Contents of /trunk/mkinitrd-magellan/busybox/libbb/copy_file.c
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Fri Apr 24 18:33:46 2009 UTC (15 years, 5 months ago) by niro
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Fri Apr 24 18:33:46 2009 UTC (15 years, 5 months ago) by niro
File MIME type: text/plain
File size: 11664 byte(s)
-updated to busybox-1.13.4
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini copy_file implementation for busybox |
4 | * |
5 | * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu> |
6 | * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp> |
7 | * |
8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
9 | * |
10 | */ |
11 | |
12 | #include "libbb.h" |
13 | |
14 | // POSIX: if exists and -i, ask (w/o -i assume yes). |
15 | // Then open w/o EXCL (yes, not unlink!). |
16 | // If open still fails and -f, try unlink, then try open again. |
17 | // Result: a mess: |
18 | // If dest is a softlink, we overwrite softlink's destination! |
19 | // (or fail, if it points to dir/nonexistent location/etc). |
20 | // This is strange, but POSIX-correct. |
21 | // coreutils cp has --remove-destination to override this... |
22 | // |
23 | // NB: we have special code which still allows for "cp file /dev/node" |
24 | // to work POSIX-ly (the only realistic case where it makes sense) |
25 | |
26 | #define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */ |
27 | |
28 | // errno must be set to relevant value ("why we cannot create dest?") |
29 | // for POSIX mode to give reasonable error message |
30 | static int ask_and_unlink(const char *dest, int flags) |
31 | { |
32 | int e = errno; |
33 | #if DO_POSIX_CP |
34 | if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) { |
35 | // Either it exists, or the *path* doesnt exist |
36 | bb_perror_msg("cannot create '%s'", dest); |
37 | return -1; |
38 | } |
39 | #endif |
40 | // If !DO_POSIX_CP, act as if -f is always in effect - we don't want |
41 | // "cannot create" msg, we want unlink to be done (silently unless -i). |
42 | |
43 | // TODO: maybe we should do it only if ctty is present? |
44 | if (flags & FILEUTILS_INTERACTIVE) { |
45 | // We would not do POSIX insanity. -i asks, |
46 | // then _unlinks_ the offender. Presto. |
47 | // (No "opening without O_EXCL", no "unlink only if -f") |
48 | // Or else we will end up having 3 open()s! |
49 | fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest); |
50 | if (!bb_ask_confirmation()) |
51 | return 0; // not allowed to overwrite |
52 | } |
53 | if (unlink(dest) < 0) { |
54 | #if ENABLE_FEATURE_VERBOSE_CP_MESSAGE |
55 | if (e == errno && e == ENOENT) { |
56 | /* e == ENOTDIR is similar: path has non-dir component, |
57 | * but in this case we don't even reach copy_file() */ |
58 | bb_error_msg("cannot create '%s': Path does not exist", dest); |
59 | return -1; // error |
60 | } |
61 | #endif |
62 | errno = e; |
63 | bb_perror_msg("cannot create '%s'", dest); |
64 | return -1; // error |
65 | } |
66 | return 1; // ok (to try again) |
67 | } |
68 | |
69 | /* Return: |
70 | * -1 error, copy not made |
71 | * 0 copy is made or user answered "no" in interactive mode |
72 | * (failures to preserve mode/owner/times are not reported in exit code) |
73 | */ |
74 | int FAST_FUNC copy_file(const char *source, const char *dest, int flags) |
75 | { |
76 | /* This is a recursive function, try to minimize stack usage */ |
77 | /* NB: each struct stat is ~100 bytes */ |
78 | struct stat source_stat; |
79 | struct stat dest_stat; |
80 | signed char retval = 0; |
81 | signed char dest_exists = 0; |
82 | signed char ovr; |
83 | |
84 | /* Inverse of cp -d ("cp without -d") */ |
85 | #define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE) |
86 | |
87 | if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) { |
88 | // This may be a dangling symlink. |
89 | // Making [sym]links to dangling symlinks works, so... |
90 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) |
91 | goto make_links; |
92 | bb_perror_msg("cannot stat '%s'", source); |
93 | return -1; |
94 | } |
95 | |
96 | if (lstat(dest, &dest_stat) < 0) { |
97 | if (errno != ENOENT) { |
98 | bb_perror_msg("cannot stat '%s'", dest); |
99 | return -1; |
100 | } |
101 | } else { |
102 | if (source_stat.st_dev == dest_stat.st_dev |
103 | && source_stat.st_ino == dest_stat.st_ino |
104 | ) { |
105 | bb_error_msg("'%s' and '%s' are the same file", source, dest); |
106 | return -1; |
107 | } |
108 | dest_exists = 1; |
109 | } |
110 | |
111 | #if ENABLE_SELINUX |
112 | if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) { |
113 | security_context_t con; |
114 | if (lgetfilecon(source, &con) >= 0) { |
115 | if (setfscreatecon(con) < 0) { |
116 | bb_perror_msg("cannot set setfscreatecon %s", con); |
117 | freecon(con); |
118 | return -1; |
119 | } |
120 | } else if (errno == ENOTSUP || errno == ENODATA) { |
121 | setfscreatecon_or_die(NULL); |
122 | } else { |
123 | bb_perror_msg("cannot lgetfilecon %s", source); |
124 | return -1; |
125 | } |
126 | } |
127 | #endif |
128 | |
129 | if (S_ISDIR(source_stat.st_mode)) { |
130 | DIR *dp; |
131 | const char *tp; |
132 | struct dirent *d; |
133 | mode_t saved_umask = 0; |
134 | |
135 | if (!(flags & FILEUTILS_RECUR)) { |
136 | bb_error_msg("omitting directory '%s'", source); |
137 | return -1; |
138 | } |
139 | |
140 | /* Did we ever create source ourself before? */ |
141 | tp = is_in_ino_dev_hashtable(&source_stat); |
142 | if (tp) { |
143 | /* We did! it's a recursion! man the lifeboats... */ |
144 | bb_error_msg("recursion detected, omitting directory '%s'", |
145 | source); |
146 | return -1; |
147 | } |
148 | |
149 | /* Create DEST */ |
150 | if (dest_exists) { |
151 | if (!S_ISDIR(dest_stat.st_mode)) { |
152 | bb_error_msg("target '%s' is not a directory", dest); |
153 | return -1; |
154 | } |
155 | /* race here: user can substitute a symlink between |
156 | * this check and actual creation of files inside dest */ |
157 | } else { |
158 | mode_t mode; |
159 | saved_umask = umask(0); |
160 | |
161 | mode = source_stat.st_mode; |
162 | if (!(flags & FILEUTILS_PRESERVE_STATUS)) |
163 | mode = source_stat.st_mode & ~saved_umask; |
164 | /* Allow owner to access new dir (at least for now) */ |
165 | mode |= S_IRWXU; |
166 | if (mkdir(dest, mode) < 0) { |
167 | umask(saved_umask); |
168 | bb_perror_msg("cannot create directory '%s'", dest); |
169 | return -1; |
170 | } |
171 | umask(saved_umask); |
172 | /* need stat info for add_to_ino_dev_hashtable */ |
173 | if (lstat(dest, &dest_stat) < 0) { |
174 | bb_perror_msg("cannot stat '%s'", dest); |
175 | return -1; |
176 | } |
177 | } |
178 | /* remember (dev,inode) of each created dir. |
179 | * NULL: name is not remembered */ |
180 | add_to_ino_dev_hashtable(&dest_stat, NULL); |
181 | |
182 | /* Recursively copy files in SOURCE */ |
183 | dp = opendir(source); |
184 | if (dp == NULL) { |
185 | retval = -1; |
186 | goto preserve_mode_ugid_time; |
187 | } |
188 | |
189 | while ((d = readdir(dp)) != NULL) { |
190 | char *new_source, *new_dest; |
191 | |
192 | new_source = concat_subpath_file(source, d->d_name); |
193 | if (new_source == NULL) |
194 | continue; |
195 | new_dest = concat_path_file(dest, d->d_name); |
196 | if (copy_file(new_source, new_dest, flags) < 0) |
197 | retval = -1; |
198 | free(new_source); |
199 | free(new_dest); |
200 | } |
201 | closedir(dp); |
202 | |
203 | if (!dest_exists |
204 | && chmod(dest, source_stat.st_mode & ~saved_umask) < 0 |
205 | ) { |
206 | bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest); |
207 | /* retval = -1; - WRONG! copy *WAS* made */ |
208 | } |
209 | goto preserve_mode_ugid_time; |
210 | } |
211 | |
212 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) { |
213 | int (*lf)(const char *oldpath, const char *newpath); |
214 | make_links: |
215 | // Hmm... maybe |
216 | // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ? |
217 | // (but realpath returns NULL on dangling symlinks...) |
218 | lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link; |
219 | if (lf(source, dest) < 0) { |
220 | ovr = ask_and_unlink(dest, flags); |
221 | if (ovr <= 0) |
222 | return ovr; |
223 | if (lf(source, dest) < 0) { |
224 | bb_perror_msg("cannot create link '%s'", dest); |
225 | return -1; |
226 | } |
227 | } |
228 | /* _Not_ jumping to preserve_mode_ugid_time: |
229 | * hard/softlinks don't have those */ |
230 | return 0; |
231 | } |
232 | |
233 | if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */ |
234 | !(flags & FILEUTILS_RECUR) |
235 | /* "cp [-opts] regular_file thing2" */ |
236 | || S_ISREG(source_stat.st_mode) |
237 | /* DEREF uses stat, which never returns S_ISLNK() == true. |
238 | * So the below is never true: */ |
239 | /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */ |
240 | ) { |
241 | int src_fd; |
242 | int dst_fd; |
243 | mode_t new_mode; |
244 | |
245 | if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) { |
246 | /* "cp -d symlink dst": create a link */ |
247 | goto dont_cat; |
248 | } |
249 | |
250 | if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) { |
251 | const char *link_target; |
252 | link_target = is_in_ino_dev_hashtable(&source_stat); |
253 | if (link_target) { |
254 | if (link(link_target, dest) < 0) { |
255 | ovr = ask_and_unlink(dest, flags); |
256 | if (ovr <= 0) |
257 | return ovr; |
258 | if (link(link_target, dest) < 0) { |
259 | bb_perror_msg("cannot create link '%s'", dest); |
260 | return -1; |
261 | } |
262 | } |
263 | return 0; |
264 | } |
265 | add_to_ino_dev_hashtable(&source_stat, dest); |
266 | } |
267 | |
268 | src_fd = open_or_warn(source, O_RDONLY); |
269 | if (src_fd < 0) |
270 | return -1; |
271 | |
272 | /* Do not try to open with weird mode fields */ |
273 | new_mode = source_stat.st_mode; |
274 | if (!S_ISREG(source_stat.st_mode)) |
275 | new_mode = 0666; |
276 | |
277 | /* POSIX way is a security problem versus symlink attacks, |
278 | * we do it only for non-symlinks, and only for non-recursive, |
279 | * non-interactive cp. NB: it is still racy |
280 | * for "cp file /home/bad_user/file" case |
281 | * (user can rm file and create a link to /etc/passwd) */ |
282 | if (DO_POSIX_CP |
283 | || (dest_exists |
284 | && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE)) |
285 | && !S_ISLNK(dest_stat.st_mode)) |
286 | ) { |
287 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode); |
288 | } else /* safe way: */ |
289 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode); |
290 | if (dst_fd == -1) { |
291 | ovr = ask_and_unlink(dest, flags); |
292 | if (ovr <= 0) { |
293 | close(src_fd); |
294 | return ovr; |
295 | } |
296 | /* It shouldn't exist. If it exists, do not open (symlink attack?) */ |
297 | dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode); |
298 | if (dst_fd < 0) { |
299 | close(src_fd); |
300 | return -1; |
301 | } |
302 | } |
303 | |
304 | #if ENABLE_SELINUX |
305 | if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT)) |
306 | && is_selinux_enabled() > 0 |
307 | ) { |
308 | security_context_t con; |
309 | if (getfscreatecon(&con) == -1) { |
310 | bb_perror_msg("getfscreatecon"); |
311 | return -1; |
312 | } |
313 | if (con) { |
314 | if (setfilecon(dest, con) == -1) { |
315 | bb_perror_msg("setfilecon:%s,%s", dest, con); |
316 | freecon(con); |
317 | return -1; |
318 | } |
319 | freecon(con); |
320 | } |
321 | } |
322 | #endif |
323 | if (bb_copyfd_eof(src_fd, dst_fd) == -1) |
324 | retval = -1; |
325 | /* Ok, writing side I can understand... */ |
326 | if (close(dst_fd) < 0) { |
327 | bb_perror_msg("cannot close '%s'", dest); |
328 | retval = -1; |
329 | } |
330 | /* ...but read size is already checked by bb_copyfd_eof */ |
331 | close(src_fd); |
332 | /* "cp /dev/something new_file" should not |
333 | * copy mode of /dev/something */ |
334 | if (!S_ISREG(source_stat.st_mode)) |
335 | return retval; |
336 | goto preserve_mode_ugid_time; |
337 | } |
338 | dont_cat: |
339 | |
340 | /* Source is a symlink or a special file */ |
341 | /* We are lazy here, a bit lax with races... */ |
342 | if (dest_exists) { |
343 | errno = EEXIST; |
344 | ovr = ask_and_unlink(dest, flags); |
345 | if (ovr <= 0) |
346 | return ovr; |
347 | } |
348 | if (S_ISLNK(source_stat.st_mode)) { |
349 | char *lpath = xmalloc_readlink_or_warn(source); |
350 | if (lpath) { |
351 | int r = symlink(lpath, dest); |
352 | free(lpath); |
353 | if (r < 0) { |
354 | bb_perror_msg("cannot create symlink '%s'", dest); |
355 | return -1; |
356 | } |
357 | if (flags & FILEUTILS_PRESERVE_STATUS) |
358 | if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0) |
359 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest); |
360 | } |
361 | /* _Not_ jumping to preserve_mode_ugid_time: |
362 | * symlinks don't have those */ |
363 | return 0; |
364 | } |
365 | if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode) |
366 | || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode) |
367 | ) { |
368 | if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) { |
369 | bb_perror_msg("cannot create '%s'", dest); |
370 | return -1; |
371 | } |
372 | } else { |
373 | bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode); |
374 | return -1; |
375 | } |
376 | |
377 | preserve_mode_ugid_time: |
378 | |
379 | if (flags & FILEUTILS_PRESERVE_STATUS |
380 | /* Cannot happen: */ |
381 | /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */ |
382 | ) { |
383 | struct utimbuf times; |
384 | |
385 | times.actime = source_stat.st_atime; |
386 | times.modtime = source_stat.st_mtime; |
387 | /* BTW, utimes sets usec-precision time - just FYI */ |
388 | if (utime(dest, ×) < 0) |
389 | bb_perror_msg("cannot preserve %s of '%s'", "times", dest); |
390 | if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) { |
391 | source_stat.st_mode &= ~(S_ISUID | S_ISGID); |
392 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest); |
393 | } |
394 | if (chmod(dest, source_stat.st_mode) < 0) |
395 | bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest); |
396 | } |
397 | |
398 | return retval; |
399 | } |