-
Notifications
You must be signed in to change notification settings - Fork 0
/
sha1_file.c
462 lines (400 loc) · 9.53 KB
/
sha1_file.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*
* This handles basic git sha1 object files - packing, unpacking,
* creation etc.
*/
#include <stdarg.h>
#include "cache.h"
const char *sha1_file_directory = NULL;
#ifndef O_NOATIME
#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
#define O_NOATIME 01000000
#else
#define O_NOATIME 0
#endif
#endif
static unsigned int sha1_file_open_flag = O_NOATIME;
static unsigned hexval(char c)
{
if (c >= '0' && c <= '9')
return c - '0';
if (c >= 'a' && c <= 'f')
return c - 'a' + 10;
if (c >= 'A' && c <= 'F')
return c - 'A' + 10;
return ~0;
}
int get_sha1_hex(const char *hex, unsigned char *sha1)
{
int i;
for (i = 0; i < 20; i++) {
unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
if (val & ~0xff)
return -1;
*sha1++ = val;
hex += 2;
}
return 0;
}
int get_sha1_file(const char *path, unsigned char *result)
{
char buffer[60];
int fd = open(path, O_RDONLY);
int len;
if (fd < 0)
return -1;
len = read(fd, buffer, sizeof(buffer));
close(fd);
if (len < 40)
return -1;
return get_sha1_hex(buffer, result);
}
int get_sha1(const char *str, unsigned char *sha1)
{
static char pathname[PATH_MAX];
static const char *prefix[] = {
"",
"refs",
"refs/tags",
"refs/heads",
"refs/snap",
NULL
};
const char *gitdir;
const char **p;
if (!get_sha1_hex(str, sha1))
return 0;
gitdir = ".git";
for (p = prefix; *p; p++) {
snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
if (!get_sha1_file(pathname, sha1))
return 0;
}
return -1;
}
char * sha1_to_hex(const unsigned char *sha1)
{
static char buffer[50];
static const char hex[] = "0123456789abcdef";
char *buf = buffer;
int i;
for (i = 0; i < 20; i++) {
unsigned int val = *sha1++;
*buf++ = hex[val >> 4];
*buf++ = hex[val & 0xf];
}
return buffer;
}
/*
* NOTE! This returns a statically allocated buffer, so you have to be
* careful about using it. Do a "strdup()" if you need to save the
* filename.
*/
char *sha1_file_name(const unsigned char *sha1)
{
int i;
static char *name, *base;
if (!base) {
char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
int len = strlen(sha1_file_directory);
base = xmalloc(len + 60);
memcpy(base, sha1_file_directory, len);
memset(base+len, 0, 60);
base[len] = '/';
base[len+3] = '/';
name = base + len + 1;
}
for (i = 0; i < 20; i++) {
static char hex[] = "0123456789abcdef";
unsigned int val = sha1[i];
char *pos = name + i*2 + (i > 0);
*pos++ = hex[val >> 4];
*pos = hex[val & 0xf];
}
return base;
}
int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
{
char header[100];
unsigned char real_sha1[20];
SHA_CTX c;
SHA1_Init(&c);
SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
SHA1_Update(&c, map, size);
SHA1_Final(real_sha1, &c);
return memcmp(sha1, real_sha1, 20) ? -1 : 0;
}
void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
{
char *filename = sha1_file_name(sha1);
struct stat st;
void *map;
int fd;
fd = open(filename, O_RDONLY | sha1_file_open_flag);
if (fd < 0) {
/* See if it works without O_NOATIME */
switch (sha1_file_open_flag) {
default:
fd = open(filename, O_RDONLY);
if (fd >= 0)
break;
/* Fallthrough */
case 0:
perror(filename);
return NULL;
}
/* If it failed once, it will probably fail again. Stop using O_NOATIME */
sha1_file_open_flag = 0;
}
if (fstat(fd, &st) < 0) {
close(fd);
return NULL;
}
map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (-1 == (int)(long)map)
return NULL;
*size = st.st_size;
return map;
}
void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
{
int ret, bytes;
z_stream stream;
char buffer[8192];
char *buf;
/* Get the data stream */
memset(&stream, 0, sizeof(stream));
stream.next_in = map;
stream.avail_in = mapsize;
stream.next_out = buffer;
stream.avail_out = sizeof(buffer);
inflateInit(&stream);
ret = inflate(&stream, 0);
if (ret < Z_OK)
return NULL;
if (sscanf(buffer, "%10s %lu", type, size) != 2)
return NULL;
bytes = strlen(buffer) + 1;
buf = xmalloc(*size);
memcpy(buf, buffer + bytes, stream.total_out - bytes);
bytes = stream.total_out - bytes;
if (bytes < *size && ret == Z_OK) {
stream.next_out = buf + bytes;
stream.avail_out = *size - bytes;
while (inflate(&stream, Z_FINISH) == Z_OK)
/* nothing */;
}
inflateEnd(&stream);
return buf;
}
void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
{
unsigned long mapsize;
void *map, *buf;
map = map_sha1_file(sha1, &mapsize);
if (map) {
buf = unpack_sha1_file(map, mapsize, type, size);
munmap(map, mapsize);
return buf;
}
return NULL;
}
void *read_object_with_reference(const unsigned char *sha1,
const unsigned char *required_type,
unsigned long *size,
unsigned char *actual_sha1_return)
{
char type[20];
void *buffer;
unsigned long isize;
unsigned char actual_sha1[20];
memcpy(actual_sha1, sha1, 20);
while (1) {
int ref_length = -1;
const char *ref_type = NULL;
buffer = read_sha1_file(actual_sha1, type, &isize);
if (!buffer)
return NULL;
if (!strcmp(type, required_type)) {
*size = isize;
if (actual_sha1_return)
memcpy(actual_sha1_return, actual_sha1, 20);
return buffer;
}
/* Handle references */
else if (!strcmp(type, "commit"))
ref_type = "tree ";
else if (!strcmp(type, "tag"))
ref_type = "object ";
else {
free(buffer);
return NULL;
}
ref_length = strlen(ref_type);
if (memcmp(buffer, ref_type, ref_length) ||
get_sha1_hex(buffer + ref_length, actual_sha1)) {
free(buffer);
return NULL;
}
/* Now we have the ID of the referred-to object in
* actual_sha1. Check again. */
}
}
int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
{
int size;
char *compressed;
z_stream stream;
unsigned char sha1[20];
SHA_CTX c;
char *filename;
char hdr[50];
int fd, hdrlen;
/* Generate the header */
hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
/* Sha1.. */
SHA1_Init(&c);
SHA1_Update(&c, hdr, hdrlen);
SHA1_Update(&c, buf, len);
SHA1_Final(sha1, &c);
if (returnsha1)
memcpy(returnsha1, sha1, 20);
filename = sha1_file_name(sha1);
fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
if (fd < 0) {
if (errno != EEXIST)
return -1;
/*
* We might do collision checking here, but we'd need to
* uncompress the old file and check it. Later.
*/
return 0;
}
/* Set it up */
memset(&stream, 0, sizeof(stream));
deflateInit(&stream, Z_BEST_COMPRESSION);
size = deflateBound(&stream, len+hdrlen);
compressed = xmalloc(size);
/* Compress it */
stream.next_out = compressed;
stream.avail_out = size;
/* First header.. */
stream.next_in = hdr;
stream.avail_in = hdrlen;
while (deflate(&stream, 0) == Z_OK)
/* nothing */
/* Then the data itself.. */
stream.next_in = buf;
stream.avail_in = len;
while (deflate(&stream, Z_FINISH) == Z_OK)
/* nothing */;
deflateEnd(&stream);
size = stream.total_out;
if (write(fd, compressed, size) != size)
die("unable to write file");
close(fd);
return 0;
}
static inline int collision_check(char *filename, void *buf, unsigned int size)
{
#ifdef COLLISION_CHECK
void *map;
int fd = open(filename, O_RDONLY);
struct stat st;
int cmp;
/* Unreadable object, or object went away? Strange. */
if (fd < 0)
return -1;
if (fstat(fd, &st) < 0 || size != st.st_size)
return -1;
map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (map == MAP_FAILED)
return -1;
cmp = memcmp(buf, map, size);
munmap(map, size);
if (cmp)
return -1;
#endif
return 0;
}
int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
{
char *filename = sha1_file_name(sha1);
int fd;
fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
if (fd < 0) {
if (errno != EEXIST)
return -1;
if (collision_check(filename, buf, size))
return error("SHA1 collision detected!"
" This is bad, bad, BAD!\a\n");
return 0;
}
write(fd, buf, size);
close(fd);
return 0;
}
int write_sha1_from_fd(const unsigned char *sha1, int fd)
{
char *filename = sha1_file_name(sha1);
int local;
z_stream stream;
unsigned char real_sha1[20];
char buf[4096];
char discard[4096];
int ret;
SHA_CTX c;
local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
if (local < 0)
return error("Couldn't open %s\n", filename);
memset(&stream, 0, sizeof(stream));
inflateInit(&stream);
SHA1_Init(&c);
do {
ssize_t size;
size = read(fd, buf, 4096);
if (size <= 0) {
close(local);
unlink(filename);
if (!size)
return error("Connection closed?");
perror("Reading from connection");
return -1;
}
write(local, buf, size);
stream.avail_in = size;
stream.next_in = buf;
do {
stream.next_out = discard;
stream.avail_out = sizeof(discard);
ret = inflate(&stream, Z_SYNC_FLUSH);
SHA1_Update(&c, discard, sizeof(discard) -
stream.avail_out);
} while (stream.avail_in && ret == Z_OK);
} while (ret == Z_OK);
inflateEnd(&stream);
close(local);
SHA1_Final(real_sha1, &c);
if (ret != Z_STREAM_END) {
unlink(filename);
return error("File %s corrupted", sha1_to_hex(sha1));
}
if (memcmp(sha1, real_sha1, 20)) {
unlink(filename);
return error("File %s has bad hash\n", sha1_to_hex(sha1));
}
return 0;
}
int has_sha1_file(const unsigned char *sha1)
{
char *filename = sha1_file_name(sha1);
struct stat st;
if (!stat(filename, &st))
return 1;
return 0;
}