Merge branch 'jk/pack-bitmap'
[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         sha1write(f, &hdr, sizeof(hdr));
187         return sizeof(hdr);
188 }
189
190 /*
191  * Update pack header with object_count and compute new SHA1 for pack data
192  * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
193  * is also returned in new_pack_sha1.
194  *
195  * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
196  * (without the header update) is computed and validated against the
197  * one provided in partial_pack_sha1.  The validation is performed at
198  * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
199  * data (i.e. from partial_pack_offset to the end) is then computed and
200  * returned in partial_pack_sha1.
201  *
202  * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
203  * partial_pack_sha1 can refer to the same buffer if the caller is not
204  * interested in the resulting SHA1 of pack data above partial_pack_offset.
205  */
206 void fixup_pack_header_footer(int pack_fd,
207                          unsigned char *new_pack_sha1,
208                          const char *pack_name,
209                          uint32_t object_count,
210                          unsigned char *partial_pack_sha1,
211                          off_t partial_pack_offset)
212 {
213         int aligned_sz, buf_sz = 8 * 1024;
214         git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
215         struct pack_header hdr;
216         char *buf;
217
218         git_SHA1_Init(&old_sha1_ctx);
219         git_SHA1_Init(&new_sha1_ctx);
220
221         if (lseek(pack_fd, 0, SEEK_SET) != 0)
222                 die_errno("Failed seeking to start of '%s'", pack_name);
223         if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
224                 die_errno("Unable to reread header of '%s'", pack_name);
225         if (lseek(pack_fd, 0, SEEK_SET) != 0)
226                 die_errno("Failed seeking to start of '%s'", pack_name);
227         git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
228         hdr.hdr_entries = htonl(object_count);
229         git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
230         write_or_die(pack_fd, &hdr, sizeof(hdr));
231         partial_pack_offset -= sizeof(hdr);
232
233         buf = xmalloc(buf_sz);
234         aligned_sz = buf_sz - sizeof(hdr);
235         for (;;) {
236                 ssize_t m, n;
237                 m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
238                         partial_pack_offset : aligned_sz;
239                 n = xread(pack_fd, buf, m);
240                 if (!n)
241                         break;
242                 if (n < 0)
243                         die_errno("Failed to checksum '%s'", pack_name);
244                 git_SHA1_Update(&new_sha1_ctx, buf, n);
245
246                 aligned_sz -= n;
247                 if (!aligned_sz)
248                         aligned_sz = buf_sz;
249
250                 if (!partial_pack_sha1)
251                         continue;
252
253                 git_SHA1_Update(&old_sha1_ctx, buf, n);
254                 partial_pack_offset -= n;
255                 if (partial_pack_offset == 0) {
256                         unsigned char sha1[20];
257                         git_SHA1_Final(sha1, &old_sha1_ctx);
258                         if (hashcmp(sha1, partial_pack_sha1) != 0)
259                                 die("Unexpected checksum for %s "
260                                     "(disk corruption?)", pack_name);
261                         /*
262                          * Now let's compute the SHA1 of the remainder of the
263                          * pack, which also means making partial_pack_offset
264                          * big enough not to matter anymore.
265                          */
266                         git_SHA1_Init(&old_sha1_ctx);
267                         partial_pack_offset = ~partial_pack_offset;
268                         partial_pack_offset -= MSB(partial_pack_offset, 1);
269                 }
270         }
271         free(buf);
272
273         if (partial_pack_sha1)
274                 git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
275         git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
276         write_or_die(pack_fd, new_pack_sha1, 20);
277         fsync_or_die(pack_fd, pack_name);
278 }
279
280 char *index_pack_lockfile(int ip_out)
281 {
282         char packname[46];
283
284         /*
285          * The first thing we expect from index-pack's output
286          * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
287          * %40s is the newly created pack SHA1 name.  In the "keep"
288          * case, we need it to remove the corresponding .keep file
289          * later on.  If we don't get that then tough luck with it.
290          */
291         if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
292             memcmp(packname, "keep\t", 5) == 0) {
293                 char path[PATH_MAX];
294                 packname[45] = 0;
295                 snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
296                          get_object_directory(), packname + 5);
297                 return xstrdup(path);
298         }
299         return NULL;
300 }
301
302 /*
303  * The per-object header is a pretty dense thing, which is
304  *  - first byte: low four bits are "size", then three bits of "type",
305  *    and the high bit is "size continues".
306  *  - each byte afterwards: low seven bits are size continuation,
307  *    with the high bit being "size continues"
308  */
309 int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
310 {
311         int n = 1;
312         unsigned char c;
313
314         if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
315                 die("bad type %d", type);
316
317         c = (type << 4) | (size & 15);
318         size >>= 4;
319         while (size) {
320                 *hdr++ = c | 0x80;
321                 c = size & 0x7f;
322                 size >>= 7;
323                 n++;
324         }
325         *hdr = c;
326         return n;
327 }
328
329 struct sha1file *create_tmp_packfile(char **pack_tmp_name)
330 {
331         char tmpname[PATH_MAX];
332         int fd;
333
334         fd = odb_mkstemp(tmpname, sizeof(tmpname), "pack/tmp_pack_XXXXXX");
335         *pack_tmp_name = xstrdup(tmpname);
336         return sha1fd(fd, *pack_tmp_name);
337 }
338
339 void finish_tmp_packfile(char *name_buffer,
340                          const char *pack_tmp_name,
341                          struct pack_idx_entry **written_list,
342                          uint32_t nr_written,
343                          struct pack_idx_option *pack_idx_opts,
344                          unsigned char sha1[])
345 {
346         const char *idx_tmp_name;
347         char *end_of_name_prefix = strrchr(name_buffer, 0);
348
349         if (adjust_shared_perm(pack_tmp_name))
350                 die_errno("unable to make temporary pack file readable");
351
352         idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
353                                       pack_idx_opts, sha1);
354         if (adjust_shared_perm(idx_tmp_name))
355                 die_errno("unable to make temporary index file readable");
356
357         sprintf(end_of_name_prefix, "%s.pack", sha1_to_hex(sha1));
358         free_pack_by_name(name_buffer);
359
360         if (rename(pack_tmp_name, name_buffer))
361                 die_errno("unable to rename temporary pack file");
362
363         sprintf(end_of_name_prefix, "%s.idx", sha1_to_hex(sha1));
364         if (rename(idx_tmp_name, name_buffer))
365                 die_errno("unable to rename temporary index file");
366
367         *end_of_name_prefix = '\0';
368
369         free((void *)idx_tmp_name);
370 }