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 After applying this patch, run these commands for a successful build:
  23
  24     ./prepare-source
  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 implied_dirs;
  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 const char *io_write_phase;
  45 @@ -73,6 +74,8 @@ int checksum_len;
  46  dev_t filesystem_dev; /* used to implement -x */
  47  unsigned int file_struct_len;
  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 @@ -259,6 +262,44 @@ static mode_t from_wire_mode(int mode)
  55         return (mode_t)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(f1->u.sum, f2->u.sum, 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 @@ -1387,6 +1428,25 @@ 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 +                       goto oom;
 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 @@ -77,6 +77,7 @@ 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 read_batch;
 135 @@ -91,12 +92,15 @@ 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  static int deletion_count = 0; /* used to implement --max-delete */
 143 +static int unexplored_dirs = 1;
 144
 145 -/* For calling delete_file() */
 146 +/* For calling delete_item() and delete_in_dir() */
 147  #define DEL_FORCE_RECURSE      (1<<1) /* recurse even w/o --force */
 148 +#define DEL_NO_DELETIONS       (1<<2)
 149  #define DEL_TERSE              (1<<3)
 150
 151
 152 @@ -106,12 +110,120 @@ static int is_backup_file(char *fn)
 153         return k > 0 && strcmp(fn+k, backup_suffix) == 0;
 154  }
 155
 156 +/* Search for a regular file that matches either (1) the size & modified
 157 + * time (plus the basename, if possible) or (2) the size & checksum.  If
 158 + * we find an exact match down to the dirname, return -1 because we found
 159 + * an up-to-date file in the transfer, not a renamed file. */
 160 +static int fattr_find(struct file_struct *f, char *fname, alloc_pool_t pool)
 161 +{
 162 +       int low = the_fattr_list.low, high = the_fattr_list.high;
 163 +       int mid, ok_match = -1, good_match = -1;
 164 +       struct file_struct *fmid;
 165 +       int diff;
 166 +
 167 +       while (low <= high) {
 168 +               mid = (low + high) / 2;
 169 +               fmid = the_fattr_list.files[mid];
 170 +               if (fmid->length != f->length) {
 171 +                       if (fmid->length < f->length)
 172 +                               low = mid + 1;
 173 +                       else
 174 +                               high = mid - 1;
 175 +                       continue;
 176 +               }
 177 +               if (always_checksum) {
 178 +                       if (!f->u.sum) {
 179 +                               if (fmid->modtime == f->modtime
 180 +                                && f_name_cmp(fmid, f) == 0)
 181 +                                       return -1; /* assume we can't help */
 182 +                               f->u.sum = pool_alloc(pool, MD4_SUM_LENGTH,
 183 +                                                     "fattr_find");
 184 +                               file_checksum(fname, f->u.sum, f->length);
 185 +                       }
 186 +                       diff = u_memcmp(fmid->u.sum, f->u.sum, checksum_len);
 187 +                       if (diff) {
 188 +                               if (diff < 0)
 189 +                                       low = mid + 1;
 190 +                               else
 191 +                                       high = mid - 1;
 192 +                               continue;
 193 +                       }
 194 +               } else {
 195 +                       if (fmid->modtime != f->modtime) {
 196 +                               if (fmid->modtime < f->modtime)
 197 +                                       low = mid + 1;
 198 +                               else
 199 +                                       high = mid - 1;
 200 +                               continue;
 201 +                       }
 202 +               }
 203 +               ok_match = mid;
 204 +               diff = u_strcmp(fmid->basename, f->basename);
 205 +               if (diff == 0) {
 206 +                       good_match = mid;
 207 +                       if (fmid->dirname == f->dirname)
 208 +                               return -1; /* file is up-to-date */
 209 +                       if (!fmid->dirname) {
 210 +                               low = mid + 1;
 211 +                               continue;
 212 +                       }
 213 +                       if (!f->dirname) {
 214 +                               high = mid - 1;
 215 +                               continue;
 216 +                       }
 217 +                       diff = u_strcmp(fmid->dirname, f->dirname);
 218 +                       if (diff == 0)
 219 +                               return -1; /* file is up-to-date */
 220 +               }
 221 +               if (diff < 0)
 222 +                       low = mid + 1;
 223 +               else
 224 +                       high = mid - 1;
 225 +       }
 226 +
 227 +       return good_match >= 0 ? good_match : ok_match;
 228 +}
 229 +
 230 +static void look_for_rename(struct file_struct *file, char *fname,
 231 +                           alloc_pool_t pool)
 232 +{
 233 +       struct file_struct *fp;
 234 +       char *partialptr, *fn;
 235 +       STRUCT_STAT st;
 236 +       int ndx;
 237 +
 238 +       if ((ndx = fattr_find(file, fname, pool)) < 0)
 239 +               return;
 240 +
 241 +       fp = the_fattr_list.files[ndx];
 242 +       fn = f_name(fp, NULL);
 243 +       /* We don't provide an alternate-basis file if there is a basis file. */
 244 +       if (link_stat(fn, &st, 0) == 0)
 245 +               return;
 246 +       if ((partialptr = partial_dir_fname(fn)) == NULL
 247 +        || !handle_partial_dir(partialptr, PDIR_CREATE))
 248 +               return;
 249 +
 250 +       /* We only use the file if we can hard-link it into our tmp dir. */
 251 +       if (link(fname, partialptr) == 0) {
 252 +               if (verbose > 2) {
 253 +                       rprintf(FINFO, "found renamed: %s => %s\n",
 254 +                               fname, partialptr);
 255 +               }
 256 +               return;
 257 +       }
 258 +
 259 +       if (errno != EEXIST)
 260 +               handle_partial_dir(partialptr, PDIR_DELETE);
 261 +}
 262
 263  /* Delete a file or directory.  If DEL_FORCE_RECURSE is set in the flags, or if
 264   * force_delete is set, this will delete recursively.
 265   *
 266   * Note that fname must point to a MAXPATHLEN buffer if the mode indicates it's
 267   * a directory! (The buffer is used for recursion, but returned unchanged.)
 268 + *
 269 + * Also Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 270   */
 271  static int delete_item(char *fname, int mode, int flags)
 272  {
 273 @@ -122,6 +234,8 @@ static int delete_item(char *fname, int
 274         char *p;
 275
 276         if (!S_ISDIR(mode)) {
 277 +               if (flags & DEL_NO_DELETIONS)
 278 +                       return 0;
 279                 if (max_delete && ++deletion_count > max_delete)
 280                         return 0;
 281                 if (make_backups && (backup_dir || !is_backup_file(fname)))
 282 @@ -144,6 +258,7 @@ static int delete_item(char *fname, int
 283
 284         zap_dir = flags & DEL_FORCE_RECURSE || force_delete;
 285         if ((max_delete && ++deletion_count > max_delete)
 286 +           || flags & DEL_NO_DELETIONS
 287             || (dry_run && zap_dir)) {
 288                 ok = 0;
 289                 errno = ENOTEMPTY;
 290 @@ -186,6 +301,8 @@ static int delete_item(char *fname, int
 291                         continue;
 292
 293                 strlcpy(p, fp->basename, remainder);
 294 +               if (detect_renamed && S_ISREG(fp->mode))
 295 +                       look_for_rename(fp, fname, dirlist->file_pool);
 296                 delete_item(fname, fp->mode, flags & ~DEL_TERSE);
 297         }
 298         flist_free(dirlist);
 299 @@ -194,7 +311,8 @@ static int delete_item(char *fname, int
 300
 301         pop_local_filters(save_filters);
 302
 303 -       if (max_delete && ++deletion_count > max_delete)
 304 +       if (flags & DEL_NO_DELETIONS
 305 +        || (max_delete && ++deletion_count > max_delete))
 306                 return 0;
 307
 308         if (do_rmdir(fname) == 0) {
 309 @@ -214,15 +332,19 @@ static int delete_item(char *fname, int
 310   * all the --delete-WHEN options.  Note that the fbuf pointer must point to a
 311   * MAXPATHLEN buffer with the name of the directory in it (the functions we
 312   * call will append names onto the end, but the old dir value will be restored
 313 - * on exit). */
 314 + * on exit).
 315 + *
 316 + * Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 317 + */
 318  static void delete_in_dir(struct file_list *flist, char *fbuf,
 319 -                         struct file_struct *file, STRUCT_STAT *stp)
 320 +                         struct file_struct *file, STRUCT_STAT *stp, int flags)
 321  {
 322         static int min_depth = MAXPATHLEN, cur_depth = -1;
 323         static void *filt_array[MAXPATHLEN/2+1];
 324         static int already_warned = 0;
 325         struct file_list *dirlist;
 326 -       char delbuf[MAXPATHLEN];
 327 +       char *p, delbuf[MAXPATHLEN];
 328 +       unsigned remainder;
 329         int dlen, i;
 330
 331         if (!flist) {
 332 @@ -236,6 +358,8 @@ static void delete_in_dir(struct file_li
 333         if (verbose > 2)
 334                 rprintf(FINFO, "delete_in_dir(%s)\n", fbuf);
 335
 336 +       flags |= DEL_FORCE_RECURSE;
 337 +
 338         if (allowed_lull)
 339                 maybe_send_keepalive();
 340
 341 @@ -243,12 +367,14 @@ static void delete_in_dir(struct file_li
 342                 return; /* Impossible... */
 343
 344         if (io_error && !(lp_ignore_errors(module_id) || ignore_errors)) {
 345 -               if (already_warned)
 346 +               if (!already_warned) {
 347 +                       rprintf(FINFO,
 348 +                           "IO error encountered -- skipping file deletion\n");
 349 +                       already_warned = 1;
 350 +               }
 351 +               if (!detect_renamed)
 352                         return;
 353 -               rprintf(FINFO,
 354 -                       "IO error encountered -- skipping file deletion\n");
 355 -               already_warned = 1;
 356 -               return;
 357 +               flags |= DEL_NO_DELETIONS;
 358         }
 359
 360         while (cur_depth >= file->dir.depth && cur_depth >= min_depth)
 361 @@ -259,6 +385,9 @@ static void delete_in_dir(struct file_li
 362         dlen = strlen(fbuf);
 363         filt_array[cur_depth] = push_local_filters(fbuf, dlen);
 364
 365 +       if (detect_renamed)
 366 +               unexplored_dirs--;
 367 +
 368         if (one_file_system) {
 369                 if (file->flags & FLAG_TOP_DIR)
 370                         filesystem_dev = stp->st_dev;
 371 @@ -268,18 +397,30 @@ static void delete_in_dir(struct file_li
 372
 373         dirlist = get_dirlist(fbuf, dlen, 0);
 374
 375 +       p = fbuf + dlen;
 376 +       if (dlen != 1 || *fbuf != '/')
 377 +               *p++ = '/';
 378 +       remainder = MAXPATHLEN - (p - fbuf);
 379 +
 380         /* If an item in dirlist is not found in flist, delete it
 381          * from the filesystem. */
 382         for (i = dirlist->count; i--; ) {
 383                 struct file_struct *fp = dirlist->files[i];
 384                 if (!fp->basename || fp->flags & FLAG_MOUNT_POINT)
 385                         continue;
 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 -                       delete_item(delbuf, fp->mode, DEL_FORCE_RECURSE);
 393 -               }
 394 +                       delete_item(delbuf, fp->mode, flags);
 395 +               } else if (detect_renamed && S_ISDIR(fp->mode))
 396 +                       unexplored_dirs++;
 397         }
 398
 399 +       fbuf[dlen] = '\0';
 400 +
 401         flist_free(dirlist);
 402  }
 403
 404 @@ -309,9 +450,9 @@ static void do_delete_pass(struct file_l
 405                  || !S_ISDIR(st.st_mode))
 406                         continue;
 407
 408 -               delete_in_dir(flist, fbuf, file, &st);
 409 +               delete_in_dir(flist, fbuf, file, &st, 0);
 410         }
 411 -       delete_in_dir(NULL, NULL, NULL, NULL);
 412 +       delete_in_dir(NULL, NULL, NULL, NULL, 0);
 413
 414         if (do_progress && !am_server)
 415                 rprintf(FINFO, "                    \r");
 416 @@ -756,6 +897,7 @@ static int try_dests_non(struct file_str
 417         return -1;
 418  }
 419
 420 +static struct bitbag *delayed_bits = NULL;
 421  static int phase = 0;
 422
 423  /* Acts on the_file_list->file's ndx'th item, whose name is fname.  If a dir,
 424 @@ -910,8 +1052,12 @@ static void recv_generator(char *fname,
 425                     && verbose && code && f_out != -1)
 426                         rprintf(code, "%s/\n", fname);
 427                 if (delete_during && f_out != -1 && !phase && dry_run < 2
 428 -                   && (file->flags & FLAG_DEL_HERE))
 429 -                       delete_in_dir(the_file_list, fname, file, &st);
 430 +                   && (file->flags & FLAG_DEL_HERE)) {
 431 +                       if (detect_renamed && statret != 0)
 432 +                               unexplored_dirs++;
 433 +                       delete_in_dir(the_file_list, fname, file, &st,
 434 +                                     delete_during < 0 ? DEL_NO_DELETIONS : 0);
 435 +               }
 436                 return;
 437         }
 438
 439 @@ -1150,8 +1296,14 @@ static void recv_generator(char *fname,
 440                     && hard_link_check(file, ndx, fname, statret, &st,
 441                                        itemizing, code, HL_SKIP))
 442                         return;
 443 -               if (stat_errno == ENOENT)
 444 +               if (stat_errno == ENOENT) {
 445 +                       if (detect_renamed && unexplored_dirs > 0
 446 +                        && file->length) {
 447 +                               bitbag_set_bit(delayed_bits, ndx);
 448 +                               return;
 449 +                       }
 450                         goto notify_others;
 451 +               }
 452                 rsyserr(FERROR, stat_errno, "recv_generator: failed to stat %s",
 453                         full_fname(fname));
 454                 return;
 455 @@ -1329,11 +1481,17 @@ void generate_files(int f_out, struct fi
 456                         (long)getpid(), flist->count);
 457         }
 458
 459 +       if (detect_renamed) {
 460 +               delayed_bits = bitbag_create(flist->count);
 461 +               if (!delete_before && !delete_during)
 462 +                       delete_during = -1;
 463 +       }
 464 +
 465         if (delete_before && !local_name && flist->count > 0)
 466                 do_delete_pass(flist);
 467         do_progress = 0;
 468
 469 -       if (append_mode || whole_file < 0)
 470 +       if (append_mode || detect_renamed || whole_file < 0)
 471                 whole_file = 0;
 472         if (verbose >= 2) {
 473                 rprintf(FINFO, "delta-transmission %s\n",
 474 @@ -1388,7 +1546,23 @@ void generate_files(int f_out, struct fi
 475         }
 476         recv_generator(NULL, NULL, 0, 0, 0, code, -1);
 477         if (delete_during)
 478 -               delete_in_dir(NULL, NULL, NULL, NULL);
 479 +               delete_in_dir(NULL, NULL, NULL, NULL, 0);
 480 +
 481 +       if (detect_renamed) {
 482 +               if (delete_during < 0)
 483 +                       delete_during = 0;
 484 +               detect_renamed = 0;
 485 +
 486 +               for (i = -1; (i = bitbag_next_bit(delayed_bits, i)) >= 0; ) {
 487 +                       struct file_struct *file = flist->files[i];
 488 +                       if (local_name)
 489 +                               strlcpy(fbuf, local_name, sizeof fbuf);
 490 +                       else
 491 +                               f_name(file, fbuf);
 492 +                       recv_generator(fbuf, file, i, itemizing,
 493 +                                      maybe_ATTRS_REPORT, code, f_out);
 494 +               }
 495 +       }
 496
 497         phase++;
 498         csum_length = SUM_LENGTH;
 499 --- old/options.c
 500 +++ new/options.c
 501 @@ -76,6 +76,7 @@ int am_generator = 0;
 502  int am_starting_up = 1;
 503  int relative_paths = -1;
 504  int implied_dirs = 1;
 505 +int detect_renamed = 0;
 506  int numeric_ids = 0;
 507  int allow_8bit_chars = 0;
 508  int force_delete = 0;
 509 @@ -334,6 +335,7 @@ void usage(enum logcode F)
 510    rprintf(F,"     --modify-window=NUM     compare mod-times with reduced accuracy\n");
 511    rprintf(F," -T, --temp-dir=DIR          create temporary files in directory DIR\n");
 512    rprintf(F," -y, --fuzzy                 find similar file for basis if no dest file\n");
 513 +  rprintf(F,"     --detect-renamed        try to find renamed files to speed up the transfer\n");
 514    rprintf(F,"     --compare-dest=DIR      also compare destination files relative to DIR\n");
 515    rprintf(F,"     --copy-dest=DIR         ... and include copies of unchanged files\n");
 516    rprintf(F,"     --link-dest=DIR         hardlink to files in DIR when unchanged\n");
 517 @@ -481,6 +483,7 @@ static struct poptOption long_options[]
 518    {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
 519    {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
 520    {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
 521 +  {"detect-renamed",   0,  POPT_ARG_NONE,   &detect_renamed, 0, 0, 0 },
 522    {"fuzzy",           'y', POPT_ARG_NONE,   &fuzzy_basis, 0, 0, 0 },
 523    {"compress",        'z', POPT_ARG_NONE,   0, 'z', 0, 0 },
 524    {"compress-level",   0,  POPT_ARG_INT,    &def_compress_level, 'z', 0, 0 },
 525 @@ -1340,7 +1343,7 @@ int parse_arguments(int *argc, const cha
 526                 inplace = 1;
 527         }
 528
 529 -       if (delay_updates && !partial_dir)
 530 +       if ((delay_updates || detect_renamed) && !partial_dir)
 531                 partial_dir = tmp_partialdir;
 532
 533         if (inplace) {
 534 @@ -1349,6 +1352,7 @@ int parse_arguments(int *argc, const cha
 535                         snprintf(err_buf, sizeof err_buf,
 536                                  "--%s cannot be used with --%s\n",
 537                                  append_mode ? "append" : "inplace",
 538 +                                detect_renamed ? "detect-renamed" :
 539                                  delay_updates ? "delay-updates" : "partial-dir");
 540                         return 0;
 541                 }
 542 @@ -1651,6 +1655,8 @@ void server_options(char **args,int *arg
 543                         args[ac++] = "--super";
 544                 if (size_only)
 545                         args[ac++] = "--size-only";
 546 +               if (detect_renamed)
 547 +                       args[ac++] = "--detect-renamed";
 548         }
 549
 550         if (modify_window_set) {
 551 --- old/rsync.yo
 552 +++ new/rsync.yo
 553 @@ -362,6 +362,7 @@ to the detailed description below for a
 554       --modify-window=NUM     compare mod-times with reduced accuracy
 555   -T, --temp-dir=DIR          create temporary files in directory DIR
 556   -y, --fuzzy                 find similar file for basis if no dest file
 557 +     --detect-renamed        try to find renamed files to speed the xfer
 558       --compare-dest=DIR      also compare received files relative to DIR
 559       --copy-dest=DIR         ... and include copies of unchanged files
 560       --link-dest=DIR         hardlink to files in DIR when unchanged
 561 @@ -1240,6 +1241,15 @@ Note that the use of the bf(--delete) op
 562  fuzzy-match files, so either use bf(--delete-after) or specify some
 563  filename exclusions if you need to prevent this.
 564
 565 +dit(bf(--detect-renamed)) This option tells rsync to scan the receiving
 566 +side for files that have been renamed, and to use any that are found as
 567 +alternate basis files to help speed up the transfer.
 568 +By default, alternate-basis files are hard-linked into a directory named
 569 +".~tmp~" in each file's destination directory, but if you've specified
 570 +the bf(--partial-dir) option, that directory will be used instead.  These
 571 +potential alternate-basis files will be removed as the transfer progresses.
 572 +This option conflicts with bf(--inplace) and bf(--append).
 573 +
 574  dit(bf(--compare-dest=DIR)) This option instructs rsync to use em(DIR) on
 575  the destination machine as an additional hierarchy to compare destination
 576  files against doing transfers (if the files are missing in the destination
 577 --- old/util.c
 578 +++ new/util.c
 579 @@ -1013,6 +1013,32 @@ int handle_partial_dir(const char *fname
 580         return 1;
 581  }
 582
 583 +/* We need to supply our own strcmp function for file list comparisons
 584 + * to ensure that signed/unsigned usage is consistent between machines. */
 585 +int u_strcmp(const char *p1, const char *p2)
 586 +{
 587 +        for ( ; *p1; p1++, p2++) {
 588 +               if (*p1 != *p2)
 589 +                       break;
 590 +       }
 591 +
 592 +       return (int)*(uchar*)p1 - (int)*(uchar*)p2;
 593 +}
 594 +
 595 +/* We need a memcmp function compares unsigned-byte values. */
 596 +int u_memcmp(const void *p1, const void *p2, size_t len)
 597 +{
 598 +       const uchar *u1 = p1;
 599 +       const uchar *u2 = p2;
 600 +
 601 +       while (len--) {
 602 +               if (*u1 != *u2)
 603 +                       return (int)*u1 - (int)*u2;
 604 +       }
 605 +
 606 +       return 0;
 607 +}
 608 +
 609  /**
 610   * Determine if a symlink points outside the current directory tree.
 611   * This is considered "unsafe" because e.g. when mirroring somebody