git-unpack-objects: re-write to read from stdin
[git/git.git] / pack-objects.c
CommitLineData
27225f2e 1#include <ctype.h>
c323ac7d
LT
2#include "cache.h"
3#include "object.h"
4#include "delta.h"
a733cb60 5#include "pack.h"
c38138cd 6#include "csum-file.h"
c323ac7d 7
d22b9290 8static const char pack_usage[] = "git-pack-objects [--window=N] [--depth=N] {--stdout | base-name} < object-list";
c323ac7d 9
c323ac7d
LT
10struct object_entry {
11 unsigned char sha1[20];
12 unsigned long size;
13 unsigned long offset;
14 unsigned int depth;
27225f2e 15 unsigned int hash;
a733cb60 16 enum object_type type;
c323ac7d
LT
17 unsigned long delta_size;
18 struct object_entry *delta;
19};
20
21static struct object_entry **sorted_by_sha, **sorted_by_type;
22static struct object_entry *objects = NULL;
23static int nr_objects = 0, nr_alloc = 0;
c323ac7d 24static const char *base_name;
e1808845 25static unsigned char pack_file_sha1[20];
c323ac7d 26
c323ac7d
LT
27static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
28{
29 unsigned long othersize, delta_size;
30 char type[10];
31 void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
32 void *delta_buf;
33
34 if (!otherbuf)
35 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
8ee378a0
JH
36 delta_buf = diff_delta(otherbuf, othersize,
37 buf, size, &delta_size, ~0UL);
75c42d8c 38 if (!delta_buf || delta_size != entry->delta_size)
c323ac7d
LT
39 die("delta size changed");
40 free(buf);
41 free(otherbuf);
42 return delta_buf;
43}
44
a733cb60
LT
45/*
46 * The per-object header is a pretty dense thing, which is
47 * - first byte: low four bits are "size", then three bits of "type",
48 * and the high bit is "size continues".
49 * - each byte afterwards: low seven bits are size continuation,
50 * with the high bit being "size continues"
51 */
52static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
53{
54 int n = 1, i;
55 unsigned char c;
56
57 if (type < OBJ_COMMIT || type > OBJ_DELTA)
58 die("bad type %d", type);
59
60 /*
61 * Shift the size up by 7 bits at a time,
62 * until you get bits in the "high four".
63 * That will be our beginning. We'll have
64 * four size bits in 28..31, then groups
65 * of seven in 21..27, 14..20, 7..13 and
66 * finally 0..6.
67 */
68 if (size) {
69 n = 5;
70 while (!(size & 0xfe000000)) {
71 size <<= 7;
72 n--;
73 }
74 }
75 c = (type << 4) | (size >> 28);
76 for (i = 1; i < n; i++) {
77 *hdr++ = c | 0x80;
78 c = (size >> 21) & 0x7f;
79 size <<= 7;
80 }
81 *hdr = c;
82 return n;
83}
84
c38138cd 85static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
c323ac7d
LT
86{
87 unsigned long size;
88 char type[10];
89 void *buf = read_sha1_file(entry->sha1, type, &size);
a733cb60 90 unsigned char header[10];
c323ac7d 91 unsigned hdrlen, datalen;
a733cb60 92 enum object_type obj_type;
c323ac7d
LT
93
94 if (!buf)
95 die("unable to read %s", sha1_to_hex(entry->sha1));
96 if (size != entry->size)
97 die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
98
99 /*
e1ddc976
JH
100 * The object header is a byte of 'type' followed by zero or
101 * more bytes of length. For deltas, the 20 bytes of delta sha1
102 * follows that.
c323ac7d 103 */
a733cb60 104 obj_type = entry->type;
c323ac7d 105 if (entry->delta) {
c323ac7d
LT
106 buf = delta_against(buf, size, entry);
107 size = entry->delta_size;
a733cb60 108 obj_type = OBJ_DELTA;
c323ac7d 109 }
a733cb60 110 hdrlen = encode_header(obj_type, size, header);
c38138cd 111 sha1write(f, header, hdrlen);
a733cb60
LT
112 if (entry->delta) {
113 sha1write(f, entry->delta, 20);
114 hdrlen += 20;
115 }
c38138cd 116 datalen = sha1write_compressed(f, buf, size);
c323ac7d
LT
117 free(buf);
118 return hdrlen + datalen;
119}
120
121static void write_pack_file(void)
122{
123 int i;
d22b9290 124 struct sha1file *f;
a733cb60 125 unsigned long offset;
c323ac7d 126 unsigned long mb;
a733cb60 127 struct pack_header hdr;
c323ac7d 128
d22b9290
LT
129 if (!base_name)
130 f = sha1fd(1, "<stdout>");
131 else
132 f = sha1create("%s.%s", base_name, "pack");
a733cb60
LT
133 hdr.hdr_signature = htonl(PACK_SIGNATURE);
134 hdr.hdr_version = htonl(1);
135 hdr.hdr_entries = htonl(nr_objects);
136 sha1write(f, &hdr, sizeof(hdr));
137 offset = sizeof(hdr);
c323ac7d
LT
138 for (i = 0; i < nr_objects; i++) {
139 struct object_entry *entry = objects + i;
140 entry->offset = offset;
141 offset += write_object(f, entry);
142 }
e1808845 143 sha1close(f, pack_file_sha1, 1);
c323ac7d
LT
144 mb = offset >> 20;
145 offset &= 0xfffff;
146}
147
148static void write_index_file(void)
149{
150 int i;
c38138cd 151 struct sha1file *f = sha1create("%s.%s", base_name, "idx");
c323ac7d
LT
152 struct object_entry **list = sorted_by_sha;
153 struct object_entry **last = list + nr_objects;
154 unsigned int array[256];
155
156 /*
157 * Write the first-level table (the list is sorted,
158 * but we use a 256-entry lookup to be able to avoid
e1808845 159 * having to do eight extra binary search iterations).
c323ac7d
LT
160 */
161 for (i = 0; i < 256; i++) {
162 struct object_entry **next = list;
163 while (next < last) {
164 struct object_entry *entry = *next;
165 if (entry->sha1[0] != i)
166 break;
167 next++;
168 }
169 array[i] = htonl(next - sorted_by_sha);
170 list = next;
171 }
c38138cd 172 sha1write(f, array, 256 * sizeof(int));
c323ac7d
LT
173
174 /*
175 * Write the actual SHA1 entries..
176 */
177 list = sorted_by_sha;
49397104 178 for (i = 0; i < nr_objects; i++) {
c323ac7d
LT
179 struct object_entry *entry = *list++;
180 unsigned int offset = htonl(entry->offset);
c38138cd
LT
181 sha1write(f, &offset, 4);
182 sha1write(f, entry->sha1, 20);
c323ac7d 183 }
e1808845
LT
184 sha1write(f, pack_file_sha1, 20);
185 sha1close(f, NULL, 1);
c323ac7d
LT
186}
187
27225f2e 188static void add_object_entry(unsigned char *sha1, unsigned int hash)
c323ac7d
LT
189{
190 unsigned int idx = nr_objects;
191 struct object_entry *entry;
192
193 if (idx >= nr_alloc) {
194 unsigned int needed = (idx + 1024) * 3 / 2;
195 objects = xrealloc(objects, needed * sizeof(*entry));
196 nr_alloc = needed;
197 }
198 entry = objects + idx;
199 memset(entry, 0, sizeof(*entry));
200 memcpy(entry->sha1, sha1, 20);
27225f2e 201 entry->hash = hash;
c323ac7d
LT
202 nr_objects = idx+1;
203}
204
205static void check_object(struct object_entry *entry)
206{
36e4d74a
JH
207 char type[20];
208
209 if (!sha1_object_info(entry->sha1, type, &entry->size)) {
210 if (!strcmp(type, "commit")) {
a733cb60 211 entry->type = OBJ_COMMIT;
36e4d74a 212 } else if (!strcmp(type, "tree")) {
a733cb60 213 entry->type = OBJ_TREE;
36e4d74a 214 } else if (!strcmp(type, "blob")) {
a733cb60 215 entry->type = OBJ_BLOB;
a69d0943 216 } else if (!strcmp(type, "tag")) {
a733cb60 217 entry->type = OBJ_TAG;
36e4d74a
JH
218 } else
219 die("unable to pack object %s of type %s",
220 sha1_to_hex(entry->sha1), type);
221 }
222 else
223 die("unable to get type of object %s",
224 sha1_to_hex(entry->sha1));
c323ac7d
LT
225}
226
227static void get_object_details(void)
228{
229 int i;
230 struct object_entry *entry = objects;
231
232 for (i = 0; i < nr_objects; i++)
233 check_object(entry++);
234}
235
236typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
237
238static entry_sort_t current_sort;
239
240static int sort_comparator(const void *_a, const void *_b)
241{
242 struct object_entry *a = *(struct object_entry **)_a;
243 struct object_entry *b = *(struct object_entry **)_b;
244 return current_sort(a,b);
245}
246
247static struct object_entry **create_sorted_list(entry_sort_t sort)
248{
249 struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
250 int i;
251
252 for (i = 0; i < nr_objects; i++)
253 list[i] = objects + i;
254 current_sort = sort;
255 qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
256 return list;
257}
258
259static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
260{
261 return memcmp(a->sha1, b->sha1, 20);
262}
263
264static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
265{
266 if (a->type < b->type)
267 return -1;
268 if (a->type > b->type)
269 return 1;
27225f2e
LT
270 if (a->hash < b->hash)
271 return -1;
272 if (a->hash > b->hash)
273 return 1;
c323ac7d
LT
274 if (a->size < b->size)
275 return -1;
276 if (a->size > b->size)
277 return 1;
278 return a < b ? -1 : (a > b);
279}
280
281struct unpacked {
282 struct object_entry *entry;
283 void *data;
284};
285
286/*
521a4f4c
LT
287 * We search for deltas _backwards_ in a list sorted by type and
288 * by size, so that we see progressively smaller and smaller files.
289 * That's because we prefer deltas to be from the bigger file
290 * to the smaller - deletes are potentially cheaper, but perhaps
291 * more importantly, the bigger file is likely the more recent
292 * one.
c323ac7d 293 */
d116a45a 294static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
c323ac7d
LT
295{
296 struct object_entry *cur_entry = cur->entry;
297 struct object_entry *old_entry = old->entry;
521a4f4c 298 unsigned long size, oldsize, delta_size, sizediff;
75c42d8c 299 long max_size;
c323ac7d
LT
300 void *delta_buf;
301
302 /* Don't bother doing diffs between different types */
303 if (cur_entry->type != old_entry->type)
304 return -1;
305
c323ac7d 306 size = cur_entry->size;
75c42d8c
LT
307 if (size < 50)
308 return -1;
c323ac7d 309 oldsize = old_entry->size;
521a4f4c
LT
310 sizediff = oldsize > size ? oldsize - size : size - oldsize;
311 if (sizediff > size / 8)
c323ac7d 312 return -1;
d116a45a
LT
313 if (old_entry->depth >= max_depth)
314 return 0;
c323ac7d
LT
315
316 /*
317 * NOTE!
318 *
319 * We always delta from the bigger to the smaller, since that's
320 * more space-efficient (deletes don't have to say _what_ they
321 * delete).
322 */
75c42d8c
LT
323 max_size = size / 2 - 20;
324 if (cur_entry->delta)
325 max_size = cur_entry->delta_size-1;
27225f2e
LT
326 if (sizediff >= max_size)
327 return -1;
8ee378a0
JH
328 delta_buf = diff_delta(old->data, oldsize,
329 cur->data, size, &delta_size, max_size);
c323ac7d 330 if (!delta_buf)
75c42d8c
LT
331 return 0;
332 cur_entry->delta = old_entry;
333 cur_entry->delta_size = delta_size;
d116a45a 334 cur_entry->depth = old_entry->depth + 1;
c323ac7d 335 free(delta_buf);
eb41ab11 336 return 0;
c323ac7d
LT
337}
338
d116a45a 339static void find_deltas(struct object_entry **list, int window, int depth)
c323ac7d 340{
521a4f4c 341 int i, idx;
c323ac7d
LT
342 unsigned int array_size = window * sizeof(struct unpacked);
343 struct unpacked *array = xmalloc(array_size);
344
345 memset(array, 0, array_size);
521a4f4c
LT
346 i = nr_objects;
347 idx = 0;
348 while (--i >= 0) {
c323ac7d
LT
349 struct object_entry *entry = list[i];
350 struct unpacked *n = array + idx;
351 unsigned long size;
352 char type[10];
353 int j;
354
355 free(n->data);
356 n->entry = entry;
357 n->data = read_sha1_file(entry->sha1, type, &size);
358 if (size != entry->size)
359 die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
78817c15
LT
360 j = window;
361 while (--j > 0) {
362 unsigned int other_idx = idx + j;
c323ac7d 363 struct unpacked *m;
78817c15
LT
364 if (other_idx >= window)
365 other_idx -= window;
c323ac7d
LT
366 m = array + other_idx;
367 if (!m->entry)
368 break;
d116a45a 369 if (try_delta(n, m, depth) < 0)
c323ac7d
LT
370 break;
371 }
521a4f4c
LT
372 idx++;
373 if (idx >= window)
374 idx = 0;
c323ac7d
LT
375 }
376}
377
378int main(int argc, char **argv)
379{
27225f2e 380 char line[PATH_MAX + 20];
d22b9290 381 int window = 10, depth = 10, pack_to_stdout = 0;
c323ac7d
LT
382 int i;
383
384 for (i = 1; i < argc; i++) {
385 const char *arg = argv[i];
386
387 if (*arg == '-') {
388 if (!strncmp("--window=", arg, 9)) {
389 char *end;
f846bbff 390 window = strtoul(arg+9, &end, 0);
c323ac7d
LT
391 if (!arg[9] || *end)
392 usage(pack_usage);
393 continue;
394 }
d116a45a
LT
395 if (!strncmp("--depth=", arg, 8)) {
396 char *end;
397 depth = strtoul(arg+8, &end, 0);
398 if (!arg[8] || *end)
399 usage(pack_usage);
400 continue;
401 }
d22b9290
LT
402 if (!strcmp("--stdout", arg)) {
403 pack_to_stdout = 1;
404 continue;
405 }
c323ac7d
LT
406 usage(pack_usage);
407 }
408 if (base_name)
409 usage(pack_usage);
410 base_name = arg;
411 }
412
d22b9290 413 if (pack_to_stdout != !base_name)
c323ac7d
LT
414 usage(pack_usage);
415
416 while (fgets(line, sizeof(line), stdin) != NULL) {
27225f2e
LT
417 unsigned int hash;
418 char *p;
c323ac7d 419 unsigned char sha1[20];
27225f2e 420
c323ac7d
LT
421 if (get_sha1_hex(line, sha1))
422 die("expected sha1, got garbage");
27225f2e
LT
423 hash = 0;
424 p = line+40;
425 while (*p) {
426 unsigned char c = *p++;
427 if (isspace(c))
428 continue;
429 hash = hash * 11 + c;
430 }
431 add_object_entry(sha1, hash);
c323ac7d
LT
432 }
433 get_object_details();
434
d22b9290 435 fprintf(stderr, "Packing %d objects\n", nr_objects);
c323ac7d
LT
436
437 sorted_by_sha = create_sorted_list(sha1_sort);
438 sorted_by_type = create_sorted_list(type_size_sort);
d116a45a
LT
439 if (window && depth)
440 find_deltas(sorted_by_type, window+1, depth);
c323ac7d
LT
441
442 write_pack_file();
d22b9290
LT
443 if (!pack_to_stdout)
444 write_index_file();
c323ac7d
LT
445 return 0;
446}