Fix cache algorithm loophole

This closes the door for unneccessary calls to cgit_fill_cache().

Noticed by Linus.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

3 files changed, 16 insertions, 11 deletions

diff --git a/cache.c b/cache.c
index b034c48..0ffa502 100644
--- a/cache.c
+++ b/cache.c
@@ -10,7 +10,7 @@
 
 const int NOLOCK = -1;
 
-int cache_lookup(struct cacheitem *item)
+void cache_prepare(struct cacheitem *item)
 {
         if (!cgit_query_repo) {
                 item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));
@@ -30,6 +30,10 @@ int cache_lookup(struct cacheitem *item)
                 else
                         item->ttl = cgit_cache_repo_ttl;
         }
+}
+
+int cache_exist(struct cacheitem *item)
+{
         if (stat(item->name, &item->st)) {
                 item->st.st_mtime = 0;
                 return 0;
diff --git a/cgit.c b/cgit.c
index 110face..7f14016 100644
--- a/cgit.c
+++ b/cgit.c
@@ -465,20 +465,20 @@ static void cgit_fill_cache(struct cacheitem *item)
 
 static void cgit_refresh_cache(struct cacheitem *item)
 {
+        cache_prepare(item);
  top:
-        if (!cache_lookup(item)) {
-                if (cache_lock(item)) {
-                        cgit_fill_cache(item);
-                        cache_unlock(item);
-                } else {
+        if (!cache_exist(item)) {
+                if (!cache_lock(item)) {
                         sched_yield();
                         goto top;
                 }
-        } else if (cache_expired(item)) {
-                if (cache_lock(item)) {
+                if (!cache_exist(item))
                         cgit_fill_cache(item);
-                        cache_unlock(item);
-                }
+                cache_unlock(item);
+        } else if (cache_expired(item) && cache_lock(item)) {
+                if (cache_expired(item))
+                        cgit_fill_cache(item);
+                cache_unlock(item);
         }
 }
 
diff --git a/cgit.h b/cgit.h
index 1e084d4..3b0994a 100644
--- a/cgit.h
+++ b/cgit.h
@@ -56,9 +56,10 @@ extern void html_link_close(void);
 
 extern int cgit_read_config(const char *filename, configfn fn);
 
-extern int cache_lookup(struct cacheitem *item);
+extern void cache_prepare(struct cacheitem *item);
 extern int cache_lock(struct cacheitem *item);
 extern int cache_unlock(struct cacheitem *item);
+extern int cache_exist(struct cacheitem *item);
 extern int cache_expired(struct cacheitem *item);
 
 #endif /* CGIT_H */