[PATCH] simplify Makefile
[git/git.git] / sha1_file.c
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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
14static unsigned hexval(char c)
15{
16 if (c >= '0' && c <= '9')
17 return c - '0';
18 if (c >= 'a' && c <= 'f')
19 return c - 'a' + 10;
20 if (c >= 'A' && c <= 'F')
21 return c - 'A' + 10;
22 return ~0;
23}
24
25int get_sha1_hex(const char *hex, unsigned char *sha1)
26{
27 int i;
28 for (i = 0; i < 20; i++) {
29 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
30 if (val & ~0xff)
31 return -1;
32 *sha1++ = val;
33 hex += 2;
34 }
35 return 0;
36}
37
38char * sha1_to_hex(const unsigned char *sha1)
39{
40 static char buffer[50];
41 static const char hex[] = "0123456789abcdef";
42 char *buf = buffer;
43 int i;
44
45 for (i = 0; i < 20; i++) {
46 unsigned int val = *sha1++;
47 *buf++ = hex[val >> 4];
48 *buf++ = hex[val & 0xf];
49 }
50 return buffer;
51}
52
53/*
54 * NOTE! This returns a statically allocated buffer, so you have to be
55 * careful about using it. Do a "strdup()" if you need to save the
56 * filename.
57 */
58char *sha1_file_name(const unsigned char *sha1)
59{
60 int i;
61 static char *name, *base;
62
63 if (!base) {
64 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
65 int len = strlen(sha1_file_directory);
66 base = malloc(len + 60);
67 memcpy(base, sha1_file_directory, len);
68 memset(base+len, 0, 60);
69 base[len] = '/';
70 base[len+3] = '/';
71 name = base + len + 1;
72 }
73 for (i = 0; i < 20; i++) {
74 static char hex[] = "0123456789abcdef";
75 unsigned int val = sha1[i];
76 char *pos = name + i*2 + (i > 0);
77 *pos++ = hex[val >> 4];
78 *pos = hex[val & 0xf];
79 }
80 return base;
81}
82
d98b46f8 83int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
0fcfd160 84{
d98b46f8 85 char header[100];
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86 unsigned char real_sha1[20];
87 SHA_CTX c;
88
89 SHA1_Init(&c);
d98b46f8 90 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
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91 SHA1_Update(&c, map, size);
92 SHA1_Final(real_sha1, &c);
93 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
94}
95
96void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
97{
98 char *filename = sha1_file_name(sha1);
99 int fd = open(filename, O_RDONLY);
100 struct stat st;
101 void *map;
102
103 if (fd < 0) {
104 perror(filename);
105 return NULL;
106 }
107 if (fstat(fd, &st) < 0) {
108 close(fd);
109 return NULL;
110 }
111 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
112 close(fd);
113 if (-1 == (int)(long)map)
114 return NULL;
115 *size = st.st_size;
116 return map;
117}
118
119void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
120{
121 int ret, bytes;
122 z_stream stream;
123 char buffer[8192];
124 char *buf;
125
126 /* Get the data stream */
127 memset(&stream, 0, sizeof(stream));
128 stream.next_in = map;
129 stream.avail_in = mapsize;
130 stream.next_out = buffer;
131 stream.avail_out = sizeof(buffer);
132
133 inflateInit(&stream);
134 ret = inflate(&stream, 0);
135 if (sscanf(buffer, "%10s %lu", type, size) != 2)
136 return NULL;
137
138 bytes = strlen(buffer) + 1;
139 buf = malloc(*size);
140 if (!buf)
141 return NULL;
142
143 memcpy(buf, buffer + bytes, stream.total_out - bytes);
144 bytes = stream.total_out - bytes;
145 if (bytes < *size && ret == Z_OK) {
146 stream.next_out = buf + bytes;
147 stream.avail_out = *size - bytes;
148 while (inflate(&stream, Z_FINISH) == Z_OK)
149 /* nothing */;
150 }
151 inflateEnd(&stream);
152 return buf;
153}
154
155void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
156{
157 unsigned long mapsize;
158 void *map, *buf;
159
160 map = map_sha1_file(sha1, &mapsize);
161 if (map) {
162 buf = unpack_sha1_file(map, mapsize, type, size);
163 munmap(map, mapsize);
164 return buf;
165 }
166 return NULL;
167}
168
169int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
170{
171 int size;
172 char *compressed;
173 z_stream stream;
174 unsigned char sha1[20];
175 SHA_CTX c;
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176 char *filename;
177 int fd;
0fcfd160 178
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179 /* Sha1.. */
180 SHA1_Init(&c);
181 SHA1_Update(&c, buf, len);
182 SHA1_Final(sha1, &c);
183
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184 if (returnsha1)
185 memcpy(returnsha1, sha1, 20);
186
187 filename = sha1_file_name(sha1);
188 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
189 if (fd < 0) {
190 if (errno != EEXIST)
191 return -1;
192
193 /*
194 * We might do collision checking here, but we'd need to
195 * uncompress the old file and check it. Later.
196 */
197 return 0;
198 }
199
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200 /* Set it up */
201 memset(&stream, 0, sizeof(stream));
202 deflateInit(&stream, Z_BEST_COMPRESSION);
203 size = deflateBound(&stream, len);
204 compressed = malloc(size);
205
206 /* Compress it */
207 stream.next_in = buf;
208 stream.avail_in = len;
209 stream.next_out = compressed;
210 stream.avail_out = size;
211 while (deflate(&stream, Z_FINISH) == Z_OK)
212 /* nothing */;
213 deflateEnd(&stream);
214 size = stream.total_out;
215
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216 if (write(fd, compressed, size) != size)
217 die("unable to write file");
218 close(fd);
219
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220 return 0;
221}
222
223static inline int collision_check(char *filename, void *buf, unsigned int size)
224{
225#ifdef COLLISION_CHECK
226 void *map;
227 int fd = open(filename, O_RDONLY);
228 struct stat st;
229 int cmp;
230
231 /* Unreadable object, or object went away? Strange. */
232 if (fd < 0)
233 return -1;
234
235 if (fstat(fd, &st) < 0 || size != st.st_size)
236 return -1;
237
238 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
239 close(fd);
240 if (map == MAP_FAILED)
241 return -1;
242 cmp = memcmp(buf, map, size);
243 munmap(map, size);
244 if (cmp)
245 return -1;
246#endif
247 return 0;
248}
249
250int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
251{
252 char *filename = sha1_file_name(sha1);
253 int fd;
254
255 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
256 if (fd < 0) {
257 if (errno != EEXIST)
258 return -1;
259 if (collision_check(filename, buf, size))
260 return error("SHA1 collision detected!"
261 " This is bad, bad, BAD!\a\n");
262 return 0;
263 }
264 write(fd, buf, size);
265 close(fd);
266 return 0;
267}