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_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_xattr(file, &sx);
 117                                         free_xattr(&sx);
 118                                 }
 119 #endif
 120                                 set_file_attrs(fbuf, file, NULL, NULL, 0);
 121                                 unmake_file(file);
 122                         }
 123                 }
 124                 *p = '/';
 125                 p += strlen(p);
 126                 if (p == end)
 127                         break;
 128                 if (mkdir_defmode(fbuf) < 0) {
 129                         rsyserr(FERROR, errno, "make_bak_dir mkdir %s failed",
 130                                 full_fname(fbuf));
 131                         return -1;
 132                 }
 133         }
 134
 135         return 0;
 136 }
 137
 138 /* Has same return codes as make_backup(). */
 139 static inline int link_or_rename(const char *from, const char *to,
 140                                  BOOL prefer_rename, STRUCT_STAT *stp)
 141 {
 142         if (S_ISLNK(stp->st_mode)) {
 143                 if (prefer_rename)
 144                         goto do_rename;
 145 #ifndef CAN_HARDLINK_SYMLINK
 146                 return 0; /* Use copy code. */
 147 #endif
 148         }
 149         if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode)) {
 150                 if (prefer_rename)
 151                         goto do_rename;
 152 #ifndef CAN_HARDLINK_SPECIAL
 153                 return 0; /* Use copy code. */
 154 #endif
 155         }
 156 #ifdef SUPPORT_HARD_LINKS
 157         if (!S_ISDIR(stp->st_mode)) {
 158                 if (do_link(from, to) == 0)
 159                         return 2;
 160                 return 0;
 161         }
 162 #endif
 163   do_rename:
 164         if (do_rename(from, to) == 0) {
 165                 if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
 166                         /* If someone has hard-linked the file into the backup
 167                          * dir, rename() might return success but do nothing! */
 168                         robust_unlink(to); /* Just in case... */
 169                 }
 170                 return 1;
 171         }
 172         return 0;
 173 }
 174
 175 /* Hard-link, rename, or copy an item to the backup name.  Returns 2 if item
 176  * was duplicated into backup area, 1 if item was moved, or 0 for failure.*/
 177 int make_backup(const char *fname, BOOL prefer_rename)
 178 {
 179         stat_x sx;
 180         struct file_struct *file;
 181         int save_preserve_xattrs;
 182         char *buf = get_backup_name(fname);
 183         int ret = 0;
 184
 185         if (!buf)
 186                 return 0;
 187
 188         init_stat_x(&sx);
 189         /* Return success if no file to keep. */
 190         if (x_lstat(fname, &sx.st, NULL) < 0)
 191                 return 1;
 192
 193         /* Try a hard-link or a rename first.  Using rename is not atomic, but
 194          * is more efficient than forcing a copy for larger files when no hard-
 195          * linking is possible. */
 196         if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 197                 goto success;
 198         if (errno == EEXIST) {
 199                 STRUCT_STAT bakst;
 200                 if (do_lstat(buf, &bakst) == 0) {
 201                         int flags = get_del_for_flag(bakst.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
 202                         if (delete_item(buf, bakst.st_mode, flags) != 0)
 203                                 return 0;
 204                 }
 205                 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 206                         goto success;
 207         } else if (backup_dir && errno == ENOENT) {
 208                 /* If the backup dir is missing, try again after making it. */
 209                 if (make_bak_dir(buf) != 0)
 210                         return 0;
 211                 if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 212                         goto success;
 213         }
 214
 215         /* Fall back to making a copy. */
 216         if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
 217                 return 1; /* the file could have disappeared */
 218
 219 #ifdef SUPPORT_ACLS
 220         if (preserve_acls && !S_ISLNK(file->mode)) {
 221                 get_acl(fname, &sx);
 222                 cache_acl(file, &sx);
 223                 free_acl(&sx);
 224         }
 225 #endif
 226 #ifdef SUPPORT_XATTRS
 227         if (preserve_xattrs) {
 228                 get_xattr(fname, &sx);
 229                 cache_xattr(file, &sx);
 230                 free_xattr(&sx);
 231         }
 232 #endif
 233
 234         /* Check to see if this is a device file, or link */
 235         if ((am_root && preserve_devices && IS_DEVICE(file->mode))
 236          || (preserve_specials && IS_SPECIAL(file->mode))) {
 237                 int save_errno;
 238                 if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0) {
 239                         save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 240                         if (errno == ENOENT && make_bak_dir(buf) == 0) {
 241                                 if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
 242                                         save_errno = errno ? errno : save_errno;
 243                                 else
 244                                         save_errno = 0;
 245                         }
 246                         if (save_errno) {
 247                                 rsyserr(FERROR, save_errno, "mknod %s failed",
 248                                         full_fname(buf));
 249                         }
 250                 } else
 251                         save_errno = 0;
 252                 if (DEBUG_GTE(BACKUP, 1) && save_errno == 0) {
 253                         rprintf(FINFO, "make_backup: DEVICE %s successful.\n",
 254                                 fname);
 255                 }
 256                 ret = 2;
 257         }
 258
 259         if (!ret && S_ISDIR(file->mode)) {
 260                 int ret_code;
 261                 /* make an empty directory */
 262                 if (do_mkdir(buf, file->mode) < 0) {
 263                         int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 264                         if (errno == ENOENT && make_bak_dir(buf) == 0) {
 265                                 if (do_mkdir(buf, file->mode) < 0)
 266                                         save_errno = errno ? errno : save_errno;
 267                                 else
 268                                         save_errno = 0;
 269                         }
 270                         if (save_errno) {
 271                                 rsyserr(FINFO, save_errno, "mkdir %s failed",
 272                                         full_fname(buf));
 273                         }
 274                 }
 275
 276                 ret_code = do_rmdir(fname);
 277                 if (DEBUG_GTE(BACKUP, 1)) {
 278                         rprintf(FINFO, "make_backup: RMDIR %s returns %i\n",
 279                                 full_fname(fname), ret_code);
 280                 }
 281                 ret = 2;
 282         }
 283
 284 #ifdef SUPPORT_LINKS
 285         if (!ret && preserve_links && S_ISLNK(file->mode)) {
 286                 const char *sl = F_SYMLINK(file);
 287                 if (safe_symlinks && unsafe_symlink(sl, buf)) {
 288                         if (INFO_GTE(SYMSAFE, 1)) {
 289                                 rprintf(FINFO, "ignoring unsafe symlink %s -> %s\n",
 290                                         full_fname(buf), sl);
 291                         }
 292                         ret = 2;
 293                 } else {
 294                         if (do_symlink(sl, buf) < 0) {
 295                                 int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
 296                                 if (errno == ENOENT && make_bak_dir(buf) == 0) {
 297                                         if (do_symlink(sl, buf) < 0)
 298                                                 save_errno = errno ? errno : save_errno;
 299                                         else
 300                                                 save_errno = 0;
 301                                 }
 302                                 if (save_errno) {
 303                                         rsyserr(FERROR, save_errno, "link %s -> \"%s\"",
 304                                                 full_fname(buf), sl);
 305                                 }
 306                         }
 307                         ret = 2;
 308                 }
 309         }
 310 #endif
 311
 312         if (!ret && !S_ISREG(file->mode)) {
 313                 rprintf(FINFO, "make_bak: skipping non-regular file %s\n",
 314                         fname);
 315                 unmake_file(file);
 316                 return 2;
 317         }
 318
 319         /* Copy to backup tree if a file. */
 320         if (!ret) {
 321                 if (copy_file(fname, buf, -1, file->mode, 1) < 0) {
 322                         rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
 323                                 full_fname(fname), buf);
 324                         unmake_file(file);
 325                         return 0;
 326                 }
 327                 ret = 2;
 328         }
 329
 330         save_preserve_xattrs = preserve_xattrs;
 331         preserve_xattrs = 0;
 332         set_file_attrs(buf, file, NULL, fname, 0);
 333         preserve_xattrs = save_preserve_xattrs;
 334
 335         unmake_file(file);
 336
 337   success:
 338         if (INFO_GTE(BACKUP, 1)) {
 339                 rprintf(FINFO, "backed up %s to %s\n",
 340                         fname, buf);
 341         }
 342         return ret;
 343 }