source: MondoRescue/branches/2.2.5/mindi-busybox/libbb/copy_file.c@ 1765

Last change on this file since 1765 was 1765, checked in by Bruno Cornec, 16 years ago

Update to busybox 1.7.2
File size: 10.5 KB
Line 
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
30static int ask_and_unlink(const char *dest, int flags)
31{
32#if DO_POSIX_CP
33 if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
34 // Either it exists, or the *path* doesnt exist
35 bb_perror_msg("cannot create '%s'", dest);
36 return -1;
37 }
38#endif
39 // If !DO_POSIX_CP, act as if -f is always in effect - we don't want
40 // "cannot create" msg, we want unlink to be done (silently unless -i).
41
42 // TODO: maybe we should do it only if ctty is present?
43 if (flags & FILEUTILS_INTERACTIVE) {
44 // We would not do POSIX insanity. -i asks,
45 // then _unlinks_ the offender. Presto.
46 // (No "opening without O_EXCL", no "unlink only if -f")
47 // Or else we will end up having 3 open()s!
48 fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
49 if (!bb_ask_confirmation())
50 return 0; // not allowed to overwrite
51 }
52 if (unlink(dest) < 0) {
53 bb_perror_msg("cannot remove '%s'", dest);
54 return -1; // error
55 }
56 return 1; // ok (to try again)
57}
58
59/* Return:
60 * -1 error, copy not made
61 * 0 copy is made or user answered "no" in interactive mode
62 * (failures to preserve mode/owner/times are not reported in exit code)
63 */
64int copy_file(const char *source, const char *dest, int flags)
65{
66 /* This is a recursive function, try to minimize stack usage */
67 /* NB: each struct stat is ~100 bytes */
68 struct stat source_stat;
69 struct stat dest_stat;
70 signed char retval = 0;
71 signed char dest_exists = 0;
72 signed char ovr;
73
74#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
75
76 if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
77 // This may be a dangling symlink.
78 // Making [sym]links to dangling symlinks works, so...
79 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
80 goto make_links;
81 bb_perror_msg("cannot stat '%s'", source);
82 return -1;
83 }
84
85 if (lstat(dest, &dest_stat) < 0) {
86 if (errno != ENOENT) {
87 bb_perror_msg("cannot stat '%s'", dest);
88 return -1;
89 }
90 } else {
91 if (source_stat.st_dev == dest_stat.st_dev
92 && source_stat.st_ino == dest_stat.st_ino
93 ) {
94 bb_error_msg("'%s' and '%s' are the same file", source, dest);
95 return -1;
96 }
97 dest_exists = 1;
98 }
99
100#if ENABLE_SELINUX
101 if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
102 security_context_t con;
103 if (lgetfilecon(source, &con) >= 0) {
104 if (setfscreatecon(con) < 0) {
105 bb_perror_msg("cannot set setfscreatecon %s", con);
106 freecon(con);
107 return -1;
108 }
109 } else if (errno == ENOTSUP || errno == ENODATA) {
110 setfscreatecon_or_die(NULL);
111 } else {
112 bb_perror_msg("cannot lgetfilecon %s", source);
113 return -1;
114 }
115 }
116#endif
117
118 if (S_ISDIR(source_stat.st_mode)) {
119 DIR *dp;
120 const char *tp;
121 struct dirent *d;
122 mode_t saved_umask = 0;
123
124 if (!(flags & FILEUTILS_RECUR)) {
125 bb_error_msg("omitting directory '%s'", source);
126 return -1;
127 }
128
129 /* Did we ever create source ourself before? */
130 tp = is_in_ino_dev_hashtable(&source_stat);
131 if (tp) {
132 /* We did! it's a recursion! man the lifeboats... */
133 bb_error_msg("recursion detected, omitting directory '%s'",
134 source);
135 return -1;
136 }
137
138 /* Create DEST */
139 if (dest_exists) {
140 if (!S_ISDIR(dest_stat.st_mode)) {
141 bb_error_msg("target '%s' is not a directory", dest);
142 return -1;
143 }
144 /* race here: user can substitute a symlink between
145 * this check and actual creation of files inside dest */
146 } else {
147 mode_t mode;
148 saved_umask = umask(0);
149
150 mode = source_stat.st_mode;
151 if (!(flags & FILEUTILS_PRESERVE_STATUS))
152 mode = source_stat.st_mode & ~saved_umask;
153 /* Allow owner to access new dir (at least for now) */
154 mode |= S_IRWXU;
155 if (mkdir(dest, mode) < 0) {
156 umask(saved_umask);
157 bb_perror_msg("cannot create directory '%s'", dest);
158 return -1;
159 }
160 umask(saved_umask);
161 /* need stat info for add_to_ino_dev_hashtable */
162 if (lstat(dest, &dest_stat) < 0) {
163 bb_perror_msg("cannot stat '%s'", dest);
164 return -1;
165 }
166 }
167 /* remember (dev,inode) of each created dir.
168 * NULL: name is not remembered */
169 add_to_ino_dev_hashtable(&dest_stat, NULL);
170
171 /* Recursively copy files in SOURCE */
172 dp = opendir(source);
173 if (dp == NULL) {
174 retval = -1;
175 goto preserve_mode_ugid_time;
176 }
177
178 while ((d = readdir(dp)) != NULL) {
179 char *new_source, *new_dest;
180
181 new_source = concat_subpath_file(source, d->d_name);
182 if (new_source == NULL)
183 continue;
184 new_dest = concat_path_file(dest, d->d_name);
185 if (copy_file(new_source, new_dest, flags) < 0)
186 retval = -1;
187 free(new_source);
188 free(new_dest);
189 }
190 closedir(dp);
191
192 if (!dest_exists
193 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
194 ) {
195 bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
196 /* retval = -1; - WRONG! copy *WAS* made */
197 }
198 goto preserve_mode_ugid_time;
199 }
200
201 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
202 int (*lf)(const char *oldpath, const char *newpath);
203 make_links:
204 // Hmm... maybe
205 // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
206 // (but realpath returns NULL on dangling symlinks...)
207 lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
208 if (lf(source, dest) < 0) {
209 ovr = ask_and_unlink(dest, flags);
210 if (ovr <= 0)
211 return ovr;
212 if (lf(source, dest) < 0) {
213 bb_perror_msg("cannot create link '%s'", dest);
214 return -1;
215 }
216 }
217 /* _Not_ jumping to preserve_mode_ugid_time:
218 * hard/softlinks don't have those */
219 return 0;
220 }
221
222 if (S_ISREG(source_stat.st_mode)
223 /* DEREF uses stat, which never returns S_ISLNK() == true. */
224 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
225 ) {
226 int src_fd;
227 int dst_fd;
228
229 if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
230 const char *link_target;
231 link_target = is_in_ino_dev_hashtable(&source_stat);
232 if (link_target) {
233 if (link(link_target, dest) < 0) {
234 ovr = ask_and_unlink(dest, flags);
235 if (ovr <= 0)
236 return ovr;
237 if (link(link_target, dest) < 0) {
238 bb_perror_msg("cannot create link '%s'", dest);
239 return -1;
240 }
241 }
242 return 0;
243 }
244 add_to_ino_dev_hashtable(&source_stat, dest);
245 }
246
247 src_fd = open_or_warn(source, O_RDONLY);
248 if (src_fd < 0)
249 return -1;
250
251 /* POSIX way is a security problem versus symlink attacks,
252 * we do it only for non-symlinks, and only for non-recursive,
253 * non-interactive cp. NB: it is still racy
254 * for "cp file /home/bad_user/file" case
255 * (user can rm file and create a link to /etc/passwd) */
256 if (DO_POSIX_CP
257 || (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
258 && !S_ISLNK(dest_stat.st_mode))
259 ) {
260 dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
261 } else /* safe way: */
262 dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
263 if (dst_fd == -1) {
264 ovr = ask_and_unlink(dest, flags);
265 if (ovr <= 0) {
266 close(src_fd);
267 return ovr;
268 }
269 /* It shouldn't exist. If it exists, do not open (symlink attack?) */
270 dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
271 if (dst_fd < 0) {
272 close(src_fd);
273 return -1;
274 }
275 }
276
277#if ENABLE_SELINUX
278 if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT)
279 || (flags & FILEUTILS_SET_SECURITY_CONTEXT))
280 && is_selinux_enabled() > 0
281 ) {
282 security_context_t con;
283 if (getfscreatecon(&con) == -1) {
284 bb_perror_msg("getfscreatecon");
285 return -1;
286 }
287 if (con) {
288 if (setfilecon(dest, con) == -1) {
289 bb_perror_msg("setfilecon:%s,%s", dest, con);
290 freecon(con);
291 return -1;
292 }
293 freecon(con);
294 }
295 }
296#endif
297 if (bb_copyfd_eof(src_fd, dst_fd) == -1)
298 retval = -1;
299 /* Ok, writing side I can understand... */
300 if (close(dst_fd) < 0) {
301 bb_perror_msg("cannot close '%s'", dest);
302 retval = -1;
303 }
304 /* ...but read size is already checked by bb_copyfd_eof */
305 close(src_fd);
306 goto preserve_mode_ugid_time;
307 }
308
309 /* Source is a symlink or a special file */
310 /* We are lazy here, a bit lax with races... */
311 if (dest_exists) {
312 errno = EEXIST;
313 ovr = ask_and_unlink(dest, flags);
314 if (ovr <= 0)
315 return ovr;
316 }
317 if (S_ISLNK(source_stat.st_mode)) {
318 char *lpath = xmalloc_readlink_or_warn(source);
319 if (lpath) {
320 int r = symlink(lpath, dest);
321 free(lpath);
322 if (r < 0) {
323 bb_perror_msg("cannot create symlink '%s'", dest);
324 return -1;
325 }
326 if (flags & FILEUTILS_PRESERVE_STATUS)
327 if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
328 bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
329 }
330 /* _Not_ jumping to preserve_mode_ugid_time:
331 * symlinks don't have those */
332 return 0;
333 }
334 if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
335 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
336 ) {
337 if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
338 bb_perror_msg("cannot create '%s'", dest);
339 return -1;
340 }
341 } else {
342 bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
343 return -1;
344 }
345
346 preserve_mode_ugid_time:
347
348 if (flags & FILEUTILS_PRESERVE_STATUS
349 /* Cannot happen: */
350 /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
351 ) {
352 struct utimbuf times;
353
354 times.actime = source_stat.st_atime;
355 times.modtime = source_stat.st_mtime;
356 /* BTW, utimes sets usec-precision time - just FYI */
357 if (utime(dest, &times) < 0)
358 bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
359 if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
360 source_stat.st_mode &= ~(S_ISUID | S_ISGID);
361 bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
362 }
363 if (chmod(dest, source_stat.st_mode) < 0)
364 bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
365 }
366
367 return retval;
368}
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