1 /* cpio.c - a basic cpio
2 *
3 * Copyright 2013 Isaac Dunham <[email protected]>
4 * Copyright 2015 Frontier Silicon Ltd.
5 *
6 * see https://www.kernel.org/doc/Documentation/early-userspace/buffer-format.txt
7 * and http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/cpio.html
8 * and http://pubs.opengroup.org/onlinepubs/7908799/xcu/cpio.html
9 *
10 * Yes, that's SUSv2, newer versions removed it, but RPM and initramfs use
11 * this archive format. We implement (only) the modern "-H newc" variant which
12 * expanded headers to 110 bytes (first field 6 bytes, rest are 8).
13 * In order: magic ino mode uid gid nlink mtime filesize devmajor devminor
14 * rdevmajor rdevminor namesize check
15 * This is the equivalent of mode -H newc in other implementations.
16 * We always do --quiet, but accept it as a compatibility NOP.
17 *
18 * TODO: export/import linux file list text format ala gen_initramfs_list.sh
19 * TODO: hardlink support, -A, -0, -a, -L, --sparse
20 * TODO: --renumber-archives (probably always?) --ignore-devno --reproducible
21
22 USE_CPIO(NEWTOY(cpio, "(ignore-devno)(renumber-inodes)(quiet)(no-preserve-owner)R(owner):md(make-directories)uLH:p|i|t|F:v(verbose)o|[!pio][!pot][!pF]", TOYFLAG_BIN))
23
24 config CPIO
25 bool "cpio"
26 default y
27 help
28 usage: cpio -{o|t|i|p DEST} [-dLtuv] [--verbose] [-F FILE] [-R [USER][:GROUP] [--no-preserve-owner]
29
30 Copy files into and out of a "newc" format cpio archive.
31
32 -d Create directories if needed
33 -F FILE Use archive FILE instead of stdin/stdout
34 -i Extract from archive into file system (stdin=archive)
35 -L Follow symlinks
36 -o Create archive (stdin=list of files, stdout=archive)
37 -p DEST Copy-pass mode, copy stdin file list to directory DEST
38 -R USER Replace owner with USER[:GROUP]
39 -t Test files (list only, stdin=archive, stdout=list of files)
40 -u Unlink existing files when extracting
41 -v Verbose
42 --no-preserve-owner Don't set ownership during extract
43 */
44
45 #define FOR_cpio
46 #include "toys.h"
47
48 GLOBALS(
49 char *F, *H, *R;
50 )
51
52 // Read strings, tail padded to 4 byte alignment. Argument "align" is amount
53 // by which start of string isn't aligned (usually 0, but header is 110 bytes
54 // which is 2 bytes off because the first field wasn't expanded from 6 to 8).
strpad(int fd,unsigned len,unsigned align)55 static char *strpad(int fd, unsigned len, unsigned align)
56 {
57 char *str;
58
59 align = (align + len) & 3;
60 if (align) len += (4-align);
61 xreadall(fd, str = xmalloc(len+1), len);
62 str[len]=0; // redundant, in case archive is bad
63
64 return str;
65 }
66
67 //convert hex to uint; mostly to allow using bits of non-terminated strings
x8u(char * hex)68 static unsigned x8u(char *hex)
69 {
70 unsigned val, inpos = 8, outpos;
71 char pattern[6];
72
73 while (*hex == '0') {
74 hex++;
75 if (!--inpos) return 0;
76 }
77 // Because scanf gratuitously treats %*X differently than printf does.
78 sprintf(pattern, "%%%dX%%n", inpos);
79 sscanf(hex, pattern, &val, &outpos);
80 if (inpos != outpos) error_exit("bad hex");
81
82 return val;
83 }
84
cpio_main(void)85 void cpio_main(void)
86 {
87 int pipe, afd = FLAG(o), reown = !geteuid() && !FLAG(no_preserve_owner),
88 empty = 1;
89 pid_t pid = 0;
90 long Ruid = -1, Rgid = -1;
91 char *tofree = 0;
92
93 if (TT.R) {
94 char *group = TT.R+strcspn(TT.R, ":.");
95
96 if (*group) {
97 Rgid = xgetgid(group+1);
98 *group = 0;
99 }
100 if (group != TT.R) Ruid = xgetuid(TT.R);
101 }
102
103 // In passthrough mode, parent stays in original dir and generates archive
104 // to pipe, child does chdir to new dir and reads archive from stdin (pipe).
105 if (FLAG(p)) {
106 if (FLAG(d)) {
107 if (!*toys.optargs) error_exit("need directory for -p");
108 if (mkdir(*toys.optargs, 0700) == -1 && errno != EEXIST)
109 perror_msg("mkdir %s", *toys.optargs);
110 }
111 if (toys.stacktop) {
112 // xpopen() doesn't return from child due to vfork(), instead restarts
113 // with !toys.stacktop
114 pid = xpopen(0, &pipe, 0);
115 afd = pipe;
116 } else {
117 // child
118 toys.optflags |= FLAG_i;
119 xchdir(*toys.optargs);
120 }
121 }
122
123 if (TT.F) {
124 int perm = FLAG(o) ? O_CREAT|O_WRONLY|O_TRUNC : O_RDONLY;
125
126 afd = xcreate(TT.F, perm, 0644);
127 }
128
129 // read cpio archive
130
131 if (FLAG(i) || FLAG(t)) for (;; empty = 0) {
132 char *name, *data;
133 unsigned mode, uid, gid, timestamp;
134 int test = FLAG(t), err = 0, size = 0, len;
135
136 free(tofree);
137 tofree = 0;
138 // read header, skipping arbitrary leading NUL bytes (concatenated archives)
139 for (;;) {
140 if (1>(len = readall(afd, toybuf+size, 110-size))) break;
141 if (size || *toybuf) {
142 size += len;
143 break;
144 }
145 for (size = 0; size<len; size++) if (toybuf[size]) break;
146 memmove(toybuf, toybuf+size, len-size);
147 size = len-size;
148 }
149 if (!size) {
150 if (empty) error_exit("empty archive");
151 else break;
152 }
153 if (size != 110 || smemcmp(toybuf, "070701", 6)) error_exit("bad header");
154 tofree = name = strpad(afd, x8u(toybuf+94), 110);
155 // TODO: this flushes hardlink detection via major/minor/ino match
156 if (!strcmp("TRAILER!!!", name)) continue;
157
158 // If you want to extract absolute paths, "cd /" and run cpio.
159 while (*name == '/') name++;
160 // TODO: remove .. entries
161
162 size = x8u(toybuf+54);
163 mode = x8u(toybuf+14);
164 uid = (Ruid>=0) ? Ruid : x8u(toybuf+22);
165 gid = (Rgid>=0) ? Rgid : x8u(toybuf+30);
166 timestamp = x8u(toybuf+46); // unsigned 32 bit, so year 2100 problem
167
168 // (This output is unaffected by --quiet.)
169 if (FLAG(t) || FLAG(v)) puts(name);
170
171 if (FLAG(u) && !test) if (unlink(name) && errno == EISDIR) rmdir(name);
172
173 if (!test && FLAG(d) && strrchr(name, '/') && mkpath(name)) {
174 perror_msg("mkpath '%s'", name);
175 test++;
176 }
177
178 // Consume entire record even if it couldn't create file, so we're
179 // properly aligned with next file.
180
181 if (S_ISDIR(mode)) {
182 if (test) continue;
183 err = mkdir(name, mode) && (errno != EEXIST && !FLAG(u));
184
185 // Creading dir/dev doesn't give us a filehandle, we have to refer to it
186 // by name to chown/utime, but how do we know it's the same item?
187 // Check that we at least have the right type of entity open, and do
188 // NOT restore dropped suid bit in this case.
189 if (S_ISDIR(mode) && reown) {
190 int fd = open(name, O_RDONLY|O_NOFOLLOW);
191 struct stat st;
192
193 if (fd != -1 && !fstat(fd, &st) && (st.st_mode&S_IFMT) == (mode&S_IFMT))
194 err = fchown(fd, uid, gid);
195 else err = 1;
196
197 close(fd);
198 }
199 } else if (S_ISREG(mode)) {
200 int fd = test ? 0 : open(name, O_CREAT|O_WRONLY|O_EXCL|O_NOFOLLOW, mode);
201
202 // If write fails, we still need to read/discard data to continue with
203 // archive. Since doing so overwrites errno, report error now
204 if (fd < 0) {
205 perror_msg("create %s", name);
206 test++;
207 }
208
209 data = toybuf;
210 while (size) {
211 if (size < sizeof(toybuf)) data = strpad(afd, size, 0);
212 else xreadall(afd, toybuf, sizeof(toybuf));
213 if (!test) xwrite(fd, data, data == toybuf ? sizeof(toybuf) : size);
214 if (data != toybuf) {
215 free(data);
216 break;
217 }
218 size -= sizeof(toybuf);
219 }
220
221 if (!test) {
222 // set owner, restore dropped suid bit
223 if (reown) err = fchown(fd, uid, gid) && fchmod(fd, mode);
224 close(fd);
225 }
226 } else {
227 data = S_ISLNK(mode) ? strpad(afd, size, 0) : 0;
228 if (!test) {
229 err = data ? symlink(data, name)
230 : mknod(name, mode, dev_makedev(x8u(toybuf+78), x8u(toybuf+86)));
231
232 // Can't get a filehandle to a symlink or a node on nodev mount,
233 // so do special chown that at least doesn't follow symlinks.
234 // We also don't chmod after, so dropped suid bit isn't restored
235 if (!err && reown) err = lchown(name, uid, gid);
236 }
237 free(data);
238 }
239
240 // Set timestamp.
241 if (!test && !err) {
242 struct timespec times[2];
243
244 memset(times, 0, sizeof(struct timespec)*2);
245 times[0].tv_sec = times[1].tv_sec = timestamp;
246 err = utimensat(AT_FDCWD, name, times, AT_SYMLINK_NOFOLLOW);
247 }
248
249 if (err) perror_msg_raw(name);
250
251 // Output cpio archive
252
253 } else {
254 char *name = 0;
255 size_t size = 0;
256 unsigned inode = 0;
257
258 for (;;) {
259 struct stat st;
260 unsigned nlen, error = 0, zero = 0;
261 int len, fd = -1;
262 char *link = 0;
263 ssize_t llen;
264
265 len = getline(&name, &size, stdin);
266 if (len<1) break;
267 if (name[len-1] == '\n') name[--len] = 0;
268 if (!len) continue;
269 nlen = len+1;
270 if ((FLAG(L)?stat:lstat)(name, &st) || (S_ISREG(st.st_mode)
271 && st.st_size && (fd = open(name, O_RDONLY))<0)
272 || (S_ISLNK(st.st_mode) && !(link = xreadlink(name))))
273 {
274 perror_msg_raw(name);
275 continue;
276 }
277 // encrypted filesystems can stat the wrong link size
278 if (link) st.st_size = strlen(link);
279
280 if (Ruid>=0) st.st_uid = Ruid;
281 if (Rgid>=0) st.st_gid = Rgid;
282 if (FLAG(no_preserve_owner)) st.st_uid = st.st_gid = 0;
283 if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode)) st.st_size = 0;
284 if (st.st_size >> 32) perror_msg("skipping >2G file '%s'", name);
285 else {
286 if (FLAG(renumber_inodes)) st.st_ino = ++inode;
287 if (FLAG(ignore_devno)) st.st_rdev = 0;
288 llen = sprintf(toybuf,
289 "070701%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X",
290 (int)st.st_ino, st.st_mode, st.st_uid, st.st_gid, (int)st.st_nlink,
291 (int)st.st_mtime, (int)st.st_size, dev_major(st.st_dev),
292 dev_minor(st.st_dev), dev_major(st.st_rdev), dev_minor(st.st_rdev),
293 nlen, 0);
294 xwrite(afd, toybuf, llen);
295 xwrite(afd, name, nlen);
296
297 // NUL Pad header up to 4 multiple bytes.
298 llen = (llen + nlen) & 3;
299 if (llen) xwrite(afd, &zero, 4-llen);
300
301 // Write out body for symlink or regular file
302 if (link) xwrite(afd, link, st.st_size);
303 else for (llen = st.st_size; llen; llen -= nlen) {
304 nlen = llen > sizeof(toybuf) ? sizeof(toybuf) : llen;
305 // If read fails, write anyway (already wrote size in header)
306 if (nlen != readall(fd, toybuf, nlen))
307 if (!error++) perror_msg("bad read from file '%s'", name);
308 xwrite(afd, toybuf, nlen);
309 }
310 llen = st.st_size & 3;
311 if (llen) xwrite(afd, &zero, 4-llen);
312 }
313 free(link);
314 xclose(fd);
315 }
316 if (CFG_TOYBOX_FREE) free(name);
317
318 // nlink=1, namesize=11, with padding
319 dprintf(afd, "070701%040X%056X%08XTRAILER!!!%c%c%c%c", 1, 11, 0, 0, 0, 0,0);
320 }
321 if (TT.F) xclose(afd);
322
323 if (FLAG(p) && pid) toys.exitval |= xpclose(pid, pipe);
324 }
325