1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <hardware/hardware.h>
18
19 #include <cutils/properties.h>
20
21 #include <dlfcn.h>
22 #include <string.h>
23 #include <pthread.h>
24 #include <errno.h>
25 #include <limits.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <unistd.h>
29
30 #define LOG_TAG "HAL"
31 #include <log/log.h>
32
33 #if !defined(__ANDROID_RECOVERY__) && defined(__ANDROID__)
34 #include <vndksupport/linker.h>
35 #endif
36
37 #ifdef __ANDROID_APEX__
38 #include <android/apexsupport.h>
39 #endif
40
41 /** Base path of the hal modules */
42 #if defined(__LP64__)
43 #define HAL_LIBRARY_SUBDIR "lib64/hw"
44 #else
45 #define HAL_LIBRARY_SUBDIR "lib/hw"
46 #endif
47
48 #define HAL_LIBRARY_PATH1 "/system/" HAL_LIBRARY_SUBDIR
49 #define HAL_LIBRARY_PATH2 "/vendor/" HAL_LIBRARY_SUBDIR
50 #define HAL_LIBRARY_PATH3 "/odm/" HAL_LIBRARY_SUBDIR
51
52 /**
53 * There are a set of variant filename for modules. The form of the filename
54 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
55 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
56 *
57 * led.trout.so
58 * led.msm7k.so
59 * led.ARMV6.so
60 * led.default.so
61 */
62
63 static const char *variant_keys[] = {
64 "ro.hardware", /* This goes first so that it can pick up a different
65 file on the emulator. */
66 "ro.product.board",
67 "ro.board.platform",
68 "ro.arch"
69 };
70
71 static const int HAL_VARIANT_KEYS_COUNT =
72 (sizeof(variant_keys)/sizeof(variant_keys[0]));
73
74 /**
75 * Load the file defined by the variant and if successful
76 * return the dlopen handle and the hmi.
77 * @return 0 = success, !0 = failure.
78 */
load(const char * id,const char * path,const struct hw_module_t ** pHmi)79 static int load(const char *id,
80 const char *path,
81 const struct hw_module_t **pHmi)
82 {
83 int status = -EINVAL;
84 void *handle = NULL;
85 struct hw_module_t *hmi = NULL;
86 #if defined(__ANDROID_VNDK__) || defined(__ANDROID_APEX__)
87 const bool try_system = false;
88 #else
89 const bool try_system = true;
90 #endif
91
92 /*
93 * load the symbols resolving undefined symbols before
94 * dlopen returns. Since RTLD_GLOBAL is not or'd in with
95 * RTLD_NOW the external symbols will not be global
96 */
97 if (try_system &&
98 strncmp(path, HAL_LIBRARY_PATH1, strlen(HAL_LIBRARY_PATH1)) == 0) {
99 /* If the library is in system partition, no need to check
100 * sphal namespace. Open it with dlopen.
101 */
102 handle = dlopen(path, RTLD_NOW);
103 } else {
104 #if defined(__ANDROID_RECOVERY__) || !defined(__ANDROID__) || defined(__ANDROID_APEX__)
105 handle = dlopen(path, RTLD_NOW);
106 #else
107 handle = android_load_sphal_library(path, RTLD_NOW);
108 #endif
109 }
110 if (handle == NULL) {
111 char const *err_str = dlerror();
112 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
113 status = -EINVAL;
114 goto done;
115 }
116
117 /* Get the address of the struct hal_module_info. */
118 const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
119 hmi = (struct hw_module_t *)dlsym(handle, sym);
120 if (hmi == NULL) {
121 ALOGE("load: couldn't find symbol %s", sym);
122 status = -EINVAL;
123 goto done;
124 }
125
126 /* Check that the id matches */
127 if (strcmp(id, hmi->id) != 0) {
128 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
129 status = -EINVAL;
130 goto done;
131 }
132
133 hmi->dso = handle;
134
135 /* success */
136 status = 0;
137
138 done:
139 if (status != 0) {
140 hmi = NULL;
141 if (handle != NULL) {
142 dlclose(handle);
143 handle = NULL;
144 }
145 } else {
146 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
147 id, path, hmi, handle);
148 }
149
150 *pHmi = hmi;
151
152 return status;
153 }
154
155 /*
156 * If path is in in_path.
157 */
path_in_path(const char * path,const char * in_path)158 static bool __attribute__ ((unused)) path_in_path(const char *path, const char *in_path) {
159 char real_path[PATH_MAX];
160 if (realpath(path, real_path) == NULL) return false;
161
162 char real_in_path[PATH_MAX];
163 if (realpath(in_path, real_in_path) == NULL) return false;
164
165 const size_t real_in_path_len = strlen(real_in_path);
166 if (strncmp(real_path, real_in_path, real_in_path_len) != 0) {
167 return false;
168 }
169
170 return strlen(real_path) > real_in_path_len &&
171 real_path[real_in_path_len] == '/';
172 }
173
174 /*
175 * Check if a HAL with given name and subname exists, if so return 0, otherwise
176 * otherwise return negative. On success path will contain the path to the HAL.
177 */
hw_module_exists(char * path,size_t path_len,const char * name,const char * subname)178 static int hw_module_exists(char *path, size_t path_len, const char *name,
179 const char *subname)
180 {
181 #ifdef __ANDROID_APEX__
182 // When used in VAPEX, it should look only into the same APEX because
183 // libhardware modules don't provide ABI stability.
184 if (__builtin_available(android __ANDROID_API_V__, *)) {
185 AApexInfo *apex_info;
186 if (AApexInfo_create(&apex_info) == AAPEXINFO_OK) {
187 snprintf(path, path_len, "/apex/%s/%s/%s.%s.so",
188 AApexInfo_getName(apex_info), HAL_LIBRARY_SUBDIR, name, subname);
189 AApexInfo_destroy(apex_info);
190 if (access(path, R_OK) == 0)
191 return 0;
192 }
193 }
194 #else // __ANDROID_APEX__
195 snprintf(path, path_len, "%s/%s.%s.so",
196 HAL_LIBRARY_PATH3, name, subname);
197 if (path_in_path(path, HAL_LIBRARY_PATH3) && access(path, R_OK) == 0)
198 return 0;
199
200 snprintf(path, path_len, "%s/%s.%s.so",
201 HAL_LIBRARY_PATH2, name, subname);
202 if (path_in_path(path, HAL_LIBRARY_PATH2) && access(path, R_OK) == 0)
203 return 0;
204
205 #ifndef __ANDROID_VNDK__
206 snprintf(path, path_len, "%s/%s.%s.so",
207 HAL_LIBRARY_PATH1, name, subname);
208 if (path_in_path(path, HAL_LIBRARY_PATH1) && access(path, R_OK) == 0)
209 return 0;
210 #endif
211
212 #endif // __ANDROID_APEX__
213
214 return -ENOENT;
215 }
216
hw_get_module_by_class(const char * class_id,const char * inst,const struct hw_module_t ** module)217 int hw_get_module_by_class(const char *class_id, const char *inst,
218 const struct hw_module_t **module)
219 {
220 int i = 0;
221 char prop[PATH_MAX] = {0};
222 char path[PATH_MAX] = {0};
223 char name[PATH_MAX] = {0};
224 char prop_name[PATH_MAX] = {0};
225
226
227 if (inst)
228 snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
229 #if defined(__ANDROID__)
230 else
231 strlcpy(name, class_id, PATH_MAX);
232 #else
233 else
234 snprintf(name, PATH_MAX, "%s", class_id);
235 #endif
236
237 /*
238 * Here we rely on the fact that calling dlopen multiple times on
239 * the same .so will simply increment a refcount (and not load
240 * a new copy of the library).
241 * We also assume that dlopen() is thread-safe.
242 */
243
244 /* First try a property specific to the class and possibly instance */
245 snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
246 if (property_get(prop_name, prop, NULL) > 0) {
247 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
248 goto found;
249 }
250 }
251
252 /* Loop through the configuration variants looking for a module */
253 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
254 if (property_get(variant_keys[i], prop, NULL) == 0) {
255 continue;
256 }
257 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
258 goto found;
259 }
260 }
261
262 /* Nothing found, try the default */
263 if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
264 goto found;
265 }
266
267 return -ENOENT;
268
269 found:
270 /* load the module, if this fails, we're doomed, and we should not try
271 * to load a different variant. */
272 return load(class_id, path, module);
273 }
274
hw_get_module(const char * id,const struct hw_module_t ** module)275 int hw_get_module(const char *id, const struct hw_module_t **module)
276 {
277 return hw_get_module_by_class(id, NULL, module);
278 }
279