Merge branch 'maint'
[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 hashcmp(a->sha1, b->sha1);
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 sha1file *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, sizeof(sorted_by_sha[0]),
65                       sha1_compare);
66         }
67         else
68                 sorted_by_sha = list = last = NULL;
69
70         if (opts->flags & WRITE_IDX_VERIFY) {
71                 assert(index_name);
72                 f = sha1fd_check(index_name);
73         } else {
74                 if (!index_name) {
75                         static char tmp_file[PATH_MAX];
76                         fd = odb_mkstemp(tmp_file, sizeof(tmp_file), "pack/tmp_idx_XXXXXX");
77                         index_name = xstrdup(tmp_file);
78                 } else {
79                         unlink(index_name);
80                         fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
81                 }
82                 if (fd < 0)
83                         die_errno("unable to create '%s'", index_name);
84                 f = sha1fd(fd, index_name);
85         }
86
87         /* if last object's offset is >= 2^31 we should use index V2 */
88         index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->version;
89
90         /* index versions 2 and above need a header */
91         if (index_version >= 2) {
92                 struct pack_idx_header hdr;
93                 hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
94                 hdr.idx_version = htonl(index_version);
95                 sha1write(f, &hdr, sizeof(hdr));
96         }
97
98         /*
99          * Write the first-level table (the list is sorted,
100          * but we use a 256-entry lookup to be able to avoid
101          * having to do eight extra binary search iterations).
102          */
103         for (i = 0; i < 256; i++) {
104                 struct pack_idx_entry **next = list;
105                 while (next < last) {
106                         struct pack_idx_entry *obj = *next;
107                         if (obj->sha1[0] != i)
108                                 break;
109                         next++;
110                 }
111                 array[i] = htonl(next - sorted_by_sha);
112                 list = next;
113         }
114         sha1write(f, array, 256 * 4);
115
116         /*
117          * Write the actual SHA1 entries..
118          */
119         list = sorted_by_sha;
120         for (i = 0; i < nr_objects; i++) {
121                 struct pack_idx_entry *obj = *list++;
122                 if (index_version < 2) {
123                         uint32_t offset = htonl(obj->offset);
124                         sha1write(f, &offset, 4);
125                 }
126                 sha1write(f, obj->sha1, 20);
127                 if ((opts->flags & WRITE_IDX_STRICT) &&
128                     (i && !hashcmp(list[-2]->sha1, obj->sha1)))
129                         die("The same object %s appears twice in the pack",
130                             sha1_to_hex(obj->sha1));
131         }
132
133         if (index_version >= 2) {
134                 unsigned int nr_large_offset = 0;
135
136                 /* write the crc32 table */
137                 list = sorted_by_sha;
138                 for (i = 0; i < nr_objects; i++) {
139                         struct pack_idx_entry *obj = *list++;
140                         uint32_t crc32_val = htonl(obj->crc32);
141                         sha1write(f, &crc32_val, 4);
142                 }
143
144                 /* write the 32-bit offset table */
145                 list = sorted_by_sha;
146                 for (i = 0; i < nr_objects; i++) {
147                         struct pack_idx_entry *obj = *list++;
148                         uint32_t offset;
149
150                         offset = (need_large_offset(obj->offset, opts)
151                                   ? (0x80000000 | nr_large_offset++)
152                                   : obj->offset);
153                         offset = htonl(offset);
154                         sha1write(f, &offset, 4);
155                 }
156
157                 /* write the large offset table */
158                 list = sorted_by_sha;
159                 while (nr_large_offset) {
160                         struct pack_idx_entry *obj = *list++;
161                         uint64_t offset = obj->offset;
162                         uint32_t split[2];
163
164                         if (!need_large_offset(offset, opts))
165                                 continue;
166                         split[0] = htonl(offset >> 32);
167                         split[1] = htonl(offset & 0xffffffff);
168                         sha1write(f, split, 8);
169                         nr_large_offset--;
170                 }
171         }
172
173         sha1write(f, sha1, 20);
174         sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
175                             ? CSUM_CLOSE : CSUM_FSYNC));
176         return index_name;
177 }
178
179 off_t write_pack_header(struct sha1file *f, uint32_t nr_entries)
180 {
181         struct pack_header hdr;
182
183         hdr.hdr_signature = htonl(PACK_SIGNATURE);
184         hdr.hdr_version = htonl(PACK_VERSION);
185         hdr.hdr_entries = htonl(nr_entries);
186         if (sha1write(f, &hdr, sizeof(hdr)))
187                 return 0;
188         return sizeof(hdr);
189 }
190
191 /*
192  * Update pack header with object_count and compute new SHA1 for pack data
193  * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
194  * is also returned in new_pack_sha1.
195  *
196  * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
197  * (without the header update) is computed and validated against the
198  * one provided in partial_pack_sha1.  The validation is performed at
199  * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
200  * data (i.e. from partial_pack_offset to the end) is then computed and
201  * returned in partial_pack_sha1.
202  *
203  * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
204  * partial_pack_sha1 can refer to the same buffer if the caller is not
205  * interested in the resulting SHA1 of pack data above partial_pack_offset.
206  */
207 void fixup_pack_header_footer(int pack_fd,
208                          unsigned char *new_pack_sha1,
209                          const char *pack_name,
210                          uint32_t object_count,
211                          unsigned char *partial_pack_sha1,
212                          off_t partial_pack_offset)
213 {
214         int aligned_sz, buf_sz = 8 * 1024;
215         git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
216         struct pack_header hdr;
217         char *buf;
218
219         git_SHA1_Init(&old_sha1_ctx);
220         git_SHA1_Init(&new_sha1_ctx);
221
222         if (lseek(pack_fd, 0, SEEK_SET) != 0)
223                 die_errno("Failed seeking to start of '%s'", pack_name);
224         if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
225                 die_errno("Unable to reread header of '%s'", pack_name);
226         if (lseek(pack_fd, 0, SEEK_SET) != 0)
227                 die_errno("Failed seeking to start of '%s'", pack_name);
228         git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
229         hdr.hdr_entries = htonl(object_count);
230         git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
231         write_or_die(pack_fd, &hdr, sizeof(hdr));
232         partial_pack_offset -= sizeof(hdr);
233
234         buf = xmalloc(buf_sz);
235         aligned_sz = buf_sz - sizeof(hdr);
236         for (;;) {
237                 ssize_t m, n;
238                 m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
239                         partial_pack_offset : aligned_sz;
240                 n = xread(pack_fd, buf, m);
241                 if (!n)
242                         break;
243                 if (n < 0)
244                         die_errno("Failed to checksum '%s'", pack_name);
245                 git_SHA1_Update(&new_sha1_ctx, buf, n);
246
247                 aligned_sz -= n;
248                 if (!aligned_sz)
249                         aligned_sz = buf_sz;
250
251                 if (!partial_pack_sha1)
252                         continue;
253
254                 git_SHA1_Update(&old_sha1_ctx, buf, n);
255                 partial_pack_offset -= n;
256                 if (partial_pack_offset == 0) {
257                         unsigned char sha1[20];
258                         git_SHA1_Final(sha1, &old_sha1_ctx);
259                         if (hashcmp(sha1, partial_pack_sha1) != 0)
260                                 die("Unexpected checksum for %s "
261                                     "(disk corruption?)", pack_name);
262                         /*
263                          * Now let's compute the SHA1 of the remainder of the
264                          * pack, which also means making partial_pack_offset
265                          * big enough not to matter anymore.
266                          */
267                         git_SHA1_Init(&old_sha1_ctx);
268                         partial_pack_offset = ~partial_pack_offset;
269                         partial_pack_offset -= MSB(partial_pack_offset, 1);
270                 }
271         }
272         free(buf);
273
274         if (partial_pack_sha1)
275                 git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
276         git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
277         write_or_die(pack_fd, new_pack_sha1, 20);
278         fsync_or_die(pack_fd, pack_name);
279 }
280
281 char *index_pack_lockfile(int ip_out)
282 {
283         char packname[46];
284
285         /*
286          * The first thing we expect from index-pack's output
287          * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
288          * %40s is the newly created pack SHA1 name.  In the "keep"
289          * case, we need it to remove the corresponding .keep file
290          * later on.  If we don't get that then tough luck with it.
291          */
292         if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
293             memcmp(packname, "keep\t", 5) == 0) {
294                 char path[PATH_MAX];
295                 packname[45] = 0;
296                 snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
297                          get_object_directory(), packname + 5);
298                 return xstrdup(path);
299         }
300         return NULL;
301 }
302
303 /*
304  * The per-object header is a pretty dense thing, which is
305  *  - first byte: low four bits are "size", then three bits of "type",
306  *    and the high bit is "size continues".
307  *  - each byte afterwards: low seven bits are size continuation,
308  *    with the high bit being "size continues"
309  */
310 int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
311 {
312         int n = 1;
313         unsigned char c;
314
315         if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
316                 die("bad type %d", type);
317
318         c = (type << 4) | (size & 15);
319         size >>= 4;
320         while (size) {
321                 *hdr++ = c | 0x80;
322                 c = size & 0x7f;
323                 size >>= 7;
324                 n++;
325         }
326         *hdr = c;
327         return n;
328 }
329
330 struct sha1file *create_tmp_packfile(char **pack_tmp_name)
331 {
332         char tmpname[PATH_MAX];
333         int fd;
334
335         fd = odb_mkstemp(tmpname, sizeof(tmpname), "pack/tmp_pack_XXXXXX");
336         *pack_tmp_name = xstrdup(tmpname);
337         return sha1fd(fd, *pack_tmp_name);
338 }
339
340 void finish_tmp_packfile(char *name_buffer,
341                          const char *pack_tmp_name,
342                          struct pack_idx_entry **written_list,
343                          uint32_t nr_written,
344                          struct pack_idx_option *pack_idx_opts,
345                          unsigned char sha1[])
346 {
347         const char *idx_tmp_name;
348         char *end_of_name_prefix = strrchr(name_buffer, 0);
349
350         if (adjust_shared_perm(pack_tmp_name))
351                 die_errno("unable to make temporary pack file readable");
352
353         idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
354                                       pack_idx_opts, sha1);
355         if (adjust_shared_perm(idx_tmp_name))
356                 die_errno("unable to make temporary index file readable");
357
358         sprintf(end_of_name_prefix, "%s.pack", sha1_to_hex(sha1));
359         free_pack_by_name(name_buffer);
360
361         if (rename(pack_tmp_name, name_buffer))
362                 die_errno("unable to rename temporary pack file");
363
364         sprintf(end_of_name_prefix, "%s.idx", sha1_to_hex(sha1));
365         if (rename(idx_tmp_name, name_buffer))
366                 die_errno("unable to rename temporary index file");
367
368         free((void *)idx_tmp_name);
369 }