fsck-cache: fix SIGSEGV on bad tag object
[git/git.git] / sha1_file.c
1 /*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 *
6 * This handles basic git sha1 object files - packing, unpacking,
7 * creation etc.
8 */
9 #include <stdarg.h>
10 #include "cache.h"
11
12 const char *sha1_file_directory = NULL;
13
14 #ifndef O_NOATIME
15 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
16 #define O_NOATIME 01000000
17 #else
18 #define O_NOATIME 0
19 #endif
20 #endif
21
22 static unsigned int sha1_file_open_flag = O_NOATIME;
23
24 static unsigned hexval(char c)
25 {
26 if (c >= '0' && c <= '9')
27 return c - '0';
28 if (c >= 'a' && c <= 'f')
29 return c - 'a' + 10;
30 if (c >= 'A' && c <= 'F')
31 return c - 'A' + 10;
32 return ~0;
33 }
34
35 int get_sha1_hex(const char *hex, unsigned char *sha1)
36 {
37 int i;
38 for (i = 0; i < 20; i++) {
39 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
40 if (val & ~0xff)
41 return -1;
42 *sha1++ = val;
43 hex += 2;
44 }
45 return 0;
46 }
47
48 int get_sha1_file(const char *path, unsigned char *result)
49 {
50 char buffer[60];
51 int fd = open(path, O_RDONLY);
52 int len;
53
54 if (fd < 0)
55 return -1;
56 len = read(fd, buffer, sizeof(buffer));
57 close(fd);
58 if (len < 40)
59 return -1;
60 return get_sha1_hex(buffer, result);
61 }
62
63 int get_sha1(const char *str, unsigned char *sha1)
64 {
65 static char pathname[PATH_MAX];
66 static const char *prefix[] = {
67 "",
68 "refs",
69 "refs/tags",
70 "refs/heads",
71 "refs/snap",
72 NULL
73 };
74 const char *gitdir;
75 const char **p;
76
77 if (!get_sha1_hex(str, sha1))
78 return 0;
79
80 gitdir = ".git";
81 for (p = prefix; *p; p++) {
82 snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
83 if (!get_sha1_file(pathname, sha1))
84 return 0;
85 }
86
87 return -1;
88 }
89
90 char * sha1_to_hex(const unsigned char *sha1)
91 {
92 static char buffer[50];
93 static const char hex[] = "0123456789abcdef";
94 char *buf = buffer;
95 int i;
96
97 for (i = 0; i < 20; i++) {
98 unsigned int val = *sha1++;
99 *buf++ = hex[val >> 4];
100 *buf++ = hex[val & 0xf];
101 }
102 return buffer;
103 }
104
105 /*
106 * NOTE! This returns a statically allocated buffer, so you have to be
107 * careful about using it. Do a "strdup()" if you need to save the
108 * filename.
109 */
110 char *sha1_file_name(const unsigned char *sha1)
111 {
112 int i;
113 static char *name, *base;
114
115 if (!base) {
116 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
117 int len = strlen(sha1_file_directory);
118 base = xmalloc(len + 60);
119 memcpy(base, sha1_file_directory, len);
120 memset(base+len, 0, 60);
121 base[len] = '/';
122 base[len+3] = '/';
123 name = base + len + 1;
124 }
125 for (i = 0; i < 20; i++) {
126 static char hex[] = "0123456789abcdef";
127 unsigned int val = sha1[i];
128 char *pos = name + i*2 + (i > 0);
129 *pos++ = hex[val >> 4];
130 *pos = hex[val & 0xf];
131 }
132 return base;
133 }
134
135 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
136 {
137 char header[100];
138 unsigned char real_sha1[20];
139 SHA_CTX c;
140
141 SHA1_Init(&c);
142 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
143 SHA1_Update(&c, map, size);
144 SHA1_Final(real_sha1, &c);
145 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
146 }
147
148 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
149 {
150 char *filename = sha1_file_name(sha1);
151 struct stat st;
152 void *map;
153 int fd;
154
155 fd = open(filename, O_RDONLY | sha1_file_open_flag);
156 if (fd < 0) {
157 /* See if it works without O_NOATIME */
158 switch (sha1_file_open_flag) {
159 default:
160 fd = open(filename, O_RDONLY);
161 if (fd >= 0)
162 break;
163 /* Fallthrough */
164 case 0:
165 perror(filename);
166 return NULL;
167 }
168
169 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
170 sha1_file_open_flag = 0;
171 }
172 if (fstat(fd, &st) < 0) {
173 close(fd);
174 return NULL;
175 }
176 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
177 close(fd);
178 if (-1 == (int)(long)map)
179 return NULL;
180 *size = st.st_size;
181 return map;
182 }
183
184 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
185 {
186 int ret, bytes;
187 z_stream stream;
188 char buffer[8192];
189 char *buf;
190
191 /* Get the data stream */
192 memset(&stream, 0, sizeof(stream));
193 stream.next_in = map;
194 stream.avail_in = mapsize;
195 stream.next_out = buffer;
196 stream.avail_out = sizeof(buffer);
197
198 inflateInit(&stream);
199 ret = inflate(&stream, 0);
200 if (ret < Z_OK)
201 return NULL;
202 if (sscanf(buffer, "%10s %lu", type, size) != 2)
203 return NULL;
204
205 bytes = strlen(buffer) + 1;
206 buf = xmalloc(*size);
207
208 memcpy(buf, buffer + bytes, stream.total_out - bytes);
209 bytes = stream.total_out - bytes;
210 if (bytes < *size && ret == Z_OK) {
211 stream.next_out = buf + bytes;
212 stream.avail_out = *size - bytes;
213 while (inflate(&stream, Z_FINISH) == Z_OK)
214 /* nothing */;
215 }
216 inflateEnd(&stream);
217 return buf;
218 }
219
220 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
221 {
222 unsigned long mapsize;
223 void *map, *buf;
224
225 map = map_sha1_file(sha1, &mapsize);
226 if (map) {
227 buf = unpack_sha1_file(map, mapsize, type, size);
228 munmap(map, mapsize);
229 return buf;
230 }
231 return NULL;
232 }
233
234 void *read_object_with_reference(const unsigned char *sha1,
235 const unsigned char *required_type,
236 unsigned long *size,
237 unsigned char *actual_sha1_return)
238 {
239 char type[20];
240 void *buffer;
241 unsigned long isize;
242 unsigned char actual_sha1[20];
243
244 memcpy(actual_sha1, sha1, 20);
245 while (1) {
246 int ref_length = -1;
247 const char *ref_type = NULL;
248
249 buffer = read_sha1_file(actual_sha1, type, &isize);
250 if (!buffer)
251 return NULL;
252 if (!strcmp(type, required_type)) {
253 *size = isize;
254 if (actual_sha1_return)
255 memcpy(actual_sha1_return, actual_sha1, 20);
256 return buffer;
257 }
258 /* Handle references */
259 else if (!strcmp(type, "commit"))
260 ref_type = "tree ";
261 else if (!strcmp(type, "tag"))
262 ref_type = "object ";
263 else {
264 free(buffer);
265 return NULL;
266 }
267 ref_length = strlen(ref_type);
268
269 if (memcmp(buffer, ref_type, ref_length) ||
270 get_sha1_hex(buffer + ref_length, actual_sha1)) {
271 free(buffer);
272 return NULL;
273 }
274 /* Now we have the ID of the referred-to object in
275 * actual_sha1. Check again. */
276 }
277 }
278
279 int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
280 {
281 int size;
282 char *compressed;
283 z_stream stream;
284 unsigned char sha1[20];
285 SHA_CTX c;
286 char *filename;
287 char hdr[50];
288 int fd, hdrlen;
289
290 /* Generate the header */
291 hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
292
293 /* Sha1.. */
294 SHA1_Init(&c);
295 SHA1_Update(&c, hdr, hdrlen);
296 SHA1_Update(&c, buf, len);
297 SHA1_Final(sha1, &c);
298
299 if (returnsha1)
300 memcpy(returnsha1, sha1, 20);
301
302 filename = sha1_file_name(sha1);
303 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
304 if (fd < 0) {
305 if (errno != EEXIST)
306 return -1;
307
308 /*
309 * We might do collision checking here, but we'd need to
310 * uncompress the old file and check it. Later.
311 */
312 return 0;
313 }
314
315 /* Set it up */
316 memset(&stream, 0, sizeof(stream));
317 deflateInit(&stream, Z_BEST_COMPRESSION);
318 size = deflateBound(&stream, len+hdrlen);
319 compressed = xmalloc(size);
320
321 /* Compress it */
322 stream.next_out = compressed;
323 stream.avail_out = size;
324
325 /* First header.. */
326 stream.next_in = hdr;
327 stream.avail_in = hdrlen;
328 while (deflate(&stream, 0) == Z_OK)
329 /* nothing */
330
331 /* Then the data itself.. */
332 stream.next_in = buf;
333 stream.avail_in = len;
334 while (deflate(&stream, Z_FINISH) == Z_OK)
335 /* nothing */;
336 deflateEnd(&stream);
337 size = stream.total_out;
338
339 if (write(fd, compressed, size) != size)
340 die("unable to write file");
341 close(fd);
342
343 return 0;
344 }
345
346 static inline int collision_check(char *filename, void *buf, unsigned int size)
347 {
348 #ifdef COLLISION_CHECK
349 void *map;
350 int fd = open(filename, O_RDONLY);
351 struct stat st;
352 int cmp;
353
354 /* Unreadable object, or object went away? Strange. */
355 if (fd < 0)
356 return -1;
357
358 if (fstat(fd, &st) < 0 || size != st.st_size)
359 return -1;
360
361 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
362 close(fd);
363 if (map == MAP_FAILED)
364 return -1;
365 cmp = memcmp(buf, map, size);
366 munmap(map, size);
367 if (cmp)
368 return -1;
369 #endif
370 return 0;
371 }
372
373 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
374 {
375 char *filename = sha1_file_name(sha1);
376 int fd;
377
378 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
379 if (fd < 0) {
380 if (errno != EEXIST)
381 return -1;
382 if (collision_check(filename, buf, size))
383 return error("SHA1 collision detected!"
384 " This is bad, bad, BAD!\a\n");
385 return 0;
386 }
387 write(fd, buf, size);
388 close(fd);
389 return 0;
390 }
391
392 int write_sha1_from_fd(const unsigned char *sha1, int fd)
393 {
394 char *filename = sha1_file_name(sha1);
395
396 int local;
397 z_stream stream;
398 unsigned char real_sha1[20];
399 char buf[4096];
400 char discard[4096];
401 int ret;
402 SHA_CTX c;
403
404 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
405
406 if (local < 0)
407 return error("Couldn't open %s\n", filename);
408
409 memset(&stream, 0, sizeof(stream));
410
411 inflateInit(&stream);
412
413 SHA1_Init(&c);
414
415 do {
416 ssize_t size;
417 size = read(fd, buf, 4096);
418 if (size <= 0) {
419 close(local);
420 unlink(filename);
421 if (!size)
422 return error("Connection closed?");
423 perror("Reading from connection");
424 return -1;
425 }
426 write(local, buf, size);
427 stream.avail_in = size;
428 stream.next_in = buf;
429 do {
430 stream.next_out = discard;
431 stream.avail_out = sizeof(discard);
432 ret = inflate(&stream, Z_SYNC_FLUSH);
433 SHA1_Update(&c, discard, sizeof(discard) -
434 stream.avail_out);
435 } while (stream.avail_in && ret == Z_OK);
436
437 } while (ret == Z_OK);
438 inflateEnd(&stream);
439
440 close(local);
441 SHA1_Final(real_sha1, &c);
442 if (ret != Z_STREAM_END) {
443 unlink(filename);
444 return error("File %s corrupted", sha1_to_hex(sha1));
445 }
446 if (memcmp(sha1, real_sha1, 20)) {
447 unlink(filename);
448 return error("File %s has bad hash\n", sha1_to_hex(sha1));
449 }
450
451 return 0;
452 }
453
454 int has_sha1_file(const unsigned char *sha1)
455 {
456 char *filename = sha1_file_name(sha1);
457 struct stat st;
458
459 if (!stat(filename, &st))
460 return 1;
461 return 0;
462 }
463
464 int index_fd(unsigned char *sha1, int fd, struct stat *st)
465 {
466 z_stream stream;
467 unsigned long size = st->st_size;
468 int max_out_bytes = size + 200;
469 void *out = xmalloc(max_out_bytes);
470 void *metadata = xmalloc(200);
471 int metadata_size;
472 void *in;
473 SHA_CTX c;
474
475 in = "";
476 if (size)
477 in = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
478 close(fd);
479 if (!out || (int)(long)in == -1)
480 return -1;
481
482 metadata_size = 1+sprintf(metadata, "blob %lu", size);
483
484 SHA1_Init(&c);
485 SHA1_Update(&c, metadata, metadata_size);
486 SHA1_Update(&c, in, size);
487 SHA1_Final(sha1, &c);
488
489 memset(&stream, 0, sizeof(stream));
490 deflateInit(&stream, Z_BEST_COMPRESSION);
491
492 /*
493 * ASCII size + nul byte
494 */
495 stream.next_in = metadata;
496 stream.avail_in = metadata_size;
497 stream.next_out = out;
498 stream.avail_out = max_out_bytes;
499 while (deflate(&stream, 0) == Z_OK)
500 /* nothing */;
501
502 /*
503 * File content
504 */
505 stream.next_in = in;
506 stream.avail_in = size;
507 while (deflate(&stream, Z_FINISH) == Z_OK)
508 /*nothing */;
509
510 deflateEnd(&stream);
511
512 return write_sha1_buffer(sha1, out, stream.total_out);
513 }