044f427392a7f65520a47c6b80ada5ff0b38326c
[git/git.git] / pack-write.c
1 #include "cache.h"
2 #include "pack.h"
3 #include "csum-file.h"
4
5 void reset_pack_idx_option(struct pack_idx_option *opts)
6 {
7 memset(opts, 0, sizeof(*opts));
8 opts->version = 2;
9 opts->off32_limit = 0x7fffffff;
10 }
11
12 static int sha1_compare(const void *_a, const void *_b)
13 {
14 struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
15 struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
16 return oidcmp(&a->oid, &b->oid);
17 }
18
19 static int cmp_uint32(const void *a_, const void *b_)
20 {
21 uint32_t a = *((uint32_t *)a_);
22 uint32_t b = *((uint32_t *)b_);
23
24 return (a < b) ? -1 : (a != b);
25 }
26
27 static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
28 {
29 uint32_t ofsval;
30
31 if ((offset >> 31) || (opts->off32_limit < offset))
32 return 1;
33 if (!opts->anomaly_nr)
34 return 0;
35 ofsval = offset;
36 return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr,
37 sizeof(ofsval), cmp_uint32);
38 }
39
40 /*
41 * On entry *sha1 contains the pack content SHA1 hash, on exit it is
42 * the SHA1 hash of sorted object names. The objects array passed in
43 * will be sorted by SHA1 on exit.
44 */
45 const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
46 int nr_objects, const struct pack_idx_option *opts,
47 const unsigned char *sha1)
48 {
49 struct hashfile *f;
50 struct pack_idx_entry **sorted_by_sha, **list, **last;
51 off_t last_obj_offset = 0;
52 uint32_t array[256];
53 int i, fd;
54 uint32_t index_version;
55
56 if (nr_objects) {
57 sorted_by_sha = objects;
58 list = sorted_by_sha;
59 last = sorted_by_sha + nr_objects;
60 for (i = 0; i < nr_objects; ++i) {
61 if (objects[i]->offset > last_obj_offset)
62 last_obj_offset = objects[i]->offset;
63 }
64 QSORT(sorted_by_sha, nr_objects, sha1_compare);
65 }
66 else
67 sorted_by_sha = list = last = NULL;
68
69 if (opts->flags & WRITE_IDX_VERIFY) {
70 assert(index_name);
71 f = hashfd_check(index_name);
72 } else {
73 if (!index_name) {
74 struct strbuf tmp_file = STRBUF_INIT;
75 fd = odb_mkstemp(&tmp_file, "pack/tmp_idx_XXXXXX");
76 index_name = strbuf_detach(&tmp_file, NULL);
77 } else {
78 unlink(index_name);
79 fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
80 if (fd < 0)
81 die_errno("unable to create '%s'", index_name);
82 }
83 f = hashfd(fd, index_name);
84 }
85
86 /* if last object's offset is >= 2^31 we should use index V2 */
87 index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->version;
88
89 /* index versions 2 and above need a header */
90 if (index_version >= 2) {
91 struct pack_idx_header hdr;
92 hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
93 hdr.idx_version = htonl(index_version);
94 hashwrite(f, &hdr, sizeof(hdr));
95 }
96
97 /*
98 * Write the first-level table (the list is sorted,
99 * but we use a 256-entry lookup to be able to avoid
100 * having to do eight extra binary search iterations).
101 */
102 for (i = 0; i < 256; i++) {
103 struct pack_idx_entry **next = list;
104 while (next < last) {
105 struct pack_idx_entry *obj = *next;
106 if (obj->oid.hash[0] != i)
107 break;
108 next++;
109 }
110 array[i] = htonl(next - sorted_by_sha);
111 list = next;
112 }
113 hashwrite(f, array, 256 * 4);
114
115 /*
116 * Write the actual SHA1 entries..
117 */
118 list = sorted_by_sha;
119 for (i = 0; i < nr_objects; i++) {
120 struct pack_idx_entry *obj = *list++;
121 if (index_version < 2) {
122 uint32_t offset = htonl(obj->offset);
123 hashwrite(f, &offset, 4);
124 }
125 hashwrite(f, obj->oid.hash, the_hash_algo->rawsz);
126 if ((opts->flags & WRITE_IDX_STRICT) &&
127 (i && !oidcmp(&list[-2]->oid, &obj->oid)))
128 die("The same object %s appears twice in the pack",
129 oid_to_hex(&obj->oid));
130 }
131
132 if (index_version >= 2) {
133 unsigned int nr_large_offset = 0;
134
135 /* write the crc32 table */
136 list = sorted_by_sha;
137 for (i = 0; i < nr_objects; i++) {
138 struct pack_idx_entry *obj = *list++;
139 uint32_t crc32_val = htonl(obj->crc32);
140 hashwrite(f, &crc32_val, 4);
141 }
142
143 /* write the 32-bit offset table */
144 list = sorted_by_sha;
145 for (i = 0; i < nr_objects; i++) {
146 struct pack_idx_entry *obj = *list++;
147 uint32_t offset;
148
149 offset = (need_large_offset(obj->offset, opts)
150 ? (0x80000000 | nr_large_offset++)
151 : obj->offset);
152 offset = htonl(offset);
153 hashwrite(f, &offset, 4);
154 }
155
156 /* write the large offset table */
157 list = sorted_by_sha;
158 while (nr_large_offset) {
159 struct pack_idx_entry *obj = *list++;
160 uint64_t offset = obj->offset;
161 uint32_t split[2];
162
163 if (!need_large_offset(offset, opts))
164 continue;
165 split[0] = htonl(offset >> 32);
166 split[1] = htonl(offset & 0xffffffff);
167 hashwrite(f, split, 8);
168 nr_large_offset--;
169 }
170 }
171
172 hashwrite(f, sha1, the_hash_algo->rawsz);
173 finalize_hashfile(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
174 ? CSUM_CLOSE : CSUM_FSYNC));
175 return index_name;
176 }
177
178 off_t write_pack_header(struct hashfile *f, uint32_t nr_entries)
179 {
180 struct pack_header hdr;
181
182 hdr.hdr_signature = htonl(PACK_SIGNATURE);
183 hdr.hdr_version = htonl(PACK_VERSION);
184 hdr.hdr_entries = htonl(nr_entries);
185 hashwrite(f, &hdr, sizeof(hdr));
186 return sizeof(hdr);
187 }
188
189 /*
190 * Update pack header with object_count and compute new SHA1 for pack data
191 * associated to pack_fd, and write that SHA1 at the end. That new SHA1
192 * is also returned in new_pack_sha1.
193 *
194 * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
195 * (without the header update) is computed and validated against the
196 * one provided in partial_pack_sha1. The validation is performed at
197 * partial_pack_offset bytes in the pack file. The SHA1 of the remaining
198 * data (i.e. from partial_pack_offset to the end) is then computed and
199 * returned in partial_pack_sha1.
200 *
201 * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
202 * partial_pack_sha1 can refer to the same buffer if the caller is not
203 * interested in the resulting SHA1 of pack data above partial_pack_offset.
204 */
205 void fixup_pack_header_footer(int pack_fd,
206 unsigned char *new_pack_hash,
207 const char *pack_name,
208 uint32_t object_count,
209 unsigned char *partial_pack_hash,
210 off_t partial_pack_offset)
211 {
212 int aligned_sz, buf_sz = 8 * 1024;
213 git_hash_ctx old_hash_ctx, new_hash_ctx;
214 struct pack_header hdr;
215 char *buf;
216 ssize_t read_result;
217
218 the_hash_algo->init_fn(&old_hash_ctx);
219 the_hash_algo->init_fn(&new_hash_ctx);
220
221 if (lseek(pack_fd, 0, SEEK_SET) != 0)
222 die_errno("Failed seeking to start of '%s'", pack_name);
223 read_result = read_in_full(pack_fd, &hdr, sizeof(hdr));
224 if (read_result < 0)
225 die_errno("Unable to reread header of '%s'", pack_name);
226 else if (read_result != sizeof(hdr))
227 die_errno("Unexpected short read for header of '%s'",
228 pack_name);
229 if (lseek(pack_fd, 0, SEEK_SET) != 0)
230 die_errno("Failed seeking to start of '%s'", pack_name);
231 the_hash_algo->update_fn(&old_hash_ctx, &hdr, sizeof(hdr));
232 hdr.hdr_entries = htonl(object_count);
233 the_hash_algo->update_fn(&new_hash_ctx, &hdr, sizeof(hdr));
234 write_or_die(pack_fd, &hdr, sizeof(hdr));
235 partial_pack_offset -= sizeof(hdr);
236
237 buf = xmalloc(buf_sz);
238 aligned_sz = buf_sz - sizeof(hdr);
239 for (;;) {
240 ssize_t m, n;
241 m = (partial_pack_hash && partial_pack_offset < aligned_sz) ?
242 partial_pack_offset : aligned_sz;
243 n = xread(pack_fd, buf, m);
244 if (!n)
245 break;
246 if (n < 0)
247 die_errno("Failed to checksum '%s'", pack_name);
248 the_hash_algo->update_fn(&new_hash_ctx, buf, n);
249
250 aligned_sz -= n;
251 if (!aligned_sz)
252 aligned_sz = buf_sz;
253
254 if (!partial_pack_hash)
255 continue;
256
257 the_hash_algo->update_fn(&old_hash_ctx, buf, n);
258 partial_pack_offset -= n;
259 if (partial_pack_offset == 0) {
260 unsigned char hash[GIT_MAX_RAWSZ];
261 the_hash_algo->final_fn(hash, &old_hash_ctx);
262 if (hashcmp(hash, partial_pack_hash) != 0)
263 die("Unexpected checksum for %s "
264 "(disk corruption?)", pack_name);
265 /*
266 * Now let's compute the SHA1 of the remainder of the
267 * pack, which also means making partial_pack_offset
268 * big enough not to matter anymore.
269 */
270 the_hash_algo->init_fn(&old_hash_ctx);
271 partial_pack_offset = ~partial_pack_offset;
272 partial_pack_offset -= MSB(partial_pack_offset, 1);
273 }
274 }
275 free(buf);
276
277 if (partial_pack_hash)
278 the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx);
279 the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx);
280 write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz);
281 fsync_or_die(pack_fd, pack_name);
282 }
283
284 char *index_pack_lockfile(int ip_out)
285 {
286 char packname[GIT_MAX_HEXSZ + 6];
287 const int len = the_hash_algo->hexsz + 6;
288
289 /*
290 * The first thing we expect from index-pack's output
291 * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
292 * %40s is the newly created pack SHA1 name. In the "keep"
293 * case, we need it to remove the corresponding .keep file
294 * later on. If we don't get that then tough luck with it.
295 */
296 if (read_in_full(ip_out, packname, len) == len && packname[len-1] == '\n') {
297 const char *name;
298 packname[len-1] = 0;
299 if (skip_prefix(packname, "keep\t", &name))
300 return xstrfmt("%s/pack/pack-%s.keep",
301 get_object_directory(), name);
302 }
303 return NULL;
304 }
305
306 /*
307 * The per-object header is a pretty dense thing, which is
308 * - first byte: low four bits are "size", then three bits of "type",
309 * and the high bit is "size continues".
310 * - each byte afterwards: low seven bits are size continuation,
311 * with the high bit being "size continues"
312 */
313 int encode_in_pack_object_header(unsigned char *hdr, int hdr_len,
314 enum object_type type, uintmax_t size)
315 {
316 int n = 1;
317 unsigned char c;
318
319 if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
320 die("bad type %d", type);
321
322 c = (type << 4) | (size & 15);
323 size >>= 4;
324 while (size) {
325 if (n == hdr_len)
326 die("object size is too enormous to format");
327 *hdr++ = c | 0x80;
328 c = size & 0x7f;
329 size >>= 7;
330 n++;
331 }
332 *hdr = c;
333 return n;
334 }
335
336 struct hashfile *create_tmp_packfile(char **pack_tmp_name)
337 {
338 struct strbuf tmpname = STRBUF_INIT;
339 int fd;
340
341 fd = odb_mkstemp(&tmpname, "pack/tmp_pack_XXXXXX");
342 *pack_tmp_name = strbuf_detach(&tmpname, NULL);
343 return hashfd(fd, *pack_tmp_name);
344 }
345
346 void finish_tmp_packfile(struct strbuf *name_buffer,
347 const char *pack_tmp_name,
348 struct pack_idx_entry **written_list,
349 uint32_t nr_written,
350 struct pack_idx_option *pack_idx_opts,
351 unsigned char sha1[])
352 {
353 const char *idx_tmp_name;
354 int basename_len = name_buffer->len;
355
356 if (adjust_shared_perm(pack_tmp_name))
357 die_errno("unable to make temporary pack file readable");
358
359 idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
360 pack_idx_opts, sha1);
361 if (adjust_shared_perm(idx_tmp_name))
362 die_errno("unable to make temporary index file readable");
363
364 strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
365
366 if (rename(pack_tmp_name, name_buffer->buf))
367 die_errno("unable to rename temporary pack file");
368
369 strbuf_setlen(name_buffer, basename_len);
370
371 strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
372 if (rename(idx_tmp_name, name_buffer->buf))
373 die_errno("unable to rename temporary index file");
374
375 strbuf_setlen(name_buffer, basename_len);
376
377 free((void *)idx_tmp_name);
378 }