/*

* Block matching used by the file-transfer code.

*

* Copyright (C) 1996 Andrew Tridgell

* Copyright (C) 1996 Paul Mackerras

* Copyright (C) 2003-2007 Wayne Davison

*

* This program is free software; you can redistribute it and/or modify

* it under the terms of the GNU General Public License version 2 as

* published by the Free Software Foundation.

*

* 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, write to the Free Software Foundation, Inc.,

* 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.

*/

#include "rsync.h"

extern int verbose;

extern int do_progress;

extern int checksum_seed;

extern int append_mode;

int updating_basis_file;

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 TABLESIZE (1<<16)

static int32 *hash_table;

#define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF)

#define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16)

static void build_hash_table(struct sum_struct *s)

{

int32 i;

if (!hash_table) {

hash_table = new_array(int32, TABLESIZE);

if (!hash_table)

out_of_memory("build_hash_table");

}

memset(hash_table, 0xFF, TABLESIZE * sizeof hash_table[0]);

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;

}

}

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!

*

* @param i If >0, the number of a matched token. If 0, indicates we

* have only literal data.

**/

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 (verbose > 2 && i >= 0) {

rprintf(FINFO,

"match at %.0f last_match=%.0f j=%d len=%ld n=%ld\n",

(double)offset, (double)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 && do_progress)

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, end;

int32 k, want_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 (verbose > 2) {

rprintf(FINFO, "hash search b=%ld len=%.0f\n",

(long)s->blength, (double)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 (verbose > 3)

rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);

offset = 0;

end = len + 1 - s->sums[s->count-1].len;

if (verbose > 3) {

rprintf(FINFO, "hash search s->blength=%ld len=%.0f count=%.0f\n",

(long)s->blength, (double)len, (double)s->count);

}

do {

int done_csum2 = 0;

int32 i;

if (verbose > 4) {

rprintf(FINFO, "offset=%.0f sum=%04x%04x\n",

(double)offset, s2 & 0xFFFF, s1 & 0xFFFF);

}

i = hash_table[SUM2HASH2(s1,s2)];

if (i < 0)

goto null_hash;

sum = (s1 & 0xffff) | (s2 << 16);

hash_hits++;

do {

int32 l;

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;

/* in-place: ensure chunk's offset is either >= our

* offset or that the data didn't move. */

if (updating_basis_file && s->sums[i].offset < offset

&& !(s->sums[i].flags & SUMFLG_SAME_OFFSET))

continue;

if (verbose > 3) {

rprintf(FINFO,

"potential match at %.0f i=%ld sum=%08x\n",

(double)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 following want_i optimization. */

if (updating_basis_file) {

int32 i2;

for (i2 = i; i2 >= 0; i2 = s->sums[i2].chain) {

if (s->sums[i2].offset != offset)

continue;

if (i2 != i) {

if (sum != s->sums[i2].sum1)

break;

if (memcmp(sum2, s->sums[i2].sum2,

s->s2length) != 0)

break;

i = i2;

}

/* This chunk was at the same offset on

* both the sender and the receiver. */

s->sums[i].flags |= SUMFLG_SAME_OFFSET;

goto set_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;

}

set_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)

{

char file_sum[MD4_SUM_LENGTH];

last_match = 0;

false_alarms = 0;

hash_hits = 0;

matches = 0;

data_transfer = 0;

sum_init(checksum_seed);

if (append_mode > 0) {

OFF_T j = 0;

for (j = CHUNK_SIZE; j < s->flength; j += CHUNK_SIZE) {

if (buf && do_progress)

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 len = (int32)(s->flength - last_match);

if (buf && do_progress)

show_progress(last_match, buf->file_size);

sum_update(map_ptr(buf, last_match, len), len);

last_match = s->flength;

}

s->count = 0;

}

if (len > 0 && s->count > 0) {

build_hash_table(s);

if (verbose > 2)

rprintf(FINFO,"built hash table\n");

hash_search(f,s,buf,len);

if (verbose > 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(file_sum);

/* If we had a read error, send a bad checksum. */

if (buf && buf->status != 0)

file_sum[0]++;

if (verbose > 2)

rprintf(FINFO,"sending file_sum\n");

write_buf(f,file_sum,MD4_SUM_LENGTH);

if (verbose > 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 (verbose <= 1)

return;

rprintf(FINFO,

"total: matches=%d hash_hits=%d false_alarms=%d data=%.0f\n",

total_matches, total_hash_hits, total_false_alarms,

(double)stats.literal_data);

}