summaryrefslogtreecommitdiff
path: root/libbb/copy_file.c
blob: 1b8befd65440e394dd0e0be119926aac3b6b6975 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
/* vi: set sw=4 ts=4: */
/*
 * Mini copy_file implementation for busybox
 *
 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
 * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include "libbb.h"

// FEATURE_NON_POSIX_CP:
//
// POSIX: if exists and -i, ask (w/o -i assume yes).
// Then open w/o EXCL (yes, not unlink!).
// If open still fails and -f, try unlink, then try open again.
// Result: a mess:
// If dest is a (sym)link, we overwrite link destination!
// (or fail, if it points to dir/nonexistent location/etc).
// This is strange, but POSIX-correct.
// coreutils cp has --remove-destination to override this...

/* Called if open of destination, link creation etc fails.
 * errno must be set to relevant value ("why we cannot create dest?")
 * to give reasonable error message */
static int ask_and_unlink(const char *dest, int flags)
{
	int e = errno;

#if !ENABLE_FEATURE_NON_POSIX_CP
	if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
		/* Either it exists, or the *path* doesnt exist */
		bb_perror_msg("can't create '%s'", dest);
		return -1;
	}
#endif
	// else: act as if -f is always in effect.
	// We don't want "can't create" msg, we want unlink to be done
	// (silently unless -i). Why? POSIX cp usually succeeds with
	// O_TRUNC open of existing file, and user is left ignorantly happy.
	// With above block unconditionally enabled, non-POSIX cp
	// will complain a lot more than POSIX one.

	/* TODO: maybe we should do it only if ctty is present? */
	if (flags & FILEUTILS_INTERACTIVE) {
		// We would not do POSIX insanity. -i asks,
		// then _unlinks_ the offender. Presto.
		// (No "opening without O_EXCL", no "unlink only if -f")
		// Or else we will end up having 3 open()s!
		fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
		if (!bb_ask_y_confirmation())
			return 0; /* not allowed to overwrite */
	}
	if (unlink(dest) < 0) {
#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
		if (e == errno && e == ENOENT) {
			/* e == ENOTDIR is similar: path has non-dir component,
			 * but in this case we don't even reach copy_file() */
			bb_error_msg("can't create '%s': Path does not exist", dest);
			return -1; /* error */
		}
#endif
		errno = e; /* do not use errno from unlink */
		bb_perror_msg("can't create '%s'", dest);
		return -1; /* error */
	}
#if ENABLE_FEATURE_CP_LONG_OPTIONS
	if (flags & FILEUTILS_RMDEST)
		if (flags & FILEUTILS_VERBOSE)
			printf("removed '%s'\n", dest);
#endif
	return 1; /* ok (to try again) */
}

/* Return:
 * -1 error, copy not made
 *  0 copy is made or user answered "no" in interactive mode
 *    (failures to preserve mode/owner/times are not reported in exit code)
 */
int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
{
	/* This is a recursive function, try to minimize stack usage */
	/* NB: each struct stat is ~100 bytes */
	struct stat source_stat;
	struct stat dest_stat;
	smallint retval = 0;
	smallint dest_exists = 0;
	smallint ovr;

/* Inverse of cp -d ("cp without -d") */
#define FLAGS_DEREF (flags & (FILEUTILS_DEREFERENCE + FILEUTILS_DEREFERENCE_L0))

	if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
		/* This may be a dangling symlink.
		 * Making [sym]links to dangling symlinks works, so... */
		if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
			goto make_links;
		bb_perror_msg("can't stat '%s'", source);
		return -1;
	}

	if (lstat(dest, &dest_stat) < 0) {
		if (errno != ENOENT) {
			bb_perror_msg("can't stat '%s'", dest);
			return -1;
		}
	} else {
		if (source_stat.st_dev == dest_stat.st_dev
		 && source_stat.st_ino == dest_stat.st_ino
		) {
			bb_error_msg("'%s' and '%s' are the same file", source, dest);
			return -1;
		}
		dest_exists = 1;
	}

#if ENABLE_SELINUX
	if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
		security_context_t con;
		if (lgetfilecon(source, &con) >= 0) {
			if (setfscreatecon(con) < 0) {
				bb_perror_msg("can't set setfscreatecon %s", con);
				freecon(con);
				return -1;
			}
		} else if (errno == ENOTSUP || errno == ENODATA) {
			setfscreatecon_or_die(NULL);
		} else {
			bb_perror_msg("can't lgetfilecon %s", source);
			return -1;
		}
	}
#endif

	if (S_ISDIR(source_stat.st_mode)) {
		DIR *dp;
		const char *tp;
		struct dirent *d;
		mode_t saved_umask = 0;

		if (!(flags & FILEUTILS_RECUR)) {
			bb_error_msg("omitting directory '%s'", source);
			return -1;
		}

		/* Did we ever create source ourself before? */
		tp = is_in_ino_dev_hashtable(&source_stat);
		if (tp) {
			/* We did! it's a recursion! man the lifeboats... */
			bb_error_msg("recursion detected, omitting directory '%s'",
					source);
			return -1;
		}

		if (dest_exists) {
			if (!S_ISDIR(dest_stat.st_mode)) {
				bb_error_msg("target '%s' is not a directory", dest);
				return -1;
			}
			/* race here: user can substitute a symlink between
			 * this check and actual creation of files inside dest */
		} else {
			/* Create DEST */
			mode_t mode;
			saved_umask = umask(0);

			mode = source_stat.st_mode;
			if (!(flags & FILEUTILS_PRESERVE_STATUS))
				mode = source_stat.st_mode & ~saved_umask;
			/* Allow owner to access new dir (at least for now) */
			mode |= S_IRWXU;
			if (mkdir(dest, mode) < 0) {
				umask(saved_umask);
				bb_perror_msg("can't create directory '%s'", dest);
				return -1;
			}
			umask(saved_umask);
			/* need stat info for add_to_ino_dev_hashtable */
			if (lstat(dest, &dest_stat) < 0) {
				bb_perror_msg("can't stat '%s'", dest);
				return -1;
			}
		}
		/* remember (dev,inode) of each created dir.
		 * NULL: name is not remembered */
		add_to_ino_dev_hashtable(&dest_stat, NULL);

		/* Recursively copy files in SOURCE */
		dp = opendir(source);
		if (dp == NULL) {
			retval = -1;
			goto preserve_mode_ugid_time;
		}

		while ((d = readdir(dp)) != NULL) {
			char *new_source, *new_dest;

			new_source = concat_subpath_file(source, d->d_name);
			if (new_source == NULL)
				continue;
			new_dest = concat_path_file(dest, d->d_name);
			if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0)
				retval = -1;
			free(new_source);
			free(new_dest);
		}
		closedir(dp);

		if (!dest_exists
		 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
		) {
			bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
			/* retval = -1; - WRONG! copy *WAS* made */
		}
		goto preserve_mode_ugid_time;
	}

	if (dest_exists) {
		if (flags & FILEUTILS_UPDATE) {
			if (source_stat.st_mtime <= dest_stat.st_mtime) {
				return 0; /* source file must be newer */
			}
		}
#if ENABLE_FEATURE_CP_LONG_OPTIONS
		if (flags & FILEUTILS_RMDEST) {
			ovr = ask_and_unlink(dest, flags);
			if (ovr <= 0)
				return ovr;
			dest_exists = 0;
		}
#endif
	}

	if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
		int (*lf)(const char *oldpath, const char *newpath);
 make_links:
		/* Hmm... maybe
		 * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
		 * (but realpath returns NULL on dangling symlinks...) */
		lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
		if (lf(source, dest) < 0) {
			ovr = ask_and_unlink(dest, flags);
			if (ovr <= 0)
				return ovr;
			if (lf(source, dest) < 0) {
				bb_perror_msg("can't create link '%s'", dest);
				return -1;
			}
		}
		/* _Not_ jumping to preserve_mode_ugid_time:
		 * (sym)links don't have those */
		return 0;
	}

	if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
	    !(flags & FILEUTILS_RECUR)
	    /* "cp [-opts] regular_file thing2" */
	 || S_ISREG(source_stat.st_mode)
	 /* DEREF uses stat, which never returns S_ISLNK() == true.
	  * So the below is never true: */
	 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
	) {
		int src_fd;
		int dst_fd;
		mode_t new_mode;

		if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
			/* "cp -d symlink dst": create a link */
			goto dont_cat;
		}

		if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
			const char *link_target;
			link_target = is_in_ino_dev_hashtable(&source_stat);
			if (link_target) {
				if (link(link_target, dest) < 0) {
					ovr = ask_and_unlink(dest, flags);
					if (ovr <= 0)
						return ovr;
					if (link(link_target, dest) < 0) {
						bb_perror_msg("can't create link '%s'", dest);
						return -1;
					}
				}
				return 0;
			}
			add_to_ino_dev_hashtable(&source_stat, dest);
		}

		src_fd = open_or_warn(source, O_RDONLY);
		if (src_fd < 0)
			return -1;

		/* Do not try to open with weird mode fields */
		new_mode = source_stat.st_mode;
		if (!S_ISREG(source_stat.st_mode))
			new_mode = 0666;

		if (ENABLE_FEATURE_NON_POSIX_CP || (flags & FILEUTILS_INTERACTIVE)) {
			/*
			 * O_CREAT|O_EXCL: require that file did not exist before creation
			 */
			dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
		} else { /* POSIX, and not "cp -i" */
			/*
			 * O_CREAT|O_TRUNC: create, or truncate (security problem versus (sym)link attacks)
			 */
			dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
		}
		if (dst_fd == -1) {
			ovr = ask_and_unlink(dest, flags);
			if (ovr <= 0) {
				close(src_fd);
				return ovr;
			}
			/* It shouldn't exist. If it exists, do not open (symlink attack?) */
			dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
			if (dst_fd < 0) {
				close(src_fd);
				return -1;
			}
		}

#if ENABLE_SELINUX
		if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
		 && is_selinux_enabled() > 0
		) {
			security_context_t con;
			if (getfscreatecon(&con) == -1) {
				bb_perror_msg("getfscreatecon");
				return -1;
			}
			if (con) {
				if (setfilecon(dest, con) == -1) {
					bb_perror_msg("setfilecon:%s,%s", dest, con);
					freecon(con);
					return -1;
				}
				freecon(con);
			}
		}
#endif
		if (bb_copyfd_eof(src_fd, dst_fd) == -1)
			retval = -1;
		/* Careful with writing... */
		if (close(dst_fd) < 0) {
			bb_perror_msg("error writing to '%s'", dest);
			retval = -1;
		}
		/* ...but read size is already checked by bb_copyfd_eof */
		close(src_fd);
		/* "cp /dev/something new_file" should not
		 * copy mode of /dev/something */
		if (!S_ISREG(source_stat.st_mode))
			return retval;
		goto preserve_mode_ugid_time;
	}
 dont_cat:

	/* Source is a symlink or a special file */
	/* We are lazy here, a bit lax with races... */
	if (dest_exists) {
		errno = EEXIST;
		ovr = ask_and_unlink(dest, flags);
		if (ovr <= 0)
			return ovr;
	}
	if (S_ISLNK(source_stat.st_mode)) {
		char *lpath = xmalloc_readlink_or_warn(source);
		if (lpath) {
			int r = symlink(lpath, dest);
			free(lpath);
			if (r < 0) {
				/* shared message */
				bb_perror_msg("can't create %slink '%s' to '%s'",
					"sym", dest, lpath
				);
				return -1;
			}
			if (flags & FILEUTILS_PRESERVE_STATUS)
				if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
					bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
		}
		/* _Not_ jumping to preserve_mode_ugid_time:
		 * symlinks don't have those */
		goto verb_and_exit;
	}
	if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
	 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
	) {
		if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
			bb_perror_msg("can't create '%s'", dest);
			return -1;
		}
	} else {
		bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
		return -1;
	}

 preserve_mode_ugid_time:

	if (flags & FILEUTILS_PRESERVE_STATUS
	/* Cannot happen: */
	/* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
	) {
		struct timeval times[2];

		times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime;
		times[1].tv_usec = times[0].tv_usec = 0;
		/* BTW, utimes sets usec-precision time - just FYI */
		if (utimes(dest, times) < 0)
			bb_perror_msg("can't preserve %s of '%s'", "times", dest);
		if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
			source_stat.st_mode &= ~(S_ISUID | S_ISGID);
			bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
		}
		if (chmod(dest, source_stat.st_mode) < 0)
			bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
	}

 verb_and_exit:
	if (flags & FILEUTILS_VERBOSE) {
		printf("'%s' -> '%s'\n", source, dest);
	}

	return retval;
}