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   We need to never return a match from fattr_find() that has a basis
  31   file.  This will ensure that we don't try to give a renamed file to
  32   a file that can't use it, while missing out on giving it to a file
  33   that could use it.
  34
  35 --- old/flist.c
  36 +++ new/flist.c
  37 @@ -55,6 +55,7 @@ extern int non_perishable_cnt;
  38  extern int prune_empty_dirs;
  39  extern int copy_links;
  40  extern int copy_unsafe_links;
  41 +extern int detect_renamed;
  42  extern int protocol_version;
  43  extern int sanitize_paths;
  44  extern struct stats stats;
  45 @@ -80,6 +81,8 @@ static int64 tmp_dev, tmp_ino;
  46  #endif
  47  static char tmp_sum[MD4_SUM_LENGTH];
  48
  49 +struct file_list the_fattr_list;
  50 +
  51  static char empty_sum[MD4_SUM_LENGTH];
  52  static int flist_count_offset; /* for --delete --progress */
  53
  54 @@ -262,6 +265,45 @@ static mode_t from_wire_mode(int mode)
  55         return mode;
  56  }
  57
  58 +static int fattr_compare(struct file_struct **file1, struct file_struct **file2)
  59 +{
  60 +       struct file_struct *f1 = *file1;
  61 +       struct file_struct *f2 = *file2;
  62 +       int64 len1 = F_LENGTH(f1), len2 = F_LENGTH(f2);
  63 +       int diff;
  64 +
  65 +       if (!f1->basename || !S_ISREG(f1->mode) || !len1) {
  66 +               if (!f2->basename || !S_ISREG(f2->mode) || !len2)
  67 +                       return 0;
  68 +               return 1;
  69 +       }
  70 +       if (!f2->basename || !S_ISREG(f2->mode) || !len2)
  71 +               return -1;
  72 +
  73 +       /* Don't use diff for values that are longer than an int. */
  74 +       if (len1 != len2)
  75 +               return len1 < len2 ? -1 : 1;
  76 +
  77 +       if (always_checksum) {
  78 +               diff = u_memcmp(F_SUM(f1), F_SUM(f2), checksum_len);
  79 +               if (diff)
  80 +                       return diff;
  81 +       } else if (f1->modtime != f2->modtime)
  82 +               return f1->modtime < f2->modtime ? -1 : 1;
  83 +
  84 +       diff = u_strcmp(f1->basename, f2->basename);
  85 +       if (diff)
  86 +               return diff;
  87 +
  88 +       if (f1->dirname == f2->dirname)
  89 +               return 0;
  90 +       if (!f1->dirname)
  91 +               return -1;
  92 +       if (!f2->dirname)
  93 +               return 1;
  94 +       return u_strcmp(f1->dirname, f2->dirname);
  95 +}
  96 +
  97  static void send_directory(int f, struct file_list *flist,
  98                            char *fbuf, int len);
  99
 100 @@ -1501,6 +1543,25 @@ struct file_list *recv_file_list(int f)
 101
 102         clean_flist(flist, relative_paths, 1);
 103
 104 +       if (detect_renamed) {
 105 +               int j = flist->count;
 106 +               the_fattr_list.count = j;
 107 +               the_fattr_list.files = new_array(struct file_struct *, j);
 108 +               if (!the_fattr_list.files)
 109 +                       out_of_memory("recv_file_list");
 110 +               memcpy(the_fattr_list.files, flist->files,
 111 +                      j * sizeof (struct file_struct *));
 112 +               qsort(the_fattr_list.files, j,
 113 +                   sizeof the_fattr_list.files[0], (int (*)())fattr_compare);
 114 +               the_fattr_list.low = 0;
 115 +               while (j-- > 0) {
 116 +                       struct file_struct *fp = the_fattr_list.files[j];
 117 +                       if (fp->basename && S_ISREG(fp->mode) && F_LENGTH(fp))
 118 +                               break;
 119 +               }
 120 +               the_fattr_list.high = j;
 121 +       }
 122 +
 123         if (f >= 0) {
 124                 recv_uid_list(f, flist);
 125
 126 --- old/generator.c
 127 +++ new/generator.c
 128 @@ -76,6 +76,7 @@ extern char *basis_dir[];
 129  extern int compare_dest;
 130  extern int copy_dest;
 131  extern int link_dest;
 132 +extern int detect_renamed;
 133  extern int whole_file;
 134  extern int list_only;
 135  extern int new_root_dir;
 136 @@ -91,6 +92,7 @@ extern char *backup_dir;
 137  extern char *backup_suffix;
 138  extern int backup_suffix_len;
 139  extern struct file_list *the_file_list;
 140 +extern struct file_list the_fattr_list;
 141  extern struct filter_list_struct server_filter_list;
 142
 143  int ignore_perishable = 0;
 144 @@ -98,12 +100,14 @@ int non_perishable_cnt = 0;
 145  int maybe_ATTRS_REPORT = 0;
 146
 147  static int deletion_count = 0; /* used to implement --max-delete */
 148 +static int unexplored_dirs = 1;
 149  static int deldelay_size = 0, deldelay_cnt = 0;
 150  static char *deldelay_buf = NULL;
 151  static int deldelay_fd = -1;
 152  static BOOL solo_file = 0;
 153
 154 -/* For calling delete_item() and delete_dir_contents(). */
 155 +/* For calling delete_item(), delete_dir_contents(), and delete_in_dir(). */
 156 +#define DEL_NO_DELETIONS       (1<<0)
 157  #define DEL_RECURSE            (1<<1) /* recurse */
 158  #define DEL_DIR_IS_EMPTY       (1<<2) /* internal delete_FUNCTIONS use only */
 159
 160 @@ -125,11 +129,120 @@ static int is_backup_file(char *fn)
 161         return k > 0 && strcmp(fn+k, backup_suffix) == 0;
 162  }
 163
 164 +/* Search for a regular file that matches either (1) the size & modified
 165 + * time (plus the basename, if possible) or (2) the size & checksum.  If
 166 + * we find an exact match down to the dirname, return -1 because we found
 167 + * an up-to-date file in the transfer, not a renamed file. */
 168 +static int fattr_find(struct file_struct *f, char *fname)
 169 +{
 170 +       int low = the_fattr_list.low, high = the_fattr_list.high;
 171 +       int mid, ok_match = -1, good_match = -1;
 172 +       struct file_struct *fmid;
 173 +       int diff;
 174 +
 175 +       while (low <= high) {
 176 +               mid = (low + high) / 2;
 177 +               fmid = the_fattr_list.files[mid];
 178 +               if (F_LENGTH(fmid) != F_LENGTH(f)) {
 179 +                       if (F_LENGTH(fmid) < F_LENGTH(f))
 180 +                               low = mid + 1;
 181 +                       else
 182 +                               high = mid - 1;
 183 +                       continue;
 184 +               }
 185 +               if (always_checksum) {
 186 +                       /* We use the FLAG_SENT flag to indicate when we
 187 +                        * have computed the checksum for an entry. */
 188 +                       if (!(f->flags & FLAG_SENT)) {
 189 +                               if (fmid->modtime == f->modtime
 190 +                                && f_name_cmp(fmid, f) == 0)
 191 +                                       return -1; /* assume we can't help */
 192 +                               file_checksum(fname, (char*)F_SUM(f), F_LENGTH(f));
 193 +                               f->flags |= FLAG_SENT;
 194 +                       }
 195 +                       diff = u_memcmp(F_SUM(fmid), F_SUM(f), checksum_len);
 196 +                       if (diff) {
 197 +                               if (diff < 0)
 198 +                                       low = mid + 1;
 199 +                               else
 200 +                                       high = mid - 1;
 201 +                               continue;
 202 +                       }
 203 +               } else {
 204 +                       if (fmid->modtime != f->modtime) {
 205 +                               if (fmid->modtime < f->modtime)
 206 +                                       low = mid + 1;
 207 +                               else
 208 +                                       high = mid - 1;
 209 +                               continue;
 210 +                       }
 211 +               }
 212 +               ok_match = mid;
 213 +               diff = u_strcmp(fmid->basename, f->basename);
 214 +               if (diff == 0) {
 215 +                       good_match = mid;
 216 +                       if (fmid->dirname == f->dirname)
 217 +                               return -1; /* file is up-to-date */
 218 +                       if (!fmid->dirname) {
 219 +                               low = mid + 1;
 220 +                               continue;
 221 +                       }
 222 +                       if (!f->dirname) {
 223 +                               high = mid - 1;
 224 +                               continue;
 225 +                       }
 226 +                       diff = u_strcmp(fmid->dirname, f->dirname);
 227 +                       if (diff == 0)
 228 +                               return -1; /* file is up-to-date */
 229 +               }
 230 +               if (diff < 0)
 231 +                       low = mid + 1;
 232 +               else
 233 +                       high = mid - 1;
 234 +       }
 235 +
 236 +       return good_match >= 0 ? good_match : ok_match;
 237 +}
 238 +
 239 +static void look_for_rename(struct file_struct *file, char *fname)
 240 +{
 241 +       struct file_struct *fp;
 242 +       char *partialptr, *fn;
 243 +       STRUCT_STAT st;
 244 +       int ndx;
 245 +
 246 +       if ((ndx = fattr_find(file, fname)) < 0)
 247 +               return;
 248 +
 249 +       fp = the_fattr_list.files[ndx];
 250 +       fn = f_name(fp, NULL);
 251 +       /* We don't provide an alternate-basis file if there is a basis file. */
 252 +       if (link_stat(fn, &st, 0) == 0)
 253 +               return;
 254 +       if ((partialptr = partial_dir_fname(fn)) == NULL
 255 +        || !handle_partial_dir(partialptr, PDIR_CREATE))
 256 +               return;
 257 +
 258 +       /* We only use the file if we can hard-link it into our tmp dir. */
 259 +       if (link(fname, partialptr) == 0) {
 260 +               if (verbose > 2) {
 261 +                       rprintf(FINFO, "found renamed: %s => %s\n",
 262 +                               fname, partialptr);
 263 +               }
 264 +               return;
 265 +       }
 266 +
 267 +       if (errno != EEXIST)
 268 +               handle_partial_dir(partialptr, PDIR_DELETE);
 269 +}
 270 +
 271  /* Delete a file or directory.  If DEL_RECURSE is set in the flags, this will
 272   * delete recursively.
 273   *
 274   * Note that fbuf must point to a MAXPATHLEN buffer if the mode indicates it's
 275   * a directory! (The buffer is used for recursion, but returned unchanged.)
 276 + *
 277 + * Also note: --detect-rename may use this routine with DEL_NO_DELETIONS set!
 278   */
 279  static enum delret delete_item(char *fbuf, int mode, char *replace, int flags)
 280  {
 281 @@ -151,6 +264,8 @@ static enum delret delete_item(char *fbu
 282                         goto check_ret;
 283                 /* OK: try to delete the directory. */
 284         }
 285 +       if (flags & DEL_NO_DELETIONS)
 286 +               return DR_SUCCESS;
 287
 288         if (!replace && max_delete >= 0 && ++deletion_count > max_delete)
 289                 return DR_AT_LIMIT;
 290 @@ -197,6 +312,8 @@ static enum delret delete_item(char *fbu
 291   * its contents, otherwise just checks for content.  Returns DR_SUCCESS or
 292   * DR_NOT_EMPTY.  Note that fname must point to a MAXPATHLEN buffer!  (The
 293   * buffer is used for recursion, but returned unchanged.)
 294 + *
 295 + * Note: --detect-rename may use this routine with DEL_NO_DELETIONS set!
 296   */
 297  static enum delret delete_dir_contents(char *fname, int flags)
 298  {
 299 @@ -216,7 +333,9 @@ static enum delret delete_dir_contents(c
 300         save_filters = push_local_filters(fname, dlen);
 301
 302         non_perishable_cnt = 0;
 303 +       flist_extra_cnt += SUM_EXTRA_CNT;
 304         dirlist = get_dirlist(fname, dlen, 0);
 305 +       flist_extra_cnt -= SUM_EXTRA_CNT;
 306         ret = non_perishable_cnt ? DR_NOT_EMPTY : DR_SUCCESS;
 307
 308         if (!dirlist->count)
 309 @@ -253,6 +372,8 @@ static enum delret delete_dir_contents(c
 310                 if (S_ISDIR(fp->mode)
 311                  && delete_dir_contents(fname, flags | DEL_RECURSE) != DR_SUCCESS)
 312                         ret = DR_NOT_EMPTY;
 313 +               if (detect_renamed && S_ISREG(fp->mode))
 314 +                       look_for_rename(fp, fname);
 315                 if (delete_item(fname, fp->mode, NULL, flags) != DR_SUCCESS)
 316                         ret = DR_NOT_EMPTY;
 317         }
 318 @@ -405,15 +526,19 @@ static void do_delayed_deletions(char *d
 319   * all the --delete-WHEN options.  Note that the fbuf pointer must point to a
 320   * MAXPATHLEN buffer with the name of the directory in it (the functions we
 321   * call will append names onto the end, but the old dir value will be restored
 322 - * on exit). */
 323 + * on exit).
 324 + *
 325 + * Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 326 + */
 327  static void delete_in_dir(struct file_list *flist, char *fbuf,
 328 -                         struct file_struct *file, STRUCT_STAT *stp)
 329 +                         struct file_struct *file, STRUCT_STAT *stp, int flags)
 330  {
 331         static int min_depth = MAXPATHLEN, cur_depth = -1;
 332         static void *filt_array[MAXPATHLEN/2+1];
 333         static int already_warned = 0;
 334         struct file_list *dirlist;
 335 -       char delbuf[MAXPATHLEN];
 336 +       char *p, delbuf[MAXPATHLEN];
 337 +       unsigned remainder;
 338         int dlen, i;
 339
 340         if (!flist) {
 341 @@ -427,6 +552,8 @@ static void delete_in_dir(struct file_li
 342         if (verbose > 2)
 343                 rprintf(FINFO, "delete_in_dir(%s)\n", fbuf);
 344
 345 +       flags |= DEL_RECURSE;
 346 +
 347         if (allowed_lull)
 348                 maybe_send_keepalive();
 349
 350 @@ -434,12 +561,14 @@ static void delete_in_dir(struct file_li
 351                 return; /* Impossible... */
 352
 353         if (io_error && !(lp_ignore_errors(module_id) || ignore_errors)) {
 354 -               if (already_warned)
 355 +               if (!already_warned) {
 356 +                       rprintf(FINFO,
 357 +                           "IO error encountered -- skipping file deletion\n");
 358 +                       already_warned = 1;
 359 +               }
 360 +               if (!detect_renamed)
 361                         return;
 362 -               rprintf(FINFO,
 363 -                       "IO error encountered -- skipping file deletion\n");
 364 -               already_warned = 1;
 365 -               return;
 366 +               flags |= DEL_NO_DELETIONS;
 367         }
 368
 369         while (cur_depth >= F_DEPTH(file) && cur_depth >= min_depth)
 370 @@ -450,6 +579,9 @@ static void delete_in_dir(struct file_li
 371         dlen = strlen(fbuf);
 372         filt_array[cur_depth] = push_local_filters(fbuf, dlen);
 373
 374 +       if (detect_renamed)
 375 +               unexplored_dirs--;
 376 +
 377         if (one_file_system) {
 378                 if (file->flags & FLAG_TOP_DIR)
 379                         filesystem_dev = stp->st_dev;
 380 @@ -459,6 +591,11 @@ static void delete_in_dir(struct file_li
 381
 382         dirlist = get_dirlist(fbuf, dlen, 0);
 383
 384 +       p = fbuf + dlen;
 385 +       if (dlen != 1 || *fbuf != '/')
 386 +               *p++ = '/';
 387 +       remainder = MAXPATHLEN - (p - fbuf);
 388 +
 389         /* If an item in dirlist is not found in flist, delete it
 390          * from the filesystem. */
 391         for (i = dirlist->count; i--; ) {
 392 @@ -471,16 +608,23 @@ static void delete_in_dir(struct file_li
 393                                         f_name(fp, NULL));
 394                         continue;
 395                 }
 396 +               if (detect_renamed && S_ISREG(fp->mode)) {
 397 +                       strlcpy(p, fp->basename, remainder);
 398 +                       look_for_rename(fp, fbuf);
 399 +               }
 400                 if (flist_find(flist, fp) < 0) {
 401                         f_name(fp, delbuf);
 402 -                       if (delete_during == 2) {
 403 +                       if (delete_during == 2 && !(flags & DEL_NO_DELETIONS)) {
 404                                 if (!remember_delete(fp, delbuf))
 405                                         break;
 406                         } else
 407 -                               delete_item(delbuf, fp->mode, NULL, DEL_RECURSE);
 408 -               }
 409 +                               delete_item(delbuf, fp->mode, NULL, flags);
 410 +               } else if (detect_renamed && S_ISDIR(fp->mode))
 411 +                       unexplored_dirs++;
 412         }
 413
 414 +       fbuf[dlen] = '\0';
 415 +
 416         flist_free(dirlist);
 417  }
 418
 419 @@ -510,9 +654,9 @@ static void do_delete_pass(struct file_l
 420                  || !S_ISDIR(st.st_mode))
 421                         continue;
 422
 423 -               delete_in_dir(flist, fbuf, file, &st);
 424 +               delete_in_dir(flist, fbuf, file, &st, 0);
 425         }
 426 -       delete_in_dir(NULL, NULL, NULL, NULL);
 427 +       delete_in_dir(NULL, NULL, NULL, NULL, 0);
 428
 429         if (do_progress && !am_server)
 430                 rprintf(FINFO, "                    \r");
 431 @@ -1047,6 +1191,7 @@ static int try_dests_non(struct file_str
 432         return j;
 433  }
 434
 435 +static struct bitbag *delayed_bits = NULL;
 436  static int phase = 0;
 437
 438  /* Acts on the_file_list->file's ndx'th item, whose name is fname.  If a dir,
 439 @@ -1232,8 +1377,12 @@ static void recv_generator(char *fname,
 440                 if (real_ret != 0 && one_file_system)
 441                         real_st.st_dev = filesystem_dev;
 442                 if (delete_during && f_out != -1 && !phase && dry_run < 2
 443 -                   && (file->flags & FLAG_XFER_DIR))
 444 -                       delete_in_dir(the_file_list, fname, file, &real_st);
 445 +                   && (file->flags & FLAG_XFER_DIR)) {
 446 +                       if (detect_renamed && real_ret != 0)
 447 +                               unexplored_dirs++;
 448 +                       delete_in_dir(the_file_list, fname, file, &real_st,
 449 +                                     delete_during < 0 ? DEL_NO_DELETIONS : 0);
 450 +               }
 451                 return;
 452         }
 453
 454 @@ -1497,8 +1646,14 @@ static void recv_generator(char *fname,
 455                 if (preserve_hard_links && F_HLINK_NOT_LAST(file))
 456                         return;
 457  #endif
 458 -               if (stat_errno == ENOENT)
 459 +               if (stat_errno == ENOENT) {
 460 +                       if (detect_renamed && unexplored_dirs > 0
 461 +                        && F_LENGTH(file)) {
 462 +                               bitbag_set_bit(delayed_bits, ndx);
 463 +                               return;
 464 +                       }
 465                         goto notify_others;
 466 +               }
 467                 rsyserr(FERROR, stat_errno, "recv_generator: failed to stat %s",
 468                         full_fname(fname));
 469                 return;
 470 @@ -1688,6 +1843,12 @@ void generate_files(int f_out, struct fi
 471                         (long)getpid(), flist->count);
 472         }
 473
 474 +       if (detect_renamed) {
 475 +               delayed_bits = bitbag_create(flist->count);
 476 +               if (!delete_before && !delete_during)
 477 +                       delete_during = -1;
 478 +       }
 479 +
 480         if (delete_before && !local_name && flist->count > 0)
 481                 do_delete_pass(flist);
 482         if (delete_during == 2) {
 483 @@ -1698,7 +1859,7 @@ void generate_files(int f_out, struct fi
 484         }
 485         do_progress = 0;
 486
 487 -       if (append_mode || whole_file < 0)
 488 +       if (append_mode || detect_renamed || whole_file < 0)
 489                 whole_file = 0;
 490         if (verbose >= 2) {
 491                 rprintf(FINFO, "delta-transmission %s\n",
 492 @@ -1754,7 +1915,22 @@ void generate_files(int f_out, struct fi
 493         }
 494         recv_generator(NULL, NULL, 0, 0, code, -1);
 495         if (delete_during)
 496 -               delete_in_dir(NULL, NULL, NULL, NULL);
 497 +               delete_in_dir(NULL, NULL, NULL, NULL, 0);
 498 +
 499 +       if (detect_renamed) {
 500 +               if (delete_during < 0)
 501 +                       delete_during = 0;
 502 +               detect_renamed = 0;
 503 +
 504 +               for (i = -1; (i = bitbag_next_bit(delayed_bits, i)) >= 0; ) {
 505 +                       struct file_struct *file = flist->files[i];
 506 +                       if (local_name)
 507 +                               strlcpy(fbuf, local_name, sizeof fbuf);
 508 +                       else
 509 +                               f_name(file, fbuf);
 510 +                       recv_generator(fbuf, file, i, itemizing, code, f_out);
 511 +               }
 512 +       }
 513
 514         phase++;
 515         csum_length = SUM_LENGTH;
 516 --- old/options.c
 517 +++ new/options.c
 518 @@ -78,6 +78,7 @@ int am_generator = 0;
 519  int am_starting_up = 1;
 520  int relative_paths = -1;
 521  int implied_dirs = 1;
 522 +int detect_renamed = 0;
 523  int numeric_ids = 0;
 524  int allow_8bit_chars = 0;
 525  int force_delete = 0;
 526 @@ -342,6 +343,7 @@ void usage(enum logcode F)
 527    rprintf(F,"     --modify-window=NUM     compare mod-times with reduced accuracy\n");
 528    rprintf(F," -T, --temp-dir=DIR          create temporary files in directory DIR\n");
 529    rprintf(F," -y, --fuzzy                 find similar file for basis if no dest file\n");
 530 +  rprintf(F,"     --detect-renamed        try to find renamed files to speed up the transfer\n");
 531    rprintf(F,"     --compare-dest=DIR      also compare destination files relative to DIR\n");
 532    rprintf(F,"     --copy-dest=DIR         ... and include copies of unchanged files\n");
 533    rprintf(F,"     --link-dest=DIR         hardlink to files in DIR when unchanged\n");
 534 @@ -496,6 +498,7 @@ static struct poptOption long_options[]
 535    {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
 536    {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
 537    {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
 538 +  {"detect-renamed",   0,  POPT_ARG_NONE,   &detect_renamed, 0, 0, 0 },
 539    {"fuzzy",           'y', POPT_ARG_NONE,   &fuzzy_basis, 0, 0, 0 },
 540    {"compress",        'z', POPT_ARG_NONE,   0, 'z', 0, 0 },
 541    {"compress-level",   0,  POPT_ARG_INT,    &def_compress_level, 'z', 0, 0 },
 542 @@ -1355,7 +1358,7 @@ int parse_arguments(int *argc, const cha
 543                 inplace = 1;
 544         }
 545
 546 -       if (delay_updates && !partial_dir)
 547 +       if ((delay_updates || detect_renamed) && !partial_dir)
 548                 partial_dir = tmp_partialdir;
 549
 550         if (inplace) {
 551 @@ -1364,6 +1367,7 @@ int parse_arguments(int *argc, const cha
 552                         snprintf(err_buf, sizeof err_buf,
 553                                  "--%s cannot be used with --%s\n",
 554                                  append_mode ? "append" : "inplace",
 555 +                                detect_renamed ? "detect-renamed" :
 556                                  delay_updates ? "delay-updates" : "partial-dir");
 557                         return 0;
 558                 }
 559 @@ -1674,6 +1678,8 @@ void server_options(char **args,int *arg
 560                         args[ac++] = "--super";
 561                 if (size_only)
 562                         args[ac++] = "--size-only";
 563 +               if (detect_renamed)
 564 +                       args[ac++] = "--detect-renamed";
 565         }
 566
 567         if (modify_window_set) {
 568 --- old/rsync.yo
 569 +++ new/rsync.yo
 570 @@ -364,6 +364,7 @@ to the detailed description below for a
 571       --modify-window=NUM     compare mod-times with reduced accuracy
 572   -T, --temp-dir=DIR          create temporary files in directory DIR
 573   -y, --fuzzy                 find similar file for basis if no dest file
 574 +     --detect-renamed        try to find renamed files to speed the xfer
 575       --compare-dest=DIR      also compare received files relative to DIR
 576       --copy-dest=DIR         ... and include copies of unchanged files
 577       --link-dest=DIR         hardlink to files in DIR when unchanged
 578 @@ -1272,6 +1273,15 @@ Note that the use of the bf(--delete) op
 579  fuzzy-match files, so either use bf(--delete-after) or specify some
 580  filename exclusions if you need to prevent this.
 581
 582 +dit(bf(--detect-renamed)) This option tells rsync to scan the receiving
 583 +side for files that have been renamed, and to use any that are found as
 584 +alternate basis files to help speed up the transfer.
 585 +By default, alternate-basis files are hard-linked into a directory named
 586 +".~tmp~" in each file's destination directory, but if you've specified
 587 +the bf(--partial-dir) option, that directory will be used instead.  These
 588 +potential alternate-basis files will be removed as the transfer progresses.
 589 +This option conflicts with bf(--inplace) and bf(--append).
 590 +
 591  dit(bf(--compare-dest=DIR)) This option instructs rsync to use em(DIR) on
 592  the destination machine as an additional hierarchy to compare destination
 593  files against doing transfers (if the files are missing in the destination
 594 --- old/util.c
 595 +++ new/util.c
 596 @@ -1027,6 +1027,32 @@ int handle_partial_dir(const char *fname
 597         return 1;
 598  }
 599
 600 +/* We need to supply our own strcmp function for file list comparisons
 601 + * to ensure that signed/unsigned usage is consistent between machines. */
 602 +int u_strcmp(const char *p1, const char *p2)
 603 +{
 604 +        for ( ; *p1; p1++, p2++) {
 605 +               if (*p1 != *p2)
 606 +                       break;
 607 +       }
 608 +
 609 +       return (int)*(uchar*)p1 - (int)*(uchar*)p2;
 610 +}
 611 +
 612 +/* We need a memcmp function compares unsigned-byte values. */
 613 +int u_memcmp(const void *p1, const void *p2, size_t len)
 614 +{
 615 +       const uchar *u1 = p1;
 616 +       const uchar *u2 = p2;
 617 +
 618 +       while (len--) {
 619 +               if (*u1 != *u2)
 620 +                       return (int)*u1 - (int)*u2;
 621 +       }
 622 +
 623 +       return 0;
 624 +}
 625 +
 626  /**
 627   * Determine if a symlink points outside the current directory tree.
 628   * This is considered "unsafe" because e.g. when mirroring somebody