diff options
Diffstat (limited to 'match.c')
| -rw-r--r-- | match.c | 445 |
1 files changed, 445 insertions, 0 deletions
@@ -0,0 +1,445 @@ +/* + * Block matching used by the file-transfer code. + * + * Copyright (C) 1996 Andrew Tridgell + * Copyright (C) 1996 Paul Mackerras + * Copyright (C) 2003-2022 Wayne Davison + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, visit the http://fsf.org website. + */ + +#include "rsync.h" +#include "inums.h" + +extern int checksum_seed; +extern int append_mode; + +extern struct name_num_item *xfer_sum_nni; +extern int xfer_sum_len; + +int updating_basis_file; +char sender_file_sum[MAX_DIGEST_LEN]; + +static int false_alarms; +static int hash_hits; +static int matches; +static int64 data_transfer; + +static int total_false_alarms; +static int total_hash_hits; +static int total_matches; + +extern struct stats stats; + +#define TRADITIONAL_TABLESIZE (1<<16) + +static uint32 tablesize; +static int32 *hash_table; + +#define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF) +#define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16) + +#define BIG_SUM2HASH(sum) ((sum)%tablesize) + +static void build_hash_table(struct sum_struct *s) +{ + static uint32 alloc_size; + int32 i; + + /* Dynamically calculate the hash table size so that the hash load + * for big files is about 80%. A number greater than the traditional + * size must be odd or s2 will not be able to span the entire set. */ + tablesize = (uint32)(s->count/8) * 10 + 11; + if (tablesize < TRADITIONAL_TABLESIZE) + tablesize = TRADITIONAL_TABLESIZE; + if (tablesize > alloc_size || tablesize < alloc_size - 16*1024) { + if (hash_table) + free(hash_table); + hash_table = new_array(int32, tablesize); + alloc_size = tablesize; + } + + memset(hash_table, 0xFF, tablesize * sizeof hash_table[0]); + + if (tablesize == TRADITIONAL_TABLESIZE) { + for (i = 0; i < s->count; i++) { + uint32 t = SUM2HASH(s->sums[i].sum1); + s->sums[i].chain = hash_table[t]; + hash_table[t] = i; + } + } else { + for (i = 0; i < s->count; i++) { + uint32 t = BIG_SUM2HASH(s->sums[i].sum1); + s->sums[i].chain = hash_table[t]; + hash_table[t] = i; + } + } +} + + +static OFF_T last_match; + + +/* Transmit a literal and/or match token. + * + * This delightfully-named function is called either when we find a + * match and need to transmit all the unmatched data leading up to it, + * or when we get bored of accumulating literal data and just need to + * transmit it. As a result of this second case, it is called even if + * we have not matched at all! + * + * If i >= 0, the number of a matched token. If < 0, indicates we have + * only literal data. A -1 will send a 0-token-int too, and a -2 sends + * only literal data, w/o any token-int. */ +static void matched(int f, struct sum_struct *s, struct map_struct *buf, OFF_T offset, int32 i) +{ + int32 n = (int32)(offset - last_match); /* max value: block_size (int32) */ + int32 j; + + if (DEBUG_GTE(DELTASUM, 2) && i >= 0) { + rprintf(FINFO, + "match at %s last_match=%s j=%d len=%ld n=%ld\n", + big_num(offset), big_num(last_match), i, + (long)s->sums[i].len, (long)n); + } + + send_token(f, i, buf, last_match, n, i < 0 ? 0 : s->sums[i].len); + data_transfer += n; + + if (i >= 0) { + stats.matched_data += s->sums[i].len; + n += s->sums[i].len; + } + + for (j = 0; j < n; j += CHUNK_SIZE) { + int32 n1 = MIN(CHUNK_SIZE, n - j); + sum_update(map_ptr(buf, last_match + j, n1), n1); + } + + if (i >= 0) + last_match = offset + s->sums[i].len; + else + last_match = offset; + + if (buf && INFO_GTE(PROGRESS, 1)) + show_progress(last_match, buf->file_size); +} + + +static void hash_search(int f,struct sum_struct *s, + struct map_struct *buf, OFF_T len) +{ + OFF_T offset, aligned_offset, end; + int32 k, want_i, aligned_i, backup; + char sum2[SUM_LENGTH]; + uint32 s1, s2, sum; + int more; + schar *map; + + /* want_i is used to encourage adjacent matches, allowing the RLL + * coding of the output to work more efficiently. */ + want_i = 0; + + if (DEBUG_GTE(DELTASUM, 2)) { + rprintf(FINFO, "hash search b=%ld len=%s\n", + (long)s->blength, big_num(len)); + } + + k = (int32)MIN(len, (OFF_T)s->blength); + + map = (schar *)map_ptr(buf, 0, k); + + sum = get_checksum1((char *)map, k); + s1 = sum & 0xFFFF; + s2 = sum >> 16; + if (DEBUG_GTE(DELTASUM, 3)) + rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k); + + offset = aligned_offset = aligned_i = 0; + + end = len + 1 - s->sums[s->count-1].len; + + if (DEBUG_GTE(DELTASUM, 3)) { + rprintf(FINFO, "hash search s->blength=%ld len=%s count=%s\n", + (long)s->blength, big_num(len), big_num(s->count)); + } + + do { + int done_csum2 = 0; + uint32 hash_entry; + int32 i, *prev; + + if (DEBUG_GTE(DELTASUM, 4)) { + rprintf(FINFO, "offset=%s sum=%04x%04x\n", + big_num(offset), s2 & 0xFFFF, s1 & 0xFFFF); + } + + if (tablesize == TRADITIONAL_TABLESIZE) { + hash_entry = SUM2HASH2(s1,s2); + if ((i = hash_table[hash_entry]) < 0) + goto null_hash; + sum = (s1 & 0xffff) | (s2 << 16); + } else { + sum = (s1 & 0xffff) | (s2 << 16); + hash_entry = BIG_SUM2HASH(sum); + if ((i = hash_table[hash_entry]) < 0) + goto null_hash; + } + prev = &hash_table[hash_entry]; + + hash_hits++; + do { + int32 l; + + /* When updating in-place, the chunk's offset must be + * either >= our offset or identical data at that offset. + * Remove any bypassed entries that we can never use. */ + if (updating_basis_file && s->sums[i].offset < offset + && !(s->sums[i].flags & SUMFLG_SAME_OFFSET)) { + *prev = s->sums[i].chain; + continue; + } + prev = &s->sums[i].chain; + + if (sum != s->sums[i].sum1) + continue; + + /* also make sure the two blocks are the same length */ + l = (int32)MIN((OFF_T)s->blength, len-offset); + if (l != s->sums[i].len) + continue; + + if (DEBUG_GTE(DELTASUM, 3)) { + rprintf(FINFO, + "potential match at %s i=%ld sum=%08x\n", + big_num(offset), (long)i, sum); + } + + if (!done_csum2) { + map = (schar *)map_ptr(buf,offset,l); + get_checksum2((char *)map,l,sum2); + done_csum2 = 1; + } + + if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) { + false_alarms++; + continue; + } + + /* When updating in-place, the best possible match is + * one with an identical offset, so we prefer that over + * the adjacent want_i optimization. */ + if (updating_basis_file) { + /* All the generator's chunks start at blength boundaries. */ + while (aligned_offset < offset) { + aligned_offset += s->blength; + aligned_i++; + } + if ((offset == aligned_offset + || (sum == 0 && l == s->blength && aligned_offset + l <= len)) + && aligned_i < s->count) { + if (i != aligned_i) { + if (sum != s->sums[aligned_i].sum1 + || l != s->sums[aligned_i].len + || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0) + goto check_want_i; + i = aligned_i; + } + if (offset != aligned_offset) { + /* We've matched some zeros in a spot that is also zeros + * further along in the basis file, if we find zeros ahead + * in the sender's file, we'll output enough literal data + * to re-align with the basis file, and get back to seeking + * instead of writing. */ + backup = (int32)(aligned_offset - last_match); + if (backup < 0) + backup = 0; + map = (schar *)map_ptr(buf, aligned_offset - backup, l + backup) + + backup; + sum = get_checksum1((char *)map, l); + if (sum != s->sums[i].sum1) + goto check_want_i; + get_checksum2((char *)map, l, sum2); + if (memcmp(sum2, s->sums[i].sum2, s->s2length) != 0) + goto check_want_i; + /* OK, we have a re-alignment match. Bump the offset + * forward to the new match point. */ + offset = aligned_offset; + } + /* This identical chunk is in the same spot in the old and new file. */ + s->sums[i].flags |= SUMFLG_SAME_OFFSET; + want_i = i; + } + } + + check_want_i: + /* we've found a match, but now check to see + * if want_i can hint at a better match. */ + if (i != want_i && want_i < s->count + && (!updating_basis_file || s->sums[want_i].offset >= offset + || s->sums[want_i].flags & SUMFLG_SAME_OFFSET) + && sum == s->sums[want_i].sum1 + && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) { + /* we've found an adjacent match - the RLL coder + * will be happy */ + i = want_i; + } + want_i = i + 1; + + matched(f,s,buf,offset,i); + offset += s->sums[i].len - 1; + k = (int32)MIN((OFF_T)s->blength, len-offset); + map = (schar *)map_ptr(buf, offset, k); + sum = get_checksum1((char *)map, k); + s1 = sum & 0xFFFF; + s2 = sum >> 16; + matches++; + break; + } while ((i = s->sums[i].chain) >= 0); + + null_hash: + backup = (int32)(offset - last_match); + /* We sometimes read 1 byte prior to last_match... */ + if (backup < 0) + backup = 0; + + /* Trim off the first byte from the checksum */ + more = offset + k < len; + map = (schar *)map_ptr(buf, offset - backup, k + more + backup) + backup; + s1 -= map[0] + CHAR_OFFSET; + s2 -= k * (map[0]+CHAR_OFFSET); + + /* Add on the next byte (if there is one) to the checksum */ + if (more) { + s1 += map[k] + CHAR_OFFSET; + s2 += s1; + } else + --k; + + /* By matching early we avoid re-reading the + data 3 times in the case where a token + match comes a long way after last + match. The 3 reads are caused by the + running match, the checksum update and the + literal send. */ + if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE) + matched(f, s, buf, offset - s->blength, -2); + } while (++offset < end); + + matched(f, s, buf, len, -1); + map_ptr(buf, len-1, 1); +} + + +/** + * Scan through a origin file, looking for sections that match + * checksums from the generator, and transmit either literal or token + * data. + * + * Also calculates the MD4 checksum of the whole file, using the md + * accumulator. This is transmitted with the file as protection + * against corruption on the wire. + * + * @param s Checksums received from the generator. If <tt>s->count == + * 0</tt>, then there are actually no checksums for this file. + * + * @param len Length of the file to send. + **/ +void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len) +{ + last_match = 0; + false_alarms = 0; + hash_hits = 0; + matches = 0; + data_transfer = 0; + + sum_init(xfer_sum_nni, checksum_seed); + + if (append_mode > 0) { + if (append_mode == 2) { + OFF_T j = 0; + for (j = CHUNK_SIZE; j < s->flength; j += CHUNK_SIZE) { + if (buf && INFO_GTE(PROGRESS, 1)) + show_progress(last_match, buf->file_size); + sum_update(map_ptr(buf, last_match, CHUNK_SIZE), + CHUNK_SIZE); + last_match = j; + } + if (last_match < s->flength) { + int32 n = (int32)(s->flength - last_match); + if (buf && INFO_GTE(PROGRESS, 1)) + show_progress(last_match, buf->file_size); + sum_update(map_ptr(buf, last_match, n), n); + } + } + last_match = s->flength; + s->count = 0; + } + + if (len > 0 && s->count > 0) { + build_hash_table(s); + + if (DEBUG_GTE(DELTASUM, 2)) + rprintf(FINFO,"built hash table\n"); + + hash_search(f, s, buf, len); + + if (DEBUG_GTE(DELTASUM, 2)) + rprintf(FINFO,"done hash search\n"); + } else { + OFF_T j; + /* by doing this in pieces we avoid too many seeks */ + for (j = last_match + CHUNK_SIZE; j < len; j += CHUNK_SIZE) + matched(f, s, buf, j, -2); + matched(f, s, buf, len, -1); + } + + sum_end(sender_file_sum); + + /* If we had a read error, send a bad checksum. We use all bits + * off as long as the checksum doesn't happen to be that, in + * which case we turn the last 0 bit into a 1. */ + if (buf && buf->status != 0) { + int i; + for (i = 0; i < xfer_sum_len && sender_file_sum[i] == 0; i++) {} + memset(sender_file_sum, 0, xfer_sum_len); + if (i == xfer_sum_len) + sender_file_sum[i-1]++; + } + + if (DEBUG_GTE(DELTASUM, 2)) + rprintf(FINFO,"sending file_sum\n"); + write_buf(f, sender_file_sum, xfer_sum_len); + + if (DEBUG_GTE(DELTASUM, 2)) { + rprintf(FINFO, "false_alarms=%d hash_hits=%d matches=%d\n", + false_alarms, hash_hits, matches); + } + + total_hash_hits += hash_hits; + total_false_alarms += false_alarms; + total_matches += matches; + stats.literal_data += data_transfer; +} + +void match_report(void) +{ + if (!DEBUG_GTE(DELTASUM, 1)) + return; + + rprintf(FINFO, + "total: matches=%d hash_hits=%d false_alarms=%d data=%s\n", + total_matches, total_hash_hits, total_false_alarms, + big_num(stats.literal_data)); +} |