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 @@ -54,6 +54,7 @@ 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 struct idev tmp_idev;
  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;
  53
  54 @@ -262,6 +265,44 @@ 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 +       int diff;
  63 +
  64 +       if (!f1->basename || !S_ISREG(f1->mode) || !f1->length) {
  65 +               if (!f2->basename || !S_ISREG(f2->mode) || !f2->length)
  66 +                       return 0;
  67 +               return 1;
  68 +       }
  69 +       if (!f2->basename || !S_ISREG(f2->mode) || !f2->length)
  70 +               return -1;
  71 +
  72 +       /* Don't use diff for values that are longer than an int. */
  73 +       if (f1->length != f2->length)
  74 +               return f1->length < f2->length ? -1 : 1;
  75 +
  76 +       if (always_checksum) {
  77 +               diff = u_memcmp(F_SUM(f1), F_SUM(f2), checksum_len);
  78 +               if (diff)
  79 +                       return diff;
  80 +       } else if (f1->modtime != f2->modtime)
  81 +               return f1->modtime < f2->modtime ? -1 : 1;
  82 +
  83 +       diff = u_strcmp(f1->basename, f2->basename);
  84 +       if (diff)
  85 +               return diff;
  86 +
  87 +       if (f1->dirname == f2->dirname)
  88 +               return 0;
  89 +       if (!f1->dirname)
  90 +               return -1;
  91 +       if (!f2->dirname)
  92 +               return 1;
  93 +       return u_strcmp(f1->dirname, f2->dirname);
  94 +}
  95 +
  96  static void send_directory(int f, struct file_list *flist,
  97                            char *fbuf, int len);
  98
  99 @@ -1414,6 +1455,25 @@ struct file_list *recv_file_list(int f)
 100
 101         clean_flist(flist, relative_paths, 1);
 102
 103 +       if (detect_renamed) {
 104 +               int j = flist->count;
 105 +               the_fattr_list.count = j;
 106 +               the_fattr_list.files = new_array(struct file_struct *, j);
 107 +               if (!the_fattr_list.files)
 108 +                       out_of_memory("recv_file_list");
 109 +               memcpy(the_fattr_list.files, flist->files,
 110 +                      j * sizeof (struct file_struct *));
 111 +               qsort(the_fattr_list.files, j,
 112 +                   sizeof the_fattr_list.files[0], (int (*)())fattr_compare);
 113 +               the_fattr_list.low = 0;
 114 +               while (j-- > 0) {
 115 +                       struct file_struct *fp = the_fattr_list.files[j];
 116 +                       if (fp->basename && S_ISREG(fp->mode) && fp->length)
 117 +                               break;
 118 +               }
 119 +               the_fattr_list.high = j;
 120 +       }
 121 +
 122         if (f >= 0) {
 123                 recv_uid_list(f, flist);
 124
 125 --- old/generator.c
 126 +++ new/generator.c
 127 @@ -76,6 +76,7 @@ extern char *basis_dir[];
 128  extern int compare_dest;
 129  extern int copy_dest;
 130  extern int link_dest;
 131 +extern int detect_renamed;
 132  extern int whole_file;
 133  extern int list_only;
 134  extern int new_root_dir;
 135 @@ -91,6 +92,7 @@ extern char *backup_dir;
 136  extern char *backup_suffix;
 137  extern int backup_suffix_len;
 138  extern struct file_list *the_file_list;
 139 +extern struct file_list the_fattr_list;
 140  extern struct filter_list_struct server_filter_list;
 141
 142  int ignore_perishable = 0;
 143 @@ -98,12 +100,14 @@ int non_perishable_cnt = 0;
 144  int maybe_ATTRS_REPORT = 0;
 145
 146  static int deletion_count = 0; /* used to implement --max-delete */
 147 +static int unexplored_dirs = 1;
 148  static int deldelay_size = 0, deldelay_cnt = 0;
 149  static char *deldelay_buf = NULL;
 150  static int deldelay_fd = -1;
 151  static BOOL solo_file = 0;
 152
 153 -/* For calling delete_item() and delete_dir_contents(). */
 154 +/* For calling delete_item(), delete_dir_contents(), and delete_in_dir(). */
 155 +#define DEL_NO_DELETIONS       (1<<0)
 156  #define DEL_RECURSE            (1<<1) /* recurse */
 157  #define DEL_DIR_IS_EMPTY       (1<<2) /* internal delete_FUNCTIONS use only */
 158
 159 @@ -125,11 +129,121 @@ static int is_backup_file(char *fn)
 160         return k > 0 && strcmp(fn+k, backup_suffix) == 0;
 161  }
 162
 163 +/* Search for a regular file that matches either (1) the size & modified
 164 + * time (plus the basename, if possible) or (2) the size & checksum.  If
 165 + * we find an exact match down to the dirname, return -1 because we found
 166 + * an up-to-date file in the transfer, not a renamed file. */
 167 +static int fattr_find(struct file_struct *f, char *fname, alloc_pool_t pool)
 168 +{
 169 +       int low = the_fattr_list.low, high = the_fattr_list.high;
 170 +       int mid, ok_match = -1, good_match = -1;
 171 +       struct file_struct *fmid;
 172 +       int diff;
 173 +
 174 +       while (low <= high) {
 175 +               mid = (low + high) / 2;
 176 +               fmid = the_fattr_list.files[mid];
 177 +               if (fmid->length != f->length) {
 178 +                       if (fmid->length < f->length)
 179 +                               low = mid + 1;
 180 +                       else
 181 +                               high = mid - 1;
 182 +                       continue;
 183 +               }
 184 +               if (always_checksum) {
 185 +                       if (!F_SUM(f)) {
 186 +                               if (fmid->modtime == f->modtime
 187 +                                && f_name_cmp(fmid, f) == 0)
 188 +                                       return -1; /* assume we can't help */
 189 +                               /* XXX update this to new checksum var idiom! */
 190 +                               F_SUM(f) = pool_alloc(pool, MD4_SUM_LENGTH,
 191 +                                                     "fattr_find");
 192 +                               file_checksum(fname, F_SUM(f), f->length);
 193 +                       }
 194 +                       diff = u_memcmp(F_SUM(fmid), F_SUM(f), checksum_len);
 195 +                       if (diff) {
 196 +                               if (diff < 0)
 197 +                                       low = mid + 1;
 198 +                               else
 199 +                                       high = mid - 1;
 200 +                               continue;
 201 +                       }
 202 +               } else {
 203 +                       if (fmid->modtime != f->modtime) {
 204 +                               if (fmid->modtime < f->modtime)
 205 +                                       low = mid + 1;
 206 +                               else
 207 +                                       high = mid - 1;
 208 +                               continue;
 209 +                       }
 210 +               }
 211 +               ok_match = mid;
 212 +               diff = u_strcmp(fmid->basename, f->basename);
 213 +               if (diff == 0) {
 214 +                       good_match = mid;
 215 +                       if (fmid->dirname == f->dirname)
 216 +                               return -1; /* file is up-to-date */
 217 +                       if (!fmid->dirname) {
 218 +                               low = mid + 1;
 219 +                               continue;
 220 +                       }
 221 +                       if (!f->dirname) {
 222 +                               high = mid - 1;
 223 +                               continue;
 224 +                       }
 225 +                       diff = u_strcmp(fmid->dirname, f->dirname);
 226 +                       if (diff == 0)
 227 +                               return -1; /* file is up-to-date */
 228 +               }
 229 +               if (diff < 0)
 230 +                       low = mid + 1;
 231 +               else
 232 +                       high = mid - 1;
 233 +       }
 234 +
 235 +       return good_match >= 0 ? good_match : ok_match;
 236 +}
 237 +
 238 +static void look_for_rename(struct file_struct *file, char *fname,
 239 +                           alloc_pool_t pool)
 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, pool)) < 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 +265,8 @@ 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 +313,8 @@ 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 @@ -253,6 +371,8 @@ static enum delret delete_dir_contents(c
 300                 if (S_ISDIR(fp->mode)
 301                  && delete_dir_contents(fname, flags | DEL_RECURSE) != DR_SUCCESS)
 302                         ret = DR_NOT_EMPTY;
 303 +               if (detect_renamed && S_ISREG(fp->mode))
 304 +                       look_for_rename(fp, fname, dirlist->file_pool);
 305                 if (delete_item(fname, fp->mode, NULL, flags) != DR_SUCCESS)
 306                         ret = DR_NOT_EMPTY;
 307         }
 308 @@ -405,15 +525,19 @@ static void do_delayed_deletions(char *d
 309   * all the --delete-WHEN options.  Note that the fbuf pointer must point to a
 310   * MAXPATHLEN buffer with the name of the directory in it (the functions we
 311   * call will append names onto the end, but the old dir value will be restored
 312 - * on exit). */
 313 + * on exit).
 314 + *
 315 + * Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 316 + */
 317  static void delete_in_dir(struct file_list *flist, char *fbuf,
 318 -                         struct file_struct *file, STRUCT_STAT *stp)
 319 +                         struct file_struct *file, STRUCT_STAT *stp, int flags)
 320  {
 321         static int min_depth = MAXPATHLEN, cur_depth = -1;
 322         static void *filt_array[MAXPATHLEN/2+1];
 323         static int already_warned = 0;
 324         struct file_list *dirlist;
 325 -       char delbuf[MAXPATHLEN];
 326 +       char *p, delbuf[MAXPATHLEN];
 327 +       unsigned remainder;
 328         int dlen, i;
 329
 330         if (!flist) {
 331 @@ -427,6 +551,8 @@ static void delete_in_dir(struct file_li
 332         if (verbose > 2)
 333                 rprintf(FINFO, "delete_in_dir(%s)\n", fbuf);
 334
 335 +       flags |= DEL_RECURSE;
 336 +
 337         if (allowed_lull)
 338                 maybe_send_keepalive();
 339
 340 @@ -434,12 +560,14 @@ static void delete_in_dir(struct file_li
 341                 return; /* Impossible... */
 342
 343         if (io_error && !(lp_ignore_errors(module_id) || ignore_errors)) {
 344 -               if (already_warned)
 345 +               if (!already_warned) {
 346 +                       rprintf(FINFO,
 347 +                           "IO error encountered -- skipping file deletion\n");
 348 +                       already_warned = 1;
 349 +               }
 350 +               if (!detect_renamed)
 351                         return;
 352 -               rprintf(FINFO,
 353 -                       "IO error encountered -- skipping file deletion\n");
 354 -               already_warned = 1;
 355 -               return;
 356 +               flags |= DEL_NO_DELETIONS;
 357         }
 358
 359         while (cur_depth >= file->dir.depth && cur_depth >= min_depth)
 360 @@ -450,6 +578,9 @@ static void delete_in_dir(struct file_li
 361         dlen = strlen(fbuf);
 362         filt_array[cur_depth] = push_local_filters(fbuf, dlen);
 363
 364 +       if (detect_renamed)
 365 +               unexplored_dirs--;
 366 +
 367         if (one_file_system) {
 368                 if (file->flags & FLAG_TOP_DIR)
 369                         filesystem_dev = stp->st_dev;
 370 @@ -459,6 +590,11 @@ static void delete_in_dir(struct file_li
 371
 372         dirlist = get_dirlist(fbuf, dlen, 0);
 373
 374 +       p = fbuf + dlen;
 375 +       if (dlen != 1 || *fbuf != '/')
 376 +               *p++ = '/';
 377 +       remainder = MAXPATHLEN - (p - fbuf);
 378 +
 379         /* If an item in dirlist is not found in flist, delete it
 380          * from the filesystem. */
 381         for (i = dirlist->count; i--; ) {
 382 @@ -471,16 +607,23 @@ static void delete_in_dir(struct file_li
 383                                         f_name(fp, NULL));
 384                         continue;
 385                 }
 386 +               if (detect_renamed && S_ISREG(fp->mode)) {
 387 +                       strlcpy(p, fp->basename, remainder);
 388 +                       look_for_rename(fp, fbuf, dirlist->file_pool);
 389 +               }
 390                 if (flist_find(flist, fp) < 0) {
 391                         f_name(fp, delbuf);
 392 -                       if (delete_during == 2) {
 393 ++                      if (delete_during == 2 && !(flags & DEL_NO_DELETIONS)) {
 394                                 if (!remember_delete(fp, delbuf))
 395                                         break;
 396                         } else
 397 -                               delete_item(delbuf, fp->mode, NULL, DEL_RECURSE);
 398 -               }
 399 +                               delete_item(delbuf, fp->mode, NULL, flags);
 400 +               } else if (detect_renamed && S_ISDIR(fp->mode))
 401 +                       unexplored_dirs++;
 402         }
 403
 404 +       fbuf[dlen] = '\0';
 405 +
 406         flist_free(dirlist);
 407  }
 408
 409 @@ -510,9 +653,9 @@ static void do_delete_pass(struct file_l
 410                  || !S_ISDIR(st.st_mode))
 411                         continue;
 412
 413 -               delete_in_dir(flist, fbuf, file, &st);
 414 +               delete_in_dir(flist, fbuf, file, &st, 0);
 415         }
 416 -       delete_in_dir(NULL, NULL, NULL, NULL);
 417 +       delete_in_dir(NULL, NULL, NULL, NULL, 0);
 418
 419         if (do_progress && !am_server)
 420                 rprintf(FINFO, "                    \r");
 421 @@ -1048,6 +1191,7 @@ static int try_dests_non(struct file_str
 422         return j;
 423  }
 424
 425 +static struct bitbag *delayed_bits = NULL;
 426  static int phase = 0;
 427
 428  /* Acts on the_file_list->file's ndx'th item, whose name is fname.  If a dir,
 429 @@ -1233,8 +1377,12 @@ static void recv_generator(char *fname,
 430                 if (real_ret != 0 && one_file_system)
 431                         real_st.st_dev = filesystem_dev;
 432                 if (delete_during && f_out != -1 && !phase && dry_run < 2
 433 -                   && (file->flags & FLAG_XFER_DIR))
 434 -                       delete_in_dir(the_file_list, fname, file, &real_st);
 435 +                   && (file->flags & FLAG_XFER_DIR)) {
 436 +                       if (detect_renamed && real_ret != 0)
 437 +                               unexplored_dirs++;
 438 +                       delete_in_dir(the_file_list, fname, file, &real_st,
 439 +                                     delete_during < 0 ? DEL_NO_DELETIONS : 0);
 440 +               }
 441                 return;
 442         }
 443
 444 @@ -1498,8 +1646,14 @@ static void recv_generator(char *fname,
 445                 if (preserve_hard_links && F_NOT_HLINK_LAST(file))
 446                         return;
 447  #endif
 448 -               if (stat_errno == ENOENT)
 449 +               if (stat_errno == ENOENT) {
 450 +                       if (detect_renamed && unexplored_dirs > 0
 451 +                        && file->length) {
 452 +                               bitbag_set_bit(delayed_bits, ndx);
 453 +                               return;
 454 +                       }
 455                         goto notify_others;
 456 +               }
 457                 rsyserr(FERROR, stat_errno, "recv_generator: failed to stat %s",
 458                         full_fname(fname));
 459                 return;
 460 @@ -1691,6 +1845,12 @@ void generate_files(int f_out, struct fi
 461                         (long)getpid(), flist->count);
 462         }
 463
 464 +       if (detect_renamed) {
 465 +               delayed_bits = bitbag_create(flist->count);
 466 +               if (!delete_before && !delete_during)
 467 +                       delete_during = -1;
 468 +       }
 469 +
 470         if (delete_before && !local_name && flist->count > 0)
 471                 do_delete_pass(flist);
 472         if (delete_during == 2) {
 473 @@ -1701,7 +1861,7 @@ void generate_files(int f_out, struct fi
 474         }
 475         do_progress = 0;
 476
 477 -       if (append_mode || whole_file < 0)
 478 +       if (append_mode || detect_renamed || whole_file < 0)
 479                 whole_file = 0;
 480         if (verbose >= 2) {
 481                 rprintf(FINFO, "delta-transmission %s\n",
 482 @@ -1757,7 +1917,23 @@ void generate_files(int f_out, struct fi
 483         }
 484         recv_generator(NULL, NULL, 0, 0, code, -1);
 485         if (delete_during)
 486 -               delete_in_dir(NULL, NULL, NULL, NULL);
 487 +               delete_in_dir(NULL, NULL, NULL, NULL, 0);
 488 +
 489 +       if (detect_renamed) {
 490 +               if (delete_during < 0)
 491 +                       delete_during = 0;
 492 +               detect_renamed = 0;
 493 +
 494 +               for (i = -1; (i = bitbag_next_bit(delayed_bits, i)) >= 0; ) {
 495 +                       struct file_struct *file = flist->files[i];
 496 +                       if (local_name)
 497 +                               strlcpy(fbuf, local_name, sizeof fbuf);
 498 +                       else
 499 +                               f_name(file, fbuf);
 500 +                       recv_generator(fbuf, file, i, itemizing,
 501 +                                      maybe_ATTRS_REPORT, code, f_out);
 502 +               }
 503 +       }
 504
 505         phase++;
 506         csum_length = SUM_LENGTH;
 507 --- old/options.c
 508 +++ new/options.c
 509 @@ -78,6 +78,7 @@ int am_generator = 0;
 510  int am_starting_up = 1;
 511  int relative_paths = -1;
 512  int implied_dirs = 1;
 513 +int detect_renamed = 0;
 514  int numeric_ids = 0;
 515  int allow_8bit_chars = 0;
 516  int force_delete = 0;
 517 @@ -343,6 +344,7 @@ void usage(enum logcode F)
 518    rprintf(F,"     --modify-window=NUM     compare mod-times with reduced accuracy\n");
 519    rprintf(F," -T, --temp-dir=DIR          create temporary files in directory DIR\n");
 520    rprintf(F," -y, --fuzzy                 find similar file for basis if no dest file\n");
 521 +  rprintf(F,"     --detect-renamed        try to find renamed files to speed up the transfer\n");
 522    rprintf(F,"     --compare-dest=DIR      also compare destination files relative to DIR\n");
 523    rprintf(F,"     --copy-dest=DIR         ... and include copies of unchanged files\n");
 524    rprintf(F,"     --link-dest=DIR         hardlink to files in DIR when unchanged\n");
 525 @@ -497,6 +499,7 @@ static struct poptOption long_options[]
 526    {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
 527    {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
 528    {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
 529 +  {"detect-renamed",   0,  POPT_ARG_NONE,   &detect_renamed, 0, 0, 0 },
 530    {"fuzzy",           'y', POPT_ARG_NONE,   &fuzzy_basis, 0, 0, 0 },
 531    {"compress",        'z', POPT_ARG_NONE,   0, 'z', 0, 0 },
 532    {"compress-level",   0,  POPT_ARG_INT,    &def_compress_level, 'z', 0, 0 },
 533 @@ -1361,7 +1364,7 @@ int parse_arguments(int *argc, const cha
 534                 inplace = 1;
 535         }
 536
 537 -       if (delay_updates && !partial_dir)
 538 +       if ((delay_updates || detect_renamed) && !partial_dir)
 539                 partial_dir = tmp_partialdir;
 540
 541         if (inplace) {
 542 @@ -1370,6 +1373,7 @@ int parse_arguments(int *argc, const cha
 543                         snprintf(err_buf, sizeof err_buf,
 544                                  "--%s cannot be used with --%s\n",
 545                                  append_mode ? "append" : "inplace",
 546 +                                detect_renamed ? "detect-renamed" :
 547                                  delay_updates ? "delay-updates" : "partial-dir");
 548                         return 0;
 549                 }
 550 @@ -1680,6 +1684,8 @@ void server_options(char **args,int *arg
 551                         args[ac++] = "--super";
 552                 if (size_only)
 553                         args[ac++] = "--size-only";
 554 +               if (detect_renamed)
 555 +                       args[ac++] = "--detect-renamed";
 556         }
 557
 558         if (modify_window_set) {
 559 --- old/rsync.yo
 560 +++ new/rsync.yo
 561 @@ -364,6 +364,7 @@ to the detailed description below for a
 562       --modify-window=NUM     compare mod-times with reduced accuracy
 563   -T, --temp-dir=DIR          create temporary files in directory DIR
 564   -y, --fuzzy                 find similar file for basis if no dest file
 565 +     --detect-renamed        try to find renamed files to speed the xfer
 566       --compare-dest=DIR      also compare received files relative to DIR
 567       --copy-dest=DIR         ... and include copies of unchanged files
 568       --link-dest=DIR         hardlink to files in DIR when unchanged
 569 @@ -1272,6 +1273,15 @@ Note that the use of the bf(--delete) op
 570  fuzzy-match files, so either use bf(--delete-after) or specify some
 571  filename exclusions if you need to prevent this.
 572
 573 +dit(bf(--detect-renamed)) This option tells rsync to scan the receiving
 574 +side for files that have been renamed, and to use any that are found as
 575 +alternate basis files to help speed up the transfer.
 576 +By default, alternate-basis files are hard-linked into a directory named
 577 +".~tmp~" in each file's destination directory, but if you've specified
 578 +the bf(--partial-dir) option, that directory will be used instead.  These
 579 +potential alternate-basis files will be removed as the transfer progresses.
 580 +This option conflicts with bf(--inplace) and bf(--append).
 581 +
 582  dit(bf(--compare-dest=DIR)) This option instructs rsync to use em(DIR) on
 583  the destination machine as an additional hierarchy to compare destination
 584  files against doing transfers (if the files are missing in the destination
 585 --- old/util.c
 586 +++ new/util.c
 587 @@ -1027,6 +1027,32 @@ int handle_partial_dir(const char *fname
 588         return 1;
 589  }
 590
 591 +/* We need to supply our own strcmp function for file list comparisons
 592 + * to ensure that signed/unsigned usage is consistent between machines. */
 593 +int u_strcmp(const char *p1, const char *p2)
 594 +{
 595 +        for ( ; *p1; p1++, p2++) {
 596 +               if (*p1 != *p2)
 597 +                       break;
 598 +       }
 599 +
 600 +       return (int)*(uchar*)p1 - (int)*(uchar*)p2;
 601 +}
 602 +
 603 +/* We need a memcmp function compares unsigned-byte values. */
 604 +int u_memcmp(const void *p1, const void *p2, size_t len)
 605 +{
 606 +       const uchar *u1 = p1;
 607 +       const uchar *u2 = p2;
 608 +
 609 +       while (len--) {
 610 +               if (*u1 != *u2)
 611 +                       return (int)*u1 - (int)*u2;
 612 +       }
 613 +
 614 +       return 0;
 615 +}
 616 +
 617  /**
 618   * Determine if a symlink points outside the current directory tree.
 619   * This is considered "unsafe" because e.g. when mirroring somebody