8 static const char pack_usage[] = "git-pack-objects [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
11 unsigned char sha1[20];
16 enum object_type type;
17 unsigned long delta_size;
18 struct object_entry *delta;
21 static int non_empty = 0;
22 static int incremental = 0;
23 static struct object_entry **sorted_by_sha, **sorted_by_type;
24 static struct object_entry *objects = NULL;
25 static int nr_objects = 0, nr_alloc = 0;
26 static const char *base_name;
27 static unsigned char pack_file_sha1[20];
29 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
31 unsigned long othersize, delta_size;
33 void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
37 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
38 delta_buf = diff_delta(otherbuf, othersize,
39 buf, size, &delta_size, 0);
40 if (!delta_buf || delta_size != entry->delta_size)
41 die("delta size changed");
48 * The per-object header is a pretty dense thing, which is
49 * - first byte: low four bits are "size", then three bits of "type",
50 * and the high bit is "size continues".
51 * - each byte afterwards: low seven bits are size continuation,
52 * with the high bit being "size continues"
54 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
59 if (type < OBJ_COMMIT || type > OBJ_DELTA)
60 die("bad type %d", type);
62 c = (type << 4) | (size & 15);
74 static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
78 void *buf = read_sha1_file(entry->sha1, type, &size);
79 unsigned char header[10];
80 unsigned hdrlen, datalen;
81 enum object_type obj_type;
84 die("unable to read %s", sha1_to_hex(entry->sha1));
85 if (size != entry->size)
86 die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
89 * The object header is a byte of 'type' followed by zero or
90 * more bytes of length. For deltas, the 20 bytes of delta sha1
93 obj_type = entry->type;
95 buf = delta_against(buf, size, entry);
96 size = entry->delta_size;
99 hdrlen = encode_header(obj_type, size, header);
100 sha1write(f, header, hdrlen);
102 sha1write(f, entry->delta, 20);
105 datalen = sha1write_compressed(f, buf, size);
107 return hdrlen + datalen;
110 static unsigned long write_one(struct sha1file *f,
111 struct object_entry *e,
112 unsigned long offset)
115 /* offset starts from header size and cannot be zero
116 * if it is written already.
120 offset += write_object(f, e);
121 /* if we are delitified, write out its base object. */
123 offset = write_one(f, e->delta, offset);
127 static void write_pack_file(void)
131 unsigned long offset;
133 struct pack_header hdr;
136 f = sha1fd(1, "<stdout>");
138 f = sha1create("%s.%s", base_name, "pack");
139 hdr.hdr_signature = htonl(PACK_SIGNATURE);
140 hdr.hdr_version = htonl(PACK_VERSION);
141 hdr.hdr_entries = htonl(nr_objects);
142 sha1write(f, &hdr, sizeof(hdr));
143 offset = sizeof(hdr);
144 for (i = 0; i < nr_objects; i++)
145 offset = write_one(f, objects + i, offset);
147 sha1close(f, pack_file_sha1, 1);
152 static void write_index_file(void)
155 struct sha1file *f = sha1create("%s.%s", base_name, "idx");
156 struct object_entry **list = sorted_by_sha;
157 struct object_entry **last = list + nr_objects;
158 unsigned int array[256];
161 * Write the first-level table (the list is sorted,
162 * but we use a 256-entry lookup to be able to avoid
163 * having to do eight extra binary search iterations).
165 for (i = 0; i < 256; i++) {
166 struct object_entry **next = list;
167 while (next < last) {
168 struct object_entry *entry = *next;
169 if (entry->sha1[0] != i)
173 array[i] = htonl(next - sorted_by_sha);
176 sha1write(f, array, 256 * sizeof(int));
179 * Write the actual SHA1 entries..
181 list = sorted_by_sha;
182 for (i = 0; i < nr_objects; i++) {
183 struct object_entry *entry = *list++;
184 unsigned int offset = htonl(entry->offset);
185 sha1write(f, &offset, 4);
186 sha1write(f, entry->sha1, 20);
188 sha1write(f, pack_file_sha1, 20);
189 sha1close(f, NULL, 1);
192 static void add_object_entry(unsigned char *sha1, unsigned int hash)
194 unsigned int idx = nr_objects;
195 struct object_entry *entry;
197 if (incremental && has_sha1_pack(sha1))
200 if (idx >= nr_alloc) {
201 unsigned int needed = (idx + 1024) * 3 / 2;
202 objects = xrealloc(objects, needed * sizeof(*entry));
205 entry = objects + idx;
206 memset(entry, 0, sizeof(*entry));
207 memcpy(entry->sha1, sha1, 20);
212 static void check_object(struct object_entry *entry)
216 if (!sha1_object_info(entry->sha1, type, &entry->size)) {
217 if (!strcmp(type, "commit")) {
218 entry->type = OBJ_COMMIT;
219 } else if (!strcmp(type, "tree")) {
220 entry->type = OBJ_TREE;
221 } else if (!strcmp(type, "blob")) {
222 entry->type = OBJ_BLOB;
223 } else if (!strcmp(type, "tag")) {
224 entry->type = OBJ_TAG;
226 die("unable to pack object %s of type %s",
227 sha1_to_hex(entry->sha1), type);
230 die("unable to get type of object %s",
231 sha1_to_hex(entry->sha1));
234 static void get_object_details(void)
237 struct object_entry *entry = objects;
239 for (i = 0; i < nr_objects; i++)
240 check_object(entry++);
243 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
245 static entry_sort_t current_sort;
247 static int sort_comparator(const void *_a, const void *_b)
249 struct object_entry *a = *(struct object_entry **)_a;
250 struct object_entry *b = *(struct object_entry **)_b;
251 return current_sort(a,b);
254 static struct object_entry **create_sorted_list(entry_sort_t sort)
256 struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
259 for (i = 0; i < nr_objects; i++)
260 list[i] = objects + i;
262 qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
266 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
268 return memcmp(a->sha1, b->sha1, 20);
271 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
273 if (a->type < b->type)
275 if (a->type > b->type)
277 if (a->hash < b->hash)
279 if (a->hash > b->hash)
281 if (a->size < b->size)
283 if (a->size > b->size)
285 return a < b ? -1 : (a > b);
289 struct object_entry *entry;
294 * We search for deltas _backwards_ in a list sorted by type and
295 * by size, so that we see progressively smaller and smaller files.
296 * That's because we prefer deltas to be from the bigger file
297 * to the smaller - deletes are potentially cheaper, but perhaps
298 * more importantly, the bigger file is likely the more recent
301 static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
303 struct object_entry *cur_entry = cur->entry;
304 struct object_entry *old_entry = old->entry;
305 unsigned long size, oldsize, delta_size, sizediff;
309 /* Don't bother doing diffs between different types */
310 if (cur_entry->type != old_entry->type)
313 size = cur_entry->size;
316 oldsize = old_entry->size;
317 sizediff = oldsize > size ? oldsize - size : size - oldsize;
318 if (sizediff > size / 8)
320 if (old_entry->depth >= max_depth)
326 * We always delta from the bigger to the smaller, since that's
327 * more space-efficient (deletes don't have to say _what_ they
330 max_size = size / 2 - 20;
331 if (cur_entry->delta)
332 max_size = cur_entry->delta_size-1;
333 if (sizediff >= max_size)
335 delta_buf = diff_delta(old->data, oldsize,
336 cur->data, size, &delta_size, max_size);
339 cur_entry->delta = old_entry;
340 cur_entry->delta_size = delta_size;
341 cur_entry->depth = old_entry->depth + 1;
346 static void find_deltas(struct object_entry **list, int window, int depth)
349 unsigned int array_size = window * sizeof(struct unpacked);
350 struct unpacked *array = xmalloc(array_size);
352 memset(array, 0, array_size);
356 struct object_entry *entry = list[i];
357 struct unpacked *n = array + idx;
364 n->data = read_sha1_file(entry->sha1, type, &size);
365 if (size != entry->size)
366 die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
369 unsigned int other_idx = idx + j;
371 if (other_idx >= window)
373 m = array + other_idx;
376 if (try_delta(n, m, depth) < 0)
385 int main(int argc, char **argv)
387 char line[PATH_MAX + 20];
388 int window = 10, depth = 10, pack_to_stdout = 0;
391 for (i = 1; i < argc; i++) {
392 const char *arg = argv[i];
395 if (!strcmp("--non-empty", arg)) {
399 if (!strcmp("--incremental", arg)) {
403 if (!strncmp("--window=", arg, 9)) {
405 window = strtoul(arg+9, &end, 0);
410 if (!strncmp("--depth=", arg, 8)) {
412 depth = strtoul(arg+8, &end, 0);
417 if (!strcmp("--stdout", arg)) {
428 if (pack_to_stdout != !base_name)
431 while (fgets(line, sizeof(line), stdin) != NULL) {
434 unsigned char sha1[20];
436 if (get_sha1_hex(line, sha1))
437 die("expected sha1, got garbage");
441 unsigned char c = *p++;
444 hash = hash * 11 + c;
446 add_object_entry(sha1, hash);
448 if (non_empty && !nr_objects)
450 get_object_details();
452 fprintf(stderr, "Packing %d objects\n", nr_objects);
454 sorted_by_sha = create_sorted_list(sha1_sort);
455 sorted_by_type = create_sorted_list(type_size_sort);
457 find_deltas(sorted_by_type, window+1, depth);