[PATCH] init-db.c: create and use safe_create_dir helper
[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
83int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
84{
85 unsigned char real_sha1[20];
86 SHA_CTX c;
87
88 SHA1_Init(&c);
89 SHA1_Update(&c, map, size);
90 SHA1_Final(real_sha1, &c);
91 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
92}
93
94void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
95{
96 char *filename = sha1_file_name(sha1);
97 int fd = open(filename, O_RDONLY);
98 struct stat st;
99 void *map;
100
101 if (fd < 0) {
102 perror(filename);
103 return NULL;
104 }
105 if (fstat(fd, &st) < 0) {
106 close(fd);
107 return NULL;
108 }
109 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
110 close(fd);
111 if (-1 == (int)(long)map)
112 return NULL;
113 *size = st.st_size;
114 return map;
115}
116
117void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
118{
119 int ret, bytes;
120 z_stream stream;
121 char buffer[8192];
122 char *buf;
123
124 /* Get the data stream */
125 memset(&stream, 0, sizeof(stream));
126 stream.next_in = map;
127 stream.avail_in = mapsize;
128 stream.next_out = buffer;
129 stream.avail_out = sizeof(buffer);
130
131 inflateInit(&stream);
132 ret = inflate(&stream, 0);
133 if (sscanf(buffer, "%10s %lu", type, size) != 2)
134 return NULL;
135
136 bytes = strlen(buffer) + 1;
137 buf = malloc(*size);
138 if (!buf)
139 return NULL;
140
141 memcpy(buf, buffer + bytes, stream.total_out - bytes);
142 bytes = stream.total_out - bytes;
143 if (bytes < *size && ret == Z_OK) {
144 stream.next_out = buf + bytes;
145 stream.avail_out = *size - bytes;
146 while (inflate(&stream, Z_FINISH) == Z_OK)
147 /* nothing */;
148 }
149 inflateEnd(&stream);
150 return buf;
151}
152
153void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
154{
155 unsigned long mapsize;
156 void *map, *buf;
157
158 map = map_sha1_file(sha1, &mapsize);
159 if (map) {
160 buf = unpack_sha1_file(map, mapsize, type, size);
161 munmap(map, mapsize);
162 return buf;
163 }
164 return NULL;
165}
166
167int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
168{
169 int size;
170 char *compressed;
171 z_stream stream;
172 unsigned char sha1[20];
173 SHA_CTX c;
174
175 /* Set it up */
176 memset(&stream, 0, sizeof(stream));
177 deflateInit(&stream, Z_BEST_COMPRESSION);
178 size = deflateBound(&stream, len);
179 compressed = malloc(size);
180
181 /* Compress it */
182 stream.next_in = buf;
183 stream.avail_in = len;
184 stream.next_out = compressed;
185 stream.avail_out = size;
186 while (deflate(&stream, Z_FINISH) == Z_OK)
187 /* nothing */;
188 deflateEnd(&stream);
189 size = stream.total_out;
190
191 /* Sha1.. */
192 SHA1_Init(&c);
193 SHA1_Update(&c, compressed, size);
194 SHA1_Final(sha1, &c);
195
196 if (write_sha1_buffer(sha1, compressed, size) < 0)
197 return -1;
198 if (returnsha1)
199 memcpy(returnsha1, sha1, 20);
200 return 0;
201}
202
203static inline int collision_check(char *filename, void *buf, unsigned int size)
204{
205#ifdef COLLISION_CHECK
206 void *map;
207 int fd = open(filename, O_RDONLY);
208 struct stat st;
209 int cmp;
210
211 /* Unreadable object, or object went away? Strange. */
212 if (fd < 0)
213 return -1;
214
215 if (fstat(fd, &st) < 0 || size != st.st_size)
216 return -1;
217
218 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
219 close(fd);
220 if (map == MAP_FAILED)
221 return -1;
222 cmp = memcmp(buf, map, size);
223 munmap(map, size);
224 if (cmp)
225 return -1;
226#endif
227 return 0;
228}
229
230int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
231{
232 char *filename = sha1_file_name(sha1);
233 int fd;
234
235 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
236 if (fd < 0) {
237 if (errno != EEXIST)
238 return -1;
239 if (collision_check(filename, buf, size))
240 return error("SHA1 collision detected!"
241 " This is bad, bad, BAD!\a\n");
242 return 0;
243 }
244 write(fd, buf, size);
245 close(fd);
246 return 0;
247}