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 incremental = 0;
22 static struct object_entry **sorted_by_sha, **sorted_by_type;
23 static struct object_entry *objects = NULL;
24 static int nr_objects = 0, nr_alloc = 0;
25 static const char *base_name;
26 static unsigned char pack_file_sha1[20];
28 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
30 unsigned long othersize, delta_size;
32 void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
36 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
37 delta_buf = diff_delta(otherbuf, othersize,
38 buf, size, &delta_size, 0);
39 if (!delta_buf || delta_size != entry->delta_size)
40 die("delta size changed");
47 * The per-object header is a pretty dense thing, which is
48 * - first byte: low four bits are "size", then three bits of "type",
49 * and the high bit is "size continues".
50 * - each byte afterwards: low seven bits are size continuation,
51 * with the high bit being "size continues"
53 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
58 if (type < OBJ_COMMIT || type > OBJ_DELTA)
59 die("bad type %d", type);
61 c = (type << 4) | (size & 15);
73 static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
77 void *buf = read_sha1_file(entry->sha1, type, &size);
78 unsigned char header[10];
79 unsigned hdrlen, datalen;
80 enum object_type obj_type;
83 die("unable to read %s", sha1_to_hex(entry->sha1));
84 if (size != entry->size)
85 die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
88 * The object header is a byte of 'type' followed by zero or
89 * more bytes of length. For deltas, the 20 bytes of delta sha1
92 obj_type = entry->type;
94 buf = delta_against(buf, size, entry);
95 size = entry->delta_size;
98 hdrlen = encode_header(obj_type, size, header);
99 sha1write(f, header, hdrlen);
101 sha1write(f, entry->delta, 20);
104 datalen = sha1write_compressed(f, buf, size);
106 return hdrlen + datalen;
109 static unsigned long write_one(struct sha1file *f,
110 struct object_entry *e,
111 unsigned long offset)
114 /* offset starts from header size and cannot be zero
115 * if it is written already.
119 offset += write_object(f, e);
120 /* if we are delitified, write out its base object. */
122 offset = write_one(f, e->delta, offset);
126 static void write_pack_file(void)
130 unsigned long offset;
132 struct pack_header hdr;
135 f = sha1fd(1, "<stdout>");
137 f = sha1create("%s.%s", base_name, "pack");
138 hdr.hdr_signature = htonl(PACK_SIGNATURE);
139 hdr.hdr_version = htonl(PACK_VERSION);
140 hdr.hdr_entries = htonl(nr_objects);
141 sha1write(f, &hdr, sizeof(hdr));
142 offset = sizeof(hdr);
143 for (i = 0; i < nr_objects; i++)
144 offset = write_one(f, objects + i, offset);
146 sha1close(f, pack_file_sha1, 1);
151 static void write_index_file(void)
154 struct sha1file *f = sha1create("%s.%s", base_name, "idx");
155 struct object_entry **list = sorted_by_sha;
156 struct object_entry **last = list + nr_objects;
157 unsigned int array[256];
160 * Write the first-level table (the list is sorted,
161 * but we use a 256-entry lookup to be able to avoid
162 * having to do eight extra binary search iterations).
164 for (i = 0; i < 256; i++) {
165 struct object_entry **next = list;
166 while (next < last) {
167 struct object_entry *entry = *next;
168 if (entry->sha1[0] != i)
172 array[i] = htonl(next - sorted_by_sha);
175 sha1write(f, array, 256 * sizeof(int));
178 * Write the actual SHA1 entries..
180 list = sorted_by_sha;
181 for (i = 0; i < nr_objects; i++) {
182 struct object_entry *entry = *list++;
183 unsigned int offset = htonl(entry->offset);
184 sha1write(f, &offset, 4);
185 sha1write(f, entry->sha1, 20);
187 sha1write(f, pack_file_sha1, 20);
188 sha1close(f, NULL, 1);
191 static void add_object_entry(unsigned char *sha1, unsigned int hash)
193 unsigned int idx = nr_objects;
194 struct object_entry *entry;
196 if (incremental && has_sha1_pack(sha1))
199 if (idx >= nr_alloc) {
200 unsigned int needed = (idx + 1024) * 3 / 2;
201 objects = xrealloc(objects, needed * sizeof(*entry));
204 entry = objects + idx;
205 memset(entry, 0, sizeof(*entry));
206 memcpy(entry->sha1, sha1, 20);
211 static void check_object(struct object_entry *entry)
215 if (!sha1_object_info(entry->sha1, type, &entry->size)) {
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 if (!strcmp(type, "tag")) {
223 entry->type = OBJ_TAG;
225 die("unable to pack object %s of type %s",
226 sha1_to_hex(entry->sha1), type);
229 die("unable to get type of object %s",
230 sha1_to_hex(entry->sha1));
233 static void get_object_details(void)
236 struct object_entry *entry = objects;
238 for (i = 0; i < nr_objects; i++)
239 check_object(entry++);
242 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
244 static entry_sort_t current_sort;
246 static int sort_comparator(const void *_a, const void *_b)
248 struct object_entry *a = *(struct object_entry **)_a;
249 struct object_entry *b = *(struct object_entry **)_b;
250 return current_sort(a,b);
253 static struct object_entry **create_sorted_list(entry_sort_t sort)
255 struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
258 for (i = 0; i < nr_objects; i++)
259 list[i] = objects + i;
261 qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
265 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
267 return memcmp(a->sha1, b->sha1, 20);
270 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
272 if (a->type < b->type)
274 if (a->type > b->type)
276 if (a->hash < b->hash)
278 if (a->hash > b->hash)
280 if (a->size < b->size)
282 if (a->size > b->size)
284 return a < b ? -1 : (a > b);
288 struct object_entry *entry;
293 * We search for deltas _backwards_ in a list sorted by type and
294 * by size, so that we see progressively smaller and smaller files.
295 * That's because we prefer deltas to be from the bigger file
296 * to the smaller - deletes are potentially cheaper, but perhaps
297 * more importantly, the bigger file is likely the more recent
300 static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
302 struct object_entry *cur_entry = cur->entry;
303 struct object_entry *old_entry = old->entry;
304 unsigned long size, oldsize, delta_size, sizediff;
308 /* Don't bother doing diffs between different types */
309 if (cur_entry->type != old_entry->type)
312 size = cur_entry->size;
315 oldsize = old_entry->size;
316 sizediff = oldsize > size ? oldsize - size : size - oldsize;
317 if (sizediff > size / 8)
319 if (old_entry->depth >= max_depth)
325 * We always delta from the bigger to the smaller, since that's
326 * more space-efficient (deletes don't have to say _what_ they
329 max_size = size / 2 - 20;
330 if (cur_entry->delta)
331 max_size = cur_entry->delta_size-1;
332 if (sizediff >= max_size)
334 delta_buf = diff_delta(old->data, oldsize,
335 cur->data, size, &delta_size, max_size);
338 cur_entry->delta = old_entry;
339 cur_entry->delta_size = delta_size;
340 cur_entry->depth = old_entry->depth + 1;
345 static void find_deltas(struct object_entry **list, int window, int depth)
348 unsigned int array_size = window * sizeof(struct unpacked);
349 struct unpacked *array = xmalloc(array_size);
351 memset(array, 0, array_size);
355 struct object_entry *entry = list[i];
356 struct unpacked *n = array + idx;
363 n->data = read_sha1_file(entry->sha1, type, &size);
364 if (size != entry->size)
365 die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
368 unsigned int other_idx = idx + j;
370 if (other_idx >= window)
372 m = array + other_idx;
375 if (try_delta(n, m, depth) < 0)
384 int main(int argc, char **argv)
386 char line[PATH_MAX + 20];
387 int window = 10, depth = 10, pack_to_stdout = 0;
390 for (i = 1; i < argc; i++) {
391 const char *arg = argv[i];
394 if (!strcmp("--incremental", arg)) {
398 if (!strncmp("--window=", arg, 9)) {
400 window = strtoul(arg+9, &end, 0);
405 if (!strncmp("--depth=", arg, 8)) {
407 depth = strtoul(arg+8, &end, 0);
412 if (!strcmp("--stdout", arg)) {
423 if (pack_to_stdout != !base_name)
426 while (fgets(line, sizeof(line), stdin) != NULL) {
429 unsigned char sha1[20];
431 if (get_sha1_hex(line, sha1))
432 die("expected sha1, got garbage");
436 unsigned char c = *p++;
439 hash = hash * 11 + c;
441 add_object_entry(sha1, hash);
443 get_object_details();
445 fprintf(stderr, "Packing %d objects\n", nr_objects);
447 sorted_by_sha = create_sorted_list(sha1_sort);
448 sorted_by_type = create_sorted_list(type_size_sort);
450 find_deltas(sorted_by_type, window+1, depth);