summaryrefslogtreecommitdiff
path: root/update-cache.c
blob: 8fcf07a6118104876770042dfd1b429c36f8c57e (plain)
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
/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"
 
/*
 * Default to not allowing changes to the list of files. The
 * tool doesn't actually care, but this makes it harder to add
 * files to the revision control by mistake by doing something
 * like "update-cache *" and suddenly having all the object
 * files be revision controlled.
 */
static int allow_add = 0, allow_remove = 0;
 
static int index_fd(const char *path, int namelen, struct cache_entry *ce, int fd, struct stat *st)
{
	z_stream stream;
	unsigned long size = st->st_size;
	int max_out_bytes = namelen + size + 200;
	void *out = malloc(max_out_bytes);
	void *metadata = malloc(namelen + 200);
	void *in;
	SHA_CTX c;
 
	in = "";
	if (size)
		in = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (!out || (int)(long)in == -1)
		return -1;
 
	memset(&stream, 0, sizeof(stream));
	deflateInit(&stream, Z_BEST_COMPRESSION);
 
	/*
	 * ASCII size + nul byte
	 */	
	stream.next_in = metadata;
	stream.avail_in = 1+sprintf(metadata, "blob %lu", size);
	stream.next_out = out;
	stream.avail_out = max_out_bytes;
	while (deflate(&stream, 0) == Z_OK)
		/* nothing */;
 
	/*
	 * File content
	 */
	stream.next_in = in;
	stream.avail_in = size;
	while (deflate(&stream, Z_FINISH) == Z_OK)
		/*nothing */;
 
	deflateEnd(&stream);
 
	SHA1_Init(&c);
	SHA1_Update(&c, out, stream.total_out);
	SHA1_Final(ce->sha1, &c);
 
	return write_sha1_buffer(ce->sha1, out, stream.total_out);
}
 
/*
 * This only updates the "non-critical" parts of the directory
 * cache, ie the parts that aren't tracked by GIT, and only used
 * to validate the cache.
 */
static void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
{
	ce->ctime.sec = st->st_ctime;
	ce->ctime.nsec = st->st_ctim.tv_nsec;
	ce->mtime.sec = st->st_mtime;
	ce->mtime.nsec = st->st_mtim.tv_nsec;
	ce->st_dev = st->st_dev;
	ce->st_ino = st->st_ino;
	ce->st_uid = st->st_uid;
	ce->st_gid = st->st_gid;
}
 
static int add_file_to_cache(char *path)
{
	int size, namelen;
	struct cache_entry *ce;
	struct stat st;
	int fd;
 
	fd = open(path, O_RDONLY);
	if (fd < 0) {
		if (errno == ENOENT) {
			if (allow_remove)
				return remove_file_from_cache(path);
		}
		return -1;
	}
	if (fstat(fd, &st) < 0) {
		close(fd);
		return -1;
	}
	namelen = strlen(path);
	size = cache_entry_size(namelen);
	ce = malloc(size);
	memset(ce, 0, size);
	memcpy(ce->name, path, namelen);
	fill_stat_cache_info(ce, &st);
	ce->st_mode = st.st_mode;
	ce->st_size = st.st_size;
	ce->namelen = namelen;
 
	if (index_fd(path, namelen, ce, fd, &st) < 0)
		return -1;
 
	return add_cache_entry(ce, allow_add);
}
 
static int match_data(int fd, void *buffer, unsigned long size)
{
	while (size) {
		char compare[1024];
		int ret = read(fd, compare, sizeof(compare));
 
		if (ret <= 0 || ret > size || memcmp(buffer, compare, ret))
			return -1;
		size -= ret;
		buffer += ret;
	}
	return 0;
}
 
static int compare_data(struct cache_entry *ce, unsigned long expected_size)
{
	int match = -1;
	int fd = open(ce->name, O_RDONLY);
 
	if (fd >= 0) {
		void *buffer;
		unsigned long size;
		char type[10];
 
		buffer = read_sha1_file(ce->sha1, type, &size);
		if (buffer) {
			if (size == expected_size && !strcmp(type, "blob"))
				match = match_data(fd, buffer, size);
			free(buffer);
		}
		close(fd);
	}
	return match;
}
 
/*
 * "refresh" does not calculate a new sha1 file or bring the
 * cache up-to-date for mode/content changes. But what it
 * _does_ do is to "re-match" the stat information of a file
 * with the cache, so that you can refresh the cache for a
 * file that hasn't been changed but where the stat entry is
 * out of date.
 *
 * For example, you'd want to do this after doing a "read-tree",
 * to link up the stat cache details with the proper files.
 */
static struct cache_entry *refresh_entry(struct cache_entry *ce)
{
	struct stat st;
	struct cache_entry *updated;
	int changed, size;
 
	if (stat(ce->name, &st) < 0)
		return NULL;
 
	changed = cache_match_stat(ce, &st);
	if (!changed)
		return ce;
 
	/*
	 * If the mode has changed, there's no point in trying
	 * to refresh the entry - it's not going to match
	 */
	if (changed & MODE_CHANGED)
		return NULL;
 
	if (compare_data(ce, st.st_size))
		return NULL;
 
	size = ce_size(ce);
	updated = malloc(size);
	memcpy(updated, ce, size);
	fill_stat_cache_info(updated, &st);
	updated->st_size = st.st_size;
	return updated;
}
 
static void refresh_cache(void)
{
	int i;
 
	for (i = 0; i < active_nr; i++) {
		struct cache_entry *ce = active_cache[i];
		struct cache_entry *new = refresh_entry(ce);
 
		if (!new) {
			printf("%s: needs update\n", ce->name);
			continue;
		}
		active_cache[i] = new;
	}
}
 
/*
 * We fundamentally don't like some paths: we don't want
 * dot or dot-dot anywhere, and in fact, we don't even want
 * any other dot-files (.git or anything else). They
 * are hidden, for chist sake.
 *
 * Also, we don't want double slashes or slashes at the
 * end that can make pathnames ambiguous. 
 */
static int verify_path(char *path)
{
	char c;
 
	goto inside;
	for (;;) {
		if (!c)
			return 1;
		if (c == '/') {
inside:
			c = *path++;
			if (c != '/' && c != '.' && c != '\0')
				continue;
			return 0;
		}
		c = *path++;
	}
}
 
static int remove_lock = 0;
 
static void remove_lock_file(void)
{
	if (remove_lock)
		unlink(".git/index.lock");
}
 
int main(int argc, char **argv)
{
	int i, newfd, entries;
	int allow_options = 1;
 
	newfd = open(".git/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600);
	if (newfd < 0)
		die("unable to create new cachefile");
 
	atexit(remove_lock_file);
	remove_lock = 1;
 
	entries = read_cache();
	if (entries < 0)
		die("cache corrupted");
 
	for (i = 1 ; i < argc; i++) {
		char *path = argv[i];
 
		if (allow_options && *path == '-') {
			if (!strcmp(path, "--")) {
				allow_options = 0;
				continue;
			}
			if (!strcmp(path, "--add")) {
				allow_add = 1;
				continue;
			}
			if (!strcmp(path, "--remove")) {
				allow_remove = 1;
				continue;
			}
			if (!strcmp(path, "--refresh")) {
				refresh_cache();
				continue;
			}
			die("unknown option %s", path);
		}
		if (!verify_path(path)) {
			fprintf(stderr, "Ignoring path %s\n", argv[i]);
			continue;
		}
		if (add_file_to_cache(path))
			die("Unable to add %s to database", path);
	}
	if (write_cache(newfd, active_cache, active_nr) ||
	    rename(".git/index.lock", ".git/index"))
		die("Unable to write new cachefile");
 
	remove_lock = 0;
	return 0;
}