d91e072f3e5480de3605fb3f1e581a938301bdfb
[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
67 if (!get_sha1_hex(str, sha1))
68 return 0;
69 if (!get_sha1_file(str, sha1))
70 return 0;
71 snprintf(pathname, sizeof(pathname), ".git/%s", str);
72 if (!get_sha1_file(pathname, sha1))
73 return 0;
74 return -1;
75 }
76
77 char * sha1_to_hex(const unsigned char *sha1)
78 {
79 static char buffer[50];
80 static const char hex[] = "0123456789abcdef";
81 char *buf = buffer;
82 int i;
83
84 for (i = 0; i < 20; i++) {
85 unsigned int val = *sha1++;
86 *buf++ = hex[val >> 4];
87 *buf++ = hex[val & 0xf];
88 }
89 return buffer;
90 }
91
92 /*
93 * NOTE! This returns a statically allocated buffer, so you have to be
94 * careful about using it. Do a "strdup()" if you need to save the
95 * filename.
96 */
97 char *sha1_file_name(const unsigned char *sha1)
98 {
99 int i;
100 static char *name, *base;
101
102 if (!base) {
103 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
104 int len = strlen(sha1_file_directory);
105 base = xmalloc(len + 60);
106 memcpy(base, sha1_file_directory, len);
107 memset(base+len, 0, 60);
108 base[len] = '/';
109 base[len+3] = '/';
110 name = base + len + 1;
111 }
112 for (i = 0; i < 20; i++) {
113 static char hex[] = "0123456789abcdef";
114 unsigned int val = sha1[i];
115 char *pos = name + i*2 + (i > 0);
116 *pos++ = hex[val >> 4];
117 *pos = hex[val & 0xf];
118 }
119 return base;
120 }
121
122 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
123 {
124 char header[100];
125 unsigned char real_sha1[20];
126 SHA_CTX c;
127
128 SHA1_Init(&c);
129 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
130 SHA1_Update(&c, map, size);
131 SHA1_Final(real_sha1, &c);
132 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
133 }
134
135 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
136 {
137 char *filename = sha1_file_name(sha1);
138 struct stat st;
139 void *map;
140 int fd;
141
142 fd = open(filename, O_RDONLY | sha1_file_open_flag);
143 if (fd < 0) {
144 /* See if it works without O_NOATIME */
145 switch (sha1_file_open_flag) {
146 default:
147 fd = open(filename, O_RDONLY);
148 if (fd >= 0)
149 break;
150 /* Fallthrough */
151 case 0:
152 perror(filename);
153 return NULL;
154 }
155
156 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
157 sha1_file_open_flag = 0;
158 }
159 if (fstat(fd, &st) < 0) {
160 close(fd);
161 return NULL;
162 }
163 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
164 close(fd);
165 if (-1 == (int)(long)map)
166 return NULL;
167 *size = st.st_size;
168 return map;
169 }
170
171 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
172 {
173 int ret, bytes;
174 z_stream stream;
175 char buffer[8192];
176 char *buf;
177
178 /* Get the data stream */
179 memset(&stream, 0, sizeof(stream));
180 stream.next_in = map;
181 stream.avail_in = mapsize;
182 stream.next_out = buffer;
183 stream.avail_out = sizeof(buffer);
184
185 inflateInit(&stream);
186 ret = inflate(&stream, 0);
187 if (ret < Z_OK)
188 return NULL;
189 if (sscanf(buffer, "%10s %lu", type, size) != 2)
190 return NULL;
191
192 bytes = strlen(buffer) + 1;
193 buf = xmalloc(*size);
194
195 memcpy(buf, buffer + bytes, stream.total_out - bytes);
196 bytes = stream.total_out - bytes;
197 if (bytes < *size && ret == Z_OK) {
198 stream.next_out = buf + bytes;
199 stream.avail_out = *size - bytes;
200 while (inflate(&stream, Z_FINISH) == Z_OK)
201 /* nothing */;
202 }
203 inflateEnd(&stream);
204 return buf;
205 }
206
207 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
208 {
209 unsigned long mapsize;
210 void *map, *buf;
211
212 map = map_sha1_file(sha1, &mapsize);
213 if (map) {
214 buf = unpack_sha1_file(map, mapsize, type, size);
215 munmap(map, mapsize);
216 return buf;
217 }
218 return NULL;
219 }
220
221 void *read_object_with_reference(const unsigned char *sha1,
222 const unsigned char *required_type,
223 unsigned long *size,
224 unsigned char *actual_sha1_return)
225 {
226 char type[20];
227 void *buffer;
228 unsigned long isize;
229 unsigned char actual_sha1[20];
230
231 memcpy(actual_sha1, sha1, 20);
232 while (1) {
233 int ref_length = -1;
234 const char *ref_type = NULL;
235
236 buffer = read_sha1_file(actual_sha1, type, &isize);
237 if (!buffer)
238 return NULL;
239 if (!strcmp(type, required_type)) {
240 *size = isize;
241 if (actual_sha1_return)
242 memcpy(actual_sha1_return, actual_sha1, 20);
243 return buffer;
244 }
245 /* Handle references */
246 else if (!strcmp(type, "commit"))
247 ref_type = "tree ";
248 else if (!strcmp(type, "tag"))
249 ref_type = "object ";
250 else {
251 free(buffer);
252 return NULL;
253 }
254 ref_length = strlen(ref_type);
255
256 if (memcmp(buffer, ref_type, ref_length) ||
257 get_sha1_hex(buffer + ref_length, actual_sha1)) {
258 free(buffer);
259 return NULL;
260 }
261 /* Now we have the ID of the referred-to object in
262 * actual_sha1. Check again. */
263 }
264 }
265
266 int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
267 {
268 int size;
269 char *compressed;
270 z_stream stream;
271 unsigned char sha1[20];
272 SHA_CTX c;
273 char *filename;
274 char hdr[50];
275 int fd, hdrlen;
276
277 /* Generate the header */
278 hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
279
280 /* Sha1.. */
281 SHA1_Init(&c);
282 SHA1_Update(&c, hdr, hdrlen);
283 SHA1_Update(&c, buf, len);
284 SHA1_Final(sha1, &c);
285
286 if (returnsha1)
287 memcpy(returnsha1, sha1, 20);
288
289 filename = sha1_file_name(sha1);
290 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
291 if (fd < 0) {
292 if (errno != EEXIST)
293 return -1;
294
295 /*
296 * We might do collision checking here, but we'd need to
297 * uncompress the old file and check it. Later.
298 */
299 return 0;
300 }
301
302 /* Set it up */
303 memset(&stream, 0, sizeof(stream));
304 deflateInit(&stream, Z_BEST_COMPRESSION);
305 size = deflateBound(&stream, len+hdrlen);
306 compressed = xmalloc(size);
307
308 /* Compress it */
309 stream.next_out = compressed;
310 stream.avail_out = size;
311
312 /* First header.. */
313 stream.next_in = hdr;
314 stream.avail_in = hdrlen;
315 while (deflate(&stream, 0) == Z_OK)
316 /* nothing */
317
318 /* Then the data itself.. */
319 stream.next_in = buf;
320 stream.avail_in = len;
321 while (deflate(&stream, Z_FINISH) == Z_OK)
322 /* nothing */;
323 deflateEnd(&stream);
324 size = stream.total_out;
325
326 if (write(fd, compressed, size) != size)
327 die("unable to write file");
328 close(fd);
329
330 return 0;
331 }
332
333 static inline int collision_check(char *filename, void *buf, unsigned int size)
334 {
335 #ifdef COLLISION_CHECK
336 void *map;
337 int fd = open(filename, O_RDONLY);
338 struct stat st;
339 int cmp;
340
341 /* Unreadable object, or object went away? Strange. */
342 if (fd < 0)
343 return -1;
344
345 if (fstat(fd, &st) < 0 || size != st.st_size)
346 return -1;
347
348 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
349 close(fd);
350 if (map == MAP_FAILED)
351 return -1;
352 cmp = memcmp(buf, map, size);
353 munmap(map, size);
354 if (cmp)
355 return -1;
356 #endif
357 return 0;
358 }
359
360 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
361 {
362 char *filename = sha1_file_name(sha1);
363 int fd;
364
365 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
366 if (fd < 0) {
367 if (errno != EEXIST)
368 return -1;
369 if (collision_check(filename, buf, size))
370 return error("SHA1 collision detected!"
371 " This is bad, bad, BAD!\a\n");
372 return 0;
373 }
374 write(fd, buf, size);
375 close(fd);
376 return 0;
377 }
378
379 int write_sha1_from_fd(const unsigned char *sha1, int fd)
380 {
381 char *filename = sha1_file_name(sha1);
382
383 int local;
384 z_stream stream;
385 unsigned char real_sha1[20];
386 char buf[4096];
387 char discard[4096];
388 int ret;
389 SHA_CTX c;
390
391 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
392
393 if (local < 0)
394 return error("Couldn't open %s\n", filename);
395
396 memset(&stream, 0, sizeof(stream));
397
398 inflateInit(&stream);
399
400 SHA1_Init(&c);
401
402 do {
403 ssize_t size;
404 size = read(fd, buf, 4096);
405 if (size <= 0) {
406 close(local);
407 unlink(filename);
408 if (!size)
409 return error("Connection closed?");
410 perror("Reading from connection");
411 return -1;
412 }
413 write(local, buf, size);
414 stream.avail_in = size;
415 stream.next_in = buf;
416 do {
417 stream.next_out = discard;
418 stream.avail_out = sizeof(discard);
419 ret = inflate(&stream, Z_SYNC_FLUSH);
420 SHA1_Update(&c, discard, sizeof(discard) -
421 stream.avail_out);
422 } while (stream.avail_in && ret == Z_OK);
423
424 } while (ret == Z_OK);
425 inflateEnd(&stream);
426
427 close(local);
428 SHA1_Final(real_sha1, &c);
429 if (ret != Z_STREAM_END) {
430 unlink(filename);
431 return error("File %s corrupted", sha1_to_hex(sha1));
432 }
433 if (memcmp(sha1, real_sha1, 20)) {
434 unlink(filename);
435 return error("File %s has bad hash\n", sha1_to_hex(sha1));
436 }
437
438 return 0;
439 }
440
441 int has_sha1_file(const unsigned char *sha1)
442 {
443 char *filename = sha1_file_name(sha1);
444 struct stat st;
445
446 if (!stat(filename, &st))
447 return 1;
448 return 0;
449 }