1/* cache.c: cache management
 2 *
 3 * Copyright (C) 2006 Lars Hjemli
 4 *
 5 * Licensed under GNU General Public License v2
 6 *   (see COPYING for full license text)
 7 */
 8
 9#include "cgit.h"
10
11const int NOLOCK = -1;
12
13int cache_exist(struct cacheitem *item)
14{
15	if (stat(item->name, &item->st)) {
16		item->st.st_mtime = 0;
17		return 0;
18	}
19	return 1;
20}
21
22int cache_create_dirs()
23{
24	char *path;
25
26	path = fmt("%s", cgit_cache_root);
27	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
28		return 0;
29
30	if (!cgit_query_repo)
31		return 0;
32
33	path = fmt("%s/%s", cgit_cache_root, cgit_query_repo);
34	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
35		return 0;
36
37	if (cgit_query_page) {
38		path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, 
39			   cgit_query_page);
40		if (mkdir(path, S_IRWXU) && errno!=EEXIST)
41			return 0;
42	}
43	return 1;
44}
45
46int cache_refill_overdue(const char *lockfile)
47{
48	struct stat st;
49
50	if (stat(lockfile, &st))
51		return 0;
52	else
53		return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
54}
55
56int cache_lock(struct cacheitem *item)
57{
58	int i = 0;
59	char *lockfile = xstrdup(fmt("%s.lock", item->name));
60
61 top:
62	if (++i > cgit_max_lock_attempts)
63		die("cache_lock: unable to lock %s: %s",
64		    item->name, strerror(errno));
65
66       	item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
67
68	if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
69		goto top;
70
71	if (item->fd == NOLOCK && errno == EEXIST &&
72	    cache_refill_overdue(lockfile) && !unlink(lockfile))
73			goto top;
74
75	free(lockfile);
76	return (item->fd > 0);
77}
78
79int cache_unlock(struct cacheitem *item)
80{
81	close(item->fd);
82	return (rename(fmt("%s.lock", item->name), item->name) == 0);
83}
84
85int cache_cancel_lock(struct cacheitem *item)
86{
87	return (unlink(fmt("%s.lock", item->name)) == 0);
88}
89
90int cache_expired(struct cacheitem *item)
91{
92	if (item->ttl < 0)
93		return 0;
94	return item->st.st_mtime + item->ttl * 60 < time(NULL);
95}