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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>
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parent
a581ed8d6c
commit
318d106300
35
cache.c
35
cache.c
@ -61,26 +61,35 @@ int cache_create_dirs()
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return 1;
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}
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int cache_refill_overdue(const char *lockfile)
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{
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struct stat st;
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if (stat(lockfile, &st))
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return 0;
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else
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return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
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}
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int cache_lock(struct cacheitem *item)
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{
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int ret;
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int i = 0;
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char *lockfile = fmt("%s.lock", item->name);
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top:
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item->fd = open(lockfile, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR|S_IWUSR);
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top:
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if (++i > cgit_max_lock_attempts)
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die("cache_lock: unable to lock %s: %s",
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item->name, strerror(errno));
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item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
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if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
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goto top;
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if (item->fd == NOLOCK && errno == EEXIST) {
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struct stat st;
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time_t t;
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if (stat(lockfile, &st))
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return ret;
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t = time(NULL);
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if (t-st.st_mtime > cgit_cache_max_create_time &&
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!unlink(lockfile))
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if (item->fd == NOLOCK && errno == EEXIST &&
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cache_refill_overdue(lockfile) && !unlink(lockfile))
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goto top;
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return 0;
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}
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return (item->fd > 0);
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}
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9
cgit.c
9
cgit.c
@ -31,6 +31,7 @@ char *cgit_virtual_root = NULL;
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char *cgit_cache_root = "/var/cache/cgit";
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int cgit_max_lock_attempts = 5;
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int cgit_cache_root_ttl = 5;
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int cgit_cache_repo_ttl = 5;
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int cgit_cache_dynamic_ttl = 5;
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@ -465,11 +466,17 @@ static void cgit_fill_cache(struct cacheitem *item)
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static void cgit_refresh_cache(struct cacheitem *item)
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{
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int i = 0;
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cache_prepare(item);
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top:
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if (++i > cgit_max_lock_attempts) {
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die("cgit_refresh_cache: unable to lock %s: %s",
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item->name, strerror(errno));
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}
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if (!cache_exist(item)) {
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if (!cache_lock(item)) {
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sched_yield();
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sleep(1);
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goto top;
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}
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if (!cache_exist(item))
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