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c323ac7d LT |
1 | #include "cache.h" |
2 | #include "object.h" | |
3 | #include "delta.h" | |
4 | ||
5 | static const char pack_usage[] = "git-pack-objects [--window=N] base-name < object-list"; | |
6 | ||
7 | enum object_type { | |
8 | OBJ_NONE, | |
9 | OBJ_COMMIT, | |
10 | OBJ_TREE, | |
11 | OBJ_BLOB, | |
12 | OBJ_DELTA // NOTE! This is _not_ the same as a "delta" object in the filesystem | |
13 | }; | |
14 | ||
15 | struct object_entry { | |
16 | unsigned char sha1[20]; | |
17 | unsigned long size; | |
18 | unsigned long offset; | |
19 | unsigned int depth; | |
20 | unsigned int flags; | |
21 | enum object_type type; | |
22 | unsigned long delta_size; | |
23 | struct object_entry *delta; | |
24 | }; | |
25 | ||
26 | static struct object_entry **sorted_by_sha, **sorted_by_type; | |
27 | static struct object_entry *objects = NULL; | |
28 | static int nr_objects = 0, nr_alloc = 0; | |
29 | static int delta_window = 10; | |
30 | static const char *base_name; | |
31 | ||
32 | struct myfile { | |
33 | int fd; | |
34 | unsigned long chars; | |
35 | unsigned char buffer[8192]; | |
36 | }; | |
37 | ||
38 | static FILE *create_file(const char *suffix) | |
39 | { | |
40 | static char filename[PATH_MAX]; | |
41 | unsigned len; | |
42 | ||
43 | len = snprintf(filename, PATH_MAX, "%s.%s", base_name, suffix); | |
44 | if (len >= PATH_MAX) | |
45 | die("you wascally wabbit, you"); | |
46 | return fopen(filename, "w"); | |
47 | } | |
48 | ||
49 | static unsigned long fwrite_compressed(void *in, unsigned long size, FILE *f) | |
50 | { | |
51 | z_stream stream; | |
52 | unsigned long maxsize; | |
53 | void *out; | |
54 | ||
55 | memset(&stream, 0, sizeof(stream)); | |
56 | deflateInit(&stream, Z_DEFAULT_COMPRESSION); | |
57 | maxsize = deflateBound(&stream, size); | |
58 | out = xmalloc(maxsize); | |
59 | ||
60 | /* Compress it */ | |
61 | stream.next_in = in; | |
62 | stream.avail_in = size; | |
63 | ||
64 | stream.next_out = out; | |
65 | stream.avail_out = maxsize; | |
66 | ||
67 | while (deflate(&stream, Z_FINISH) == Z_OK) | |
68 | /* nothing */; | |
69 | deflateEnd(&stream); | |
70 | ||
71 | size = stream.total_out; | |
72 | fwrite(out, size, 1, f); | |
73 | free(out); | |
74 | return size; | |
75 | } | |
76 | ||
77 | static void *delta_against(void *buf, unsigned long size, struct object_entry *entry) | |
78 | { | |
79 | unsigned long othersize, delta_size; | |
80 | char type[10]; | |
81 | void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize); | |
82 | void *delta_buf; | |
83 | ||
84 | if (!otherbuf) | |
85 | die("unable to read %s", sha1_to_hex(entry->delta->sha1)); | |
86 | delta_buf = diff_delta(buf, size, otherbuf, othersize, &delta_size); | |
87 | if (delta_size != entry->delta_size) | |
88 | die("delta size changed"); | |
89 | free(buf); | |
90 | free(otherbuf); | |
91 | return delta_buf; | |
92 | } | |
93 | ||
94 | static unsigned long write_object(FILE *f, struct object_entry *entry) | |
95 | { | |
96 | unsigned long size; | |
97 | char type[10]; | |
98 | void *buf = read_sha1_file(entry->sha1, type, &size); | |
99 | char header[21]; | |
100 | unsigned hdrlen, datalen; | |
101 | ||
102 | if (!buf) | |
103 | die("unable to read %s", sha1_to_hex(entry->sha1)); | |
104 | if (size != entry->size) | |
105 | die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size); | |
106 | ||
107 | /* | |
108 | * The object header is a byte of 'type' followed by four bytes of | |
109 | * length, except for deltas that has the 20 bytes of delta sha | |
110 | * instead. | |
111 | */ | |
112 | header[0] = ".CTB"[entry->type]; | |
113 | datalen = htonl(size); | |
114 | memcpy(header+1, &datalen, 4); | |
115 | hdrlen = 5; | |
116 | if (entry->delta) { | |
117 | memcpy(header+1, entry->delta, 20); | |
118 | buf = delta_against(buf, size, entry); | |
119 | size = entry->delta_size; | |
120 | hdrlen = 21; | |
121 | } | |
122 | fwrite(header, hdrlen, 1, f); | |
123 | datalen = fwrite_compressed(buf, size, f); | |
124 | free(buf); | |
125 | return hdrlen + datalen; | |
126 | } | |
127 | ||
128 | static void write_pack_file(void) | |
129 | { | |
130 | int i; | |
131 | FILE *f = create_file("pack"); | |
132 | unsigned long offset = 0; | |
133 | unsigned long mb; | |
134 | ||
135 | for (i = 0; i < nr_objects; i++) { | |
136 | struct object_entry *entry = objects + i; | |
137 | entry->offset = offset; | |
138 | offset += write_object(f, entry); | |
139 | } | |
140 | fclose(f); | |
141 | mb = offset >> 20; | |
142 | offset &= 0xfffff; | |
143 | } | |
144 | ||
145 | static void write_index_file(void) | |
146 | { | |
147 | int i; | |
148 | FILE *f = create_file("idx"); | |
149 | struct object_entry **list = sorted_by_sha; | |
150 | struct object_entry **last = list + nr_objects; | |
151 | unsigned int array[256]; | |
152 | ||
153 | /* | |
154 | * Write the first-level table (the list is sorted, | |
155 | * but we use a 256-entry lookup to be able to avoid | |
156 | * having to do eight extra binary search iterations) | |
157 | */ | |
158 | for (i = 0; i < 256; i++) { | |
159 | struct object_entry **next = list; | |
160 | while (next < last) { | |
161 | struct object_entry *entry = *next; | |
162 | if (entry->sha1[0] != i) | |
163 | break; | |
164 | next++; | |
165 | } | |
166 | array[i] = htonl(next - sorted_by_sha); | |
167 | list = next; | |
168 | } | |
169 | fwrite(array, 256, sizeof(int), f); | |
170 | ||
171 | /* | |
172 | * Write the actual SHA1 entries.. | |
173 | */ | |
174 | list = sorted_by_sha; | |
175 | for (i < 0; i < nr_objects; i++) { | |
176 | struct object_entry *entry = *list++; | |
177 | unsigned int offset = htonl(entry->offset); | |
178 | fwrite(&offset, 4, 1, f); | |
179 | fwrite(entry->sha1, 20, 1, f); | |
180 | } | |
181 | fclose(f); | |
182 | } | |
183 | ||
184 | static void add_object_entry(unsigned char *sha1) | |
185 | { | |
186 | unsigned int idx = nr_objects; | |
187 | struct object_entry *entry; | |
188 | ||
189 | if (idx >= nr_alloc) { | |
190 | unsigned int needed = (idx + 1024) * 3 / 2; | |
191 | objects = xrealloc(objects, needed * sizeof(*entry)); | |
192 | nr_alloc = needed; | |
193 | } | |
194 | entry = objects + idx; | |
195 | memset(entry, 0, sizeof(*entry)); | |
196 | memcpy(entry->sha1, sha1, 20); | |
197 | nr_objects = idx+1; | |
198 | } | |
199 | ||
200 | static void check_object(struct object_entry *entry) | |
201 | { | |
202 | char buffer[128]; | |
203 | char type[10]; | |
204 | unsigned long mapsize; | |
205 | z_stream stream; | |
206 | void *map; | |
207 | ||
208 | map = map_sha1_file(entry->sha1, &mapsize); | |
209 | if (!map) | |
210 | die("unable to map %s", sha1_to_hex(entry->sha1)); | |
211 | if (unpack_sha1_header(&stream, map, mapsize, buffer, sizeof(buffer)) < 0) | |
212 | die("unable to unpack %s header", sha1_to_hex(entry->sha1)); | |
213 | munmap(map, mapsize); | |
214 | if (parse_sha1_header(buffer, type, &entry->size) < 0) | |
215 | die("unable to parse %s header", sha1_to_hex(entry->sha1)); | |
216 | if (!strcmp(type, "commit")) { | |
217 | entry->type = OBJ_COMMIT; | |
218 | } else if (!strcmp(type, "tree")) { | |
219 | entry->type = OBJ_TREE; | |
220 | } else if (!strcmp(type, "blob")) { | |
221 | entry->type = OBJ_BLOB; | |
222 | } else | |
223 | die("unable to pack object %s of type %s", sha1_to_hex(entry->sha1), type); | |
224 | } | |
225 | ||
226 | static void get_object_details(void) | |
227 | { | |
228 | int i; | |
229 | struct object_entry *entry = objects; | |
230 | ||
231 | for (i = 0; i < nr_objects; i++) | |
232 | check_object(entry++); | |
233 | } | |
234 | ||
235 | typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *); | |
236 | ||
237 | static entry_sort_t current_sort; | |
238 | ||
239 | static int sort_comparator(const void *_a, const void *_b) | |
240 | { | |
241 | struct object_entry *a = *(struct object_entry **)_a; | |
242 | struct object_entry *b = *(struct object_entry **)_b; | |
243 | return current_sort(a,b); | |
244 | } | |
245 | ||
246 | static struct object_entry **create_sorted_list(entry_sort_t sort) | |
247 | { | |
248 | struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *)); | |
249 | int i; | |
250 | ||
251 | for (i = 0; i < nr_objects; i++) | |
252 | list[i] = objects + i; | |
253 | current_sort = sort; | |
254 | qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator); | |
255 | return list; | |
256 | } | |
257 | ||
258 | static int sha1_sort(const struct object_entry *a, const struct object_entry *b) | |
259 | { | |
260 | return memcmp(a->sha1, b->sha1, 20); | |
261 | } | |
262 | ||
263 | static int type_size_sort(const struct object_entry *a, const struct object_entry *b) | |
264 | { | |
265 | if (a->type < b->type) | |
266 | return -1; | |
267 | if (a->type > b->type) | |
268 | return 1; | |
269 | if (a->size < b->size) | |
270 | return -1; | |
271 | if (a->size > b->size) | |
272 | return 1; | |
273 | return a < b ? -1 : (a > b); | |
274 | } | |
275 | ||
276 | struct unpacked { | |
277 | struct object_entry *entry; | |
278 | void *data; | |
279 | }; | |
280 | ||
281 | /* | |
282 | * We search for deltas in a list sorted by type and by size, and | |
283 | * walk the "old" chain backwards in the list, so if the type | |
284 | * has changed or the size difference is too big, there's no point | |
285 | * in even continuing the walk, since the other old objects are | |
286 | * going to be even smaller or of a different type. So return -1 | |
287 | * once we determine that there's no point even trying. | |
288 | */ | |
289 | static int try_delta(struct unpacked *cur, struct unpacked *old) | |
290 | { | |
291 | struct object_entry *cur_entry = cur->entry; | |
292 | struct object_entry *old_entry = old->entry; | |
293 | unsigned long size, oldsize, delta_size; | |
294 | void *delta_buf; | |
295 | ||
296 | /* Don't bother doing diffs between different types */ | |
297 | if (cur_entry->type != old_entry->type) | |
298 | return -1; | |
299 | ||
300 | /* Size is guaranteed to be larger than or equal to oldsize */ | |
301 | size = cur_entry->size; | |
302 | oldsize = old_entry->size; | |
303 | if (size - oldsize > oldsize / 4) | |
304 | return -1; | |
305 | ||
306 | /* | |
307 | * NOTE! | |
308 | * | |
309 | * We always delta from the bigger to the smaller, since that's | |
310 | * more space-efficient (deletes don't have to say _what_ they | |
311 | * delete). | |
312 | */ | |
313 | delta_buf = diff_delta(cur->data, size, old->data, oldsize, &delta_size); | |
314 | if (!delta_buf) | |
315 | die("unable to create delta"); | |
316 | if (delta_size + 20 < size / 2) { | |
317 | if (!cur_entry->delta || cur_entry->delta_size > delta_size) { | |
318 | cur_entry->delta = old_entry; | |
319 | cur_entry->delta_size = delta_size; | |
320 | } | |
321 | } | |
322 | free(delta_buf); | |
323 | } | |
324 | ||
325 | static void find_deltas(struct object_entry **list, int window) | |
326 | { | |
327 | unsigned int i; | |
328 | unsigned int array_size = window * sizeof(struct unpacked); | |
329 | struct unpacked *array = xmalloc(array_size); | |
330 | ||
331 | memset(array, 0, array_size); | |
332 | for (i = 0; i < nr_objects; i++) { | |
333 | unsigned int idx = i % window; | |
334 | struct object_entry *entry = list[i]; | |
335 | struct unpacked *n = array + idx; | |
336 | unsigned long size; | |
337 | char type[10]; | |
338 | int j; | |
339 | ||
340 | free(n->data); | |
341 | n->entry = entry; | |
342 | n->data = read_sha1_file(entry->sha1, type, &size); | |
343 | if (size != entry->size) | |
344 | die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size); | |
345 | for (j = 0; j < window; j++) { | |
346 | unsigned int other_idx = idx - 1 - j; | |
347 | struct unpacked *m; | |
348 | if (other_idx < 0) | |
349 | other_idx += window; | |
350 | m = array + other_idx; | |
351 | if (!m->entry) | |
352 | break; | |
353 | if (try_delta(n, m) < 0) | |
354 | break; | |
355 | } | |
356 | } | |
357 | } | |
358 | ||
359 | int main(int argc, char **argv) | |
360 | { | |
361 | char line[128]; | |
362 | int i; | |
363 | ||
364 | for (i = 1; i < argc; i++) { | |
365 | const char *arg = argv[i]; | |
366 | ||
367 | if (*arg == '-') { | |
368 | if (!strncmp("--window=", arg, 9)) { | |
369 | char *end; | |
370 | delta_window = strtoul(arg+9, &end, 0); | |
371 | if (!arg[9] || *end) | |
372 | usage(pack_usage); | |
373 | continue; | |
374 | } | |
375 | usage(pack_usage); | |
376 | } | |
377 | if (base_name) | |
378 | usage(pack_usage); | |
379 | base_name = arg; | |
380 | } | |
381 | ||
382 | if (!base_name) | |
383 | usage(pack_usage); | |
384 | ||
385 | while (fgets(line, sizeof(line), stdin) != NULL) { | |
386 | unsigned char sha1[20]; | |
387 | if (get_sha1_hex(line, sha1)) | |
388 | die("expected sha1, got garbage"); | |
389 | add_object_entry(sha1); | |
390 | } | |
391 | get_object_details(); | |
392 | ||
393 | printf("Packing %d objects\n", nr_objects); | |
394 | ||
395 | sorted_by_sha = create_sorted_list(sha1_sort); | |
396 | sorted_by_type = create_sorted_list(type_size_sort); | |
397 | if (delta_window) | |
398 | find_deltas(sorted_by_type, delta_window); | |
399 | ||
400 | write_pack_file(); | |
401 | write_index_file(); | |
402 | return 0; | |
403 | } |