summaryrefslogtreecommitdiff
path: root/backup.c
blob: be406bef83003e604555d9a1158b80f76778657e (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
/*
 * Backup handling code.
 *
 * Copyright (C) 1999 Andrew Tridgell
 * Copyright (C) 2003-2020 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"
#include "ifuncs.h"

extern int am_root;
extern int preserve_acls;
extern int preserve_xattrs;
extern int preserve_devices;
extern int preserve_specials;
extern int preserve_links;
extern int safe_symlinks;
extern int backup_dir_len;
extern unsigned int backup_dir_remainder;
extern char backup_dir_buf[MAXPATHLEN];
extern char *backup_suffix;
extern char *backup_dir;

/* Returns -1 on error, 0 on missing dir, and 1 on present dir. */
static int validate_backup_dir(void)
{
	STRUCT_STAT st;

	if (do_lstat(backup_dir_buf, &st) < 0) {
		if (errno == ENOENT)
			return 0;
		rsyserr(FERROR, errno, "backup lstat %s failed", backup_dir_buf);
		return -1;
	}
	if (!S_ISDIR(st.st_mode)) {
		int flags = get_del_for_flag(st.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
		if (delete_item(backup_dir_buf, st.st_mode, flags) == 0)
			return 0;
		return -1;
	}
	return 1;
}

/* Create a backup path from the given fname, putting the result into
 * backup_dir_buf.  Any new directories (compared to the prior backup
 * path) are ensured to exist as directories, replacing anything else
 * that may be in the way (e.g. a symlink). */
static BOOL copy_valid_path(const char *fname)
{
	const char *f;
	int val;
	BOOL ret = True;
	stat_x sx;
	char *b, *rel = backup_dir_buf + backup_dir_len, *name = rel;

	for (f = fname, b = rel; *f && *f == *b; f++, b++) {
		if (*b == '/')
			name = b + 1;
	}

	if (stringjoin(rel, backup_dir_remainder, fname, backup_suffix, NULL) >= backup_dir_remainder) {
		rprintf(FERROR, "backup filename too long\n");
		*name = '\0';
		return False;
	}

	for ( ; ; name = b + 1) {
		if ((b = strchr(name, '/')) == NULL)
			return True;
		*b = '\0';

		val = validate_backup_dir();
		if (val == 0)
			break;
		if (val < 0) {
			*name = '\0';
			return False;
		}

		*b = '/';
	}

	init_stat_x(&sx);

	for ( ; b; name = b + 1, b = strchr(name, '/')) {
		*b = '\0';

		while (do_mkdir(backup_dir_buf, ACCESSPERMS) < 0) {
			if (errno == EEXIST) {
				val = validate_backup_dir();
				if (val > 0)
					break;
				if (val == 0)
					continue;
			} else
				rsyserr(FERROR, errno, "backup mkdir %s failed", backup_dir_buf);
			*name = '\0';
			ret = False;
			goto cleanup;
		}

		/* Try to transfer the directory settings of the actual dir
		 * that the files are coming from. */
		if (x_stat(rel, &sx.st, NULL) < 0)
			rsyserr(FERROR, errno, "backup stat %s failed", full_fname(rel));
		else {
			struct file_struct *file;
			if (!(file = make_file(rel, NULL, NULL, 0, NO_FILTERS)))
				continue;
#ifdef SUPPORT_ACLS
			if (preserve_acls && !S_ISLNK(file->mode)) {
				get_acl(rel, &sx);
				cache_tmp_acl(file, &sx);
				free_acl(&sx);
			}
#endif
#ifdef SUPPORT_XATTRS
			if (preserve_xattrs) {
				get_xattr(rel, &sx);
				cache_tmp_xattr(file, &sx);
				free_xattr(&sx);
			}
#endif
			set_file_attrs(backup_dir_buf, file, NULL, NULL, 0);
			unmake_file(file);
		}

		*b = '/';
	}

  cleanup:

#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
#endif
#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
#endif

	return ret;
}

/* Make a complete pathname for backup file and verify any new path elements. */
char *get_backup_name(const char *fname)
{
	if (backup_dir) {
		static int initialized = 0;
		if (!initialized) {
			int ret;
			if (backup_dir_len > 1)
				backup_dir_buf[backup_dir_len-1] = '\0';
			ret = make_path(backup_dir_buf, 0);
			if (backup_dir_len > 1)
				backup_dir_buf[backup_dir_len-1] = '/';
			if (ret < 0)
				return NULL;
			initialized = 1;
		}
		/* copy fname into backup_dir_buf while validating the dirs. */
		if (copy_valid_path(fname))
			return backup_dir_buf;
		/* copy_valid_path() has printed an error message. */
		return NULL;
	}

	if (stringjoin(backup_dir_buf, MAXPATHLEN, fname, backup_suffix, NULL) < MAXPATHLEN)
		return backup_dir_buf;

	rprintf(FERROR, "backup filename too long\n");
	return NULL;
}

/* Has same return codes as make_backup(). */
static inline int link_or_rename(const char *from, const char *to,
				 BOOL prefer_rename, STRUCT_STAT *stp)
{
#ifdef SUPPORT_HARD_LINKS
	if (!prefer_rename) {
#ifndef CAN_HARDLINK_SYMLINK
		if (S_ISLNK(stp->st_mode))
			return 0; /* Use copy code. */
#endif
#ifndef CAN_HARDLINK_SPECIAL
		if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode))
			return 0; /* Use copy code. */
#endif
		if (do_link(from, to) == 0) {
			if (DEBUG_GTE(BACKUP, 1))
				rprintf(FINFO, "make_backup: HLINK %s successful.\n", from);
			return 2;
		}
		/* We prefer to rename a regular file rather than copy it. */
		if (!S_ISREG(stp->st_mode) || errno == EEXIST || errno == EISDIR)
			return 0;
	}
#endif
	if (do_rename(from, to) == 0) {
		if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
			/* If someone has hard-linked the file into the backup
			 * dir, rename() might return success but do nothing! */
			robust_unlink(from); /* Just in case... */
		}
		if (DEBUG_GTE(BACKUP, 1))
			rprintf(FINFO, "make_backup: RENAME %s successful.\n", from);
		return 1;
	}
	return 0;
}

/* Hard-link, rename, or copy an item to the backup name.  Returns 0 for
 * failure, 1 if item was moved, 2 if item was duplicated or hard linked
 * into backup area, or 3 if item doesn't exist or isn't a regular file. */
int make_backup(const char *fname, BOOL prefer_rename)
{
	stat_x sx;
	struct file_struct *file;
	int save_preserve_xattrs;
	char *buf;
	int ret = 0;

	init_stat_x(&sx);
	/* Return success if no file to keep. */
	if (x_lstat(fname, &sx.st, NULL) < 0)
		return 3;

	if (!(buf = get_backup_name(fname)))
		return 0;

	/* Try a hard-link or a rename first.  Using rename is not atomic, but
	 * is more efficient than forcing a copy for larger files when no hard-
	 * linking is possible. */
	if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
		goto success;
	if (errno == EEXIST || errno == EISDIR) {
		STRUCT_STAT bakst;
		if (do_lstat(buf, &bakst) == 0) {
			int flags = get_del_for_flag(bakst.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
			if (delete_item(buf, bakst.st_mode, flags) != 0)
				return 0;
		}
		if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
			goto success;
	}

	/* Fall back to making a copy. */
	if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
		return 3; /* the file could have disappeared */

#ifdef SUPPORT_ACLS
	if (preserve_acls && !S_ISLNK(file->mode)) {
		get_acl(fname, &sx);
		cache_tmp_acl(file, &sx);
		free_acl(&sx);
	}
#endif
#ifdef SUPPORT_XATTRS
	if (preserve_xattrs) {
		get_xattr(fname, &sx);
		cache_tmp_xattr(file, &sx);
		free_xattr(&sx);
	}
#endif

	/* Check to see if this is a device file, or link */
	if ((am_root && preserve_devices && IS_DEVICE(file->mode))
	 || (preserve_specials && IS_SPECIAL(file->mode))) {
		if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
			rsyserr(FERROR, errno, "mknod %s failed", full_fname(buf));
		else if (DEBUG_GTE(BACKUP, 1))
			rprintf(FINFO, "make_backup: DEVICE %s successful.\n", fname);
		ret = 2;
	}

#ifdef SUPPORT_LINKS
	if (!ret && preserve_links && S_ISLNK(file->mode)) {
		const char *sl = F_SYMLINK(file);
		if (safe_symlinks && unsafe_symlink(sl, fname)) {
			if (INFO_GTE(SYMSAFE, 1)) {
				rprintf(FINFO, "not backing up unsafe symlink \"%s\" -> \"%s\"\n",
					fname, sl);
			}
			ret = 2;
		} else {
			if (do_symlink(sl, buf) < 0)
				rsyserr(FERROR, errno, "link %s -> \"%s\"", full_fname(buf), sl);
			else if (DEBUG_GTE(BACKUP, 1))
				rprintf(FINFO, "make_backup: SYMLINK %s successful.\n", fname);
			ret = 2;
		}
	}
#endif

	if (!ret && !S_ISREG(file->mode)) {
		rprintf(FINFO, "make_bak: skipping non-regular file %s\n", fname);
		unmake_file(file);
#ifdef SUPPORT_ACLS
		uncache_tmp_acls();
#endif
#ifdef SUPPORT_XATTRS
		uncache_tmp_xattrs();
#endif
		return 3;
	}

	/* Copy to backup tree if a file. */
	if (!ret) {
		if (copy_file(fname, buf, -1, file->mode) < 0) {
			rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
				full_fname(fname), buf);
			unmake_file(file);
#ifdef SUPPORT_ACLS
			uncache_tmp_acls();
#endif
#ifdef SUPPORT_XATTRS
			uncache_tmp_xattrs();
#endif
			return 0;
		}
		if (DEBUG_GTE(BACKUP, 1))
			rprintf(FINFO, "make_backup: COPY %s successful.\n", fname);
		ret = 2;
	}

	save_preserve_xattrs = preserve_xattrs;
	preserve_xattrs = 0;
	set_file_attrs(buf, file, NULL, fname, ATTRS_ACCURATE_TIME);
	preserve_xattrs = save_preserve_xattrs;

	unmake_file(file);
#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
#endif
#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
#endif

  success:
	if (INFO_GTE(BACKUP, 1))
		rprintf(FINFO, "backed up %s to %s\n", fname, buf);
	return ret;
}