Fix overzealous setting of mtime & tweak time comparisons
[rsync.git] / backup.c
blobbe406bef83003e604555d9a1158b80f76778657e
1 /*
2 * Backup handling code.
4 * Copyright (C) 1999 Andrew Tridgell
5 * Copyright (C) 2003-2020 Wayne Davison
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, visit the http://fsf.org website.
21 #include "rsync.h"
22 #include "ifuncs.h"
24 extern int am_root;
25 extern int preserve_acls;
26 extern int preserve_xattrs;
27 extern int preserve_devices;
28 extern int preserve_specials;
29 extern int preserve_links;
30 extern int safe_symlinks;
31 extern int backup_dir_len;
32 extern unsigned int backup_dir_remainder;
33 extern char backup_dir_buf[MAXPATHLEN];
34 extern char *backup_suffix;
35 extern char *backup_dir;
37 /* Returns -1 on error, 0 on missing dir, and 1 on present dir. */
38 static int validate_backup_dir(void)
40 STRUCT_STAT st;
42 if (do_lstat(backup_dir_buf, &st) < 0) {
43 if (errno == ENOENT)
44 return 0;
45 rsyserr(FERROR, errno, "backup lstat %s failed", backup_dir_buf);
46 return -1;
48 if (!S_ISDIR(st.st_mode)) {
49 int flags = get_del_for_flag(st.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
50 if (delete_item(backup_dir_buf, st.st_mode, flags) == 0)
51 return 0;
52 return -1;
54 return 1;
57 /* Create a backup path from the given fname, putting the result into
58 * backup_dir_buf. Any new directories (compared to the prior backup
59 * path) are ensured to exist as directories, replacing anything else
60 * that may be in the way (e.g. a symlink). */
61 static BOOL copy_valid_path(const char *fname)
63 const char *f;
64 int val;
65 BOOL ret = True;
66 stat_x sx;
67 char *b, *rel = backup_dir_buf + backup_dir_len, *name = rel;
69 for (f = fname, b = rel; *f && *f == *b; f++, b++) {
70 if (*b == '/')
71 name = b + 1;
74 if (stringjoin(rel, backup_dir_remainder, fname, backup_suffix, NULL) >= backup_dir_remainder) {
75 rprintf(FERROR, "backup filename too long\n");
76 *name = '\0';
77 return False;
80 for ( ; ; name = b + 1) {
81 if ((b = strchr(name, '/')) == NULL)
82 return True;
83 *b = '\0';
85 val = validate_backup_dir();
86 if (val == 0)
87 break;
88 if (val < 0) {
89 *name = '\0';
90 return False;
93 *b = '/';
96 init_stat_x(&sx);
98 for ( ; b; name = b + 1, b = strchr(name, '/')) {
99 *b = '\0';
101 while (do_mkdir(backup_dir_buf, ACCESSPERMS) < 0) {
102 if (errno == EEXIST) {
103 val = validate_backup_dir();
104 if (val > 0)
105 break;
106 if (val == 0)
107 continue;
108 } else
109 rsyserr(FERROR, errno, "backup mkdir %s failed", backup_dir_buf);
110 *name = '\0';
111 ret = False;
112 goto cleanup;
115 /* Try to transfer the directory settings of the actual dir
116 * that the files are coming from. */
117 if (x_stat(rel, &sx.st, NULL) < 0)
118 rsyserr(FERROR, errno, "backup stat %s failed", full_fname(rel));
119 else {
120 struct file_struct *file;
121 if (!(file = make_file(rel, NULL, NULL, 0, NO_FILTERS)))
122 continue;
123 #ifdef SUPPORT_ACLS
124 if (preserve_acls && !S_ISLNK(file->mode)) {
125 get_acl(rel, &sx);
126 cache_tmp_acl(file, &sx);
127 free_acl(&sx);
129 #endif
130 #ifdef SUPPORT_XATTRS
131 if (preserve_xattrs) {
132 get_xattr(rel, &sx);
133 cache_tmp_xattr(file, &sx);
134 free_xattr(&sx);
136 #endif
137 set_file_attrs(backup_dir_buf, file, NULL, NULL, 0);
138 unmake_file(file);
141 *b = '/';
144 cleanup:
146 #ifdef SUPPORT_ACLS
147 uncache_tmp_acls();
148 #endif
149 #ifdef SUPPORT_XATTRS
150 uncache_tmp_xattrs();
151 #endif
153 return ret;
156 /* Make a complete pathname for backup file and verify any new path elements. */
157 char *get_backup_name(const char *fname)
159 if (backup_dir) {
160 static int initialized = 0;
161 if (!initialized) {
162 int ret;
163 if (backup_dir_len > 1)
164 backup_dir_buf[backup_dir_len-1] = '\0';
165 ret = make_path(backup_dir_buf, 0);
166 if (backup_dir_len > 1)
167 backup_dir_buf[backup_dir_len-1] = '/';
168 if (ret < 0)
169 return NULL;
170 initialized = 1;
172 /* copy fname into backup_dir_buf while validating the dirs. */
173 if (copy_valid_path(fname))
174 return backup_dir_buf;
175 /* copy_valid_path() has printed an error message. */
176 return NULL;
179 if (stringjoin(backup_dir_buf, MAXPATHLEN, fname, backup_suffix, NULL) < MAXPATHLEN)
180 return backup_dir_buf;
182 rprintf(FERROR, "backup filename too long\n");
183 return NULL;
186 /* Has same return codes as make_backup(). */
187 static inline int link_or_rename(const char *from, const char *to,
188 BOOL prefer_rename, STRUCT_STAT *stp)
190 #ifdef SUPPORT_HARD_LINKS
191 if (!prefer_rename) {
192 #ifndef CAN_HARDLINK_SYMLINK
193 if (S_ISLNK(stp->st_mode))
194 return 0; /* Use copy code. */
195 #endif
196 #ifndef CAN_HARDLINK_SPECIAL
197 if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode))
198 return 0; /* Use copy code. */
199 #endif
200 if (do_link(from, to) == 0) {
201 if (DEBUG_GTE(BACKUP, 1))
202 rprintf(FINFO, "make_backup: HLINK %s successful.\n", from);
203 return 2;
205 /* We prefer to rename a regular file rather than copy it. */
206 if (!S_ISREG(stp->st_mode) || errno == EEXIST || errno == EISDIR)
207 return 0;
209 #endif
210 if (do_rename(from, to) == 0) {
211 if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
212 /* If someone has hard-linked the file into the backup
213 * dir, rename() might return success but do nothing! */
214 robust_unlink(from); /* Just in case... */
216 if (DEBUG_GTE(BACKUP, 1))
217 rprintf(FINFO, "make_backup: RENAME %s successful.\n", from);
218 return 1;
220 return 0;
223 /* Hard-link, rename, or copy an item to the backup name. Returns 0 for
224 * failure, 1 if item was moved, 2 if item was duplicated or hard linked
225 * into backup area, or 3 if item doesn't exist or isn't a regular file. */
226 int make_backup(const char *fname, BOOL prefer_rename)
228 stat_x sx;
229 struct file_struct *file;
230 int save_preserve_xattrs;
231 char *buf;
232 int ret = 0;
234 init_stat_x(&sx);
235 /* Return success if no file to keep. */
236 if (x_lstat(fname, &sx.st, NULL) < 0)
237 return 3;
239 if (!(buf = get_backup_name(fname)))
240 return 0;
242 /* Try a hard-link or a rename first. Using rename is not atomic, but
243 * is more efficient than forcing a copy for larger files when no hard-
244 * linking is possible. */
245 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
246 goto success;
247 if (errno == EEXIST || errno == EISDIR) {
248 STRUCT_STAT bakst;
249 if (do_lstat(buf, &bakst) == 0) {
250 int flags = get_del_for_flag(bakst.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
251 if (delete_item(buf, bakst.st_mode, flags) != 0)
252 return 0;
254 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
255 goto success;
258 /* Fall back to making a copy. */
259 if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
260 return 3; /* the file could have disappeared */
262 #ifdef SUPPORT_ACLS
263 if (preserve_acls && !S_ISLNK(file->mode)) {
264 get_acl(fname, &sx);
265 cache_tmp_acl(file, &sx);
266 free_acl(&sx);
268 #endif
269 #ifdef SUPPORT_XATTRS
270 if (preserve_xattrs) {
271 get_xattr(fname, &sx);
272 cache_tmp_xattr(file, &sx);
273 free_xattr(&sx);
275 #endif
277 /* Check to see if this is a device file, or link */
278 if ((am_root && preserve_devices && IS_DEVICE(file->mode))
279 || (preserve_specials && IS_SPECIAL(file->mode))) {
280 if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
281 rsyserr(FERROR, errno, "mknod %s failed", full_fname(buf));
282 else if (DEBUG_GTE(BACKUP, 1))
283 rprintf(FINFO, "make_backup: DEVICE %s successful.\n", fname);
284 ret = 2;
287 #ifdef SUPPORT_LINKS
288 if (!ret && preserve_links && S_ISLNK(file->mode)) {
289 const char *sl = F_SYMLINK(file);
290 if (safe_symlinks && unsafe_symlink(sl, fname)) {
291 if (INFO_GTE(SYMSAFE, 1)) {
292 rprintf(FINFO, "not backing up unsafe symlink \"%s\" -> \"%s\"\n",
293 fname, sl);
295 ret = 2;
296 } else {
297 if (do_symlink(sl, buf) < 0)
298 rsyserr(FERROR, errno, "link %s -> \"%s\"", full_fname(buf), sl);
299 else if (DEBUG_GTE(BACKUP, 1))
300 rprintf(FINFO, "make_backup: SYMLINK %s successful.\n", fname);
301 ret = 2;
304 #endif
306 if (!ret && !S_ISREG(file->mode)) {
307 rprintf(FINFO, "make_bak: skipping non-regular file %s\n", fname);
308 unmake_file(file);
309 #ifdef SUPPORT_ACLS
310 uncache_tmp_acls();
311 #endif
312 #ifdef SUPPORT_XATTRS
313 uncache_tmp_xattrs();
314 #endif
315 return 3;
318 /* Copy to backup tree if a file. */
319 if (!ret) {
320 if (copy_file(fname, buf, -1, file->mode) < 0) {
321 rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
322 full_fname(fname), buf);
323 unmake_file(file);
324 #ifdef SUPPORT_ACLS
325 uncache_tmp_acls();
326 #endif
327 #ifdef SUPPORT_XATTRS
328 uncache_tmp_xattrs();
329 #endif
330 return 0;
332 if (DEBUG_GTE(BACKUP, 1))
333 rprintf(FINFO, "make_backup: COPY %s successful.\n", fname);
334 ret = 2;
337 save_preserve_xattrs = preserve_xattrs;
338 preserve_xattrs = 0;
339 set_file_attrs(buf, file, NULL, fname, ATTRS_ACCURATE_TIME);
340 preserve_xattrs = save_preserve_xattrs;
342 unmake_file(file);
343 #ifdef SUPPORT_ACLS
344 uncache_tmp_acls();
345 #endif
346 #ifdef SUPPORT_XATTRS
347 uncache_tmp_xattrs();
348 #endif
350 success:
351 if (INFO_GTE(BACKUP, 1))
352 rprintf(FINFO, "backed up %s to %s\n", fname, buf);
353 return ret;