Thread-safe xmalloc and xrealloc needs a recursive mutex
[git/dscho.git] / pack-write.c
blob9f47cf9961212242bc01082944e83fb54da2a515
1 #include "cache.h"
2 #include "pack.h"
3 #include "csum-file.h"
5 uint32_t pack_idx_default_version = 2;
6 uint32_t pack_idx_off32_limit = 0x7fffffff;
8 static int sha1_compare(const void *_a, const void *_b)
10         struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
11         struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
12         return hashcmp(a->sha1, b->sha1);
16  * On entry *sha1 contains the pack content SHA1 hash, on exit it is
17  * the SHA1 hash of sorted object names. The objects array passed in
18  * will be sorted by SHA1 on exit.
19  */
20 const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
21                            int nr_objects, unsigned char *sha1)
23         struct sha1file *f;
24         struct pack_idx_entry **sorted_by_sha, **list, **last;
25         off_t last_obj_offset = 0;
26         uint32_t array[256];
27         int i, fd;
28         git_SHA_CTX ctx;
29         uint32_t index_version;
31         if (nr_objects) {
32                 sorted_by_sha = objects;
33                 list = sorted_by_sha;
34                 last = sorted_by_sha + nr_objects;
35                 for (i = 0; i < nr_objects; ++i) {
36                         if (objects[i]->offset > last_obj_offset)
37                                 last_obj_offset = objects[i]->offset;
38                 }
39                 qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
40                       sha1_compare);
41         }
42         else
43                 sorted_by_sha = list = last = NULL;
45         if (!index_name) {
46                 static char tmpfile[PATH_MAX];
47                 fd = odb_mkstemp(tmpfile, sizeof(tmpfile), "pack/tmp_idx_XXXXXX");
48                 index_name = xstrdup(tmpfile);
49         } else {
50                 unlink(index_name);
51                 fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
52         }
53         if (fd < 0)
54                 die_errno("unable to create '%s'", index_name);
55         f = sha1fd(fd, index_name);
57         /* if last object's offset is >= 2^31 we should use index V2 */
58         index_version = (last_obj_offset >> 31) ? 2 : pack_idx_default_version;
60         /* index versions 2 and above need a header */
61         if (index_version >= 2) {
62                 struct pack_idx_header hdr;
63                 hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
64                 hdr.idx_version = htonl(index_version);
65                 sha1write(f, &hdr, sizeof(hdr));
66         }
68         /*
69          * Write the first-level table (the list is sorted,
70          * but we use a 256-entry lookup to be able to avoid
71          * having to do eight extra binary search iterations).
72          */
73         for (i = 0; i < 256; i++) {
74                 struct pack_idx_entry **next = list;
75                 while (next < last) {
76                         struct pack_idx_entry *obj = *next;
77                         if (obj->sha1[0] != i)
78                                 break;
79                         next++;
80                 }
81                 array[i] = htonl(next - sorted_by_sha);
82                 list = next;
83         }
84         sha1write(f, array, 256 * 4);
86         /* compute the SHA1 hash of sorted object names. */
87         git_SHA1_Init(&ctx);
89         /*
90          * Write the actual SHA1 entries..
91          */
92         list = sorted_by_sha;
93         for (i = 0; i < nr_objects; i++) {
94                 struct pack_idx_entry *obj = *list++;
95                 if (index_version < 2) {
96                         uint32_t offset = htonl(obj->offset);
97                         sha1write(f, &offset, 4);
98                 }
99                 sha1write(f, obj->sha1, 20);
100                 git_SHA1_Update(&ctx, obj->sha1, 20);
101         }
103         if (index_version >= 2) {
104                 unsigned int nr_large_offset = 0;
106                 /* write the crc32 table */
107                 list = sorted_by_sha;
108                 for (i = 0; i < nr_objects; i++) {
109                         struct pack_idx_entry *obj = *list++;
110                         uint32_t crc32_val = htonl(obj->crc32);
111                         sha1write(f, &crc32_val, 4);
112                 }
114                 /* write the 32-bit offset table */
115                 list = sorted_by_sha;
116                 for (i = 0; i < nr_objects; i++) {
117                         struct pack_idx_entry *obj = *list++;
118                         uint32_t offset = (obj->offset <= pack_idx_off32_limit) ?
119                                 obj->offset : (0x80000000 | nr_large_offset++);
120                         offset = htonl(offset);
121                         sha1write(f, &offset, 4);
122                 }
124                 /* write the large offset table */
125                 list = sorted_by_sha;
126                 while (nr_large_offset) {
127                         struct pack_idx_entry *obj = *list++;
128                         uint64_t offset = obj->offset;
129                         if (offset > pack_idx_off32_limit) {
130                                 uint32_t split[2];
131                                 split[0] = htonl(offset >> 32);
132                                 split[1] = htonl(offset & 0xffffffff);
133                                 sha1write(f, split, 8);
134                                 nr_large_offset--;
135                         }
136                 }
137         }
139         sha1write(f, sha1, 20);
140         sha1close(f, NULL, CSUM_FSYNC);
141         git_SHA1_Final(sha1, &ctx);
142         return index_name;
146  * Update pack header with object_count and compute new SHA1 for pack data
147  * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
148  * is also returned in new_pack_sha1.
150  * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
151  * (without the header update) is computed and validated against the
152  * one provided in partial_pack_sha1.  The validation is performed at
153  * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
154  * data (i.e. from partial_pack_offset to the end) is then computed and
155  * returned in partial_pack_sha1.
157  * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
158  * partial_pack_sha1 can refer to the same buffer if the caller is not
159  * interested in the resulting SHA1 of pack data above partial_pack_offset.
160  */
161 void fixup_pack_header_footer(int pack_fd,
162                          unsigned char *new_pack_sha1,
163                          const char *pack_name,
164                          uint32_t object_count,
165                          unsigned char *partial_pack_sha1,
166                          off_t partial_pack_offset)
168         int aligned_sz, buf_sz = 8 * 1024;
169         git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
170         struct pack_header hdr;
171         char *buf;
173         git_SHA1_Init(&old_sha1_ctx);
174         git_SHA1_Init(&new_sha1_ctx);
176         if (lseek(pack_fd, 0, SEEK_SET) != 0)
177                 die_errno("Failed seeking to start of '%s'", pack_name);
178         if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
179                 die_errno("Unable to reread header of '%s'", pack_name);
180         if (lseek(pack_fd, 0, SEEK_SET) != 0)
181                 die_errno("Failed seeking to start of '%s'", pack_name);
182         git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
183         hdr.hdr_entries = htonl(object_count);
184         git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
185         write_or_die(pack_fd, &hdr, sizeof(hdr));
186         partial_pack_offset -= sizeof(hdr);
188         buf = xmalloc(buf_sz);
189         aligned_sz = buf_sz - sizeof(hdr);
190         for (;;) {
191                 ssize_t m, n;
192                 m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
193                         partial_pack_offset : aligned_sz;
194                 n = xread(pack_fd, buf, m);
195                 if (!n)
196                         break;
197                 if (n < 0)
198                         die_errno("Failed to checksum '%s'", pack_name);
199                 git_SHA1_Update(&new_sha1_ctx, buf, n);
201                 aligned_sz -= n;
202                 if (!aligned_sz)
203                         aligned_sz = buf_sz;
205                 if (!partial_pack_sha1)
206                         continue;
208                 git_SHA1_Update(&old_sha1_ctx, buf, n);
209                 partial_pack_offset -= n;
210                 if (partial_pack_offset == 0) {
211                         unsigned char sha1[20];
212                         git_SHA1_Final(sha1, &old_sha1_ctx);
213                         if (hashcmp(sha1, partial_pack_sha1) != 0)
214                                 die("Unexpected checksum for %s "
215                                     "(disk corruption?)", pack_name);
216                         /*
217                          * Now let's compute the SHA1 of the remainder of the
218                          * pack, which also means making partial_pack_offset
219                          * big enough not to matter anymore.
220                          */
221                         git_SHA1_Init(&old_sha1_ctx);
222                         partial_pack_offset = ~partial_pack_offset;
223                         partial_pack_offset -= MSB(partial_pack_offset, 1);
224                 }
225         }
226         free(buf);
228         if (partial_pack_sha1)
229                 git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
230         git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
231         write_or_die(pack_fd, new_pack_sha1, 20);
232         fsync_or_die(pack_fd, pack_name);
235 char *index_pack_lockfile(int ip_out)
237         char packname[46];
239         /*
240          * The first thing we expect from index-pack's output
241          * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
242          * %40s is the newly created pack SHA1 name.  In the "keep"
243          * case, we need it to remove the corresponding .keep file
244          * later on.  If we don't get that then tough luck with it.
245          */
246         if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
247             memcmp(packname, "keep\t", 5) == 0) {
248                 char path[PATH_MAX];
249                 packname[45] = 0;
250                 snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
251                          get_object_directory(), packname + 5);
252                 return xstrdup(path);
253         }
254         return NULL;