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