neocgit

a more 'modern' version of cgit
Log | Files | Refs | Submodules | README | LICENSE | git clone https://git.ne02ptzero.me/git/neocgit

commit 318d106300102c19d114a4ea89265b0a4060d9cb
parent a581ed8d6c15b0734b082fbadf0a907c2b170423
Author: Lars Hjemli <hjemli@gmail.com>
Date:   Mon, 11 Dec 2006 12:10:12 +0100

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>

Diffstat:
Mcache.c | 35++++++++++++++++++++++-------------
Mcgit.c | 9++++++++-
Mcgit.h | 1+
3 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/cache.c b/cache.c @@ -61,26 +61,35 @@ int cache_create_dirs() 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 ret; + int i = 0; char *lockfile = fmt("%s.lock", item->name); - top: - item->fd = open(lockfile, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR|S_IWUSR); + 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) { - struct stat st; - time_t t; - if (stat(lockfile, &st)) - return ret; - t = time(NULL); - if (t-st.st_mtime > cgit_cache_max_create_time && - !unlink(lockfile)) + + if (item->fd == NOLOCK && errno == EEXIST && + cache_refill_overdue(lockfile) && !unlink(lockfile)) goto top; - return 0; - } + return (item->fd > 0); } diff --git a/cgit.c b/cgit.c @@ -31,6 +31,7 @@ char *cgit_virtual_root = NULL; char *cgit_cache_root = "/var/cache/cgit"; +int cgit_max_lock_attempts = 5; int cgit_cache_root_ttl = 5; int cgit_cache_repo_ttl = 5; int cgit_cache_dynamic_ttl = 5; @@ -465,11 +466,17 @@ static void cgit_fill_cache(struct cacheitem *item) static void cgit_refresh_cache(struct cacheitem *item) { + int i = 0; + cache_prepare(item); top: + if (++i > cgit_max_lock_attempts) { + die("cgit_refresh_cache: unable to lock %s: %s", + item->name, strerror(errno)); + } if (!cache_exist(item)) { if (!cache_lock(item)) { - sched_yield(); + sleep(1); goto top; } if (!cache_exist(item)) diff --git a/cgit.h b/cgit.h @@ -23,6 +23,7 @@ extern char *cgit_logo_link; extern char *cgit_virtual_root; extern char *cgit_cache_root; +extern int cgit_max_lock_attempts; extern int cgit_cache_root_ttl; extern int cgit_cache_repo_ttl; extern int cgit_cache_dynamic_ttl;