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/*
* Block matching used by the file-transfer code.
*
* Copyright (C) 1996 Andrew Tridgell
* Copyright (C) 1996 Paul Mackerras
* Copyright (C) 2003-2014 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 int checksum_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);
if (!hash_table)
out_of_memory("build_hash_table");
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(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);
}
if (sum_end(sender_file_sum) != checksum_len)
overflow_exit("checksum_len"); /* Impossible... */
/* 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 < checksum_len && sender_file_sum[i] == 0; i++) {}
memset(sender_file_sum, 0, checksum_len);
if (i == checksum_len)
sender_file_sum[i-1]++;
}
if (DEBUG_GTE(DELTASUM, 2))
rprintf(FINFO,"sending file_sum\n");
write_buf(f, sender_file_sum, checksum_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));
}