?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Improve interior dashes in long options.
[rsync.git] / match.c
blobdfd6af2c979ccca52b34fd32b8af1fa6a992f1d9
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) 2003-2023 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
28 extern struct name_num_item *xfer_sum_nni;
29 extern int xfer_sum_len;
30
31 int updating_basis_file;
32 char sender_file_sum[MAX_DIGEST_LEN];
33
34 static int false_alarms;
35 static int hash_hits;
36 static int matches;
37 static int64 data_transfer;
38
39 static int total_false_alarms;
40 static int total_hash_hits;
41 static int total_matches;
42
43 extern struct stats stats;
44
45 #define TRADITIONAL_TABLESIZE (1<<16)
46
47 static uint32 tablesize;
48 static int32 *hash_table;
49
50 #define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF)
51 #define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16)
52
53 #define BIG_SUM2HASH(sum) ((sum)%tablesize)
54
55 static void build_hash_table(struct sum_struct *s)
56 {
57 static uint32 alloc_size;
58 int32 i;
59
60 /* Dynamically calculate the hash table size so that the hash load
61 * for big files is about 80%. A number greater than the traditional
62 * size must be odd or s2 will not be able to span the entire set. */
63 tablesize = (uint32)(s->count/8) * 10 + 11;
64 if (tablesize < TRADITIONAL_TABLESIZE)
65 tablesize = TRADITIONAL_TABLESIZE;
66 if (tablesize > alloc_size || tablesize < alloc_size - 16*1024) {
67 if (hash_table)
68 free(hash_table);
69 hash_table = new_array(int32, tablesize);
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[MAX_DIGEST_LEN];
146 uint32 s1, s2, sum;
147 int more;
148 schar *map;
149
150 // prevent possible memory leaks
151 memset(sum2, 0, sizeof sum2);
152
153 /* want_i is used to encourage adjacent matches, allowing the RLL
154 * coding of the output to work more efficiently. */
155 want_i = 0;
156
157 if (DEBUG_GTE(DELTASUM, 2)) {
158 rprintf(FINFO, "hash search b=%ld len=%s\n",
159 (long)s->blength, big_num(len));
160 }
161
162 k = (int32)MIN(len, (OFF_T)s->blength);
163
164 map = (schar *)map_ptr(buf, 0, k);
165
166 sum = get_checksum1((char *)map, k);
167 s1 = sum & 0xFFFF;
168 s2 = sum >> 16;
169 if (DEBUG_GTE(DELTASUM, 3))
170 rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);
171
172 offset = aligned_offset = aligned_i = 0;
173
174 end = len + 1 - s->sums[s->count-1].len;
175
176 if (DEBUG_GTE(DELTASUM, 3)) {
177 rprintf(FINFO, "hash search s->blength=%ld len=%s count=%s\n",
178 (long)s->blength, big_num(len), big_num(s->count));
179 }
180
181 do {
182 int done_csum2 = 0;
183 uint32 hash_entry;
184 int32 i, *prev;
185
186 if (DEBUG_GTE(DELTASUM, 4)) {
187 rprintf(FINFO, "offset=%s sum=%04x%04x\n",
188 big_num(offset), s2 & 0xFFFF, s1 & 0xFFFF);
189 }
190
191 if (tablesize == TRADITIONAL_TABLESIZE) {
192 hash_entry = SUM2HASH2(s1,s2);
193 if ((i = hash_table[hash_entry]) < 0)
194 goto null_hash;
195 sum = (s1 & 0xffff) | (s2 << 16);
196 } else {
197 sum = (s1 & 0xffff) | (s2 << 16);
198 hash_entry = BIG_SUM2HASH(sum);
199 if ((i = hash_table[hash_entry]) < 0)
200 goto null_hash;
201 }
202 prev = &hash_table[hash_entry];
203
204 hash_hits++;
205 do {
206 int32 l;
207
208 /* When updating in-place, the chunk's offset must be
209 * either >= our offset or identical data at that offset.
210 * Remove any bypassed entries that we can never use. */
211 if (updating_basis_file && s->sums[i].offset < offset
212 && !(s->sums[i].flags & SUMFLG_SAME_OFFSET)) {
213 *prev = s->sums[i].chain;
214 continue;
215 }
216 prev = &s->sums[i].chain;
217
218 if (sum != s->sums[i].sum1)
219 continue;
220
221 /* also make sure the two blocks are the same length */
222 l = (int32)MIN((OFF_T)s->blength, len-offset);
223 if (l != s->sums[i].len)
224 continue;
225
226 if (DEBUG_GTE(DELTASUM, 3)) {
227 rprintf(FINFO,
228 "potential match at %s i=%ld sum=%08x\n",
229 big_num(offset), (long)i, sum);
230 }
231
232 if (!done_csum2) {
233 map = (schar *)map_ptr(buf,offset,l);
234 get_checksum2((char *)map,l,sum2);
235 done_csum2 = 1;
236 }
237
238 if (memcmp(sum2, sum2_at(s, i), s->s2length) != 0) {
239 false_alarms++;
240 continue;
241 }
242
243 /* When updating in-place, the best possible match is
244 * one with an identical offset, so we prefer that over
245 * the adjacent want_i optimization. */
246 if (updating_basis_file) {
247 /* All the generator's chunks start at blength boundaries. */
248 while (aligned_offset < offset) {
249 aligned_offset += s->blength;
250 aligned_i++;
251 }
252 if ((offset == aligned_offset
253 || (sum == 0 && l == s->blength && aligned_offset + l <= len))
254 && aligned_i < s->count) {
255 if (i != aligned_i) {
256 if (sum != s->sums[aligned_i].sum1
257 || l != s->sums[aligned_i].len
258 || memcmp(sum2, sum2_at(s, aligned_i), s->s2length) != 0)
259 goto check_want_i;
260 i = aligned_i;
261 }
262 if (offset != aligned_offset) {
263 /* We've matched some zeros in a spot that is also zeros
264 * further along in the basis file, if we find zeros ahead
265 * in the sender's file, we'll output enough literal data
266 * to re-align with the basis file, and get back to seeking
267 * instead of writing. */
268 backup = (int32)(aligned_offset - last_match);
269 if (backup < 0)
270 backup = 0;
271 map = (schar *)map_ptr(buf, aligned_offset - backup, l + backup)
272 + backup;
273 sum = get_checksum1((char *)map, l);
274 if (sum != s->sums[i].sum1)
275 goto check_want_i;
276 get_checksum2((char *)map, l, sum2);
277 if (memcmp(sum2, sum2_at(s, i), s->s2length) != 0)
278 goto check_want_i;
279 /* OK, we have a re-alignment match. Bump the offset
280 * forward to the new match point. */
281 offset = aligned_offset;
282 }
283 /* This identical chunk is in the same spot in the old and new file. */
284 s->sums[i].flags |= SUMFLG_SAME_OFFSET;
285 want_i = i;
286 }
287 }
288
289 check_want_i:
290 /* we've found a match, but now check to see
291 * if want_i can hint at a better match. */
292 if (i != want_i && want_i < s->count
293 && (!updating_basis_file || s->sums[want_i].offset >= offset
294 || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
295 && sum == s->sums[want_i].sum1
296 && memcmp(sum2, sum2_at(s, want_i), s->s2length) == 0) {
297 /* we've found an adjacent match - the RLL coder
298 * will be happy */
299 i = want_i;
300 }
301 want_i = i + 1;
302
303 matched(f,s,buf,offset,i);
304 offset += s->sums[i].len - 1;
305 k = (int32)MIN((OFF_T)s->blength, len-offset);
306 map = (schar *)map_ptr(buf, offset, k);
307 sum = get_checksum1((char *)map, k);
308 s1 = sum & 0xFFFF;
309 s2 = sum >> 16;
310 matches++;
311 break;
312 } while ((i = s->sums[i].chain) >= 0);
313
314 null_hash:
315 backup = (int32)(offset - last_match);
316 /* We sometimes read 1 byte prior to last_match... */
317 if (backup < 0)
318 backup = 0;
319
320 /* Trim off the first byte from the checksum */
321 more = offset + k < len;
322 map = (schar *)map_ptr(buf, offset - backup, k + more + backup) + backup;
323 s1 -= map[0] + CHAR_OFFSET;
324 s2 -= k * (map[0]+CHAR_OFFSET);
325
326 /* Add on the next byte (if there is one) to the checksum */
327 if (more) {
328 s1 += map[k] + CHAR_OFFSET;
329 s2 += s1;
330 } else
331 --k;
332
333 /* By matching early we avoid re-reading the
334 data 3 times in the case where a token
335 match comes a long way after last
336 match. The 3 reads are caused by the
337 running match, the checksum update and the
338 literal send. */
339 if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
340 matched(f, s, buf, offset - s->blength, -2);
341 } while (++offset < end);
342
343 matched(f, s, buf, len, -1);
344 map_ptr(buf, len-1, 1);
345 }
346
347
348 /**
349 * Scan through a origin file, looking for sections that match
350 * checksums from the generator, and transmit either literal or token
351 * data.
352 *
353 * Also calculates the MD4 checksum of the whole file, using the md
354 * accumulator. This is transmitted with the file as protection
355 * against corruption on the wire.
356 *
357 * @param s Checksums received from the generator. If <tt>s->count ==
358 * 0</tt>, then there are actually no checksums for this file.
359 *
360 * @param len Length of the file to send.
361 **/
362 void match_sums(int f, struct sum_struct *s, struct map_struct *buf, OFF_T len)
363 {
364 last_match = 0;
365 false_alarms = 0;
366 hash_hits = 0;
367 matches = 0;
368 data_transfer = 0;
369
370 sum_init(xfer_sum_nni, checksum_seed);
371
372 if (append_mode > 0) {
373 if (append_mode == 2) {
374 OFF_T j = 0;
375 for (j = CHUNK_SIZE; j < s->flength; j += CHUNK_SIZE) {
376 if (buf && INFO_GTE(PROGRESS, 1))
377 show_progress(last_match, buf->file_size);
378 sum_update(map_ptr(buf, last_match, CHUNK_SIZE),
379 CHUNK_SIZE);
380 last_match = j;
381 }
382 if (last_match < s->flength) {
383 int32 n = (int32)(s->flength - last_match);
384 if (buf && INFO_GTE(PROGRESS, 1))
385 show_progress(last_match, buf->file_size);
386 sum_update(map_ptr(buf, last_match, n), n);
387 }
388 }
389 last_match = s->flength;
390 s->count = 0;
391 }
392
393 if (len > 0 && s->count > 0) {
394 build_hash_table(s);
395
396 if (DEBUG_GTE(DELTASUM, 2))
397 rprintf(FINFO,"built hash table\n");
398
399 hash_search(f, s, buf, len);
400
401 if (DEBUG_GTE(DELTASUM, 2))
402 rprintf(FINFO,"done hash search\n");
403 } else {
404 OFF_T j;
405 /* by doing this in pieces we avoid too many seeks */
406 for (j = last_match + CHUNK_SIZE; j < len; j += CHUNK_SIZE)
407 matched(f, s, buf, j, -2);
408 matched(f, s, buf, len, -1);
409 }
410
411 sum_end(sender_file_sum);
412
413 /* If we had a read error, send a bad checksum. We use all bits
414 * off as long as the checksum doesn't happen to be that, in
415 * which case we turn the last 0 bit into a 1. */
416 if (buf && buf->status != 0) {
417 int i;
418 for (i = 0; i < xfer_sum_len && sender_file_sum[i] == 0; i++) {}
419 memset(sender_file_sum, 0, xfer_sum_len);
420 if (i == xfer_sum_len)
421 sender_file_sum[i-1]++;
422 }
423
424 if (DEBUG_GTE(DELTASUM, 2))
425 rprintf(FINFO,"sending file_sum\n");
426 write_buf(f, sender_file_sum, xfer_sum_len);
427
428 if (DEBUG_GTE(DELTASUM, 2)) {
429 rprintf(FINFO, "false_alarms=%d hash_hits=%d matches=%d\n",
430 false_alarms, hash_hits, matches);
431 }
432
433 total_hash_hits += hash_hits;
434 total_false_alarms += false_alarms;
435 total_matches += matches;
436 stats.literal_data += data_transfer;
437 }
438
439 void match_report(void)
440 {
441 if (!DEBUG_GTE(DELTASUM, 1))
442 return;
443
444 rprintf(FINFO,
445 "total: matches=%d hash_hits=%d false_alarms=%d data=%s\n",
446 total_matches, total_hash_hits, total_false_alarms,
447 big_num(stats.literal_data));
448 }
rsync: a fast, versatile, remote (and local) file-copying tool