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	if (!cgit_query_repo)
 49		return 0;
 50
 51	path = fmt("%s/%s", cgit_cache_root, cgit_query_repo);
 52	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
 53		return 0;
 54
 55	if (cgit_query_page) {
 56		path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, 
 57			   cgit_query_page);
 58		if (mkdir(path, S_IRWXU) && errno!=EEXIST)
 59			return 0;
 60	}
 61	return 1;
 62}
 63
 64int cache_refill_overdue(const char *lockfile)
 65{
 66	struct stat st;
 67
 68	if (stat(lockfile, &st))
 69		return 0;
 70	else
 71		return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
 72}
 73
 74int cache_lock(struct cacheitem *item)
 75{
 76	int i = 0;
 77	char *lockfile = xstrdup(fmt("%s.lock", item->name));
 78
 79 top:
 80	if (++i > cgit_max_lock_attempts)
 81		die("cache_lock: unable to lock %s: %s",
 82		    item->name, strerror(errno));
 83
 84       	item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
 85
 86	if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
 87		goto top;
 88
 89	if (item->fd == NOLOCK && errno == EEXIST &&
 90	    cache_refill_overdue(lockfile) && !unlink(lockfile))
 91			goto top;
 92
 93	free(lockfile);
 94	return (item->fd > 0);
 95}
 96
 97int cache_unlock(struct cacheitem *item)
 98{
 99	close(item->fd);
100	return (rename(fmt("%s.lock", item->name), item->name) == 0);
101}
102
103int cache_cancel_lock(struct cacheitem *item)
104{
105	return (unlink(fmt("%s.lock", item->name)) == 0);
106}
107
108int cache_expired(struct cacheitem *item)
109{
110	if (item->ttl < 0)
111		return 0;
112	return item->st.st_mtime + item->ttl * 60 < time(NULL);
113}