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 @@ -51,6 +51,7 @@ 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 struct stats stats;
  45 @@ -68,6 +69,8 @@ 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 @@ -250,6 +253,44 @@ 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(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 @@ -1379,6 +1420,25 @@ 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 @@ -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 @@ -91,12 +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_item() */
 146 +/* For calling delete_item() and delete_in_dir() */
 147  #define DEL_RECURSE            (1<<1) /* recurse */
 148 +#define DEL_NO_DELETIONS       (1<<2)
 149
 150  enum nonregtype {
 151      TYPE_DIR, TYPE_SPECIAL, TYPE_DEVICE, TYPE_SYMLINK
 152 @@ -116,6 +120,113 @@ 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_RECURSE is set in the flags, this will
 264   * delete recursively.
 265   *
 266 @@ -185,6 +296,8 @@ static enum delret delete_item(char *fna
 267  /* Prep directory is to be deleted, so delete all its contents.  Note
 268   * that fname must point to a MAXPATHLEN buffer!  (The buffer is used
 269   * for recursion, but returned unchanged.)
 270 + *
 271 + * Note: --detect-rename may use this routine with DEL_NO_DELETIONS set!
 272   */
 273  static enum delret delete_dir_contents(char *fname, int flags)
 274  {
 275 @@ -221,6 +334,16 @@ static enum delret delete_dir_contents(c
 276                 }
 277
 278                 strlcpy(p, fp->basename, remainder);
 279 +               if (detect_renamed) {
 280 +                       if (S_ISDIR(fp->mode) && flags & DEL_NO_DELETIONS) {
 281 +                               delete_dir_contents(fname, flags);
 282 +                               continue;
 283 +                       }
 284 +                       if (S_ISREG(fp->mode))
 285 +                               look_for_rename(fp, fname, dirlist->file_pool);
 286 +                       if (flags & DEL_NO_DELETIONS)
 287 +                               continue;
 288 +               }
 289                 result = delete_item(fname, fp->mode, NULL, flags);
 290                 if (result != DR_SUCCESS && ret == DR_SUCCESS)
 291                         ret = result == DR_PINNED ? result : DR_NOT_EMPTY;
 292 @@ -239,15 +362,19 @@ static enum delret delete_dir_contents(c
 293   * all the --delete-WHEN options.  Note that the fbuf pointer must point to a
 294   * MAXPATHLEN buffer with the name of the directory in it (the functions we
 295   * call will append names onto the end, but the old dir value will be restored
 296 - * on exit). */
 297 + * on exit).
 298 + *
 299 + * Note:  --detect-rename may use this routine with DEL_NO_DELETIONS set!
 300 + */
 301  static void delete_in_dir(struct file_list *flist, char *fbuf,
 302 -                         struct file_struct *file, STRUCT_STAT *stp)
 303 +                         struct file_struct *file, STRUCT_STAT *stp, int flags)
 304  {
 305         static int min_depth = MAXPATHLEN, cur_depth = -1;
 306         static void *filt_array[MAXPATHLEN/2+1];
 307         static int already_warned = 0;
 308         struct file_list *dirlist;
 309 -       char delbuf[MAXPATHLEN];
 310 +       char *p, delbuf[MAXPATHLEN];
 311 +       unsigned remainder;
 312         int dlen, i;
 313
 314         if (!flist) {
 315 @@ -261,6 +388,8 @@ static void delete_in_dir(struct file_li
 316         if (verbose > 2)
 317                 rprintf(FINFO, "delete_in_dir(%s)\n", fbuf);
 318
 319 +       flags |= DEL_RECURSE;
 320 +
 321         if (allowed_lull)
 322                 maybe_send_keepalive();
 323
 324 @@ -268,12 +397,14 @@ static void delete_in_dir(struct file_li
 325                 return; /* Impossible... */
 326
 327         if (io_error && !(lp_ignore_errors(module_id) || ignore_errors)) {
 328 -               if (already_warned)
 329 +               if (!already_warned) {
 330 +                       rprintf(FINFO,
 331 +                           "IO error encountered -- skipping file deletion\n");
 332 +                       already_warned = 1;
 333 +               }
 334 +               if (!detect_renamed)
 335                         return;
 336 -               rprintf(FINFO,
 337 -                       "IO error encountered -- skipping file deletion\n");
 338 -               already_warned = 1;
 339 -               return;
 340 +               flags |= DEL_NO_DELETIONS;
 341         }
 342
 343         while (cur_depth >= file->dir.depth && cur_depth >= min_depth)
 344 @@ -284,6 +415,9 @@ static void delete_in_dir(struct file_li
 345         dlen = strlen(fbuf);
 346         filt_array[cur_depth] = push_local_filters(fbuf, dlen);
 347
 348 +       if (detect_renamed)
 349 +               unexplored_dirs--;
 350 +
 351         if (one_file_system) {
 352                 if (file->flags & FLAG_TOP_DIR)
 353                         filesystem_dev = stp->st_dev;
 354 @@ -293,6 +427,11 @@ static void delete_in_dir(struct file_li
 355
 356         dirlist = get_dirlist(fbuf, dlen, 0);
 357
 358 +       p = fbuf + dlen;
 359 +       if (dlen != 1 || *fbuf != '/')
 360 +               *p++ = '/';
 361 +       remainder = MAXPATHLEN - (p - fbuf);
 362 +
 363         /* If an item in dirlist is not found in flist, delete it
 364          * from the filesystem. */
 365         for (i = dirlist->count; i--; ) {
 366 @@ -305,12 +444,19 @@ static void delete_in_dir(struct file_li
 367                                         f_name(fp, NULL));
 368                         continue;
 369                 }
 370 +               if (detect_renamed && S_ISREG(fp->mode)) {
 371 +                       strlcpy(p, fp->basename, remainder);
 372 +                       look_for_rename(fp, fbuf, dirlist->file_pool);
 373 +               }
 374                 if (flist_find(flist, fp) < 0) {
 375                         f_name(fp, delbuf);
 376 -                       delete_item(delbuf, fp->mode, NULL, DEL_RECURSE);
 377 -               }
 378 +                       delete_item(delbuf, fp->mode, NULL, flags);
 379 +               } else if (detect_renamed && S_ISDIR(fp->mode))
 380 +                       unexplored_dirs++;
 381         }
 382
 383 +       fbuf[dlen] = '\0';
 384 +
 385         flist_free(dirlist);
 386  }
 387
 388 @@ -340,9 +486,9 @@ static void do_delete_pass(struct file_l
 389                  || !S_ISDIR(st.st_mode))
 390                         continue;
 391
 392 -               delete_in_dir(flist, fbuf, file, &st);
 393 +               delete_in_dir(flist, fbuf, file, &st, 0);
 394         }
 395 -       delete_in_dir(NULL, NULL, NULL, NULL);
 396 +       delete_in_dir(NULL, NULL, NULL, NULL, 0);
 397
 398         if (do_progress && !am_server)
 399                 rprintf(FINFO, "                    \r");
 400 @@ -871,6 +1017,7 @@ static int try_dests_non(struct file_str
 401         return j;
 402  }
 403
 404 +static struct bitbag *delayed_bits = NULL;
 405  static int phase = 0;
 406
 407  /* Acts on the_file_list->file's ndx'th item, whose name is fname.  If a dir,
 408 @@ -1056,8 +1203,12 @@ static void recv_generator(char *fname,
 409                 if (real_ret != 0 && one_file_system)
 410                         real_st.st_dev = filesystem_dev;
 411                 if (delete_during && f_out != -1 && !phase && dry_run < 2
 412 -                   && (file->flags & FLAG_DEL_HERE))
 413 -                       delete_in_dir(the_file_list, fname, file, &real_st);
 414 +                   && (file->flags & FLAG_DEL_HERE)) {
 415 +                       if (detect_renamed && real_ret != 0)
 416 +                               unexplored_dirs++;
 417 +                       delete_in_dir(the_file_list, fname, file, &real_st,
 418 +                                     delete_during < 0 ? DEL_NO_DELETIONS : 0);
 419 +               }
 420                 return;
 421         }
 422
 423 @@ -1309,8 +1460,14 @@ static void recv_generator(char *fname,
 424                     && hard_link_check(file, ndx, fname, statret, &st,
 425                                        itemizing, code, HL_SKIP))
 426                         return;
 427 -               if (stat_errno == ENOENT)
 428 +               if (stat_errno == ENOENT) {
 429 +                       if (detect_renamed && unexplored_dirs > 0
 430 +                        && file->length) {
 431 +                               bitbag_set_bit(delayed_bits, ndx);
 432 +                               return;
 433 +                       }
 434                         goto notify_others;
 435 +               }
 436                 rsyserr(FERROR, stat_errno, "recv_generator: failed to stat %s",
 437                         full_fname(fname));
 438                 return;
 439 @@ -1496,11 +1653,17 @@ void generate_files(int f_out, struct fi
 440                         (long)getpid(), flist->count);
 441         }
 442
 443 +       if (detect_renamed) {
 444 +               delayed_bits = bitbag_create(flist->count);
 445 +               if (!delete_before && !delete_during)
 446 +                       delete_during = -1;
 447 +       }
 448 +
 449         if (delete_before && !local_name && flist->count > 0)
 450                 do_delete_pass(flist);
 451         do_progress = 0;
 452
 453 -       if (append_mode || whole_file < 0)
 454 +       if (append_mode || detect_renamed || whole_file < 0)
 455                 whole_file = 0;
 456         if (verbose >= 2) {
 457                 rprintf(FINFO, "delta-transmission %s\n",
 458 @@ -1555,7 +1718,23 @@ void generate_files(int f_out, struct fi
 459         }
 460         recv_generator(NULL, NULL, 0, 0, 0, code, -1);
 461         if (delete_during)
 462 -               delete_in_dir(NULL, NULL, NULL, NULL);
 463 +               delete_in_dir(NULL, NULL, NULL, NULL, 0);
 464 +
 465 +       if (detect_renamed) {
 466 +               if (delete_during < 0)
 467 +                       delete_during = 0;
 468 +               detect_renamed = 0;
 469 +
 470 +               for (i = -1; (i = bitbag_next_bit(delayed_bits, i)) >= 0; ) {
 471 +                       struct file_struct *file = flist->files[i];
 472 +                       if (local_name)
 473 +                               strlcpy(fbuf, local_name, sizeof fbuf);
 474 +                       else
 475 +                               f_name(file, fbuf);
 476 +                       recv_generator(fbuf, file, i, itemizing,
 477 +                                      maybe_ATTRS_REPORT, code, f_out);
 478 +               }
 479 +       }
 480
 481         phase++;
 482         csum_length = SUM_LENGTH;
 483 --- old/options.c
 484 +++ new/options.c
 485 @@ -78,6 +78,7 @@ int am_generator = 0;
 486  int am_starting_up = 1;
 487  int relative_paths = -1;
 488  int implied_dirs = 1;
 489 +int detect_renamed = 0;
 490  int numeric_ids = 0;
 491  int allow_8bit_chars = 0;
 492  int force_delete = 0;
 493 @@ -346,6 +347,7 @@ void usage(enum logcode F)
 494    rprintf(F,"     --modify-window=NUM     compare mod-times with reduced accuracy\n");
 495    rprintf(F," -T, --temp-dir=DIR          create temporary files in directory DIR\n");
 496    rprintf(F," -y, --fuzzy                 find similar file for basis if no dest file\n");
 497 +  rprintf(F,"     --detect-renamed        try to find renamed files to speed up the transfer\n");
 498    rprintf(F,"     --compare-dest=DIR      also compare destination files relative to DIR\n");
 499    rprintf(F,"     --copy-dest=DIR         ... and include copies of unchanged files\n");
 500    rprintf(F,"     --link-dest=DIR         hardlink to files in DIR when unchanged\n");
 501 @@ -499,6 +501,7 @@ static struct poptOption long_options[]
 502    {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
 503    {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
 504    {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
 505 +  {"detect-renamed",   0,  POPT_ARG_NONE,   &detect_renamed, 0, 0, 0 },
 506    {"fuzzy",           'y', POPT_ARG_NONE,   &fuzzy_basis, 0, 0, 0 },
 507    {"compress",        'z', POPT_ARG_NONE,   0, 'z', 0, 0 },
 508    {"compress-level",   0,  POPT_ARG_INT,    &def_compress_level, 'z', 0, 0 },
 509 @@ -1362,7 +1365,7 @@ int parse_arguments(int *argc, const cha
 510                 inplace = 1;
 511         }
 512
 513 -       if (delay_updates && !partial_dir)
 514 +       if ((delay_updates || detect_renamed) && !partial_dir)
 515                 partial_dir = tmp_partialdir;
 516
 517         if (inplace) {
 518 @@ -1371,6 +1374,7 @@ int parse_arguments(int *argc, const cha
 519                         snprintf(err_buf, sizeof err_buf,
 520                                  "--%s cannot be used with --%s\n",
 521                                  append_mode ? "append" : "inplace",
 522 +                                detect_renamed ? "detect-renamed" :
 523                                  delay_updates ? "delay-updates" : "partial-dir");
 524                         return 0;
 525                 }
 526 @@ -1674,6 +1678,8 @@ void server_options(char **args,int *arg
 527                         args[ac++] = "--super";
 528                 if (size_only)
 529                         args[ac++] = "--size-only";
 530 +               if (detect_renamed)
 531 +                       args[ac++] = "--detect-renamed";
 532         }
 533
 534         if (modify_window_set) {
 535 --- old/rsync.yo
 536 +++ new/rsync.yo
 537 @@ -363,6 +363,7 @@ to the detailed description below for a
 538       --modify-window=NUM     compare mod-times with reduced accuracy
 539   -T, --temp-dir=DIR          create temporary files in directory DIR
 540   -y, --fuzzy                 find similar file for basis if no dest file
 541 +     --detect-renamed        try to find renamed files to speed the xfer
 542       --compare-dest=DIR      also compare received files relative to DIR
 543       --copy-dest=DIR         ... and include copies of unchanged files
 544       --link-dest=DIR         hardlink to files in DIR when unchanged
 545 @@ -1264,6 +1265,15 @@ Note that the use of the bf(--delete) op
 546  fuzzy-match files, so either use bf(--delete-after) or specify some
 547  filename exclusions if you need to prevent this.
 548
 549 +dit(bf(--detect-renamed)) This option tells rsync to scan the receiving
 550 +side for files that have been renamed, and to use any that are found as
 551 +alternate basis files to help speed up the transfer.
 552 +By default, alternate-basis files are hard-linked into a directory named
 553 +".~tmp~" in each file's destination directory, but if you've specified
 554 +the bf(--partial-dir) option, that directory will be used instead.  These
 555 +potential alternate-basis files will be removed as the transfer progresses.
 556 +This option conflicts with bf(--inplace) and bf(--append).
 557 +
 558  dit(bf(--compare-dest=DIR)) This option instructs rsync to use em(DIR) on
 559  the destination machine as an additional hierarchy to compare destination
 560  files against doing transfers (if the files are missing in the destination
 561 --- old/util.c
 562 +++ new/util.c
 563 @@ -1025,6 +1025,32 @@ int handle_partial_dir(const char *fname
 564         return 1;
 565  }
 566
 567 +/* We need to supply our own strcmp function for file list comparisons
 568 + * to ensure that signed/unsigned usage is consistent between machines. */
 569 +int u_strcmp(const char *p1, const char *p2)
 570 +{
 571 +        for ( ; *p1; p1++, p2++) {
 572 +               if (*p1 != *p2)
 573 +                       break;
 574 +       }
 575 +
 576 +       return (int)*(uchar*)p1 - (int)*(uchar*)p2;
 577 +}
 578 +
 579 +/* We need a memcmp function compares unsigned-byte values. */
 580 +int u_memcmp(const void *p1, const void *p2, size_t len)
 581 +{
 582 +       const uchar *u1 = p1;
 583 +       const uchar *u2 = p2;
 584 +
 585 +       while (len--) {
 586 +               if (*u1 != *u2)
 587 +                       return (int)*u1 - (int)*u2;
 588 +       }
 589 +
 590 +       return 0;
 591 +}
 592 +
 593  /**
 594   * Determine if a symlink points outside the current directory tree.
 595   * This is considered "unsafe" because e.g. when mirroring somebody