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-rw-r--r--match.c445
1 files changed, 445 insertions, 0 deletions
diff --git a/match.c b/match.c
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index 0000000..6243994
--- /dev/null
+++ b/match.c
@@ -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));
+}