Factor out "read_sha1_file" into mapping/inflating/unmapping.
[git/git.git] / read-cache.c
CommitLineData
8bc9a0c7
LT
1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
e83c5163
LT
6#include "cache.h"
7
8const char *sha1_file_directory = NULL;
9struct cache_entry **active_cache = NULL;
10unsigned int active_nr = 0, active_alloc = 0;
11
12void usage(const char *err)
13{
14 fprintf(stderr, "read-tree: %s\n", err);
15 exit(1);
16}
17
18static unsigned hexval(char c)
19{
20 if (c >= '0' && c <= '9')
21 return c - '0';
22 if (c >= 'a' && c <= 'f')
23 return c - 'a' + 10;
24 if (c >= 'A' && c <= 'F')
25 return c - 'A' + 10;
26 return ~0;
27}
28
29int get_sha1_hex(char *hex, unsigned char *sha1)
30{
31 int i;
32 for (i = 0; i < 20; i++) {
33 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
34 if (val & ~0xff)
35 return -1;
36 *sha1++ = val;
37 hex += 2;
38 }
39 return 0;
40}
41
42char * sha1_to_hex(unsigned char *sha1)
43{
44 static char buffer[50];
45 static const char hex[] = "0123456789abcdef";
46 char *buf = buffer;
47 int i;
48
49 for (i = 0; i < 20; i++) {
50 unsigned int val = *sha1++;
51 *buf++ = hex[val >> 4];
52 *buf++ = hex[val & 0xf];
53 }
54 return buffer;
55}
56
57/*
58 * NOTE! This returns a statically allocated buffer, so you have to be
59 * careful about using it. Do a "strdup()" if you need to save the
60 * filename.
61 */
62char *sha1_file_name(unsigned char *sha1)
63{
64 int i;
65 static char *name, *base;
66
67 if (!base) {
68 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
69 int len = strlen(sha1_file_directory);
70 base = malloc(len + 60);
71 memcpy(base, sha1_file_directory, len);
72 memset(base+len, 0, 60);
73 base[len] = '/';
74 base[len+3] = '/';
75 name = base + len + 1;
76 }
77 for (i = 0; i < 20; i++) {
78 static char hex[] = "0123456789abcdef";
79 unsigned int val = sha1[i];
80 char *pos = name + i*2 + (i > 0);
81 *pos++ = hex[val >> 4];
82 *pos = hex[val & 0xf];
83 }
84 return base;
85}
86
24778e33 87void *map_sha1_file(unsigned char *sha1, unsigned long *size)
e83c5163 88{
e83c5163 89 char *filename = sha1_file_name(sha1);
24778e33
LT
90 int fd = open(filename, O_RDONLY);
91 struct stat st;
92 void *map;
e83c5163 93
e83c5163
LT
94 if (fd < 0) {
95 perror(filename);
96 return NULL;
97 }
98 if (fstat(fd, &st) < 0) {
24778e33 99 close(fd);
e83c5163
LT
100 return NULL;
101 }
102 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
103 close(fd);
104 if (-1 == (int)(long)map)
105 return NULL;
24778e33
LT
106 *size = st.st_size;
107 return map;
108}
109
110void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
111{
112 int ret, bytes;
113 z_stream stream;
114 char buffer[8192];
115 char *buf;
e83c5163
LT
116
117 /* Get the data stream */
118 memset(&stream, 0, sizeof(stream));
119 stream.next_in = map;
24778e33 120 stream.avail_in = mapsize;
e83c5163
LT
121 stream.next_out = buffer;
122 stream.avail_out = sizeof(buffer);
123
124 inflateInit(&stream);
125 ret = inflate(&stream, 0);
126 if (sscanf(buffer, "%10s %lu", type, size) != 2)
127 return NULL;
24778e33 128
e83c5163
LT
129 bytes = strlen(buffer) + 1;
130 buf = malloc(*size);
131 if (!buf)
132 return NULL;
133
134 memcpy(buf, buffer + bytes, stream.total_out - bytes);
135 bytes = stream.total_out - bytes;
136 if (bytes < *size && ret == Z_OK) {
137 stream.next_out = buf + bytes;
138 stream.avail_out = *size - bytes;
139 while (inflate(&stream, Z_FINISH) == Z_OK)
140 /* nothing */;
141 }
142 inflateEnd(&stream);
143 return buf;
144}
145
24778e33
LT
146void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size)
147{
148 unsigned long mapsize;
149 void *map, *buf;
150
151 map = map_sha1_file(sha1, &mapsize);
152 if (map) {
153 buf = unpack_sha1_file(map, mapsize, type, size);
154 munmap(map, mapsize);
155 return buf;
156 }
157 return NULL;
158}
159
e83c5163
LT
160int write_sha1_file(char *buf, unsigned len)
161{
162 int size;
163 char *compressed;
164 z_stream stream;
165 unsigned char sha1[20];
166 SHA_CTX c;
167
168 /* Set it up */
169 memset(&stream, 0, sizeof(stream));
170 deflateInit(&stream, Z_BEST_COMPRESSION);
171 size = deflateBound(&stream, len);
172 compressed = malloc(size);
173
174 /* Compress it */
175 stream.next_in = buf;
176 stream.avail_in = len;
177 stream.next_out = compressed;
178 stream.avail_out = size;
179 while (deflate(&stream, Z_FINISH) == Z_OK)
180 /* nothing */;
181 deflateEnd(&stream);
182 size = stream.total_out;
183
184 /* Sha1.. */
185 SHA1_Init(&c);
186 SHA1_Update(&c, compressed, size);
187 SHA1_Final(sha1, &c);
188
189 if (write_sha1_buffer(sha1, compressed, size) < 0)
190 return -1;
191 printf("%s\n", sha1_to_hex(sha1));
192 return 0;
193}
194
195int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size)
196{
197 char *filename = sha1_file_name(sha1);
19b2860c 198 int fd;
e83c5163
LT
199
200 fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
201 if (fd < 0)
202 return (errno == EEXIST) ? 0 : -1;
203 write(fd, buf, size);
204 close(fd);
205 return 0;
206}
207
208static int error(const char * string)
209{
210 fprintf(stderr, "error: %s\n", string);
211 return -1;
212}
213
214static int verify_hdr(struct cache_header *hdr, unsigned long size)
215{
216 SHA_CTX c;
217 unsigned char sha1[20];
218
219 if (hdr->signature != CACHE_SIGNATURE)
220 return error("bad signature");
221 if (hdr->version != 1)
222 return error("bad version");
223 SHA1_Init(&c);
224 SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
225 SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
226 SHA1_Final(sha1, &c);
227 if (memcmp(sha1, hdr->sha1, 20))
228 return error("bad header sha1");
229 return 0;
230}
231
232int read_cache(void)
233{
234 int fd, i;
235 struct stat st;
236 unsigned long size, offset;
237 void *map;
238 struct cache_header *hdr;
239
240 errno = EBUSY;
241 if (active_cache)
242 return error("more than one cachefile");
243 errno = ENOENT;
244 sha1_file_directory = getenv(DB_ENVIRONMENT);
245 if (!sha1_file_directory)
246 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
247 if (access(sha1_file_directory, X_OK) < 0)
248 return error("no access to SHA1 file directory");
249 fd = open(".dircache/index", O_RDONLY);
250 if (fd < 0)
251 return (errno == ENOENT) ? 0 : error("open failed");
252
19b2860c 253 size = 0; // avoid gcc warning
e83c5163
LT
254 map = (void *)-1;
255 if (!fstat(fd, &st)) {
256 map = NULL;
257 size = st.st_size;
258 errno = EINVAL;
259 if (size > sizeof(struct cache_header))
260 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
261 }
262 close(fd);
263 if (-1 == (int)(long)map)
264 return error("mmap failed");
265
266 hdr = map;
267 if (verify_hdr(hdr, size) < 0)
268 goto unmap;
269
270 active_nr = hdr->entries;
271 active_alloc = alloc_nr(active_nr);
272 active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
273
274 offset = sizeof(*hdr);
275 for (i = 0; i < hdr->entries; i++) {
276 struct cache_entry *ce = map + offset;
277 offset = offset + ce_size(ce);
278 active_cache[i] = ce;
279 }
280 return active_nr;
281
282unmap:
283 munmap(map, size);
284 errno = EINVAL;
285 return error("verify header failed");
286}
287