match.c

   1 /*
   2  * Block matching used by the file-transfer code.
   3  *
   4  * Copyright (C) 1996 Andrew Tridgell
   5  * Copyright (C) 1996 Paul Mackerras
   6  * Copyright (C) 2003-2014 Wayne Davison
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 3 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, visit the http://fsf.org website.
  20  */
  21
  22 #include "rsync.h"
  23 #include "inums.h"
  24
  25 extern int checksum_seed;
  26 extern int append_mode;
  27 extern int checksum_len;
  28
  29 int updating_basis_file;
  30 char sender_file_sum[MAX_DIGEST_LEN];
  31
  32 static int false_alarms;
  33 static int hash_hits;
  34 static int matches;
  35 static int64 data_transfer;
  36
  37 static int total_false_alarms;
  38 static int total_hash_hits;
  39 static int total_matches;
  40
  41 extern struct stats stats;
  42
  43 #define TRADITIONAL_TABLESIZE (1<<16)
  44
  45 static uint32 tablesize;
  46 static int32 *hash_table;
  47
  48 #define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF)
  49 #define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16)
  50
  51 #define BIG_SUM2HASH(sum) ((sum)%tablesize)
  52
  53 static void build_hash_table(struct sum_struct *s)
  54 {
  55         static uint32 alloc_size;
  56         int32 i;
  57
  58         /* Dynamically calculate the hash table size so that the hash load
  59          * for big files is about 80%.  A number greater than the traditional
  60          * size must be odd or s2 will not be able to span the entire set. */
  61         tablesize = (uint32)(s->count/8) * 10 + 11;
  62         if (tablesize < TRADITIONAL_TABLESIZE)
  63                 tablesize = TRADITIONAL_TABLESIZE;
  64         if (tablesize > alloc_size || tablesize < alloc_size - 16*1024) {
  65                 if (hash_table)
  66                         free(hash_table);
  67                 hash_table = new_array(int32, tablesize);
  68                 if (!hash_table)
  69                         out_of_memory("build_hash_table");
  70                 alloc_size = tablesize;
  71         }
  72
  73         memset(hash_table, 0xFF, tablesize * sizeof hash_table[0]);
  74
  75         if (tablesize == TRADITIONAL_TABLESIZE) {
  76                 for (i = 0; i < s->count; i++) {
  77                         uint32 t = SUM2HASH(s->sums[i].sum1);
  78                         s->sums[i].chain = hash_table[t];
  79                         hash_table[t] = i;
  80                 }
  81         } else {
  82                 for (i = 0; i < s->count; i++) {
  83                         uint32 t = BIG_SUM2HASH(s->sums[i].sum1);
  84                         s->sums[i].chain = hash_table[t];
  85                         hash_table[t] = i;
  86                 }
  87         }
  88 }
  89
  90
  91 static OFF_T last_match;
  92
  93
  94 /* Transmit a literal and/or match token.
  95  *
  96  * This delightfully-named function is called either when we find a
  97  * match and need to transmit all the unmatched data leading up to it,
  98  * or when we get bored of accumulating literal data and just need to
  99  * transmit it.  As a result of this second case, it is called even if
 100  * we have not matched at all!
 101  *
 102  * If i >= 0, the number of a matched token.  If < 0, indicates we have
 103  * only literal data.  A -1 will send a 0-token-int too, and a -2 sends
 104  * only literal data, w/o any token-int. */
 105 static void matched(int f, struct sum_struct *s, struct map_struct *buf,
 106                     OFF_T offset, int32 i)
 107 {
 108         int32 n = (int32)(offset - last_match); /* max value: block_size (int32) */
 109         int32 j;
 110
 111         if (DEBUG_GTE(DELTASUM, 2) && i >= 0) {
 112                 rprintf(FINFO,
 113                         "match at %s last_match=%s j=%d len=%ld n=%ld\n",
 114                         big_num(offset), big_num(last_match), i,
 115                         (long)s->sums[i].len, (long)n);
 116         }
 117
 118         send_token(f, i, buf, last_match, n, i < 0 ? 0 : s->sums[i].len);
 119         data_transfer += n;
 120
 121         if (i >= 0) {
 122                 stats.matched_data += s->sums[i].len;
 123                 n += s->sums[i].len;
 124         }
 125
 126         for (j = 0; j < n; j += CHUNK_SIZE) {
 127                 int32 n1 = MIN(CHUNK_SIZE, n - j);
 128                 sum_update(map_ptr(buf, last_match + j, n1), n1);
 129         }
 130
 131         if (i >= 0)
 132                 last_match = offset + s->sums[i].len;
 133         else
 134                 last_match = offset;
 135
 136         if (buf && INFO_GTE(PROGRESS, 1))
 137                 show_progress(last_match, buf->file_size);
 138 }
 139
 140
 141 static void hash_search(int f,struct sum_struct *s,
 142                         struct map_struct *buf, OFF_T len)
 143 {
 144         OFF_T offset, aligned_offset, end;
 145         int32 k, want_i, aligned_i, backup;
 146         char sum2[SUM_LENGTH];
 147         uint32 s1, s2, sum;
 148         int more;
 149         schar *map;
 150
 151         /* want_i is used to encourage adjacent matches, allowing the RLL
 152          * coding of the output to work more efficiently. */
 153         want_i = 0;
 154
 155         if (DEBUG_GTE(DELTASUM, 2)) {
 156                 rprintf(FINFO, "hash search b=%ld len=%s\n",
 157                         (long)s->blength, big_num(len));
 158         }
 159
 160         k = (int32)MIN(len, (OFF_T)s->blength);
 161
 162         map = (schar *)map_ptr(buf, 0, k);
 163
 164         sum = get_checksum1((char *)map, k);
 165         s1 = sum & 0xFFFF;
 166         s2 = sum >> 16;
 167         if (DEBUG_GTE(DELTASUM, 3))
 168                 rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);
 169
 170         offset = aligned_offset = aligned_i = 0;
 171
 172         end = len + 1 - s->sums[s->count-1].len;
 173
 174         if (DEBUG_GTE(DELTASUM, 3)) {
 175                 rprintf(FINFO, "hash search s->blength=%ld len=%s count=%s\n",
 176                         (long)s->blength, big_num(len), big_num(s->count));
 177         }
 178
 179         do {
 180                 int done_csum2 = 0;
 181                 uint32 hash_entry;
 182                 int32 i, *prev;
 183
 184                 if (DEBUG_GTE(DELTASUM, 4)) {
 185                         rprintf(FINFO, "offset=%s sum=%04x%04x\n",
 186                                 big_num(offset), s2 & 0xFFFF, s1 & 0xFFFF);
 187                 }
 188
 189                 if (tablesize == TRADITIONAL_TABLESIZE) {
 190                         hash_entry = SUM2HASH2(s1,s2);
 191                         if ((i = hash_table[hash_entry]) < 0)
 192                                 goto null_hash;
 193                         sum = (s1 & 0xffff) | (s2 << 16);
 194                 } else {
 195                         sum = (s1 & 0xffff) | (s2 << 16);
 196                         hash_entry = BIG_SUM2HASH(sum);
 197                         if ((i = hash_table[hash_entry]) < 0)
 198                                 goto null_hash;
 199                 }
 200                 prev = &hash_table[hash_entry];
 201
 202                 hash_hits++;
 203                 do {
 204                         int32 l;
 205
 206                         /* When updating in-place, the chunk's offset must be
 207                          * either >= our offset or identical data at that offset.
 208                          * Remove any bypassed entries that we can never use. */
 209                         if (updating_basis_file && s->sums[i].offset < offset
 210                             && !(s->sums[i].flags & SUMFLG_SAME_OFFSET)) {
 211                                 *prev = s->sums[i].chain;
 212                                 continue;
 213                         }
 214                         prev = &s->sums[i].chain;
 215
 216                         if (sum != s->sums[i].sum1)
 217                                 continue;
 218
 219                         /* also make sure the two blocks are the same length */
 220                         l = (int32)MIN((OFF_T)s->blength, len-offset);
 221                         if (l != s->sums[i].len)
 222                                 continue;
 223
 224                         if (DEBUG_GTE(DELTASUM, 3)) {
 225                                 rprintf(FINFO,
 226                                         "potential match at %s i=%ld sum=%08x\n",
 227                                         big_num(offset), (long)i, sum);
 228                         }
 229
 230                         if (!done_csum2) {
 231                                 map = (schar *)map_ptr(buf,offset,l);
 232                                 get_checksum2((char *)map,l,sum2);
 233                                 done_csum2 = 1;
 234                         }
 235
 236                         if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
 237                                 false_alarms++;
 238                                 continue;
 239                         }
 240
 241                         /* When updating in-place, the best possible match is
 242                          * one with an identical offset, so we prefer that over
 243                          * the adjacent want_i optimization. */
 244                         if (updating_basis_file) {
 245                                 /* All the generator's chunks start at blength boundaries. */
 246                                 while (aligned_offset < offset) {
 247                                         aligned_offset += s->blength;
 248                                         aligned_i++;
 249                                 }
 250                                 if ((offset == aligned_offset
 251                                   || (sum == 0 && l == s->blength && aligned_offset + l <= len))
 252                                  && aligned_i < s->count) {
 253                                         if (i != aligned_i) {
 254                                                 if (sum != s->sums[aligned_i].sum1
 255                                                  || l != s->sums[aligned_i].len
 256                                                  || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0)
 257                                                         goto check_want_i;
 258                                                 i = aligned_i;
 259                                         }
 260                                         if (offset != aligned_offset) {
 261                                                 /* We've matched some zeros in a spot that is also zeros
 262                                                  * further along in the basis file, if we find zeros ahead
 263                                                  * in the sender's file, we'll output enough literal data
 264                                                  * to re-align with the basis file, and get back to seeking
 265                                                  * instead of writing. */
 266                                                 backup = (int32)(aligned_offset - last_match);
 267                                                 if (backup < 0)
 268                                                         backup = 0;
 269                                                 map = (schar *)map_ptr(buf, aligned_offset - backup, l + backup)
 270                                                     + backup;
 271                                                 sum = get_checksum1((char *)map, l);
 272                                                 if (sum != s->sums[i].sum1)
 273                                                         goto check_want_i;
 274                                                 get_checksum2((char *)map, l, sum2);
 275                                                 if (memcmp(sum2, s->sums[i].sum2, s->s2length) != 0)
 276                                                         goto check_want_i;
 277                                                 /* OK, we have a re-alignment match.  Bump the offset
 278                                                  * forward to the new match point. */
 279                                                 offset = aligned_offset;
 280                                         }
 281                                         /* This identical chunk is in the same spot in the old and new file. */
 282                                         s->sums[i].flags |= SUMFLG_SAME_OFFSET;
 283                                         want_i = i;
 284                                 }
 285                         }
 286
 287                   check_want_i:
 288                         /* we've found a match, but now check to see
 289                          * if want_i can hint at a better match. */
 290                         if (i != want_i && want_i < s->count
 291                             && (!updating_basis_file || s->sums[want_i].offset >= offset
 292                              || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
 293                             && sum == s->sums[want_i].sum1
 294                             && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) {
 295                                 /* we've found an adjacent match - the RLL coder
 296                                  * will be happy */
 297                                 i = want_i;
 298                         }
 299                         want_i = i + 1;
 300
 301                         matched(f,s,buf,offset,i);
 302                         offset += s->sums[i].len - 1;
 303                         k = (int32)MIN((OFF_T)s->blength, len-offset);
 304                         map = (schar *)map_ptr(buf, offset, k);
 305                         sum = get_checksum1((char *)map, k);
 306                         s1 = sum & 0xFFFF;
 307                         s2 = sum >> 16;
 308                         matches++;
 309                         break;
 310                 } while ((i = s->sums[i].chain) >= 0);
 311
 312           null_hash:
 313                 backup = (int32)(offset - last_match);
 314                 /* We sometimes read 1 byte prior to last_match... */
 315                 if (backup < 0)
 316                         backup = 0;
 317
 318                 /* Trim off the first byte from the checksum */
 319                 more = offset + k < len;
 320                 map = (schar *)map_ptr(buf, offset - backup, k + more + backup)
 321                     + backup;
 322                 s1 -= map[0] + CHAR_OFFSET;
 323                 s2 -= k * (map[0]+CHAR_OFFSET);
 324
 325                 /* Add on the next byte (if there is one) to the checksum */
 326                 if (more) {
 327                         s1 += map[k] + CHAR_OFFSET;
 328                         s2 += s1;
 329                 } else
 330                         --k;
 331
 332                 /* By matching early we avoid re-reading the
 333                    data 3 times in the case where a token
 334                    match comes a long way after last
 335                    match. The 3 reads are caused by the
 336                    running match, the checksum update and the
 337                    literal send. */
 338                 if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
 339                         matched(f, s, buf, offset - s->blength, -2);
 340         } while (++offset < end);
 341
 342         matched(f, s, buf, len, -1);
 343         map_ptr(buf, len-1, 1);
 344 }
 345
 346
 347 /**
 348  * Scan through a origin file, looking for sections that match
 349  * checksums from the generator, and transmit either literal or token
 350  * data.
 351  *
 352  * Also calculates the MD4 checksum of the whole file, using the md
 353  * accumulator.  This is transmitted with the file as protection
 354  * against corruption on the wire.
 355  *
 356  * @param s Checksums received from the generator.  If <tt>s->count ==
 357  * 0</tt>, then there are actually no checksums for this file.
 358  *
 359  * @param len Length of the file to send.
 360  **/
 361 void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len)
 362 {
 363         last_match = 0;
 364         false_alarms = 0;
 365         hash_hits = 0;
 366         matches = 0;
 367         data_transfer = 0;
 368
 369         sum_init(checksum_seed);
 370
 371         if (append_mode > 0) {
 372                 if (append_mode == 2) {
 373                         OFF_T j = 0;
 374                         for (j = CHUNK_SIZE; j < s->flength; j += CHUNK_SIZE) {
 375                                 if (buf && INFO_GTE(PROGRESS, 1))
 376                                         show_progress(last_match, buf->file_size);
 377                                 sum_update(map_ptr(buf, last_match, CHUNK_SIZE),
 378                                            CHUNK_SIZE);
 379                                 last_match = j;
 380                         }
 381                         if (last_match < s->flength) {
 382                                 int32 n = (int32)(s->flength - last_match);
 383                                 if (buf && INFO_GTE(PROGRESS, 1))
 384                                         show_progress(last_match, buf->file_size);
 385                                 sum_update(map_ptr(buf, last_match, n), n);
 386                         }
 387                 }
 388                 last_match = s->flength;
 389                 s->count = 0;
 390         }
 391
 392         if (len > 0 && s->count > 0) {
 393                 build_hash_table(s);
 394
 395                 if (DEBUG_GTE(DELTASUM, 2))
 396                         rprintf(FINFO,"built hash table\n");
 397
 398                 hash_search(f, s, buf, len);
 399
 400                 if (DEBUG_GTE(DELTASUM, 2))
 401                         rprintf(FINFO,"done hash search\n");
 402         } else {
 403                 OFF_T j;
 404                 /* by doing this in pieces we avoid too many seeks */
 405                 for (j = last_match + CHUNK_SIZE; j < len; j += CHUNK_SIZE)
 406                         matched(f, s, buf, j, -2);
 407                 matched(f, s, buf, len, -1);
 408         }
 409
 410         if (sum_end(sender_file_sum) != checksum_len)
 411                 overflow_exit("checksum_len"); /* Impossible... */
 412
 413         /* If we had a read error, send a bad checksum.  We use all bits
 414          * off as long as the checksum doesn't happen to be that, in
 415          * which case we turn the last 0 bit into a 1. */
 416         if (buf && buf->status != 0) {
 417                 int i;
 418                 for (i = 0; i < checksum_len && sender_file_sum[i] == 0; i++) {}
 419                 memset(sender_file_sum, 0, checksum_len);
 420                 if (i == checksum_len)
 421                         sender_file_sum[i-1]++;
 422         }
 423
 424         if (DEBUG_GTE(DELTASUM, 2))
 425                 rprintf(FINFO,"sending file_sum\n");
 426         write_buf(f, sender_file_sum, checksum_len);
 427
 428         if (DEBUG_GTE(DELTASUM, 2)) {
 429                 rprintf(FINFO, "false_alarms=%d hash_hits=%d matches=%d\n",
 430                         false_alarms, hash_hits, matches);
 431         }
 432
 433         total_hash_hits += hash_hits;
 434         total_false_alarms += false_alarms;
 435         total_matches += matches;
 436         stats.literal_data += data_transfer;
 437 }
 438
 439 void match_report(void)
 440 {
 441         if (!DEBUG_GTE(DELTASUM, 1))
 442                 return;
 443
 444         rprintf(FINFO,
 445                 "total: matches=%d  hash_hits=%d  false_alarms=%d data=%s\n",
 446                 total_matches, total_hash_hits, total_false_alarms,
 447                 big_num(stats.literal_data));
 448 }