neocgit

a more 'modern' version of cgit
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commit fbaf1171b4e343929dd43ecac7cd9d1c692b84ec
parent 44923f8953c66dc9b852316b655ab3b5aec9478e
Author: Lars Hjemli <hjemli@gmail.com>
Date:   Mon, 11 Dec 2006 22:53:50 +0100

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>

Diffstat:
Mcache.c | 5+++++
Mcgit.c | 14++++++++++----
Mcgit.h | 1+
3 files changed, 16 insertions(+), 4 deletions(-)

diff --git 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 @@ -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 @@ -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);