[PATCH] Rename and extend read_tree_with_tree_or_commit_sha1
[git/git.git] / sha1_file.c
CommitLineData
0fcfd160
LT
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
12const char *sha1_file_directory = NULL;
13
144bde78
LT
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
22static unsigned int sha1_file_open_flag = O_NOATIME;
23
0fcfd160
LT
24static 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
35int 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
48char * sha1_to_hex(const unsigned char *sha1)
49{
50 static char buffer[50];
51 static const char hex[] = "0123456789abcdef";
52 char *buf = buffer;
53 int i;
54
55 for (i = 0; i < 20; i++) {
56 unsigned int val = *sha1++;
57 *buf++ = hex[val >> 4];
58 *buf++ = hex[val & 0xf];
59 }
60 return buffer;
61}
62
63/*
64 * NOTE! This returns a statically allocated buffer, so you have to be
65 * careful about using it. Do a "strdup()" if you need to save the
66 * filename.
67 */
68char *sha1_file_name(const unsigned char *sha1)
69{
70 int i;
71 static char *name, *base;
72
73 if (!base) {
74 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
75 int len = strlen(sha1_file_directory);
812666c8 76 base = xmalloc(len + 60);
0fcfd160
LT
77 memcpy(base, sha1_file_directory, len);
78 memset(base+len, 0, 60);
79 base[len] = '/';
80 base[len+3] = '/';
81 name = base + len + 1;
82 }
83 for (i = 0; i < 20; i++) {
84 static char hex[] = "0123456789abcdef";
85 unsigned int val = sha1[i];
86 char *pos = name + i*2 + (i > 0);
87 *pos++ = hex[val >> 4];
88 *pos = hex[val & 0xf];
89 }
90 return base;
91}
92
d98b46f8 93int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
0fcfd160 94{
d98b46f8 95 char header[100];
0fcfd160
LT
96 unsigned char real_sha1[20];
97 SHA_CTX c;
98
99 SHA1_Init(&c);
d98b46f8 100 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
0fcfd160
LT
101 SHA1_Update(&c, map, size);
102 SHA1_Final(real_sha1, &c);
103 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
104}
105
106void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
107{
108 char *filename = sha1_file_name(sha1);
0fcfd160
LT
109 struct stat st;
110 void *map;
144bde78 111 int fd;
0fcfd160 112
144bde78 113 fd = open(filename, O_RDONLY | sha1_file_open_flag);
0fcfd160 114 if (fd < 0) {
144bde78
LT
115 /* See if it works without O_NOATIME */
116 switch (sha1_file_open_flag) {
117 default:
118 fd = open(filename, O_RDONLY);
119 if (fd >= 0)
120 break;
121 /* Fallthrough */
122 case 0:
123 perror(filename);
124 return NULL;
125 }
126
127 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
128 sha1_file_open_flag = 0;
0fcfd160
LT
129 }
130 if (fstat(fd, &st) < 0) {
131 close(fd);
132 return NULL;
133 }
134 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
135 close(fd);
136 if (-1 == (int)(long)map)
137 return NULL;
138 *size = st.st_size;
139 return map;
140}
141
142void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
143{
144 int ret, bytes;
145 z_stream stream;
146 char buffer[8192];
147 char *buf;
148
149 /* Get the data stream */
150 memset(&stream, 0, sizeof(stream));
151 stream.next_in = map;
152 stream.avail_in = mapsize;
153 stream.next_out = buffer;
154 stream.avail_out = sizeof(buffer);
155
156 inflateInit(&stream);
157 ret = inflate(&stream, 0);
a44c9a5e
LT
158 if (ret < Z_OK)
159 return NULL;
0fcfd160
LT
160 if (sscanf(buffer, "%10s %lu", type, size) != 2)
161 return NULL;
162
163 bytes = strlen(buffer) + 1;
812666c8 164 buf = xmalloc(*size);
0fcfd160
LT
165
166 memcpy(buf, buffer + bytes, stream.total_out - bytes);
167 bytes = stream.total_out - bytes;
168 if (bytes < *size && ret == Z_OK) {
169 stream.next_out = buf + bytes;
170 stream.avail_out = *size - bytes;
171 while (inflate(&stream, Z_FINISH) == Z_OK)
172 /* nothing */;
173 }
174 inflateEnd(&stream);
175 return buf;
176}
177
178void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
179{
180 unsigned long mapsize;
181 void *map, *buf;
182
183 map = map_sha1_file(sha1, &mapsize);
184 if (map) {
185 buf = unpack_sha1_file(map, mapsize, type, size);
186 munmap(map, mapsize);
187 return buf;
188 }
189 return NULL;
190}
191
40469ee9
JH
192void *read_object_with_reference(const unsigned char *sha1,
193 const unsigned char *required_type,
194 unsigned long *size,
195 unsigned char *actual_sha1_return)
f4913f91
JH
196{
197 char type[20];
198 void *buffer;
199 unsigned long isize;
40469ee9 200 unsigned char actual_sha1[20];
f4913f91 201
40469ee9
JH
202 memcpy(actual_sha1, sha1, 20);
203 while (1) {
204 int ref_length = -1;
205 const char *ref_type = NULL;
f4913f91 206
40469ee9
JH
207 buffer = read_sha1_file(actual_sha1, type, &isize);
208 if (!buffer)
209 return NULL;
210 if (!strcmp(type, required_type)) {
211 *size = isize;
212 if (actual_sha1_return)
213 memcpy(actual_sha1_return, actual_sha1, 20);
214 return buffer;
215 }
216 /* Handle references */
217 else if (!strcmp(type, "commit"))
218 ref_type = "tree ";
219 else if (!strcmp(type, "tag"))
220 ref_type = "object ";
221 else {
222 free(buffer);
223 return NULL;
224 }
225 ref_length = strlen(ref_type);
f4913f91 226
40469ee9
JH
227 if (memcmp(buffer, ref_type, ref_length) ||
228 get_sha1_hex(buffer + ref_length, actual_sha1)) {
229 free(buffer);
230 return NULL;
231 }
232 /* Now we have the ID of the referred-to object in
233 * actual_sha1. Check again. */
f4913f91 234 }
f4913f91
JH
235}
236
f5b913c9 237int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
0fcfd160
LT
238{
239 int size;
240 char *compressed;
241 z_stream stream;
242 unsigned char sha1[20];
243 SHA_CTX c;
706bc531 244 char *filename;
a44c9a5e
LT
245 char hdr[50];
246 int fd, hdrlen;
247
248 /* Generate the header */
f5b913c9 249 hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
0fcfd160 250
d98b46f8
LT
251 /* Sha1.. */
252 SHA1_Init(&c);
a44c9a5e 253 SHA1_Update(&c, hdr, hdrlen);
d98b46f8
LT
254 SHA1_Update(&c, buf, len);
255 SHA1_Final(sha1, &c);
256
706bc531
LT
257 if (returnsha1)
258 memcpy(returnsha1, sha1, 20);
259
260 filename = sha1_file_name(sha1);
261 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
262 if (fd < 0) {
263 if (errno != EEXIST)
264 return -1;
265
266 /*
267 * We might do collision checking here, but we'd need to
268 * uncompress the old file and check it. Later.
269 */
270 return 0;
271 }
272
0fcfd160
LT
273 /* Set it up */
274 memset(&stream, 0, sizeof(stream));
275 deflateInit(&stream, Z_BEST_COMPRESSION);
a44c9a5e 276 size = deflateBound(&stream, len+hdrlen);
812666c8 277 compressed = xmalloc(size);
0fcfd160
LT
278
279 /* Compress it */
0fcfd160
LT
280 stream.next_out = compressed;
281 stream.avail_out = size;
a44c9a5e
LT
282
283 /* First header.. */
284 stream.next_in = hdr;
285 stream.avail_in = hdrlen;
286 while (deflate(&stream, 0) == Z_OK)
287 /* nothing */
288
289 /* Then the data itself.. */
290 stream.next_in = buf;
291 stream.avail_in = len;
0fcfd160
LT
292 while (deflate(&stream, Z_FINISH) == Z_OK)
293 /* nothing */;
294 deflateEnd(&stream);
295 size = stream.total_out;
296
706bc531
LT
297 if (write(fd, compressed, size) != size)
298 die("unable to write file");
299 close(fd);
300
0fcfd160
LT
301 return 0;
302}
303
304static inline int collision_check(char *filename, void *buf, unsigned int size)
305{
306#ifdef COLLISION_CHECK
307 void *map;
308 int fd = open(filename, O_RDONLY);
309 struct stat st;
310 int cmp;
311
312 /* Unreadable object, or object went away? Strange. */
313 if (fd < 0)
314 return -1;
315
316 if (fstat(fd, &st) < 0 || size != st.st_size)
317 return -1;
318
319 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
320 close(fd);
321 if (map == MAP_FAILED)
322 return -1;
323 cmp = memcmp(buf, map, size);
324 munmap(map, size);
325 if (cmp)
326 return -1;
327#endif
328 return 0;
329}
330
331int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
332{
333 char *filename = sha1_file_name(sha1);
334 int fd;
335
336 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
337 if (fd < 0) {
338 if (errno != EEXIST)
339 return -1;
340 if (collision_check(filename, buf, size))
341 return error("SHA1 collision detected!"
342 " This is bad, bad, BAD!\a\n");
343 return 0;
344 }
345 write(fd, buf, size);
346 close(fd);
347 return 0;
348}
8237b185
DB
349
350int write_sha1_from_fd(const unsigned char *sha1, int fd)
351{
352 char *filename = sha1_file_name(sha1);
353
354 int local;
355 z_stream stream;
356 unsigned char real_sha1[20];
357 char buf[4096];
358 char discard[4096];
359 int ret;
360 SHA_CTX c;
361
362 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
363
364 if (local < 0)
365 return error("Couldn't open %s\n", filename);
366
367 memset(&stream, 0, sizeof(stream));
368
369 inflateInit(&stream);
370
371 SHA1_Init(&c);
372
373 do {
374 ssize_t size;
375 size = read(fd, buf, 4096);
376 if (size <= 0) {
377 close(local);
378 unlink(filename);
379 if (!size)
380 return error("Connection closed?");
381 perror("Reading from connection");
382 return -1;
383 }
384 write(local, buf, size);
385 stream.avail_in = size;
386 stream.next_in = buf;
387 do {
388 stream.next_out = discard;
389 stream.avail_out = sizeof(discard);
390 ret = inflate(&stream, Z_SYNC_FLUSH);
391 SHA1_Update(&c, discard, sizeof(discard) -
392 stream.avail_out);
393 } while (stream.avail_in && ret == Z_OK);
394
395 } while (ret == Z_OK);
396 inflateEnd(&stream);
397
398 close(local);
399 SHA1_Final(real_sha1, &c);
400 if (ret != Z_STREAM_END) {
401 unlink(filename);
402 return error("File %s corrupted", sha1_to_hex(sha1));
403 }
404 if (memcmp(sha1, real_sha1, 20)) {
405 unlink(filename);
406 return error("File %s has bad hash\n", sha1_to_hex(sha1));
407 }
408
409 return 0;
410}
411
412int has_sha1_file(const unsigned char *sha1)
413{
414 char *filename = sha1_file_name(sha1);
415 struct stat st;
416
417 if (!stat(filename, &st))
418 return 1;
419 return 0;
420}