backup.c

   1 /*
   2  * Backup handling code.
   3  *
   4  * Copyright (C) 1999 Andrew Tridgell
   5  * Copyright (C) 2003-2009 Wayne Davison
   6  *
   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.
  11  *
  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.
  16  *
  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.
  19  */
  20
  21 #include "rsync.h"
  22 #include "ifuncs.h"
  23
  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;
  36
  37 /* make a complete pathname for backup file */
  38 char *get_backup_name(const char *fname)
  39 {
  40         if (backup_dir) {
  41                 if (stringjoin(backup_dir_buf + backup_dir_len, backup_dir_remainder,
  42                                fname, backup_suffix, NULL) < backup_dir_remainder)
  43                         return backup_dir_buf;
  44         } else {
  45                 if (stringjoin(backup_dir_buf, MAXPATHLEN,
  46                                fname, backup_suffix, NULL) < MAXPATHLEN)
  47                         return backup_dir_buf;
  48         }
  49
  50         rprintf(FERROR, "backup filename too long\n");
  51         return NULL;
  52 }
  53
  54 /****************************************************************************
  55 Create a directory given an absolute path, perms based upon another directory
  56 path
  57 ****************************************************************************/
  58 int make_bak_dir(const char *fullpath)
  59 {
  60         char fbuf[MAXPATHLEN], *rel, *end, *p;
  61         struct file_struct *file;
  62         int len = backup_dir_len;
  63         stat_x sx;
  64
  65         while (*fullpath == '.' && fullpath[1] == '/') {
  66                 fullpath += 2;
  67                 len -= 2;
  68         }
  69
  70         if (strlcpy(fbuf, fullpath, sizeof fbuf) >= sizeof fbuf)
  71                 return -1;
  72
  73         rel = fbuf + len;
  74         end = p = rel + strlen(rel);
  75
  76         /* Try to find an existing dir, starting from the deepest dir. */
  77         while (1) {
  78                 if (--p == fbuf)
  79                         return -1;
  80                 if (*p == '/') {
  81                         *p = '\0';
  82                         if (mkdir_defmode(fbuf) == 0)
  83                                 break;
  84                         if (errno != ENOENT) {
  85                                 rsyserr(FERROR, errno,
  86                                         "make_bak_dir mkdir %s failed",
  87                                         full_fname(fbuf));
  88                                 return -1;
  89                         }
  90                 }
  91         }
  92
  93         /* Make all the dirs that we didn't find on the way here. */
  94         while (1) {
  95                 if (p >= rel) {
  96                         /* Try to transfer the directory settings of the
  97                          * actual dir that the files are coming from. */
  98                         init_stat_x(&sx);
  99                         if (x_stat(rel, &sx.st, NULL) < 0) {
 100                                 rsyserr(FERROR, errno,
 101                                         "make_bak_dir stat %s failed",
 102                                         full_fname(rel));
 103                         } else {
 104                                 if (!(file = make_file(rel, NULL, NULL, 0, NO_FILTERS)))
 105                                         continue;
 106 #ifdef SUPPORT_ACLS
 107                                 if (preserve_acls && !S_ISLNK(file->mode)) {
 108                                         get_acl(rel, &sx);
 109                                         cache_tmp_acl(file, &sx);
 110                                         free_acl(&sx);
 111                                 }
 112 #endif
 113 #ifdef SUPPORT_XATTRS
 114                                 if (preserve_xattrs) {
 115                                         get_xattr(rel, &sx);
 116                                         cache_tmp_xattr(file, &sx);
 117                                         free_xattr(&sx);
 118                                 }
 119 #endif
 120                                 set_file_attrs(fbuf, file, NULL, NULL, 0);
 121                                 unmake_file(file);
 122 #ifdef SUPPORT_ACLS
 123                                 uncache_tmp_acls();
 124 #endif
 125 #ifdef SUPPORT_XATTRS
 126                                 uncache_tmp_xattrs();
 127 #endif
 128                         }
 129                 }
 130                 *p = '/';
 131                 p += strlen(p);
 132                 if (p == end)
 133                         break;
 134                 if (mkdir_defmode(fbuf) < 0) {
 135                         rsyserr(FERROR, errno, "make_bak_dir mkdir %s failed",
 136                                 full_fname(fbuf));
 137                         return -1;
 138                 }
 139         }
 140
 141         return 0;
 142 }
 143
 144 /* Has same return codes as make_backup(). */
 145 static inline int link_or_rename(const char *from, const char *to,
 146                                  BOOL prefer_rename, STRUCT_STAT *stp)
 147 {
 148 #ifdef SUPPORT_HARD_LINKS
 149         if (!prefer_rename) {
 150 #ifndef CAN_HARDLINK_SYMLINK
 151                 if (S_ISLNK(stp->st_mode))
 152                         return 0; /* Use copy code. */
 153 #endif
 154 #ifndef CAN_HARDLINK_SPECIAL
 155                 if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode))
 156                         return 0; /* Use copy code. */
 157 #endif
 158                 if (do_link(from, to) == 0)
 159                         return 2;
 160                 /* We prefer to rename a regular file rather than copy it. */
 161                 if (!S_ISREG(stp->st_mode) || errno == EEXIST || errno == EISDIR)
 162                         return 0;
 163         }
 164 #endif
 165         if (do_rename(from, to) == 0) {
 166                 if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
 167                         /* If someone has hard-linked the file into the backup
 168                          * dir, rename() might return success but do nothing! */
 169                         robust_unlink(from); /* Just in case... */
 170                 }
 171                 return 1;
 172         }
 173         return 0;
 174 }
 175
 176 /* Hard-link, rename, or copy an item to the backup name.  Returns 2 if item
 177  * was duplicated into backup area, 1 if item was moved, or 0 for failure.*/
 178 int make_backup(const char *fname, BOOL prefer_rename)
 179 {
 180         stat_x sx;
 181         struct file_struct *file;
 182         int save_preserve_xattrs;
 183         char *buf = get_backup_name(fname);
 184         int ret = 0;
 185
 186         if (!buf)
 187                 return 0;
 188
 189         init_stat_x(&sx);
 190         /* Return success if no file to keep. */
 191         if (x_lstat(fname, &sx.st, NULL) < 0)
 192                 return 1;
 193
 194         /* Try a hard-link or a rename first.  Using rename is not atomic, but
 195          * is more efficient than forcing a copy for larger files when no hard-
 196          * linking is possible. */
 197         if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 198                 goto success;
 199         if (errno == EEXIST || errno == EISDIR) {
 200                 STRUCT_STAT bakst;
 201                 if (do_lstat(buf, &bakst) == 0) {
 202                         int flags = get_del_for_flag(bakst.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
 203                         if (delete_item(buf, bakst.st_mode, flags) != 0)
 204                                 return 0;
 205                 }
 206                 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 207                         goto success;
 208         } else if (backup_dir && errno == ENOENT) {
 209                 /* If the backup dir is missing, try again after making it. */
 210                 if (make_bak_dir(buf) != 0)
 211                         return 0;
 212                 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 213                         goto success;
 214         }
 215
 216         /* Fall back to making a copy. */
 217         if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
 218                 return 1; /* the file could have disappeared */
 219
 220 #ifdef SUPPORT_ACLS
 221         if (preserve_acls && !S_ISLNK(file->mode)) {
 222                 get_acl(fname, &sx);
 223                 cache_tmp_acl(file, &sx);
 224                 free_acl(&sx);
 225         }
 226 #endif
 227 #ifdef SUPPORT_XATTRS
 228         if (preserve_xattrs) {
 229                 get_xattr(fname, &sx);
 230                 cache_tmp_xattr(file, &sx);
 231                 free_xattr(&sx);
 232         }
 233 #endif
 234
 235         /* Check to see if this is a device file, or link */
 236         if ((am_root && preserve_devices && IS_DEVICE(file->mode))
 237          || (preserve_specials && IS_SPECIAL(file->mode))) {
 238                 int save_errno;
 239                 if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0) {
 240                         save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 241                         if (errno == ENOENT && make_bak_dir(buf) == 0) {
 242                                 if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
 243                                         save_errno = errno ? errno : save_errno;
 244                                 else
 245                                         save_errno = 0;
 246                         }
 247                         if (save_errno) {
 248                                 rsyserr(FERROR, save_errno, "mknod %s failed",
 249                                         full_fname(buf));
 250                         }
 251                 } else
 252                         save_errno = 0;
 253                 if (DEBUG_GTE(BACKUP, 1) && save_errno == 0) {
 254                         rprintf(FINFO, "make_backup: DEVICE %s successful.\n",
 255                                 fname);
 256                 }
 257                 ret = 2;
 258         }
 259
 260         if (!ret && S_ISDIR(file->mode)) {
 261                 int ret_code;
 262                 /* make an empty directory */
 263                 if (do_mkdir(buf, file->mode) < 0) {
 264                         int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 265                         if (errno == ENOENT && make_bak_dir(buf) == 0) {
 266                                 if (do_mkdir(buf, file->mode) < 0)
 267                                         save_errno = errno ? errno : save_errno;
 268                                 else
 269                                         save_errno = 0;
 270                         }
 271                         if (save_errno) {
 272                                 rsyserr(FINFO, save_errno, "mkdir %s failed",
 273                                         full_fname(buf));
 274                         }
 275                 }
 276
 277                 ret_code = do_rmdir(fname);
 278                 if (DEBUG_GTE(BACKUP, 1)) {
 279                         rprintf(FINFO, "make_backup: RMDIR %s returns %i\n",
 280                                 full_fname(fname), ret_code);
 281                 }
 282                 ret = 2;
 283         }
 284
 285 #ifdef SUPPORT_LINKS
 286         if (!ret && preserve_links && S_ISLNK(file->mode)) {
 287                 const char *sl = F_SYMLINK(file);
 288                 if (safe_symlinks && unsafe_symlink(sl, fname)) {
 289                         if (INFO_GTE(SYMSAFE, 1)) {
 290                                 rprintf(FINFO, "ignoring unsafe symlink %s -> %s\n",
 291                                         full_fname(buf), sl);
 292                         }
 293                         ret = 2;
 294                 } else {
 295                         if (do_symlink(sl, buf) < 0) {
 296                                 int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 297                                 if (errno == ENOENT && make_bak_dir(buf) == 0) {
 298                                         if (do_symlink(sl, buf) < 0)
 299                                                 save_errno = errno ? errno : save_errno;
 300                                         else
 301                                                 save_errno = 0;
 302                                 }
 303                                 if (save_errno) {
 304                                         rsyserr(FERROR, save_errno, "link %s -> \"%s\"",
 305                                                 full_fname(buf), sl);
 306                                 }
 307                         }
 308                         ret = 2;
 309                 }
 310         }
 311 #endif
 312
 313         if (!ret && !S_ISREG(file->mode)) {
 314                 rprintf(FINFO, "make_bak: skipping non-regular file %s\n",
 315                         fname);
 316                 unmake_file(file);
 317 #ifdef SUPPORT_ACLS
 318                 uncache_tmp_acls();
 319 #endif
 320 #ifdef SUPPORT_XATTRS
 321                 uncache_tmp_xattrs();
 322 #endif
 323                 return 2;
 324         }
 325
 326         /* Copy to backup tree if a file. */
 327         if (!ret) {
 328                 if (copy_file(fname, buf, -1, file->mode, 1) < 0) {
 329                         rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
 330                                 full_fname(fname), buf);
 331                         unmake_file(file);
 332 #ifdef SUPPORT_ACLS
 333                         uncache_tmp_acls();
 334 #endif
 335 #ifdef SUPPORT_XATTRS
 336                         uncache_tmp_xattrs();
 337 #endif
 338                         return 0;
 339                 }
 340                 ret = 2;
 341         }
 342
 343         save_preserve_xattrs = preserve_xattrs;
 344         preserve_xattrs = 0;
 345         set_file_attrs(buf, file, NULL, fname, 0);
 346         preserve_xattrs = save_preserve_xattrs;
 347
 348         unmake_file(file);
 349 #ifdef SUPPORT_ACLS
 350         uncache_tmp_acls();
 351 #endif
 352 #ifdef SUPPORT_XATTRS
 353         uncache_tmp_xattrs();
 354 #endif
 355
 356   success:
 357         if (INFO_GTE(BACKUP, 1)) {
 358                 rprintf(FINFO, "backed up %s to %s\n",
 359                         fname, buf);
 360         }
 361         return ret;
 362 }