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>
diff --git a/cgit.c b/cgit.c
index d1abaa0..0f72f2d 100644
--- a/cgit.c
+++ b/cgit.c
@@ -61,13 +61,19 @@
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);
+ }
}
}