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