        case _DRM_STAT_UNLOCKS:
            stats->data[i].long_name = "Unlocks";
            stats->data[i].rate_name = "Unl/s";
            SET_COUNT;
            break;
        case _DRM_STAT_IRQ:
            stats->data[i].long_name = "IRQs";
            stats->data[i].rate_name = "IRQ/s";
            SET_COUNT;
            break;
        case _DRM_STAT_PRIMARY:
            stats->data[i].long_name = "Primary Bytes";
            stats->data[i].rate_name = "PB/s";
            SET_BYTE;
            break;
        case _DRM_STAT_SECONDARY:
            stats->data[i].long_name = "Secondary Bytes";
            stats->data[i].rate_name = "SB/s";
            SET_BYTE;
            break;
        case _DRM_STAT_DMA:
            stats->data[i].long_name = "DMA";
            stats->data[i].rate_name = "DMA/s";
            SET_COUNT;
            break;
        case _DRM_STAT_SPECIAL:
            stats->data[i].long_name = "Special DMA";
            stats->data[i].rate_name = "dma/s";
            SET_COUNT;
            break;
        case _DRM_STAT_MISSED:
            stats->data[i].long_name = "Miss";
            stats->data[i].rate_name = "Ms/s";
            SET_COUNT;
            break;
        case _DRM_STAT_VALUE:
            stats->data[i].long_name = "Value";
            stats->data[i].rate_name = "Value";
            SET_VALUE;
            break;
        case _DRM_STAT_BYTE:
            stats->data[i].long_name = "Bytes";
            stats->data[i].rate_name = "B/s";
            SET_BYTE;
            break;
        case _DRM_STAT_COUNT:
        default:
            stats->data[i].long_name = "Count";
            stats->data[i].rate_name = "Cnt/s";
            SET_COUNT;
            break;
        }
    }
    return 0;
}

/**
 * Issue a set-version ioctl.
 *
 * \param fd file descriptor.
 * \param drmCommandIndex command index
 * \param data source pointer of the data to be read and written.
 * \param size size of the data to be read and written.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * It issues a read-write ioctl given by
 * \code DRM_COMMAND_BASE + drmCommandIndex \endcode.
 */
drm_public int drmSetInterfaceVersion(int fd, drmSetVersion *version)
{
    int retcode = 0;
    drm_set_version_t sv;

    memclear(sv);
    sv.drm_di_major = version->drm_di_major;
    sv.drm_di_minor = version->drm_di_minor;
    sv.drm_dd_major = version->drm_dd_major;
    sv.drm_dd_minor = version->drm_dd_minor;

    if (drmIoctl(fd, DRM_IOCTL_SET_VERSION, &sv)) {
        retcode = -errno;
    }

    version->drm_di_major = sv.drm_di_major;
    version->drm_di_minor = sv.drm_di_minor;
    version->drm_dd_major = sv.drm_dd_major;
    version->drm_dd_minor = sv.drm_dd_minor;

    return retcode;
}

/**
 * Send a device-specific command.
 *
 * \param fd file descriptor.
 * \param drmCommandIndex command index
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * It issues a ioctl given by
 * \code DRM_COMMAND_BASE + drmCommandIndex \endcode.
 */
drm_public int drmCommandNone(int fd, unsigned long drmCommandIndex)
{
    unsigned long request;

    request = DRM_IO( DRM_COMMAND_BASE + drmCommandIndex);

    if (drmIoctl(fd, request, NULL)) {
        return -errno;
    }
    return 0;
}


/**
 * Send a device-specific read command.
 *
 * \param fd file descriptor.
 * \param drmCommandIndex command index
 * \param data destination pointer of the data to be read.
 * \param size size of the data to be read.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * It issues a read ioctl given by
 * \code DRM_COMMAND_BASE + drmCommandIndex \endcode.
 */
drm_public int drmCommandRead(int fd, unsigned long drmCommandIndex,
                              void *data, unsigned long size)
{
    unsigned long request;

    request = DRM_IOC( DRM_IOC_READ, DRM_IOCTL_BASE,
        DRM_COMMAND_BASE + drmCommandIndex, size);

    if (drmIoctl(fd, request, data)) {
        return -errno;
    }
    return 0;
}


/**
 * Send a device-specific write command.
 *
 * \param fd file descriptor.
 * \param drmCommandIndex command index
 * \param data source pointer of the data to be written.
 * \param size size of the data to be written.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * It issues a write ioctl given by
 * \code DRM_COMMAND_BASE + drmCommandIndex \endcode.
 */
drm_public int drmCommandWrite(int fd, unsigned long drmCommandIndex,
                               void *data, unsigned long size)
{
    unsigned long request;

    request = DRM_IOC( DRM_IOC_WRITE, DRM_IOCTL_BASE,
        DRM_COMMAND_BASE + drmCommandIndex, size);

    if (drmIoctl(fd, request, data)) {
        return -errno;
    }
    return 0;
}


/**
 * Send a device-specific read-write command.
 *
 * \param fd file descriptor.
 * \param drmCommandIndex command index
 * \param data source pointer of the data to be read and written.
 * \param size size of the data to be read and written.
 *
 * \return zero on success, or a negative value on failure.
 *
 * \internal
 * It issues a read-write ioctl given by
 * \code DRM_COMMAND_BASE + drmCommandIndex \endcode.
 */
drm_public int drmCommandWriteRead(int fd, unsigned long drmCommandIndex,
                                   void *data, unsigned long size)
{
    unsigned long request;

    request = DRM_IOC( DRM_IOC_READ|DRM_IOC_WRITE, DRM_IOCTL_BASE,
        DRM_COMMAND_BASE + drmCommandIndex, size);

    if (drmIoctl(fd, request, data))
        return -errno;
    return 0;
}

#define DRM_MAX_FDS 16
static struct {
    char *BusID;
    int fd;
    int refcount;
    int type;
} connection[DRM_MAX_FDS];

static int nr_fds = 0;

drm_public int drmOpenOnce(void *unused, const char *BusID, int *newlyopened)
{
    return drmOpenOnceWithType(BusID, newlyopened, DRM_NODE_PRIMARY);
}

drm_public int drmOpenOnceWithType(const char *BusID, int *newlyopened,
                                   int type)
{
    int i;
    int fd;

    for (i = 0; i < nr_fds; i++)
        if ((strcmp(BusID, connection[i].BusID) == 0) &&
            (connection[i].type == type)) {
            connection[i].refcount++;
            *newlyopened = 0;
            return connection[i].fd;
        }

    fd = drmOpenWithType(NULL, BusID, type);
    if (fd < 0 || nr_fds == DRM_MAX_FDS)
        return fd;

    connection[nr_fds].BusID = strdup(BusID);
    connection[nr_fds].fd = fd;
    connection[nr_fds].refcount = 1;
    connection[nr_fds].type = type;
    *newlyopened = 1;

    if (0)
        fprintf(stderr, "saved connection %d for %s %d\n",
                nr_fds, connection[nr_fds].BusID,
                strcmp(BusID, connection[nr_fds].BusID));

    nr_fds++;

    return fd;
}

drm_public void drmCloseOnce(int fd)
{
    int i;

    for (i = 0; i < nr_fds; i++) {
        if (fd == connection[i].fd) {
            if (--connection[i].refcount == 0) {
                drmClose(connection[i].fd);
                free(connection[i].BusID);

                if (i < --nr_fds)
                    connection[i] = connection[nr_fds];

                return;
            }
        }
    }
}

drm_public int drmSetMaster(int fd)
{
        return drmIoctl(fd, DRM_IOCTL_SET_MASTER, NULL);
}

drm_public int drmDropMaster(int fd)
{
        return drmIoctl(fd, DRM_IOCTL_DROP_MASTER, NULL);
}

drm_public int drmIsMaster(int fd)
{
        /* Detect master by attempting something that requires master.
         *
         * Authenticating magic tokens requires master and 0 is an
         * internal kernel detail which we could use. Attempting this on
         * a master fd would fail therefore fail with EINVAL because 0
         * is invalid.
         *
         * A non-master fd will fail with EACCES, as the kernel checks
         * for master before attempting to do anything else.
         *
         * Since we don't want to leak implementation details, use
         * EACCES.
         */
        return drmAuthMagic(fd, 0) != -EACCES;
}

drm_public char *drmGetDeviceNameFromFd(int fd)
{
#ifdef __FreeBSD__
    struct stat sbuf;
    int maj, min;
    int nodetype;

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);
    nodetype = drmGetMinorType(maj, min);
    return drmGetMinorNameForFD(fd, nodetype);
#else
    char name[128];
    struct stat sbuf;
    dev_t d;
    int i;

    /* The whole drmOpen thing is a fiasco and we need to find a way
     * back to just using open(2).  For now, however, lets just make
     * things worse with even more ad hoc directory walking code to
     * discover the device file name. */

    fstat(fd, &sbuf);
    d = sbuf.st_rdev;

    for (i = 0; i < DRM_MAX_MINOR; i++) {
        snprintf(name, sizeof name, DRM_DEV_NAME, DRM_DIR_NAME, i);
        if (stat(name, &sbuf) == 0 && sbuf.st_rdev == d)
            break;
    }
    if (i == DRM_MAX_MINOR)
        return NULL;

    return strdup(name);
#endif
}

static bool drmNodeIsDRM(int maj, int min)
{
#ifdef __linux__
    char path[64];
    struct stat sbuf;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device/drm",
             maj, min);
    return stat(path, &sbuf) == 0;
#elif defined(__FreeBSD__)
    char name[SPECNAMELEN];

    if (!devname_r(makedev(maj, min), S_IFCHR, name, sizeof(name)))
      return 0;
    /* Handle drm/ and dri/ as both are present in different FreeBSD version
     * FreeBSD on amd64/i386/powerpc external kernel modules create node in
     * in /dev/drm/ and links in /dev/dri while a WIP in kernel driver creates
     * only device nodes in /dev/dri/ */
    return (!strncmp(name, "drm/", 4) || !strncmp(name, "dri/", 4));
#else
    return maj == DRM_MAJOR;
#endif
}

drm_public int drmGetNodeTypeFromFd(int fd)
{
    struct stat sbuf;
    int maj, min, type;

    if (fstat(fd, &sbuf))
        return -1;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode)) {
        errno = EINVAL;
        return -1;
    }

    type = drmGetMinorType(maj, min);
    if (type == -1)
        errno = ENODEV;
    return type;
}

drm_public int drmPrimeHandleToFD(int fd, uint32_t handle, uint32_t flags,
                                  int *prime_fd)
{
    struct drm_prime_handle args;
    int ret;

    memclear(args);
    args.fd = -1;
    args.handle = handle;
    args.flags = flags;
    ret = drmIoctl(fd, DRM_IOCTL_PRIME_HANDLE_TO_FD, &args);
    if (ret)
        return ret;

    *prime_fd = args.fd;
    return 0;
}

drm_public int drmPrimeFDToHandle(int fd, int prime_fd, uint32_t *handle)
{
    struct drm_prime_handle args;
    int ret;

    memclear(args);
    args.fd = prime_fd;
    ret = drmIoctl(fd, DRM_IOCTL_PRIME_FD_TO_HANDLE, &args);
    if (ret)
        return ret;

    *handle = args.handle;
    return 0;
}

drm_public int drmCloseBufferHandle(int fd, uint32_t handle)
{
    struct drm_gem_close args;

    memclear(args);
    args.handle = handle;
    return drmIoctl(fd, DRM_IOCTL_GEM_CLOSE, &args);
}

static char *drmGetMinorNameForFD(int fd, int type)
{
#ifdef __linux__
    DIR *sysdir;
    struct dirent *ent;
    struct stat sbuf;
    const char *name = drmGetMinorName(type);
    int len;
    char dev_name[64], buf[64];
    int maj, min;

    if (!name)
        return NULL;

    len = strlen(name);

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return NULL;

    snprintf(buf, sizeof(buf), "/sys/dev/char/%d:%d/device/drm", maj, min);

    sysdir = opendir(buf);
    if (!sysdir)
        return NULL;

    while ((ent = readdir(sysdir))) {
        if (strncmp(ent->d_name, name, len) == 0) {
            if (snprintf(dev_name, sizeof(dev_name), DRM_DIR_NAME "/%s",
                        ent->d_name) < 0)
                return NULL;

            closedir(sysdir);
            return strdup(dev_name);
        }
    }

    closedir(sysdir);
    return NULL;
#elif defined(__FreeBSD__)
    struct stat sbuf;
    char dname[SPECNAMELEN];
    const char *mname;
    char name[SPECNAMELEN];
    int id, maj, min, nodetype, i;

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return NULL;

    if (!devname_r(sbuf.st_rdev, S_IFCHR, dname, sizeof(dname)))
        return NULL;

    /* Handle both /dev/drm and /dev/dri
     * FreeBSD on amd64/i386/powerpc external kernel modules create node in
     * in /dev/drm/ and links in /dev/dri while a WIP in kernel driver creates
     * only device nodes in /dev/dri/ */

    /* Get the node type represented by fd so we can deduce the target name */
    nodetype = drmGetMinorType(maj, min);
    if (nodetype == -1)
        return (NULL);
    mname = drmGetMinorName(type);

    for (i = 0; i < SPECNAMELEN; i++) {
        if (isalpha(dname[i]) == 0 && dname[i] != '/')
           break;
    }
    if (dname[i] == '\0')
        return (NULL);

    id = (int)strtol(&dname[i], NULL, 10);
    id -= drmGetMinorBase(nodetype);
    snprintf(name, sizeof(name), DRM_DIR_NAME "/%s%d", mname,
         id + drmGetMinorBase(type));

    return strdup(name);
#else
    struct stat sbuf;
    char buf[PATH_MAX + 1];
    const char *dev_name = drmGetDeviceName(type);
    unsigned int maj, min;
    int n;

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return NULL;

    if (!dev_name)
        return NULL;

    n = snprintf(buf, sizeof(buf), dev_name, DRM_DIR_NAME, min);
    if (n == -1 || n >= sizeof(buf))
        return NULL;

    return strdup(buf);
#endif
}

drm_public char *drmGetPrimaryDeviceNameFromFd(int fd)
{
    return drmGetMinorNameForFD(fd, DRM_NODE_PRIMARY);
}

drm_public char *drmGetRenderDeviceNameFromFd(int fd)
{
    return drmGetMinorNameForFD(fd, DRM_NODE_RENDER);
}

#ifdef __linux__
static char * DRM_PRINTFLIKE(2, 3)
sysfs_uevent_get(const char *path, const char *fmt, ...)
{
    char filename[PATH_MAX + 1], *key, *line = NULL, *value = NULL;
    size_t size = 0, len;
    ssize_t num;
    va_list ap;
    FILE *fp;

    va_start(ap, fmt);
    num = vasprintf(&key, fmt, ap);
    va_end(ap);
    len = num;

    snprintf(filename, sizeof(filename), "%s/uevent", path);

    fp = fopen(filename, "r");
    if (!fp) {
        free(key);
        return NULL;
    }

    while ((num = getline(&line, &size, fp)) >= 0) {
        if ((strncmp(line, key, len) == 0) && (line[len] == '=')) {
            char *start = line + len + 1, *end = line + num - 1;

            if (*end != '\n')
                end++;

            value = strndup(start, end - start);
            break;
        }
    }

    free(line);
    fclose(fp);

    free(key);

    return value;
}
#endif

/* Little white lie to avoid major rework of the existing code */
#define DRM_BUS_VIRTIO 0x10

#ifdef __linux__
static int get_subsystem_type(const char *device_path)
{
    char path[PATH_MAX + 1] = "";
    char link[PATH_MAX + 1] = "";
    char *name;
    struct {
        const char *name;
        int bus_type;
    } bus_types[] = {
        { "/pci", DRM_BUS_PCI },
        { "/usb", DRM_BUS_USB },
        { "/platform", DRM_BUS_PLATFORM },
        { "/spi", DRM_BUS_PLATFORM },
        { "/host1x", DRM_BUS_HOST1X },
        { "/virtio", DRM_BUS_VIRTIO },
    };

    strncpy(path, device_path, PATH_MAX);
    strncat(path, "/subsystem", PATH_MAX);

    if (readlink(path, link, PATH_MAX) < 0)
        return -errno;

    name = strrchr(link, '/');
    if (!name)
        return -EINVAL;

    for (unsigned i = 0; i < ARRAY_SIZE(bus_types); i++) {
        if (strncmp(name, bus_types[i].name, strlen(bus_types[i].name)) == 0)
            return bus_types[i].bus_type;
    }

    return -EINVAL;
}
#endif

static int drmParseSubsystemType(int maj, int min)
{
#ifdef __linux__
    char path[PATH_MAX + 1] = "";
    char real_path[PATH_MAX + 1] = "";
    int subsystem_type;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);

    subsystem_type = get_subsystem_type(path);
    /* Try to get the parent (underlying) device type */
    if (subsystem_type == DRM_BUS_VIRTIO) {
        /* Assume virtio-pci on error */
        if (!realpath(path, real_path))
            return DRM_BUS_VIRTIO;
        strncat(path, "/..", PATH_MAX);
        subsystem_type = get_subsystem_type(path);
        if (subsystem_type < 0)
            return DRM_BUS_VIRTIO;
     }
    return subsystem_type;
#elif defined(__OpenBSD__) || defined(__DragonFly__) || defined(__FreeBSD__)
    return DRM_BUS_PCI;
#else
#warning "Missing implementation of drmParseSubsystemType"
    return -EINVAL;
#endif
}

#ifdef __linux__
static void
get_pci_path(int maj, int min, char *pci_path)
{
    char path[PATH_MAX + 1], *term;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);
    if (!realpath(path, pci_path)) {
        strcpy(pci_path, path);
        return;
    }

    term = strrchr(pci_path, '/');
    if (term && strncmp(term, "/virtio", 7) == 0)
        *term = 0;
}
#endif

#ifdef __FreeBSD__
static int get_sysctl_pci_bus_info(int maj, int min, drmPciBusInfoPtr info)
{
    char dname[SPECNAMELEN];
    char sysctl_name[16];
    char sysctl_val[256];
    size_t sysctl_len;
    int id, type, nelem;
    unsigned int rdev, majmin, domain, bus, dev, func;

    rdev = makedev(maj, min);
    if (!devname_r(rdev, S_IFCHR, dname, sizeof(dname)))
      return -EINVAL;

    if (sscanf(dname, "drm/%d\n", &id) != 1)
        return -EINVAL;
    type = drmGetMinorType(maj, min);
    if (type == -1)
        return -EINVAL;

    /* BUG: This above section is iffy, since it mandates that a driver will
     * create both card and render node.
     * If it does not, the next DRM device will create card#X and
     * renderD#(128+X)-1.
     * This is a possibility in FreeBSD but for now there is no good way for
     * obtaining the info.
     */
    switch (type) {
    case DRM_NODE_PRIMARY:
         break;
    case DRM_NODE_RENDER:
         id -= 128;
         break;
    }
    if (id < 0)
        return -EINVAL;

    if (snprintf(sysctl_name, sizeof(sysctl_name), "hw.dri.%d.busid", id) <= 0)
      return -EINVAL;
    sysctl_len = sizeof(sysctl_val);
    if (sysctlbyname(sysctl_name, sysctl_val, &sysctl_len, NULL, 0))
      return -EINVAL;

    #define bus_fmt "pci:%04x:%02x:%02x.%u"

    nelem = sscanf(sysctl_val, bus_fmt, &domain, &bus, &dev, &func);
    if (nelem != 4)
      return -EINVAL;
    info->domain = domain;
    info->bus = bus;
    info->dev = dev;
    info->func = func;

    return 0;
}
#endif

static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
{
#ifdef __linux__
    unsigned int domain, bus, dev, func;
    char pci_path[PATH_MAX + 1], *value;
    int num;

    get_pci_path(maj, min, pci_path);

    value = sysfs_uevent_get(pci_path, "PCI_SLOT_NAME");
    if (!value)
        return -ENOENT;

    num = sscanf(value, "%04x:%02x:%02x.%1u", &domain, &bus, &dev, &func);
    free(value);

    if (num != 4)
        return -EINVAL;

    info->domain = domain;
    info->bus = bus;
    info->dev = dev;
    info->func = func;

    return 0;
#elif defined(__OpenBSD__) || defined(__DragonFly__)
    struct drm_pciinfo pinfo;
    int fd, type;

    type = drmGetMinorType(maj, min);
    if (type == -1)
        return -ENODEV;

    fd = drmOpenMinor(min, 0, type);
    if (fd < 0)
        return -errno;

    if (drmIoctl(fd, DRM_IOCTL_GET_PCIINFO, &pinfo)) {
        close(fd);
        return -errno;
    }
    close(fd);

    info->domain = pinfo.domain;
    info->bus = pinfo.bus;
    info->dev = pinfo.dev;
    info->func = pinfo.func;

    return 0;
#elif defined(__FreeBSD__)
    return get_sysctl_pci_bus_info(maj, min, info);
#else
#warning "Missing implementation of drmParsePciBusInfo"
    return -EINVAL;
#endif
}

drm_public int drmDevicesEqual(drmDevicePtr a, drmDevicePtr b)
{
    if (a == NULL || b == NULL)
        return 0;

    if (a->bustype != b->bustype)
        return 0;

    switch (a->bustype) {
    case DRM_BUS_PCI:
        return memcmp(a->businfo.pci, b->businfo.pci, sizeof(drmPciBusInfo)) == 0;

    case DRM_BUS_USB:
        return memcmp(a->businfo.usb, b->businfo.usb, sizeof(drmUsbBusInfo)) == 0;

    case DRM_BUS_PLATFORM:
        return memcmp(a->businfo.platform, b->businfo.platform, sizeof(drmPlatformBusInfo)) == 0;

    case DRM_BUS_HOST1X:
        return memcmp(a->businfo.host1x, b->businfo.host1x, sizeof(drmHost1xBusInfo)) == 0;

    default:
        break;
    }

    return 0;
}

static int drmGetNodeType(const char *name)
{
    if (strncmp(name, DRM_RENDER_MINOR_NAME,
        sizeof(DRM_RENDER_MINOR_NAME) - 1) == 0)
        return DRM_NODE_RENDER;

    if (strncmp(name, DRM_PRIMARY_MINOR_NAME,
        sizeof(DRM_PRIMARY_MINOR_NAME) - 1) == 0)
        return DRM_NODE_PRIMARY;

    return -EINVAL;
}

static int drmGetMaxNodeName(void)
{
    return sizeof(DRM_DIR_NAME) +
           MAX3(sizeof(DRM_PRIMARY_MINOR_NAME),
                sizeof(DRM_CONTROL_MINOR_NAME),
                sizeof(DRM_RENDER_MINOR_NAME)) +
           3 /* length of the node number */;
}

#ifdef __linux__
static int parse_separate_sysfs_files(int maj, int min,
                                      drmPciDeviceInfoPtr device,
                                      bool ignore_revision)
{
    static const char *attrs[] = {
      "revision", /* Older kernels are missing the file, so check for it first */
      "vendor",
      "device",
      "subsystem_vendor",
      "subsystem_device",
    };
    char path[PATH_MAX + 1], pci_path[PATH_MAX + 1];
    unsigned int data[ARRAY_SIZE(attrs)];
    FILE *fp;
    int ret;

    get_pci_path(maj, min, pci_path);

    for (unsigned i = ignore_revision ? 1 : 0; i < ARRAY_SIZE(attrs); i++) {
        if (snprintf(path, PATH_MAX, "%s/%s", pci_path, attrs[i]) < 0)
            return -errno;

        fp = fopen(path, "r");
        if (!fp)
            return -errno;

        ret = fscanf(fp, "%x", &data[i]);
        fclose(fp);
        if (ret != 1)
            return -errno;

    }

    device->revision_id = ignore_revision ? 0xff : data[0] & 0xff;
    device->vendor_id = data[1] & 0xffff;
    device->device_id = data[2] & 0xffff;
    device->subvendor_id = data[3] & 0xffff;
    device->subdevice_id = data[4] & 0xffff;

    return 0;
}

static int parse_config_sysfs_file(int maj, int min,
                                   drmPciDeviceInfoPtr device)
{
    char path[PATH_MAX + 1], pci_path[PATH_MAX + 1];
    unsigned char config[64];
    int fd, ret;

    get_pci_path(maj, min, pci_path);

    if (snprintf(path, PATH_MAX, "%s/config", pci_path) < 0)
        return -errno;

    fd = open(path, O_RDONLY);
    if (fd < 0)
        return -errno;

    ret = read(fd, config, sizeof(config));
    close(fd);
    if (ret < 0)
        return -errno;

    device->vendor_id = config[0] | (config[1] << 8);
    device->device_id = config[2] | (config[3] << 8);
    device->revision_id = config[8];
    device->subvendor_id = config[44] | (config[45] << 8);
    device->subdevice_id = config[46] | (config[47] << 8);

    return 0;
}
#endif

static int drmParsePciDeviceInfo(int maj, int min,
                                 drmPciDeviceInfoPtr device,
                                 uint32_t flags)
{
#ifdef __linux__
    if (!(flags & DRM_DEVICE_GET_PCI_REVISION))
        return parse_separate_sysfs_files(maj, min, device, true);

    if (parse_separate_sysfs_files(maj, min, device, false))
        return parse_config_sysfs_file(maj, min, device);

    return 0;
#elif defined(__OpenBSD__) || defined(__DragonFly__)
    struct drm_pciinfo pinfo;
    int fd, type;

    type = drmGetMinorType(maj, min);
    if (type == -1)
        return -ENODEV;

    fd = drmOpenMinor(min, 0, type);
    if (fd < 0)
        return -errno;

    if (drmIoctl(fd, DRM_IOCTL_GET_PCIINFO, &pinfo)) {
        close(fd);
        return -errno;
    }
    close(fd);

    device->vendor_id = pinfo.vendor_id;
    device->device_id = pinfo.device_id;
    device->revision_id = pinfo.revision_id;
    device->subvendor_id = pinfo.subvendor_id;
    device->subdevice_id = pinfo.subdevice_id;

    return 0;
#elif defined(__FreeBSD__)
    drmPciBusInfo info;
    struct pci_conf_io pc;
    struct pci_match_conf patterns[1];
    struct pci_conf results[1];
    int fd, error;

    if (get_sysctl_pci_bus_info(maj, min, &info) != 0)
        return -EINVAL;

    fd = open("/dev/pci", O_RDONLY);
    if (fd < 0)
        return -errno;

    bzero(&patterns, sizeof(patterns));
    patterns[0].pc_sel.pc_domain = info.domain;
    patterns[0].pc_sel.pc_bus = info.bus;
    patterns[0].pc_sel.pc_dev = info.dev;
    patterns[0].pc_sel.pc_func = info.func;
    patterns[0].flags = PCI_GETCONF_MATCH_DOMAIN | PCI_GETCONF_MATCH_BUS
                      | PCI_GETCONF_MATCH_DEV | PCI_GETCONF_MATCH_FUNC;
    bzero(&pc, sizeof(struct pci_conf_io));
    pc.num_patterns = 1;
    pc.pat_buf_len = sizeof(patterns);
    pc.patterns = patterns;
    pc.match_buf_len = sizeof(results);
    pc.matches = results;

    if (ioctl(fd, PCIOCGETCONF, &pc) || pc.status == PCI_GETCONF_ERROR) {
        error = errno;
        close(fd);
        return -error;
    }
    close(fd);

    device->vendor_id = results[0].pc_vendor;
    device->device_id = results[0].pc_device;
    device->subvendor_id = results[0].pc_subvendor;
    device->subdevice_id = results[0].pc_subdevice;
    device->revision_id = results[0].pc_revid;

    return 0;
#else
#warning "Missing implementation of drmParsePciDeviceInfo"
    return -EINVAL;
#endif
}

static void drmFreePlatformDevice(drmDevicePtr device)
{
    if (device->deviceinfo.platform) {
        if (device->deviceinfo.platform->compatible) {
            char **compatible = device->deviceinfo.platform->compatible;

            while (*compatible) {
                free(*compatible);
                compatible++;
            }

            free(device->deviceinfo.platform->compatible);
        }
    }
}

static void drmFreeHost1xDevice(drmDevicePtr device)
{
    if (device->deviceinfo.host1x) {
        if (device->deviceinfo.host1x->compatible) {
            char **compatible = device->deviceinfo.host1x->compatible;

            while (*compatible) {
                free(*compatible);
                compatible++;
            }

            free(device->deviceinfo.host1x->compatible);
        }
    }
}

drm_public void drmFreeDevice(drmDevicePtr *device)
{
    if (device == NULL)
        return;

    if (*device) {
        switch ((*device)->bustype) {
        case DRM_BUS_PLATFORM:
            drmFreePlatformDevice(*device);
            break;

        case DRM_BUS_HOST1X:
            drmFreeHost1xDevice(*device);
            break;
        }
    }

    free(*device);
    *device = NULL;
}

drm_public void drmFreeDevices(drmDevicePtr devices[], int count)
{
    int i;

    if (devices == NULL)
        return;

    for (i = 0; i < count; i++)
        if (devices[i])
            drmFreeDevice(&devices[i]);
}

static drmDevicePtr drmDeviceAlloc(unsigned int type, const char *node,
                                   size_t bus_size, size_t device_size,
                                   char **ptrp)
{
    size_t max_node_length, extra, size;
    drmDevicePtr device;
    unsigned int i;
    char *ptr;

    max_node_length = ALIGN(drmGetMaxNodeName(), sizeof(void *));
    extra = DRM_NODE_MAX * (sizeof(void *) + max_node_length);

    size = sizeof(*device) + extra + bus_size + device_size;

    device = calloc(1, size);
    if (!device)
        return NULL;

    device->available_nodes = 1 << type;

    ptr = (char *)device + sizeof(*device);
    device->nodes = (char **)ptr;

    ptr += DRM_NODE_MAX * sizeof(void *);

    for (i = 0; i < DRM_NODE_MAX; i++) {
        device->nodes[i] = ptr;
        ptr += max_node_length;
    }

    memcpy(device->nodes[type], node, max_node_length);

    *ptrp = ptr;

    return device;
}

static int drmProcessPciDevice(drmDevicePtr *device,
                               const char *node, int node_type,
                               int maj, int min, bool fetch_deviceinfo,
                               uint32_t flags)
{
    drmDevicePtr dev;
    char *addr;
    int ret;

    dev = drmDeviceAlloc(node_type, node, sizeof(drmPciBusInfo),
                         sizeof(drmPciDeviceInfo), &addr);
    if (!dev)
        return -ENOMEM;

    dev->bustype = DRM_BUS_PCI;

    dev->businfo.pci = (drmPciBusInfoPtr)addr;

    ret = drmParsePciBusInfo(maj, min, dev->businfo.pci);
    if (ret)
        goto free_device;

    // Fetch the device info if the user has requested it
    if (fetch_deviceinfo) {
        addr += sizeof(drmPciBusInfo);
        dev->deviceinfo.pci = (drmPciDeviceInfoPtr)addr;

        ret = drmParsePciDeviceInfo(maj, min, dev->deviceinfo.pci, flags);
        if (ret)
            goto free_device;
    }

    *device = dev;

    return 0;

free_device:
    free(dev);
    return ret;
}

#ifdef __linux__
static int drm_usb_dev_path(int maj, int min, char *path, size_t len)
{
    char *value, *tmp_path, *slash;
    bool usb_device, usb_interface;

    snprintf(path, len, "/sys/dev/char/%d:%d/device", maj, min);

    value = sysfs_uevent_get(path, "DEVTYPE");
    if (!value)
        return -ENOENT;

    usb_device = strcmp(value, "usb_device") == 0;
    usb_interface = strcmp(value, "usb_interface") == 0;
    free(value);

    if (usb_device)
        return 0;
    if (!usb_interface)
        return -ENOTSUP;

    /* The parent of a usb_interface is a usb_device */

    tmp_path = realpath(path, NULL);
    if (!tmp_path)
        return -errno;

    slash = strrchr(tmp_path, '/');
    if (!slash) {
        free(tmp_path);
        return -EINVAL;
    }

    *slash = '\0';

    if (snprintf(path, len, "%s", tmp_path) >= (int)len) {
        free(tmp_path);
        return -EINVAL;
    }

    free(tmp_path);
    return 0;
}
#endif

static int drmParseUsbBusInfo(int maj, int min, drmUsbBusInfoPtr info)
{
#ifdef __linux__
    char path[PATH_MAX + 1], *value;
    unsigned int bus, dev;
    int ret;

    ret = drm_usb_dev_path(maj, min, path, sizeof(path));
    if (ret < 0)
        return ret;

    value = sysfs_uevent_get(path, "BUSNUM");
    if (!value)
        return -ENOENT;

    ret = sscanf(value, "%03u", &bus);
    free(value);

    if (ret <= 0)
        return -errno;

    value = sysfs_uevent_get(path, "DEVNUM");
    if (!value)
        return -ENOENT;

    ret = sscanf(value, "%03u", &dev);
    free(value);

    if (ret <= 0)
        return -errno;

    info->bus = bus;
    info->dev = dev;

    return 0;
#else
#warning "Missing implementation of drmParseUsbBusInfo"
    return -EINVAL;
#endif
}

static int drmParseUsbDeviceInfo(int maj, int min, drmUsbDeviceInfoPtr info)
{
#ifdef __linux__
    char path[PATH_MAX + 1], *value;
    unsigned int vendor, product;
    int ret;

    ret = drm_usb_dev_path(maj, min, path, sizeof(path));
    if (ret < 0)
        return ret;

    value = sysfs_uevent_get(path, "PRODUCT");
    if (!value)
        return -ENOENT;

    ret = sscanf(value, "%x/%x", &vendor, &product);
    free(value);

    if (ret <= 0)
        return -errno;

    info->vendor = vendor;
    info->product = product;

    return 0;
#else
#warning "Missing implementation of drmParseUsbDeviceInfo"
    return -EINVAL;
#endif
}

static int drmProcessUsbDevice(drmDevicePtr *device, const char *node,
                               int node_type, int maj, int min,
                               bool fetch_deviceinfo, uint32_t flags)
{
    drmDevicePtr dev;
    char *ptr;
    int ret;

    dev = drmDeviceAlloc(node_type, node, sizeof(drmUsbBusInfo),
                         sizeof(drmUsbDeviceInfo), &ptr);
    if (!dev)
        return -ENOMEM;

    dev->bustype = DRM_BUS_USB;

    dev->businfo.usb = (drmUsbBusInfoPtr)ptr;

    ret = drmParseUsbBusInfo(maj, min, dev->businfo.usb);
    if (ret < 0)
        goto free_device;

    if (fetch_deviceinfo) {
        ptr += sizeof(drmUsbBusInfo);
        dev->deviceinfo.usb = (drmUsbDeviceInfoPtr)ptr;

        ret = drmParseUsbDeviceInfo(maj, min, dev->deviceinfo.usb);
        if (ret < 0)
            goto free_device;
    }

    *device = dev;

    return 0;

free_device:
    free(dev);
    return ret;
}

static int drmParseOFBusInfo(int maj, int min, char *fullname)
{
#ifdef __linux__
    char path[PATH_MAX + 1], *name, *tmp_name;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);

    name = sysfs_uevent_get(path, "OF_FULLNAME");
    tmp_name = name;
    if (!name) {
        /* If the device lacks OF data, pick the MODALIAS info */
        name = sysfs_uevent_get(path, "MODALIAS");
        if (!name)
            return -ENOENT;

        /* .. and strip the MODALIAS=[platform,usb...]: part. */
        tmp_name = strrchr(name, ':');
        if (!tmp_name) {
            free(name);
            return -ENOENT;
        }
        tmp_name++;
    }

    strncpy(fullname, tmp_name, DRM_PLATFORM_DEVICE_NAME_LEN);
    fullname[DRM_PLATFORM_DEVICE_NAME_LEN - 1] = '\0';
    free(name);

    return 0;
#else
#warning "Missing implementation of drmParseOFBusInfo"
    return -EINVAL;
#endif
}

static int drmParseOFDeviceInfo(int maj, int min, char ***compatible)
{
#ifdef __linux__
    char path[PATH_MAX + 1], *value, *tmp_name;
    unsigned int count, i;
    int err;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);

    value = sysfs_uevent_get(path, "OF_COMPATIBLE_N");
    if (value) {
        sscanf(value, "%u", &count);
        free(value);
    } else {
        /* Assume one entry if the device lack OF data */
        count = 1;
    }

    *compatible = calloc(count + 1, sizeof(char *));
    if (!*compatible)
        return -ENOMEM;

    for (i = 0; i < count; i++) {
        value = sysfs_uevent_get(path, "OF_COMPATIBLE_%u", i);
        tmp_name = value;
        if (!value) {
            /* If the device lacks OF data, pick the MODALIAS info */
            value = sysfs_uevent_get(path, "MODALIAS");
            if (!value) {
                err = -ENOENT;
                goto free;
            }

            /* .. and strip the MODALIAS=[platform,usb...]: part. */
            tmp_name = strrchr(value, ':');
            if (!tmp_name) {
                free(value);
                return -ENOENT;
            }
            tmp_name = strdup(tmp_name + 1);
            free(value);
        }

        (*compatible)[i] = tmp_name;
    }

    return 0;

free:
    while (i--)
        free((*compatible)[i]);

    free(*compatible);
    return err;
#else
#warning "Missing implementation of drmParseOFDeviceInfo"
    return -EINVAL;
#endif
}

static int drmProcessPlatformDevice(drmDevicePtr *device,
                                    const char *node, int node_type,
                                    int maj, int min, bool fetch_deviceinfo,
                                    uint32_t flags)
{
    drmDevicePtr dev;
    char *ptr;
    int ret;

    dev = drmDeviceAlloc(node_type, node, sizeof(drmPlatformBusInfo),
                         sizeof(drmPlatformDeviceInfo), &ptr);
    if (!dev)
        return -ENOMEM;

    dev->bustype = DRM_BUS_PLATFORM;

    dev->businfo.platform = (drmPlatformBusInfoPtr)ptr;

    ret = drmParseOFBusInfo(maj, min, dev->businfo.platform->fullname);
    if (ret < 0)
        goto free_device;

    if (fetch_deviceinfo) {
        ptr += sizeof(drmPlatformBusInfo);
        dev->deviceinfo.platform = (drmPlatformDeviceInfoPtr)ptr;

        ret = drmParseOFDeviceInfo(maj, min, &dev->deviceinfo.platform->compatible);
        if (ret < 0)
            goto free_device;
    }

    *device = dev;

    return 0;

free_device:
    free(dev);
    return ret;
}

static int drmProcessHost1xDevice(drmDevicePtr *device,
                                  const char *node, int node_type,
                                  int maj, int min, bool fetch_deviceinfo,
                                  uint32_t flags)
{
    drmDevicePtr dev;
    char *ptr;
    int ret;

    dev = drmDeviceAlloc(node_type, node, sizeof(drmHost1xBusInfo),
                         sizeof(drmHost1xDeviceInfo), &ptr);
    if (!dev)
        return -ENOMEM;

    dev->bustype = DRM_BUS_HOST1X;

    dev->businfo.host1x = (drmHost1xBusInfoPtr)ptr;

    ret = drmParseOFBusInfo(maj, min, dev->businfo.host1x->fullname);
    if (ret < 0)
        goto free_device;

    if (fetch_deviceinfo) {
        ptr += sizeof(drmHost1xBusInfo);
        dev->deviceinfo.host1x = (drmHost1xDeviceInfoPtr)ptr;

        ret = drmParseOFDeviceInfo(maj, min, &dev->deviceinfo.host1x->compatible);
        if (ret < 0)
            goto free_device;
    }

    *device = dev;

    return 0;

free_device:
    free(dev);
    return ret;
}

static int
process_device(drmDevicePtr *device, const char *d_name,
               int req_subsystem_type,
               bool fetch_deviceinfo, uint32_t flags)
{
    struct stat sbuf;
    char node[PATH_MAX + 1];
    int node_type, subsystem_type, written;
    unsigned int maj, min;
    const int max_node_length = ALIGN(drmGetMaxNodeName(), sizeof(void *));

    node_type = drmGetNodeType(d_name);
    if (node_type < 0)
        return -1;

    written = snprintf(node, PATH_MAX, "%s/%s", DRM_DIR_NAME, d_name);
    if (written < 0)
        return -1;

    /* anything longer than this will be truncated in drmDeviceAlloc.
     * Account for NULL byte
     */
    if (written + 1 > max_node_length)
        return -1;

    if (stat(node, &sbuf))
        return -1;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return -1;

    subsystem_type = drmParseSubsystemType(maj, min);
    if (req_subsystem_type != -1 && req_subsystem_type != subsystem_type)
        return -1;

    switch (subsystem_type) {
    case DRM_BUS_PCI:
    case DRM_BUS_VIRTIO:
        return drmProcessPciDevice(device, node, node_type, maj, min,
                                   fetch_deviceinfo, flags);
    case DRM_BUS_USB:
        return drmProcessUsbDevice(device, node, node_type, maj, min,
                                   fetch_deviceinfo, flags);
    case DRM_BUS_PLATFORM:
        return drmProcessPlatformDevice(device, node, node_type, maj, min,
                                        fetch_deviceinfo, flags);
    case DRM_BUS_HOST1X:
        return drmProcessHost1xDevice(device, node, node_type, maj, min,
                                      fetch_deviceinfo, flags);
    default:
        return -1;
   }
}

/* Consider devices located on the same bus as duplicate and fold the respective
 * entries into a single one.
 *
 * Note: this leaves "gaps" in the array, while preserving the length.
 */
static void drmFoldDuplicatedDevices(drmDevicePtr local_devices[], int count)
{
    int node_type, i, j;

    for (i = 0; i < count; i++) {
        for (j = i + 1; j < count; j++) {
            if (drmDevicesEqual(local_devices[i], local_devices[j])) {
                local_devices[i]->available_nodes |= local_devices[j]->available_nodes;
                node_type = log2_int(local_devices[j]->available_nodes);
                memcpy(local_devices[i]->nodes[node_type],
                       local_devices[j]->nodes[node_type], drmGetMaxNodeName());
                drmFreeDevice(&local_devices[j]);
            }
        }
    }
}

/* Check that the given flags are valid returning 0 on success */
static int
drm_device_validate_flags(uint32_t flags)
{
        return (flags & ~DRM_DEVICE_GET_PCI_REVISION);
}

static bool
drm_device_has_rdev(drmDevicePtr device, dev_t find_rdev)
{
    struct stat sbuf;

    for (int i = 0; i < DRM_NODE_MAX; i++) {
        if (device->available_nodes & 1 << i) {
            if (stat(device->nodes[i], &sbuf) == 0 &&
                sbuf.st_rdev == find_rdev)
                return true;
        }
    }
    return false;
}

/*
 * The kernel drm core has a number of places that assume maximum of
 * 3x64 devices nodes. That's 64 for each of primary, control and
 * render nodes. Rounded it up to 256 for simplicity.
 */
#define MAX_DRM_NODES 256

/**
 * Get information about a device from its dev_t identifier
 *
 * \param find_rdev dev_t identifier of the device
 * \param flags feature/behaviour bitmask
 * \param device the address of a drmDevicePtr where the information
 *               will be allocated in stored
 *
 * \return zero on success, negative error code otherwise.
 */
drm_public int drmGetDeviceFromDevId(dev_t find_rdev, uint32_t flags, drmDevicePtr *device)
{
#ifdef __OpenBSD__
    /*
     * DRI device nodes on OpenBSD are not in their own directory, they reside
     * in /dev along with a large number of statically generated /dev nodes.
     * Avoid stat'ing all of /dev needlessly by implementing this custom path.
     */
    drmDevicePtr     d;
    char             node[PATH_MAX + 1];
    const char      *dev_name;
    int              node_type, subsystem_type;
    int              maj, min, n, ret;
    const int        max_node_length = ALIGN(drmGetMaxNodeName(), sizeof(void *));
    struct stat      sbuf;

    if (device == NULL)
        return -EINVAL;

    maj = major(find_rdev);
    min = minor(find_rdev);

    if (!drmNodeIsDRM(maj, min))
        return -EINVAL;

    node_type = drmGetMinorType(maj, min);
    if (node_type == -1)
        return -ENODEV;

    dev_name = drmGetDeviceName(node_type);
    if (!dev_name)
        return -EINVAL;

    /* anything longer than this will be truncated in drmDeviceAlloc.
     * Account for NULL byte
     */
    n = snprintf(node, PATH_MAX, dev_name, DRM_DIR_NAME, min);
    if (n == -1 || n >= PATH_MAX)
      return -errno;
    if (n + 1 > max_node_length)
        return -EINVAL;
    if (stat(node, &sbuf))
        return -EINVAL;

    subsystem_type = drmParseSubsystemType(maj, min);
    if (subsystem_type != DRM_BUS_PCI)
        return -ENODEV;

    ret = drmProcessPciDevice(&d, node, node_type, maj, min, true, flags);
    if (ret)
        return ret;

    *device = d;

    return 0;
#else
    drmDevicePtr local_devices[MAX_DRM_NODES];
    drmDevicePtr d;
    DIR *sysdir;
    struct dirent *dent;
    int subsystem_type;
    int maj, min;
    int ret, i, node_count;

    if (drm_device_validate_flags(flags))
        return -EINVAL;

    if (device == NULL)
        return -EINVAL;

    maj = major(find_rdev);
    min = minor(find_rdev);

    if (!drmNodeIsDRM(maj, min))
        return -EINVAL;

    subsystem_type = drmParseSubsystemType(maj, min);
    if (subsystem_type < 0)
        return subsystem_type;

    sysdir = opendir(DRM_DIR_NAME);
    if (!sysdir)
        return -errno;

    i = 0;
    while ((dent = readdir(sysdir))) {
        ret = process_device(&d, dent->d_name, subsystem_type, true, flags);
        if (ret)
            continue;

        if (i >= MAX_DRM_NODES) {
            fprintf(stderr, "More than %d drm nodes detected. "
                    "Please report a bug - that should not happen.\n"
                    "Skipping extra nodes\n", MAX_DRM_NODES);
            break;
        }
        local_devices[i] = d;
        i++;
    }
    node_count = i;

    drmFoldDuplicatedDevices(local_devices, node_count);

    *device = NULL;

    for (i = 0; i < node_count; i++) {
        if (!local_devices[i])
            continue;

        if (drm_device_has_rdev(local_devices[i], find_rdev))
            *device = local_devices[i];
        else
            drmFreeDevice(&local_devices[i]);
    }

    closedir(sysdir);
    if (*device == NULL)
        return -ENODEV;
    return 0;
#endif
}

drm_public int drmGetNodeTypeFromDevId(dev_t devid)
{
    int maj, min, node_type;

    maj = major(devid);
    min = minor(devid);

    if (!drmNodeIsDRM(maj, min))
        return -EINVAL;

    node_type = drmGetMinorType(maj, min);
    if (node_type == -1)
        return -ENODEV;

    return node_type;
}

/**
 * Get information about the opened drm device
 *
 * \param fd file descriptor of the drm device
 * \param flags feature/behaviour bitmask
 * \param device the address of a drmDevicePtr where the information
 *               will be allocated in stored
 *
 * \return zero on success, negative error code otherwise.
 *
 * \note Unlike drmGetDevice it does not retrieve the pci device revision field
 * unless the DRM_DEVICE_GET_PCI_REVISION \p flag is set.
 */
drm_public int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device)
{
    struct stat sbuf;

    if (fd == -1)
        return -EINVAL;

    if (fstat(fd, &sbuf))
        return -errno;

    if (!S_ISCHR(sbuf.st_mode))
        return -EINVAL;

    return drmGetDeviceFromDevId(sbuf.st_rdev, flags, device);
}

/**
 * Get information about the opened drm device
 *
 * \param fd file descriptor of the drm device
 * \param device the address of a drmDevicePtr where the information
 *               will be allocated in stored
 *
 * \return zero on success, negative error code otherwise.
 */
drm_public int drmGetDevice(int fd, drmDevicePtr *device)
{
    return drmGetDevice2(fd, DRM_DEVICE_GET_PCI_REVISION, device);
}

/**
 * Get drm devices on the system
 *
 * \param flags feature/behaviour bitmask
 * \param devices the array of devices with drmDevicePtr elements
 *                can be NULL to get the device number first
 * \param max_devices the maximum number of devices for the array
 *
 * \return on error - negative error code,
 *         if devices is NULL - total number of devices available on the system,
 *         alternatively the number of devices stored in devices[], which is
 *         capped by the max_devices.
 *
 * \note Unlike drmGetDevices it does not retrieve the pci device revision field
 * unless the DRM_DEVICE_GET_PCI_REVISION \p flag is set.
 */
drm_public int drmGetDevices2(uint32_t flags, drmDevicePtr devices[],
                              int max_devices)
{
    drmDevicePtr local_devices[MAX_DRM_NODES];
    drmDevicePtr device;
    DIR *sysdir;
    struct dirent *dent;
    int ret, i, node_count, device_count;

    if (drm_device_validate_flags(flags))
        return -EINVAL;

    sysdir = opendir(DRM_DIR_NAME);
    if (!sysdir)
        return -errno;

    i = 0;
    while ((dent = readdir(sysdir))) {
        ret = process_device(&device, dent->d_name, -1, devices != NULL, flags);
        if (ret)
            continue;

        if (i >= MAX_DRM_NODES) {
            fprintf(stderr, "More than %d drm nodes detected. "
                    "Please report a bug - that should not happen.\n"
                    "Skipping extra nodes\n", MAX_DRM_NODES);
            break;
        }
        local_devices[i] = device;
        i++;
    }
    node_count = i;

    drmFoldDuplicatedDevices(local_devices, node_count);

    device_count = 0;
    for (i = 0; i < node_count; i++) {
        if (!local_devices[i])
            continue;

        if ((devices != NULL) && (device_count < max_devices))
            devices[device_count] = local_devices[i];
        else
            drmFreeDevice(&local_devices[i]);

        device_count++;
    }

    closedir(sysdir);

    if (devices != NULL)
        return MIN2(device_count, max_devices);

    return device_count;
}

/**
 * Get drm devices on the system
 *
 * \param devices the array of devices with drmDevicePtr elements
 *                can be NULL to get the device number first
 * \param max_devices the maximum number of devices for the array
 *
 * \return on error - negative error code,
 *         if devices is NULL - total number of devices available on the system,
 *         alternatively the number of devices stored in devices[], which is
 *         capped by the max_devices.
 */
drm_public int drmGetDevices(drmDevicePtr devices[], int max_devices)
{
    return drmGetDevices2(DRM_DEVICE_GET_PCI_REVISION, devices, max_devices);
}

drm_public char *drmGetDeviceNameFromFd2(int fd)
{
#ifdef __linux__
    struct stat sbuf;
    char path[PATH_MAX + 1], *value;
    unsigned int maj, min;

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return NULL;

    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d", maj, min);

    value = sysfs_uevent_get(path, "DEVNAME");
    if (!value)
        return NULL;

    snprintf(path, sizeof(path), "/dev/%s", value);
    free(value);

    return strdup(path);
#elif defined(__FreeBSD__)
    return drmGetDeviceNameFromFd(fd);
#else
    struct stat      sbuf;
    char             node[PATH_MAX + 1];
    const char      *dev_name;
    int              node_type;
    int              maj, min, n;

    if (fstat(fd, &sbuf))
        return NULL;

    maj = major(sbuf.st_rdev);
    min = minor(sbuf.st_rdev);

    if (!drmNodeIsDRM(maj, min) || !S_ISCHR(sbuf.st_mode))
        return NULL;

    node_type = drmGetMinorType(maj, min);
    if (node_type == -1)
        return NULL;

    dev_name = drmGetDeviceName(node_type);
    if (!dev_name)
        return NULL;

    n = snprintf(node, PATH_MAX, dev_name, DRM_DIR_NAME, min);
    if (n == -1 || n >= PATH_MAX)
      return NULL;

    return strdup(node);
#endif
}

drm_public int drmSyncobjCreate(int fd, uint32_t flags, uint32_t *handle)
{
    struct drm_syncobj_create args;
    int ret;

    memclear(args);
    args.flags = flags;
    args.handle = 0;
    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_CREATE, &args);
    if (ret)
        return ret;
    *handle = args.handle;
    return 0;
}

drm_public int drmSyncobjDestroy(int fd, uint32_t handle)
{
    struct drm_syncobj_destroy args;

    memclear(args);
    args.handle = handle;
    return drmIoctl(fd, DRM_IOCTL_SYNCOBJ_DESTROY, &args);
}

drm_public int drmSyncobjHandleToFD(int fd, uint32_t handle, int *obj_fd)
{
    struct drm_syncobj_handle args;
    int ret;

    memclear(args);
    args.fd = -1;
    args.handle = handle;
    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, &args);
    if (ret)
        return ret;
    *obj_fd = args.fd;
    return 0;
}

drm_public int drmSyncobjFDToHandle(int fd, int obj_fd, uint32_t *handle)
{
    struct drm_syncobj_handle args;
    int ret;

    memclear(args);
    args.fd = obj_fd;
    args.handle = 0;
    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, &args);
    if (ret)
        return ret;
    *handle = args.handle;
    return 0;
}

drm_public int drmSyncobjImportSyncFile(int fd, uint32_t handle,
                                        int sync_file_fd)
{
    struct drm_syncobj_handle args;

    memclear(args);
    args.fd = sync_file_fd;
    args.handle = handle;
    args.flags = DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE;
    return drmIoctl(fd, DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, &args);
}

drm_public int drmSyncobjExportSyncFile(int fd, uint32_t handle,
                                        int *sync_file_fd)
{
    struct drm_syncobj_handle args;
    int ret;

    memclear(args);
    args.fd = -1;
    args.handle = handle;
    args.flags = DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE;
    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, &args);
    if (ret)
        return ret;
    *sync_file_fd = args.fd;
    return 0;
}

drm_public int drmSyncobjWait(int fd, uint32_t *handles, unsigned num_handles,
                              int64_t timeout_nsec, unsigned flags,
                              uint32_t *first_signaled)
{
    struct drm_syncobj_wait args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.timeout_nsec = timeout_nsec;
    args.count_handles = num_handles;
    args.flags = flags;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_WAIT, &args);
    if (ret < 0)
        return -errno;

    if (first_signaled)
        *first_signaled = args.first_signaled;
    return ret;
}

drm_public int drmSyncobjReset(int fd, const uint32_t *handles,
                               uint32_t handle_count)
{
    struct drm_syncobj_array args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.count_handles = handle_count;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_RESET, &args);
    return ret;
}

drm_public int drmSyncobjSignal(int fd, const uint32_t *handles,
                                uint32_t handle_count)
{
    struct drm_syncobj_array args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.count_handles = handle_count;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_SIGNAL, &args);
    return ret;
}

drm_public int drmSyncobjTimelineSignal(int fd, const uint32_t *handles,
					uint64_t *points, uint32_t handle_count)
{
    struct drm_syncobj_timeline_array args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.points = (uintptr_t)points;
    args.count_handles = handle_count;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL, &args);
    return ret;
}

drm_public int drmSyncobjTimelineWait(int fd, uint32_t *handles, uint64_t *points,
				      unsigned num_handles,
				      int64_t timeout_nsec, unsigned flags,
				      uint32_t *first_signaled)
{
    struct drm_syncobj_timeline_wait args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.points = (uintptr_t)points;
    args.timeout_nsec = timeout_nsec;
    args.count_handles = num_handles;
    args.flags = flags;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT, &args);
    if (ret < 0)
        return -errno;

    if (first_signaled)
        *first_signaled = args.first_signaled;
    return ret;
}


drm_public int drmSyncobjQuery(int fd, uint32_t *handles, uint64_t *points,
			       uint32_t handle_count)
{
    struct drm_syncobj_timeline_array args;
    int ret;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.points = (uintptr_t)points;
    args.count_handles = handle_count;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_QUERY, &args);
    if (ret)
        return ret;
    return 0;
}

drm_public int drmSyncobjQuery2(int fd, uint32_t *handles, uint64_t *points,
				uint32_t handle_count, uint32_t flags)
{
    struct drm_syncobj_timeline_array args;

    memclear(args);
    args.handles = (uintptr_t)handles;
    args.points = (uintptr_t)points;
    args.count_handles = handle_count;
    args.flags = flags;

    return drmIoctl(fd, DRM_IOCTL_SYNCOBJ_QUERY, &args);
}


drm_public int drmSyncobjTransfer(int fd,
				  uint32_t dst_handle, uint64_t dst_point,
				  uint32_t src_handle, uint64_t src_point,
				  uint32_t flags)
{
    struct drm_syncobj_transfer args;
    int ret;

    memclear(args);
    args.src_handle = src_handle;
    args.dst_handle = dst_handle;
    args.src_point = src_point;
    args.dst_point = dst_point;
    args.flags = flags;

    ret = drmIoctl(fd, DRM_IOCTL_SYNCOBJ_TRANSFER, &args);

    return ret;
}

drm_public int drmSyncobjEventfd(int fd, uint32_t handle, uint64_t point, int ev_fd,
                                 uint32_t flags)
{
    struct drm_syncobj_eventfd args;

    memclear(args);
    args.handle = handle;
    args.point = point;
    args.fd = ev_fd;
    args.flags = flags;

    return drmIoctl(fd, DRM_IOCTL_SYNCOBJ_EVENTFD, &args);
}

static char *
drmGetFormatModifierFromSimpleTokens(uint64_t modifier)
{
    unsigned int i;

    for (i = 0; i < ARRAY_SIZE(drm_format_modifier_table); i++) {
        if (drm_format_modifier_table[i].modifier == modifier)
            return strdup(drm_format_modifier_table[i].modifier_name);
    }

    return NULL;
}

/** Retrieves a human-readable representation of a vendor (as a string) from
 * the format token modifier
 *
 * \param modifier the format modifier token
 * \return a char pointer to the human-readable form of the vendor. Caller is
 * responsible for freeing it.
 */
drm_public char *
drmGetFormatModifierVendor(uint64_t modifier)
{
    unsigned int i;
    uint8_t vendor = fourcc_mod_get_vendor(modifier);

    for (i = 0; i < ARRAY_SIZE(drm_format_modifier_vendor_table); i++) {
        if (drm_format_modifier_vendor_table[i].vendor == vendor)
            return strdup(drm_format_modifier_vendor_table[i].vendor_name);
    }

    return NULL;
}

/** Retrieves a human-readable representation string from a format token
 * modifier
 *
 * If the dedicated function was not able to extract a valid name or searching
 * the format modifier was not in the table, this function would return NULL.
 *
 * \param modifier the token format
 * \return a malloc'ed string representation of the modifier. Caller is
 * responsible for freeing the string returned.
 *
 */
drm_public char *
drmGetFormatModifierName(uint64_t modifier)
{
    uint8_t vendorid = fourcc_mod_get_vendor(modifier);
    char *modifier_found = NULL;
    unsigned int i;

    for (i = 0; i < ARRAY_SIZE(modifier_format_vendor_table); i++) {
        if (modifier_format_vendor_table[i].vendor == vendorid)
            modifier_found = modifier_format_vendor_table[i].vendor_cb(modifier);
    }

    if (!modifier_found)
        return drmGetFormatModifierFromSimpleTokens(modifier);

    return modifier_found;
}

/**
 * Get a human-readable name for a DRM FourCC format.
 *
 * \param format The format.
 * \return A malloc'ed string containing the format name. Caller is responsible
 * for freeing it.
 */
drm_public char *
drmGetFormatName(uint32_t format)
{
    char *str, code[5];
    const char *be;
    size_t str_size, i;

    be = (format & DRM_FORMAT_BIG_ENDIAN) ? "_BE" : "";
    format &= ~DRM_FORMAT_BIG_ENDIAN;

    if (format == DRM_FORMAT_INVALID)
        return strdup("INVALID");

    code[0] = (char) ((format >> 0) & 0xFF);
    code[1] = (char) ((format >> 8) & 0xFF);
    code[2] = (char) ((format >> 16) & 0xFF);
    code[3] = (char) ((format >> 24) & 0xFF);
    code[4] = '\0';

    /* Trim spaces at the end */
    for (i = 3; i > 0 && code[i] == ' '; i--)
        code[i] = '\0';

    str_size = strlen(code) + strlen(be) + 1;
    str = malloc(str_size);
    if (!str)
        return NULL;

    snprintf(str, str_size, "%s%s", code, be);

    return str;
}