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
 13void cache_prepare(struct cacheitem *item)
 14{
 15	if (!cgit_query_repo) {
 16		item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));
 17		item->ttl = cgit_cache_root_ttl;
 18	} else if (!cgit_query_page) {
 19		item->name = xstrdup(fmt("%s/%s/index.html", cgit_cache_root, 
 20			   cgit_query_repo));
 21		item->ttl = cgit_cache_repo_ttl;
 22	} else {
 23		item->name = xstrdup(fmt("%s/%s/%s/%s.html", cgit_cache_root, 
 24			   cgit_query_repo, cgit_query_page, 
 25			   cgit_querystring));
 26		if (cgit_query_has_symref)
 27			item->ttl = cgit_cache_dynamic_ttl;
 28		else if (cgit_query_has_sha1)
 29			item->ttl = cgit_cache_static_ttl;
 30		else
 31			item->ttl = cgit_cache_repo_ttl;
 32	}
 33}
 34
 35int cache_exist(struct cacheitem *item)
 36{
 37	if (stat(item->name, &item->st)) {
 38		item->st.st_mtime = 0;
 39		return 0;
 40	}
 41	return 1;
 42}
 43
 44int cache_create_dirs()
 45{
 46	char *path;
 47
 48	path = fmt("%s", cgit_cache_root);
 49	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
 50		return 0;
 51
 52	if (!cgit_query_repo)
 53		return 0;
 54
 55	path = fmt("%s/%s", cgit_cache_root, cgit_query_repo);
 56	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
 57		return 0;
 58
 59	if (cgit_query_page) {
 60		path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, 
 61			   cgit_query_page);
 62		if (mkdir(path, S_IRWXU) && errno!=EEXIST)
 63			return 0;
 64	}
 65	return 1;
 66}
 67
 68int cache_refill_overdue(const char *lockfile)
 69{
 70	struct stat st;
 71
 72	if (stat(lockfile, &st))
 73		return 0;
 74	else
 75		return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
 76}
 77
 78int cache_lock(struct cacheitem *item)
 79{
 80	int i = 0;
 81	char *lockfile = xstrdup(fmt("%s.lock", item->name));
 82
 83 top:
 84	if (++i > cgit_max_lock_attempts)
 85		die("cache_lock: unable to lock %s: %s",
 86		    item->name, strerror(errno));
 87
 88       	item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
 89
 90	if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
 91		goto top;
 92
 93	if (item->fd == NOLOCK && errno == EEXIST &&
 94	    cache_refill_overdue(lockfile) && !unlink(lockfile))
 95			goto top;
 96
 97	free(lockfile);
 98	return (item->fd > 0);
 99}
100
101int cache_unlock(struct cacheitem *item)
102{
103	close(item->fd);
104	return (rename(fmt("%s.lock", item->name), item->name) == 0);
105}
106
107int cache_cancel_lock(struct cacheitem *item)
108{
109	return (unlink(fmt("%s.lock", item->name)) == 0);
110}
111
112int cache_expired(struct cacheitem *item)
113{
114	if (item->ttl < 0)
115		return 0;
116	return item->st.st_mtime + item->ttl * 60 < time(NULL);
117}