cgitsb/cache.c
Lars Hjemli 318d106300 Avoid infinite loops in caching layer
Add a global variable, cgit_max_lock_attemps, to avoid the possibility of
infinite loops when failing to acquire a lockfile. This could happen on
broken setups or under crazy server load.

Incidentally, this also fixes a lurking bug in cache_lock() where an
uninitialized returnvalue was used.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
2006-12-11 12:10:12 +01:00

108 rader
2.3 KiB
C

/* cache.c: cache management
*
* Copyright (C) 2006 Lars Hjemli
*
* Licensed under GNU General Public License v2
* (see COPYING for full license text)
*/
#include "cgit.h"
const int NOLOCK = -1;
void cache_prepare(struct cacheitem *item)
{
if (!cgit_query_repo) {
item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));
item->ttl = cgit_cache_root_ttl;
} else if (!cgit_query_page) {
item->name = xstrdup(fmt("%s/%s/index.html", cgit_cache_root,
cgit_query_repo));
item->ttl = cgit_cache_repo_ttl;
} else {
item->name = xstrdup(fmt("%s/%s/%s/%s.html", cgit_cache_root,
cgit_query_repo, cgit_query_page,
cgit_querystring));
if (cgit_query_has_symref)
item->ttl = cgit_cache_dynamic_ttl;
else if (cgit_query_has_sha1)
item->ttl = cgit_cache_static_ttl;
else
item->ttl = cgit_cache_repo_ttl;
}
}
int cache_exist(struct cacheitem *item)
{
if (stat(item->name, &item->st)) {
item->st.st_mtime = 0;
return 0;
}
return 1;
}
int cache_create_dirs()
{
char *path;
if (!cgit_query_repo)
return 0;
path = fmt("%s/%s", cgit_cache_root, cgit_query_repo);
if (mkdir(path, S_IRWXU) && errno!=EEXIST)
return 0;
if (cgit_query_page) {
path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo,
cgit_query_page);
if (mkdir(path, S_IRWXU) && errno!=EEXIST)
return 0;
}
return 1;
}
int cache_refill_overdue(const char *lockfile)
{
struct stat st;
if (stat(lockfile, &st))
return 0;
else
return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
}
int cache_lock(struct cacheitem *item)
{
int i = 0;
char *lockfile = fmt("%s.lock", item->name);
top:
if (++i > cgit_max_lock_attempts)
die("cache_lock: unable to lock %s: %s",
item->name, strerror(errno));
item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
goto top;
if (item->fd == NOLOCK && errno == EEXIST &&
cache_refill_overdue(lockfile) && !unlink(lockfile))
goto top;
return (item->fd > 0);
}
int cache_unlock(struct cacheitem *item)
{
close(item->fd);
return (rename(fmt("%s.lock", item->name), item->name) == 0);
}
int cache_expired(struct cacheitem *item)
{
if (item->ttl < 0)
return 0;
return item->st.st_mtime + item->ttl * 60 < time(NULL);
}