detect-renamed.diff

   1 This patch adds the --detect-renamed option which makes rsync notice files
   2 that either (1) match in size & modify-time (plus the basename, if possible)
   3 or (2) match in size & checksum (when --checksum was also specified) and use
   4 each match as an alternate basis file to speed up the transfer.
   5
   6 The algorithm attempts to scan the receiving-side's files in an efficient
   7 manner.  If --delete[-before] is enabled, we'll take advantage of the
   8 pre-transfer delete pass to prepare any alternate-basis-file matches we
   9 might find.  If --delete-before is not enabled, rsync does the rename scan
  10 during the regular file-sending scan (scanning each directory right before
  11 the generator starts updating files from that dir).  In this latter mode,
  12 rsync might delay the updating of a file (if no alternate-basis match was
  13 yet found) until the full scan of the receiving side is complete, at which
  14 point any delayed files are processed.
  15
  16 I chose to hard-link the alternate-basis files into a ".~tmp~" subdir that
  17 takes advantage of rsync's pre-existing partial-dir logic.  This uses less
  18 memory than trying to keep track of the matches internally, and also allows
  19 any deletions or file-updates to occur normally without interfering with
  20 these alternate-basis discoveries.
  21
  22 To use this patch, run these commands for a successful build:
  23
  24     patch -p1 <patches/detect-renamed.diff
  25     ./configure                                 (optional if already run)
  26     make
  27
  28 TODO:
  29
  30   The routine that makes missing directories for files that get renamed
  31   down into a new sub-hierarchy doesn't properly handle the case where some
  32   path elements might exist but not be a dir yet.  We need to either change
  33   our stash-ahead algorithm (to not require unknown path elements) or we
  34   need to create a better path-making routine.
  35
  36   We need to never return a match from fattr_find() that has a basis
  37   file.  This will ensure that we don't try to give a renamed file to
  38   a file that can't use it, while missing out on giving it to a file
  39   that could use it.
  40
  41 based-on: d4fc18f3755987ccea6e7f43609f862aa0254c5a
  42 diff --git a/backup.c b/backup.c
  43 --- a/backup.c
  44 +++ b/backup.c
  45 @@ -162,7 +162,7 @@ char *get_backup_name(const char *fname)
  46                         int ret;
  47                         if (backup_dir_len > 1)
  48                                 backup_dir_buf[backup_dir_len-1] = '\0';
  49 -                       ret = make_path(backup_dir_buf, 0);
  50 +                       ret = make_path(backup_dir_buf, ACCESSPERMS, 0);
  51                         if (backup_dir_len > 1)
  52                                 backup_dir_buf[backup_dir_len-1] = '/';
  53                         if (ret < 0)
  54 diff --git a/compat.c b/compat.c
  55 --- a/compat.c
  56 +++ b/compat.c
  57 @@ -38,6 +38,7 @@ extern int checksum_seed;
  58  extern int basis_dir_cnt;
  59  extern int prune_empty_dirs;
  60  extern int protocol_version;
  61 +extern int detect_renamed;
  62  extern int protect_args;
  63  extern int preserve_uid;
  64  extern int preserve_gid;
  65 @@ -156,6 +157,7 @@ void set_allow_inc_recurse(void)
  66                 allow_inc_recurse = 0;
  67         else if (!am_sender
  68          && (delete_before || delete_after
  69 +         || detect_renamed
  70           || delay_updates || prune_empty_dirs))
  71                 allow_inc_recurse = 0;
  72         else if (am_server && !local_server
  73 diff --git a/delete.c b/delete.c
  74 --- a/delete.c
  75 +++ b/delete.c
  76 @@ -25,6 +25,7 @@
  77  extern int am_root;
  78  extern int make_backups;
  79  extern int max_delete;
  80 +extern int detect_renamed;
  81  extern char *backup_dir;
  82  extern char *backup_suffix;
  83  extern int backup_suffix_len;
  84 @@ -44,6 +45,8 @@ static inline int is_backup_file(char *fn)
  85   * its contents, otherwise just checks for content.  Returns DR_SUCCESS or
  86   * DR_NOT_EMPTY.  Note that fname must point to a MAXPATHLEN buffer!  (The
  87   * buffer is used for recursion, but returned unchanged.)
  88 + *
  89 + * Note: --detect-rename may use this routine with DEL_NO_DELETIONS set!
  90   */
  91  static enum delret delete_dir_contents(char *fname, uint16 flags)
  92  {
  93 @@ -63,7 +66,9 @@ static enum delret delete_dir_contents(char *fname, uint16 flags)
  94         save_filters = push_local_filters(fname, dlen);
  95
  96         non_perishable_cnt = 0;
  97 +       file_extra_cnt += SUM_EXTRA_CNT;
  98         dirlist = get_dirlist(fname, dlen, 0);
  99 +       file_extra_cnt -= SUM_EXTRA_CNT;
 100         ret = non_perishable_cnt ? DR_NOT_EMPTY : DR_SUCCESS;
 101
 102         if (!dirlist->used)
 103 @@ -103,7 +108,8 @@ static enum delret delete_dir_contents(char *fname, uint16 flags)
 104                 if (S_ISDIR(fp->mode)) {
 105                         if (delete_dir_contents(fname, flags | DEL_RECURSE) != DR_SUCCESS)
 106                                 ret = DR_NOT_EMPTY;
 107 -               }
 108 +               } else if (detect_renamed && S_ISREG(fp->mode))
 109 +                       look_for_rename(fp, fname);
 110                 if (delete_item(fname, fp->mode, flags) != DR_SUCCESS)
 111                         ret = DR_NOT_EMPTY;
 112         }
 113 @@ -126,6 +132,8 @@ static enum delret delete_dir_contents(char *fname, uint16 flags)
 114   *
 115   * Note that fbuf must point to a MAXPATHLEN buffer if the mode indicates it's
 116   * a directory! (The buffer is used for recursion, but returned unchanged.)
 117 + *
 118 + * Also note: --detect-rename may use this routine with DEL_NO_DELETIONS set!
 119   */
 120  enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
 121  {
 122 @@ -153,6 +161,9 @@ enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
 123                 /* OK: try to delete the directory. */
 124         }
 125
 126 +       if (flags & DEL_NO_DELETIONS)
 127 +               return DR_SUCCESS;
 128 +
 129         if (!(flags & DEL_MAKE_ROOM) && max_delete >= 0 && stats.deleted_files >= max_delete) {
 130                 skipped_deletes++;
 131                 return DR_AT_LIMIT;
 132 diff --git a/flist.c b/flist.c
 133 --- a/flist.c
 134 +++ b/flist.c
 135 @@ -63,6 +63,7 @@ extern int non_perishable_cnt;
 136  extern int prune_empty_dirs;
 137  extern int copy_links;
 138  extern int copy_unsafe_links;
 139 +extern int detect_renamed;
 140  extern int protocol_version;
 141  extern int sanitize_paths;
 142  extern int munge_symlinks;
 143 @@ -129,6 +130,8 @@ static int64 tmp_dev = -1, tmp_ino;
 144  #endif
 145  static char tmp_sum[MAX_DIGEST_LEN];
 146
 147 +struct file_list the_fattr_list;
 148 +
 149  static char empty_sum[MAX_DIGEST_LEN];
 150  static int flist_count_offset; /* for --delete --progress */
 151  static int show_filelist_progress;
 152 @@ -275,6 +278,45 @@ static inline int is_excluded(const char *fname, int is_dir, int filter_level)
 153         return name_is_excluded(fname, is_dir ? NAME_IS_DIR : NAME_IS_FILE, filter_level);
 154  }
 155
 156 +static int fattr_compare(struct file_struct **file1, struct file_struct **file2)
 157 +{
 158 +       struct file_struct *f1 = *file1;
 159 +       struct file_struct *f2 = *file2;
 160 +       int64 len1 = F_LENGTH(f1), len2 = F_LENGTH(f2);
 161 +       int diff;
 162 +
 163 +       if (!f1->basename || !S_ISREG(f1->mode) || !len1) {
 164 +               if (!f2->basename || !S_ISREG(f2->mode) || !len2)
 165 +                       return 0;
 166 +               return 1;
 167 +       }
 168 +       if (!f2->basename || !S_ISREG(f2->mode) || !len2)
 169 +               return -1;
 170 +
 171 +       /* Don't use diff for values that are longer than an int. */
 172 +       if (len1 != len2)
 173 +               return len1 < len2 ? -1 : 1;
 174 +
 175 +       if (always_checksum) {
 176 +               diff = u_memcmp(F_SUM(f1), F_SUM(f2), flist_csum_len);
 177 +               if (diff)
 178 +                       return diff;
 179 +       } else if (f1->modtime != f2->modtime)
 180 +               return f1->modtime < f2->modtime ? -1 : 1;
 181 +
 182 +       diff = u_strcmp(f1->basename, f2->basename);
 183 +       if (diff)
 184 +               return diff;
 185 +
 186 +       if (f1->dirname == f2->dirname)
 187 +               return 0;
 188 +       if (!f1->dirname)
 189 +               return -1;
 190 +       if (!f2->dirname)
 191 +               return 1;
 192 +       return u_strcmp(f1->dirname, f2->dirname);
 193 +}
 194 +
 195  static void send_directory(int f, struct file_list *flist,
 196                            char *fbuf, int len, int flags);
 197
 198 @@ -2635,6 +2677,25 @@ struct file_list *recv_file_list(int f, int dir_ndx)
 199          * for a non-relative transfer in recv_file_entry(). */
 200         flist_sort_and_clean(flist, relative_paths);
 201
 202 +       if (detect_renamed) {
 203 +               int j = flist->used;
 204 +               the_fattr_list.used = j;
 205 +               the_fattr_list.files = new_array(struct file_struct *, j);
 206 +               if (!the_fattr_list.files)
 207 +                       out_of_memory("recv_file_list");
 208 +               memcpy(the_fattr_list.files, flist->files,
 209 +                      j * sizeof (struct file_struct *));
 210 +               qsort(the_fattr_list.files, j,
 211 +                     sizeof the_fattr_list.files[0], (int (*)())fattr_compare);
 212 +               the_fattr_list.low = 0;
 213 +               while (j-- > 0) {
 214 +                       struct file_struct *fp = the_fattr_list.files[j];
 215 +                       if (fp->basename && S_ISREG(fp->mode) && F_LENGTH(fp))
 216 +                               break;
 217 +               }
 218 +               the_fattr_list.high = j;
 219 +       }
 220 +
 221         if (protocol_version < 30) {
 222                 /* Recv the io_error flag */
 223                 int err = read_int(f);
 224 diff --git a/generator.c b/generator.c
 225 --- a/generator.c
 226 +++ b/generator.c
 227 @@ -80,6 +80,7 @@ extern char *partial_dir;
 228  extern int compare_dest;
 229  extern int copy_dest;
 230  extern int link_dest;
 231 +extern int detect_renamed;
 232  extern int whole_file;
 233  extern int list_only;
 234  extern int read_batch;
 235 @@ -98,11 +99,13 @@ extern char *tmpdir;
 236  extern char *basis_dir[MAX_BASIS_DIRS+1];
 237  extern struct file_list *cur_flist, *first_flist, *dir_flist;
 238  extern filter_rule_list filter_list, daemon_filter_list;
 239 +extern struct file_list the_fattr_list;
 240
 241  int maybe_ATTRS_REPORT = 0;
 242  int maybe_ATTRS_SET_NANO = 0;
 243
 244  static dev_t dev_zero;
 245 +static int unexplored_dirs = 1;
 246  static int deldelay_size = 0, deldelay_cnt = 0;
 247  static char *deldelay_buf = NULL;
 248  static int deldelay_fd = -1;
 249 @@ -273,13 +276,18 @@ static void do_delayed_deletions(char *delbuf)
 250   * all the --delete-WHEN options.  Note that the fbuf pointer must point to a
 251   * MAXPATHLEN buffer with the name of the directory in it (the functions we
 252   * call will append names onto the end, but the old dir value will be restored
 253 - * on exit). */
 254 -static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev)
 255 + * on exit).
 256 + *
 257 + * Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 258 + */
 259 +static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev,
 260 +                         int del_flags)
 261  {
 262         static int already_warned = 0;
 263         struct file_list *dirlist;
 264 -       char delbuf[MAXPATHLEN];
 265 -       int dlen, i;
 266 +       char *p, delbuf[MAXPATHLEN];
 267 +       unsigned remainder;
 268 +       int dlen, i, restore_dot = 0;
 269
 270         if (!fbuf) {
 271                 change_local_filter_dir(NULL, 0, 0);
 272 @@ -293,17 +301,22 @@ static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev)
 273                 maybe_send_keepalive(time(NULL), MSK_ALLOW_FLUSH);
 274
 275         if (io_error & IOERR_GENERAL && !ignore_errors) {
 276 -               if (already_warned)
 277 +               if (!already_warned) {
 278 +                       rprintf(FINFO,
 279 +                           "IO error encountered -- skipping file deletion\n");
 280 +                       already_warned = 1;
 281 +               }
 282 +               if (!detect_renamed)
 283                         return;
 284 -               rprintf(FINFO,
 285 -                       "IO error encountered -- skipping file deletion\n");
 286 -               already_warned = 1;
 287 -               return;
 288 +               del_flags |= DEL_NO_DELETIONS;
 289         }
 290
 291         dlen = strlen(fbuf);
 292         change_local_filter_dir(fbuf, dlen, F_DEPTH(file));
 293
 294 +       if (detect_renamed)
 295 +               unexplored_dirs--;
 296 +
 297         if (one_file_system) {
 298                 if (file->flags & FLAG_TOP_DIR)
 299                         filesystem_dev = *fs_dev;
 300 @@ -313,6 +326,14 @@ static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev)
 301
 302         dirlist = get_dirlist(fbuf, dlen, 0);
 303
 304 +       p = fbuf + dlen;
 305 +       if (dlen == 1 && *fbuf == '.') {
 306 +               restore_dot = 1;
 307 +               p = fbuf;
 308 +       } else if (dlen != 1 || *fbuf != '/')
 309 +               *p++ = '/';
 310 +       remainder = MAXPATHLEN - (p - fbuf);
 311 +
 312         /* If an item in dirlist is not found in flist, delete it
 313          * from the filesystem. */
 314         for (i = dirlist->used; i--; ) {
 315 @@ -325,6 +346,10 @@ static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev)
 316                                         f_name(fp, NULL));
 317                         continue;
 318                 }
 319 +               if (detect_renamed && S_ISREG(fp->mode)) {
 320 +                       strlcpy(p, fp->basename, remainder);
 321 +                       look_for_rename(fp, fbuf);
 322 +               }
 323                 /* Here we want to match regardless of file type.  Replacement
 324                  * of a file with one of another type is handled separately by
 325                  * a delete_item call with a DEL_MAKE_ROOM flag. */
 326 @@ -333,14 +358,19 @@ static void delete_in_dir(char *fbuf, struct file_struct *file, dev_t *fs_dev)
 327                         if (!(fp->mode & S_IWUSR) && !am_root && fp->flags & FLAG_OWNED_BY_US)
 328                                 flags |= DEL_NO_UID_WRITE;
 329                         f_name(fp, delbuf);
 330 -                       if (delete_during == 2) {
 331 -                               if (!remember_delete(fp, delbuf, flags))
 332 +                       if (delete_during == 2 && !(del_flags & DEL_NO_DELETIONS)) {
 333 +                               if (!remember_delete(fp, delbuf, del_flags | flags))
 334                                         break;
 335                         } else
 336 -                               delete_item(delbuf, fp->mode, flags);
 337 -               }
 338 +                               delete_item(delbuf, fp->mode, del_flags | flags);
 339 +               } else if (detect_renamed && S_ISDIR(fp->mode))
 340 +                       unexplored_dirs++;
 341         }
 342
 343 +       if (restore_dot)
 344 +               fbuf[0] = '.';
 345 +       fbuf[dlen] = '\0';
 346 +
 347         flist_free(dirlist);
 348  }
 349
 350 @@ -376,14 +406,125 @@ static void do_delete_pass(void)
 351                  || !S_ISDIR(st.st_mode))
 352                         continue;
 353
 354 -               delete_in_dir(fbuf, file, &st.st_dev);
 355 +               delete_in_dir(fbuf, file, &st.st_dev, 0);
 356         }
 357 -       delete_in_dir(NULL, NULL, &dev_zero);
 358 +       delete_in_dir(NULL, NULL, &dev_zero, 0);
 359
 360         if (INFO_GTE(FLIST, 2) && !am_server)
 361                 rprintf(FINFO, "                    \r");
 362  }
 363
 364 +/* Search for a regular file that matches either (1) the size & modified
 365 + * time (plus the basename, if possible) or (2) the size & checksum.  If
 366 + * we find an exact match down to the dirname, return -1 because we found
 367 + * an up-to-date file in the transfer, not a renamed file. */
 368 +static int fattr_find(struct file_struct *f, char *fname)
 369 +{
 370 +       int low = the_fattr_list.low, high = the_fattr_list.high;
 371 +       int mid, ok_match = -1, good_match = -1;
 372 +       struct file_struct *fmid;
 373 +       int diff;
 374 +
 375 +       while (low <= high) {
 376 +               mid = (low + high) / 2;
 377 +               fmid = the_fattr_list.files[mid];
 378 +               if (F_LENGTH(fmid) != F_LENGTH(f)) {
 379 +                       if (F_LENGTH(fmid) < F_LENGTH(f))
 380 +                               low = mid + 1;
 381 +                       else
 382 +                               high = mid - 1;
 383 +                       continue;
 384 +               }
 385 +               if (always_checksum) {
 386 +                       /* We use the FLAG_FILE_SENT flag to indicate when we
 387 +                        * have computed the checksum for an entry. */
 388 +                       if (!(f->flags & FLAG_FILE_SENT)) {
 389 +                               STRUCT_STAT st;
 390 +                               if (fmid->modtime == f->modtime
 391 +                                && f_name_cmp(fmid, f) == 0)
 392 +                                       return -1; /* assume we can't help */
 393 +                               st.st_size = F_LENGTH(f);
 394 +                               st.st_mtime = f->modtime;
 395 +                               file_checksum(fname, &st, F_SUM(f));
 396 +                               f->flags |= FLAG_FILE_SENT;
 397 +                       }
 398 +                       diff = u_memcmp(F_SUM(fmid), F_SUM(f), flist_csum_len);
 399 +                       if (diff) {
 400 +                               if (diff < 0)
 401 +                                       low = mid + 1;
 402 +                               else
 403 +                                       high = mid - 1;
 404 +                               continue;
 405 +                       }
 406 +               } else {
 407 +                       if (fmid->modtime != f->modtime) {
 408 +                               if (fmid->modtime < f->modtime)
 409 +                                       low = mid + 1;
 410 +                               else
 411 +                                       high = mid - 1;
 412 +                               continue;
 413 +                       }
 414 +               }
 415 +               ok_match = mid;
 416 +               diff = u_strcmp(fmid->basename, f->basename);
 417 +               if (diff == 0) {
 418 +                       good_match = mid;
 419 +                       if (fmid->dirname == f->dirname)
 420 +                               return -1; /* file is up-to-date */
 421 +                       if (!fmid->dirname) {
 422 +                               low = mid + 1;
 423 +                               continue;
 424 +                       }
 425 +                       if (!f->dirname) {
 426 +                               high = mid - 1;
 427 +                               continue;
 428 +                       }
 429 +                       diff = u_strcmp(fmid->dirname, f->dirname);
 430 +                       if (diff == 0)
 431 +                               return -1; /* file is up-to-date */
 432 +               }
 433 +               if (diff < 0)
 434 +                       low = mid + 1;
 435 +               else
 436 +                       high = mid - 1;
 437 +       }
 438 +
 439 +       return good_match >= 0 ? good_match : ok_match;
 440 +}
 441 +
 442 +void look_for_rename(struct file_struct *file, char *fname)
 443 +{
 444 +       struct file_struct *fp;
 445 +       char *partialptr, *fn;
 446 +       STRUCT_STAT st;
 447 +       int ndx;
 448 +
 449 +       if (!partial_dir || (ndx = fattr_find(file, fname)) < 0)
 450 +               return;
 451 +
 452 +       fp = the_fattr_list.files[ndx];
 453 +       fn = f_name(fp, NULL);
 454 +       /* We don't provide an alternate-basis file if there is a basis file. */
 455 +       if (link_stat(fn, &st, 0) == 0)
 456 +               return;
 457 +
 458 +       if (!dry_run) {
 459 +               if ((partialptr = partial_dir_fname(fn)) == NULL
 460 +                || !handle_partial_dir(partialptr, PDIR_CREATE))
 461 +                       return;
 462 +               /* We only use the file if we can hard-link it into our tmp dir. */
 463 +               if (link(fname, partialptr) != 0) {
 464 +                       if (errno != EEXIST)
 465 +                               handle_partial_dir(partialptr, PDIR_DELETE);
 466 +                       return;
 467 +               }
 468 +       }
 469 +
 470 +       /* I think this falls into the -vv category with "%s is uptodate", etc. */
 471 +       if (INFO_GTE(MISC, 2))
 472 +               rprintf(FINFO, "found renamed: %s => %s\n", fname, fn);
 473 +}
 474 +
 475  static inline int time_diff(STRUCT_STAT *stp, struct file_struct *file)
 476  {
 477  #ifdef ST_MTIME_NSEC
 478 @@ -1162,6 +1303,7 @@ static void list_file_entry(struct file_struct *f)
 479         }
 480  }
 481
 482 +static struct bitbag *delayed_bits = NULL;
 483  static int phase = 0;
 484  static int dflt_perms;
 485
 486 @@ -1292,7 +1434,7 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 487                          && do_stat(dn, &sx.st) < 0) {
 488                                 if (dry_run)
 489                                         goto parent_is_dry_missing;
 490 -                               if (make_path(fname, MKP_DROP_NAME | MKP_SKIP_SLASH) < 0) {
 491 +                               if (make_path(fname, ACCESSPERMS, MKP_DROP_NAME | MKP_SKIP_SLASH) < 0) {
 492                                         rsyserr(FERROR_XFER, errno,
 493                                                 "recv_generator: mkdir %s failed",
 494                                                 full_fname(dn));
 495 @@ -1430,7 +1572,7 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 496                 }
 497                 if (real_ret != 0 && do_mkdir(fname,file->mode|added_perms) < 0 && errno != EEXIST) {
 498                         if (!relative_paths || errno != ENOENT
 499 -                        || make_path(fname, MKP_DROP_NAME | MKP_SKIP_SLASH) < 0
 500 +                        || make_path(fname, ACCESSPERMS, MKP_DROP_NAME | MKP_SKIP_SLASH) < 0
 501                          || (do_mkdir(fname, file->mode|added_perms) < 0 && errno != EEXIST)) {
 502                                 rsyserr(FERROR_XFER, errno,
 503                                         "recv_generator: mkdir %s failed",
 504 @@ -1479,9 +1621,12 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 505                 }
 506                 else if (delete_during && f_out != -1 && !phase
 507                     && !(file->flags & FLAG_MISSING_DIR)) {
 508 -                       if (file->flags & FLAG_CONTENT_DIR)
 509 -                               delete_in_dir(fname, file, &real_sx.st.st_dev);
 510 -                       else
 511 +                       if (file->flags & FLAG_CONTENT_DIR) {
 512 +                               if (detect_renamed && real_ret != 0)
 513 +                                       unexplored_dirs++;
 514 +                               delete_in_dir(fname, file, &real_sx.st.st_dev,
 515 +                                             delete_during < 0 ? DEL_NO_DELETIONS : 0);
 516 +                       } else
 517                                 change_local_filter_dir(fname, strlen(fname), F_DEPTH(file));
 518                 }
 519                 prior_dir_file = file;
 520 @@ -1762,8 +1907,14 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 521                         goto cleanup;
 522                 }
 523  #endif
 524 -               if (stat_errno == ENOENT)
 525 +               if (stat_errno == ENOENT) {
 526 +                       if (detect_renamed && unexplored_dirs > 0
 527 +                        && F_LENGTH(file)) {
 528 +                               bitbag_set_bit(delayed_bits, ndx);
 529 +                               return;
 530 +                       }
 531                         goto notify_others;
 532 +               }
 533                 rsyserr(FERROR_XFER, stat_errno, "recv_generator: failed to stat %s",
 534                         full_fname(fname));
 535                 goto cleanup;
 536 @@ -2227,6 +2378,12 @@ void generate_files(int f_out, const char *local_name)
 537         if (DEBUG_GTE(GENR, 1))
 538                 rprintf(FINFO, "generator starting pid=%d\n", (int)getpid());
 539
 540 +       if (detect_renamed) {
 541 +               delayed_bits = bitbag_create(cur_flist->used);
 542 +               if (!delete_before && !delete_during)
 543 +                       delete_during = -1;
 544 +       }
 545 +
 546         if (delete_before && !solo_file && cur_flist->used > 0)
 547                 do_delete_pass();
 548         if (delete_during == 2) {
 549 @@ -2237,7 +2394,7 @@ void generate_files(int f_out, const char *local_name)
 550         }
 551         info_levels[INFO_FLIST] = info_levels[INFO_PROGRESS] = 0;
 552
 553 -       if (append_mode > 0 || whole_file < 0)
 554 +       if (append_mode > 0 || detect_renamed || whole_file < 0)
 555                 whole_file = 0;
 556         if (DEBUG_GTE(FLIST, 1)) {
 557                 rprintf(FINFO, "delta-transmission %s\n",
 558 @@ -2273,7 +2430,7 @@ void generate_files(int f_out, const char *local_name)
 559                                                 dirdev = MAKEDEV(DEV_MAJOR(devp), DEV_MINOR(devp));
 560                                         } else
 561                                                 dirdev = MAKEDEV(0, 0);
 562 -                                       delete_in_dir(fbuf, fp, &dirdev);
 563 +                                       delete_in_dir(fbuf, fp, &dirdev, 0);
 564                                 } else
 565                                         change_local_filter_dir(fbuf, strlen(fbuf), F_DEPTH(fp));
 566                         }
 567 @@ -2320,7 +2477,21 @@ void generate_files(int f_out, const char *local_name)
 568         } while ((cur_flist = cur_flist->next) != NULL);
 569
 570         if (delete_during)
 571 -               delete_in_dir(NULL, NULL, &dev_zero);
 572 +               delete_in_dir(NULL, NULL, &dev_zero, 0);
 573 +       if (detect_renamed) {
 574 +               if (delete_during < 0)
 575 +                       delete_during = 0;
 576 +               detect_renamed = 0;
 577 +
 578 +               for (i = -1; (i = bitbag_next_bit(delayed_bits, i)) >= 0; ) {
 579 +                       struct file_struct *file = cur_flist->files[i];
 580 +                       if (local_name)
 581 +                               strlcpy(fbuf, local_name, sizeof fbuf);
 582 +                       else
 583 +                               f_name(file, fbuf);
 584 +                       recv_generator(fbuf, file, i, itemizing, code, f_out);
 585 +               }
 586 +       }
 587         phase++;
 588         if (DEBUG_GTE(GENR, 1))
 589                 rprintf(FINFO, "generate_files phase=%d\n", phase);
 590 diff --git a/options.c b/options.c
 591 --- a/options.c
 592 +++ b/options.c
 593 @@ -86,6 +86,7 @@ int am_server = 0;
 594  int am_sender = 0;
 595  int am_starting_up = 1;
 596  int relative_paths = -1;
 597 +int detect_renamed = 0;
 598  int implied_dirs = 1;
 599  int missing_args = 0; /* 0 = FERROR_XFER, 1 = ignore, 2 = delete */
 600  int numeric_ids = 0;
 601 @@ -894,6 +895,7 @@ static struct poptOption long_options[] = {
 602    {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
 603    {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
 604    {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
 605 +  {"detect-renamed",   0,  POPT_ARG_NONE,   &detect_renamed, 0, 0, 0 },
 606    {"fuzzy",           'y', POPT_ARG_NONE,   0, 'y', 0, 0 },
 607    {"no-fuzzy",         0,  POPT_ARG_VAL,    &fuzzy_basis, 0, 0, 0 },
 608    {"no-y",             0,  POPT_ARG_VAL,    &fuzzy_basis, 0, 0, 0 },
 609 @@ -2289,7 +2291,7 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 610                 inplace = 1;
 611         }
 612
 613 -       if (delay_updates && !partial_dir)
 614 +       if ((delay_updates || detect_renamed) && !partial_dir)
 615                 partial_dir = tmp_partialdir;
 616
 617         if (inplace) {
 618 @@ -2298,6 +2300,7 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 619                         snprintf(err_buf, sizeof err_buf,
 620                                  "--%s cannot be used with --%s\n",
 621                                  append_mode ? "append" : "inplace",
 622 +                                detect_renamed ? "detect-renamed" :
 623                                  delay_updates ? "delay-updates" : "partial-dir");
 624                         return 0;
 625                 }
 626 @@ -2700,6 +2703,8 @@ void server_options(char **args, int *argc_p)
 627                         args[ac++] = "--super";
 628                 if (size_only)
 629                         args[ac++] = "--size-only";
 630 +               if (detect_renamed)
 631 +                       args[ac++] = "--detect-renamed";
 632                 if (do_stats)
 633                         args[ac++] = "--stats";
 634         } else {
 635 diff --git a/receiver.c b/receiver.c
 636 --- a/receiver.c
 637 +++ b/receiver.c
 638 @@ -217,7 +217,7 @@ int open_tmpfile(char *fnametmp, const char *fname, struct file_struct *file)
 639          * information should have been previously transferred, but that may
 640          * not be the case with -R */
 641         if (fd == -1 && relative_paths && errno == ENOENT
 642 -        && make_path(fnametmp, MKP_SKIP_SLASH | MKP_DROP_NAME) == 0) {
 643 +        && make_path(fnametmp, ACCESSPERMS, MKP_SKIP_SLASH | MKP_DROP_NAME) == 0) {
 644                 /* Get back to name with XXXXXX in it. */
 645                 get_tmpname(fnametmp, fname, False);
 646                 fd = do_mkstemp(fnametmp, (file->mode|added_perms) & INITACCESSPERMS);
 647 diff --git a/rsync.1.md b/rsync.1.md
 648 --- a/rsync.1.md
 649 +++ b/rsync.1.md
 650 @@ -417,6 +417,7 @@ detailed description below for a complete description.
 651  --modify-window=NUM, -@  set the accuracy for mod-time comparisons
 652  --temp-dir=DIR, -T       create temporary files in directory DIR
 653  --fuzzy, -y              find similar file for basis if no dest file
 654 +--detect-renamed         try to find renamed files to speed the xfer
 655  --compare-dest=DIR       also compare destination files relative to DIR
 656  --copy-dest=DIR          ... and include copies of unchanged files
 657  --link-dest=DIR          hardlink to files in DIR when unchanged
 658 @@ -2157,6 +2158,22 @@ your home directory (remove the '=' for that).
 659      fuzzy-match files, so either use `--delete-after` or specify some filename
 660      exclusions if you need to prevent this.
 661
 662 +0.  `--detect-renamed`
 663 +
 664 +    With this option, for each new source file (call it `src/S`), rsync looks
 665 +    for a file `dest/D` anywhere in the destination that passes the quick check
 666 +    with `src/S`.  If such a `dest/D` is found, rsync uses it as an alternate
 667 +    basis for transferring `S`.  The idea is that if `src/S` was renamed from
 668 +    `src/D` (as opposed to `src/S` passing the quick check with `dest/D` by
 669 +    coincidence), the delta-transfer algorithm will find that all the data
 670 +    matches between `src/S` and `dest/D`, and the transfer will be really fast.
 671 +
 672 +    By default, alternate-basis files are hard-linked into a directory named
 673 +    ".~tmp~" in each file's destination directory, but if you've specified the
 674 +    `--partial-dir` option, that directory will be used instead.  These
 675 +    otential alternate-basis files will be removed as the transfer progresses.
 676 +    This option conflicts with `--inplace` and `--append`.
 677 +
 678  0.  `--compare-dest=DIR`
 679
 680      This option instructs rsync to use _DIR_ on the destination machine as an
 681 diff --git a/rsync.h b/rsync.h
 682 --- a/rsync.h
 683 +++ b/rsync.h
 684 @@ -265,7 +265,7 @@ enum msgcode {
 685  #define NDX_DEL_STATS -3
 686  #define NDX_FLIST_OFFSET -101
 687
 688 -/* For calling delete_item() and delete_dir_contents(). */
 689 +/* For calling delete_item(), delete_dir_contents(), and delete_in_dir(). */
 690  #define DEL_NO_UID_WRITE       (1<<0) /* file/dir has our uid w/o write perm */
 691  #define DEL_RECURSE            (1<<1) /* if dir, delete all contents */
 692  #define DEL_DIR_IS_EMPTY       (1<<2) /* internal delete_FUNCTIONS use only */
 693 @@ -275,6 +275,7 @@ enum msgcode {
 694  #define DEL_FOR_DEVICE         (1<<6) /* making room for a replacement device */
 695  #define DEL_FOR_SPECIAL        (1<<7) /* making room for a replacement special */
 696  #define DEL_FOR_BACKUP         (1<<8) /* the delete is for a backup operation */
 697 +#define DEL_NO_DELETIONS       (1<<9) /* just check for renames w/o deleting */
 698
 699  #define DEL_MAKE_ROOM (DEL_FOR_FILE|DEL_FOR_DIR|DEL_FOR_SYMLINK|DEL_FOR_DEVICE|DEL_FOR_SPECIAL)
 700
 701 diff --git a/util.c b/util.c
 702 --- a/util.c
 703 +++ b/util.c
 704 @@ -182,7 +182,7 @@ int set_times(const char *fname, STRUCT_STAT *stp)
 705  /* Create any necessary directories in fname.  Any missing directories are
 706   * created with default permissions.  Returns < 0 on error, or the number
 707   * of directories created. */
 708 -int make_path(char *fname, int flags)
 709 +int make_path(char *fname, mode_t mode, int flags)
 710  {
 711         char *end, *p;
 712         int ret = 0;
 713 @@ -213,7 +213,7 @@ int make_path(char *fname, int flags)
 714                                 else
 715                                         errno = ENOTDIR;
 716                         }
 717 -               } else if (do_mkdir(fname, ACCESSPERMS) == 0) {
 718 +               } else if (do_mkdir(fname, mode) == 0) {
 719                         ret++;
 720                         break;
 721                 }
 722 @@ -252,7 +252,7 @@ int make_path(char *fname, int flags)
 723                 p += strlen(p);
 724                 if (ret < 0) /* Skip mkdir on error, but keep restoring the path. */
 725                         continue;
 726 -               if (do_mkdir(fname, ACCESSPERMS) < 0)
 727 +               if (do_mkdir(fname, mode) < 0)
 728                         ret = -ret - 1;
 729                 else
 730                         ret++;
 731 @@ -1174,6 +1174,32 @@ char *normalize_path(char *path, BOOL force_newbuf, unsigned int *len_ptr)
 732         return path;
 733  }
 734
 735 +/* We need to supply our own strcmp function for file list comparisons
 736 + * to ensure that signed/unsigned usage is consistent between machines. */
 737 +int u_strcmp(const char *p1, const char *p2)
 738 +{
 739 +        for ( ; *p1; p1++, p2++) {
 740 +               if (*p1 != *p2)
 741 +                       break;
 742 +       }
 743 +
 744 +       return (int)*(uchar*)p1 - (int)*(uchar*)p2;
 745 +}
 746 +
 747 +/* We need a memcmp function compares unsigned-byte values. */
 748 +int u_memcmp(const void *p1, const void *p2, size_t len)
 749 +{
 750 +       const uchar *u1 = p1;
 751 +       const uchar *u2 = p2;
 752 +
 753 +       while (len--) {
 754 +               if (*u1 != *u2)
 755 +                       return (int)*u1 - (int)*u2;
 756 +       }
 757 +
 758 +       return 0;
 759 +}
 760 +
 761  /**
 762   * Return a quoted string with the full pathname of the indicated filename.
 763   * The string " (in MODNAME)" may also be appended.  The returned pointer
 764 @@ -1267,7 +1293,7 @@ int handle_partial_dir(const char *fname, int create)
 765                         }
 766                         statret = -1;
 767                 }
 768 -               if (statret < 0 && do_mkdir(dir, 0700) < 0) {
 769 +               if (statret < 0 && make_path(dir, 0700, 0) < 0) {
 770                         *fn = '/';
 771                         return 0;
 772                 }