diff options
| author | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 22:53:50 +0100 |
|---|---|---|
| committer | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 22:53:50 +0100 |
| commit | fbaf1171b4e343929dd43ecac7cd9d1c692b84ec (patch) | |
| tree | 40b7007b2e1e85f2e91e052b33555df2e9fb5e14 | |
| parent | 44923f8953c66dc9b852316b655ab3b5aec9478e (diff) | |
Don't truncate valid cachefiles
An embarrassing thinko in cgit_check_cache() would truncate valid cachefiles
in the following situation:
1) process A notices a missing/expired cachefile
2) process B gets scheduled, locks, fills and unlocks the cachefile
3) process A gets scheduled, locks the cachefile, notices that the cachefile
now exist/is not expired anymore, and continues to overwrite it with an
empty lockfile.
Thanks to Linus for noticing (again).
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
| -rw-r--r-- | cache.c | 5 | ||||
| -rw-r--r-- | cgit.c | 14 | ||||
| -rw-r--r-- | cgit.h | 1 |
3 files changed, 16 insertions, 4 deletions
diff --git a/cache.c b/cache.c index 2e1ef8c..b947a34 100644 --- a/cache.c +++ b/cache.c @@ -99,6 +99,11 @@ int cache_unlock(struct cacheitem *item) return (rename(fmt("%s.lock", item->name), item->name) == 0); } +int cache_cancel_lock(struct cacheitem *item) +{ + return (unlink(fmt("%s.lock", item->name)) == 0); +} + int cache_expired(struct cacheitem *item) { if (item->ttl < 0) diff --git a/cgit.c b/cgit.c index d1abaa0..0f72f2d 100644 --- a/cgit.c +++ b/cgit.c @@ -61,13 +61,19 @@ static void cgit_check_cache(struct cacheitem *item) sleep(1); goto top; } - if (!cache_exist(item)) + if (!cache_exist(item)) { cgit_fill_cache(item); - cache_unlock(item); + cache_unlock(item); + } else { + cache_cancel_lock(item); + } } else if (cache_expired(item) && cache_lock(item)) { - if (cache_expired(item)) + if (cache_expired(item)) { cgit_fill_cache(item); - cache_unlock(item); + cache_unlock(item); + } else { + cache_cancel_lock(item); + } } } diff --git a/cgit.h b/cgit.h index c1dcc97..c9554a7 100644 --- a/cgit.h +++ b/cgit.h @@ -66,6 +66,7 @@ extern int cgit_parse_query(char *txt, configfn fn); extern void cache_prepare(struct cacheitem *item); extern int cache_lock(struct cacheitem *item); extern int cache_unlock(struct cacheitem *item); +extern int cache_cancel_lock(struct cacheitem *item); extern int cache_exist(struct cacheitem *item); extern int cache_expired(struct cacheitem *item); |