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) 2003-2020 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 xfersum_type;
  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, OFF_T offset, int32 i)
 106 {
 107         int32 n = (int32)(offset - last_match); /* max value: block_size (int32) */
 108         int32 j;
 109
 110         if (DEBUG_GTE(DELTASUM, 2) && i >= 0) {
 111                 rprintf(FINFO,
 112                         "match at %s last_match=%s j=%d len=%ld n=%ld\n",
 113                         big_num(offset), big_num(last_match), i,
 114                         (long)s->sums[i].len, (long)n);
 115         }
 116
 117         send_token(f, i, buf, last_match, n, i < 0 ? 0 : s->sums[i].len);
 118         data_transfer += n;
 119
 120         if (i >= 0) {
 121                 stats.matched_data += s->sums[i].len;
 122                 n += s->sums[i].len;
 123         }
 124
 125         for (j = 0; j < n; j += CHUNK_SIZE) {
 126                 int32 n1 = MIN(CHUNK_SIZE, n - j);
 127                 sum_update(map_ptr(buf, last_match + j, n1), n1);
 128         }
 129
 130         if (i >= 0)
 131                 last_match = offset + s->sums[i].len;
 132         else
 133                 last_match = offset;
 134
 135         if (buf && INFO_GTE(PROGRESS, 1))
 136                 show_progress(last_match, buf->file_size);
 137 }
 138
 139
 140 static void hash_search(int f,struct sum_struct *s,
 141                         struct map_struct *buf, OFF_T len)
 142 {
 143         OFF_T offset, aligned_offset, end;
 144         int32 k, want_i, aligned_i, backup;
 145         char sum2[SUM_LENGTH];
 146         uint32 s1, s2, sum;
 147         int more;
 148         schar *map;
 149
 150         /* want_i is used to encourage adjacent matches, allowing the RLL
 151          * coding of the output to work more efficiently. */
 152         want_i = 0;
 153
 154         if (DEBUG_GTE(DELTASUM, 2)) {
 155                 rprintf(FINFO, "hash search b=%ld len=%s\n",
 156                         (long)s->blength, big_num(len));
 157         }
 158
 159         k = (int32)MIN(len, (OFF_T)s->blength);
 160
 161         map = (schar *)map_ptr(buf, 0, k);
 162
 163         sum = get_checksum1((char *)map, k);
 164         s1 = sum & 0xFFFF;
 165         s2 = sum >> 16;
 166         if (DEBUG_GTE(DELTASUM, 3))
 167                 rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);
 168
 169         offset = aligned_offset = aligned_i = 0;
 170
 171         end = len + 1 - s->sums[s->count-1].len;
 172
 173         if (DEBUG_GTE(DELTASUM, 3)) {
 174                 rprintf(FINFO, "hash search s->blength=%ld len=%s count=%s\n",
 175                         (long)s->blength, big_num(len), big_num(s->count));
 176         }
 177
 178         do {
 179                 int done_csum2 = 0;
 180                 uint32 hash_entry;
 181                 int32 i, *prev;
 182
 183                 if (DEBUG_GTE(DELTASUM, 4)) {
 184                         rprintf(FINFO, "offset=%s sum=%04x%04x\n",
 185                                 big_num(offset), s2 & 0xFFFF, s1 & 0xFFFF);
 186                 }
 187
 188                 if (tablesize == TRADITIONAL_TABLESIZE) {
 189                         hash_entry = SUM2HASH2(s1,s2);
 190                         if ((i = hash_table[hash_entry]) < 0)
 191                                 goto null_hash;
 192                         sum = (s1 & 0xffff) | (s2 << 16);
 193                 } else {
 194                         sum = (s1 & 0xffff) | (s2 << 16);
 195                         hash_entry = BIG_SUM2HASH(sum);
 196                         if ((i = hash_table[hash_entry]) < 0)
 197                                 goto null_hash;
 198                 }
 199                 prev = &hash_table[hash_entry];
 200
 201                 hash_hits++;
 202                 do {
 203                         int32 l;
 204
 205                         /* When updating in-place, the chunk's offset must be
 206                          * either >= our offset or identical data at that offset.
 207                          * Remove any bypassed entries that we can never use. */
 208                         if (updating_basis_file && s->sums[i].offset < offset
 209                          && !(s->sums[i].flags & SUMFLG_SAME_OFFSET)) {
 210                                 *prev = s->sums[i].chain;
 211                                 continue;
 212                         }
 213                         prev = &s->sums[i].chain;
 214
 215                         if (sum != s->sums[i].sum1)
 216                                 continue;
 217
 218                         /* also make sure the two blocks are the same length */
 219                         l = (int32)MIN((OFF_T)s->blength, len-offset);
 220                         if (l != s->sums[i].len)
 221                                 continue;
 222
 223                         if (DEBUG_GTE(DELTASUM, 3)) {
 224                                 rprintf(FINFO,
 225                                         "potential match at %s i=%ld sum=%08x\n",
 226                                         big_num(offset), (long)i, sum);
 227                         }
 228
 229                         if (!done_csum2) {
 230                                 map = (schar *)map_ptr(buf,offset,l);
 231                                 get_checksum2((char *)map,l,sum2);
 232                                 done_csum2 = 1;
 233                         }
 234
 235                         if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
 236                                 false_alarms++;
 237                                 continue;
 238                         }
 239
 240                         /* When updating in-place, the best possible match is
 241                          * one with an identical offset, so we prefer that over
 242                          * the adjacent want_i optimization. */
 243                         if (updating_basis_file) {
 244                                 /* All the generator's chunks start at blength boundaries. */
 245                                 while (aligned_offset < offset) {
 246                                         aligned_offset += s->blength;
 247                                         aligned_i++;
 248                                 }
 249                                 if ((offset == aligned_offset
 250                                   || (sum == 0 && l == s->blength && aligned_offset + l <= len))
 251                                  && aligned_i < s->count) {
 252                                         if (i != aligned_i) {
 253                                                 if (sum != s->sums[aligned_i].sum1
 254                                                  || l != s->sums[aligned_i].len
 255                                                  || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0)
 256                                                         goto check_want_i;
 257                                                 i = aligned_i;
 258                                         }
 259                                         if (offset != aligned_offset) {
 260                                                 /* We've matched some zeros in a spot that is also zeros
 261                                                  * further along in the basis file, if we find zeros ahead
 262                                                  * in the sender's file, we'll output enough literal data
 263                                                  * to re-align with the basis file, and get back to seeking
 264                                                  * instead of writing. */
 265                                                 backup = (int32)(aligned_offset - last_match);
 266                                                 if (backup < 0)
 267                                                         backup = 0;
 268                                                 map = (schar *)map_ptr(buf, aligned_offset - backup, l + backup)
 269                                                     + backup;
 270                                                 sum = get_checksum1((char *)map, l);
 271                                                 if (sum != s->sums[i].sum1)
 272                                                         goto check_want_i;
 273                                                 get_checksum2((char *)map, l, sum2);
 274                                                 if (memcmp(sum2, s->sums[i].sum2, s->s2length) != 0)
 275                                                         goto check_want_i;
 276                                                 /* OK, we have a re-alignment match.  Bump the offset
 277                                                  * forward to the new match point. */
 278                                                 offset = aligned_offset;
 279                                         }
 280                                         /* This identical chunk is in the same spot in the old and new file. */
 281                                         s->sums[i].flags |= SUMFLG_SAME_OFFSET;
 282                                         want_i = i;
 283                                 }
 284                         }
 285
 286                   check_want_i:
 287                         /* we've found a match, but now check to see
 288                          * if want_i can hint at a better match. */
 289                         if (i != want_i && want_i < s->count
 290                          && (!updating_basis_file || s->sums[want_i].offset >= offset
 291                           || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
 292                          && sum == s->sums[want_i].sum1
 293                          && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) {
 294                                 /* we've found an adjacent match - the RLL coder
 295                                  * will be happy */
 296                                 i = want_i;
 297                         }
 298                         want_i = i + 1;
 299
 300                         matched(f,s,buf,offset,i);
 301                         offset += s->sums[i].len - 1;
 302                         k = (int32)MIN((OFF_T)s->blength, len-offset);
 303                         map = (schar *)map_ptr(buf, offset, k);
 304                         sum = get_checksum1((char *)map, k);
 305                         s1 = sum & 0xFFFF;
 306                         s2 = sum >> 16;
 307                         matches++;
 308                         break;
 309                 } while ((i = s->sums[i].chain) >= 0);
 310
 311           null_hash:
 312                 backup = (int32)(offset - last_match);
 313                 /* We sometimes read 1 byte prior to last_match... */
 314                 if (backup < 0)
 315                         backup = 0;
 316
 317                 /* Trim off the first byte from the checksum */
 318                 more = offset + k < len;
 319                 map = (schar *)map_ptr(buf, offset - backup, k + more + backup) + backup;
 320                 s1 -= map[0] + CHAR_OFFSET;
 321                 s2 -= k * (map[0]+CHAR_OFFSET);
 322
 323                 /* Add on the next byte (if there is one) to the checksum */
 324                 if (more) {
 325                         s1 += map[k] + CHAR_OFFSET;
 326                         s2 += s1;
 327                 } else
 328                         --k;
 329
 330                 /* By matching early we avoid re-reading the
 331                    data 3 times in the case where a token
 332                    match comes a long way after last
 333                    match. The 3 reads are caused by the
 334                    running match, the checksum update and the
 335                    literal send. */
 336                 if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
 337                         matched(f, s, buf, offset - s->blength, -2);
 338         } while (++offset < end);
 339
 340         matched(f, s, buf, len, -1);
 341         map_ptr(buf, len-1, 1);
 342 }
 343
 344
 345 /**
 346  * Scan through a origin file, looking for sections that match
 347  * checksums from the generator, and transmit either literal or token
 348  * data.
 349  *
 350  * Also calculates the MD4 checksum of the whole file, using the md
 351  * accumulator.  This is transmitted with the file as protection
 352  * against corruption on the wire.
 353  *
 354  * @param s Checksums received from the generator.  If <tt>s->count ==
 355  * 0</tt>, then there are actually no checksums for this file.
 356  *
 357  * @param len Length of the file to send.
 358  **/
 359 void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len)
 360 {
 361         int sum_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(xfersum_type, 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         sum_len = sum_end(sender_file_sum);
 411
 412         /* If we had a read error, send a bad checksum.  We use all bits
 413          * off as long as the checksum doesn't happen to be that, in
 414          * which case we turn the last 0 bit into a 1. */
 415         if (buf && buf->status != 0) {
 416                 int i;
 417                 for (i = 0; i < sum_len && sender_file_sum[i] == 0; i++) {}
 418                 memset(sender_file_sum, 0, sum_len);
 419                 if (i == sum_len)
 420                         sender_file_sum[i-1]++;
 421         }
 422
 423         if (DEBUG_GTE(DELTASUM, 2))
 424                 rprintf(FINFO,"sending file_sum\n");
 425         write_buf(f, sender_file_sum, sum_len);
 426
 427         if (DEBUG_GTE(DELTASUM, 2)) {
 428                 rprintf(FINFO, "false_alarms=%d hash_hits=%d matches=%d\n",
 429                         false_alarms, hash_hits, matches);
 430         }
 431
 432         total_hash_hits += hash_hits;
 433         total_false_alarms += false_alarms;
 434         total_matches += matches;
 435         stats.literal_data += data_transfer;
 436 }
 437
 438 void match_report(void)
 439 {
 440         if (!DEBUG_GTE(DELTASUM, 1))
 441                 return;
 442
 443         rprintf(FINFO,
 444                 "total: matches=%d  hash_hits=%d  false_alarms=%d data=%s\n",
 445                 total_matches, total_hash_hits, total_false_alarms,
 446                 big_num(stats.literal_data));
 447 }