1#include "cache.h"
2#include "pack.h"
3#include "csum-file.h"
4void 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}
11static 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}
18static 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 return (a < b) ? -1 : (a != b);
25}
26static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
28{
29 uint32_t ofsval;
30 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/*
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 */
45const 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 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 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 /* 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 /* 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 /*
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 /*
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 if (index_version >= 2) {
134 unsigned int nr_large_offset = 0;
135 /* 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 /* 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 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 /* 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 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 sha1write(f, sha1, 20);
174 sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
175 ? CSUM_CLOSE : CSUM_FSYNC));
176 return index_name;
177}
178off_t write_pack_header(struct sha1file *f, uint32_t nr_entries)
180{
181 struct pack_header hdr;
182 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/*
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 */
206void 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 git_SHA1_Init(&old_sha1_ctx);
219 git_SHA1_Init(&new_sha1_ctx);
220 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 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 aligned_sz -= n;
247 if (!aligned_sz)
248 aligned_sz = buf_sz;
249 if (!partial_pack_sha1)
251 continue;
252 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 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}
279char *index_pack_lockfile(int ip_out)
281{
282 char packname[46];
283 /*
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 const char *name;
293 packname[45] = 0;
294 if (skip_prefix(packname, "keep\t", &name))
295 return xstrfmt("%s/pack/pack-%s.keep",
296 get_object_directory(), name);
297 }
298 return NULL;
299}
300/*
302 * The per-object header is a pretty dense thing, which is
303 * - first byte: low four bits are "size", then three bits of "type",
304 * and the high bit is "size continues".
305 * - each byte afterwards: low seven bits are size continuation,
306 * with the high bit being "size continues"
307 */
308int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
309{
310 int n = 1;
311 unsigned char c;
312 if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
314 die("bad type %d", type);
315 c = (type << 4) | (size & 15);
317 size >>= 4;
318 while (size) {
319 *hdr++ = c | 0x80;
320 c = size & 0x7f;
321 size >>= 7;
322 n++;
323 }
324 *hdr = c;
325 return n;
326}
327struct sha1file *create_tmp_packfile(char **pack_tmp_name)
329{
330 char tmpname[PATH_MAX];
331 int fd;
332 fd = odb_mkstemp(tmpname, sizeof(tmpname), "pack/tmp_pack_XXXXXX");
334 *pack_tmp_name = xstrdup(tmpname);
335 return sha1fd(fd, *pack_tmp_name);
336}
337void finish_tmp_packfile(struct strbuf *name_buffer,
339 const char *pack_tmp_name,
340 struct pack_idx_entry **written_list,
341 uint32_t nr_written,
342 struct pack_idx_option *pack_idx_opts,
343 unsigned char sha1[])
344{
345 const char *idx_tmp_name;
346 int basename_len = name_buffer->len;
347 if (adjust_shared_perm(pack_tmp_name))
349 die_errno("unable to make temporary pack file readable");
350 idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
352 pack_idx_opts, sha1);
353 if (adjust_shared_perm(idx_tmp_name))
354 die_errno("unable to make temporary index file readable");
355 strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
357 if (rename(pack_tmp_name, name_buffer->buf))
359 die_errno("unable to rename temporary pack file");
360 strbuf_setlen(name_buffer, basename_len);
362 strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
364 if (rename(idx_tmp_name, name_buffer->buf))
365 die_errno("unable to rename temporary index file");
366 strbuf_setlen(name_buffer, basename_len);
368 free((void *)idx_tmp_name);
370}