1 files changed, 291 insertions, 68 deletions

diff --git a/cache.c b/cache.c
index 89f7ecd..e590d7b 100644
--- a/cache.c
+++ b/cache.c
@@ -4,117 +4,340 @@
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
+ *
+ *
+ * The cache is just a directory structure where each file is a cache slot,
+ * and each filename is based on the hash of some key (e.g. the cgit url).
+ * Each file contains the full key followed by the cached content for that
+ * key.
+ *
  */
 
 #include "cgit.h"
 #include "cache.h"
 
-const int NOLOCK = -1;
+#define CACHE_BUFSIZE (1024 * 4)
+
+struct cache_slot {
+        const char *key;
+        int keylen;
+        int ttl;
+        cache_fill_fn fn;
+        void *cbdata;
+        int cache_fd;
+        int lock_fd;
+        const char *cache_name;
+        const char *lock_name;
+        int match;
+        struct stat cache_st;
+        struct stat lock_st;
+        int bufsize;
+        char buf[CACHE_BUFSIZE];
+};
 
-char *cache_safe_filename(const char *unsafe)
+/* Open an existing cache slot and fill the cache buffer with
+ * (part of) the content of the cache file. Return 0 on success
+ * and errno otherwise.
+ */
+static int open_slot(struct cache_slot *slot)
 {
-        static char buf[4][PATH_MAX];
-        static int bufidx;
-        char *s;
-        char c;
-
-        bufidx++;
-        bufidx &= 3;
-        s = buf[bufidx];
-
-        while(unsafe && (c = *unsafe++) != 0) {
-                if (c == '/' || c == ' ' || c == '&' || c == '|' ||
-                    c == '>' || c == '<' || c == '.')
-                        c = '_';
-                *s++ = c;
-        }
-        *s = '\0';
-        return buf[bufidx];
+        char *bufz;
+        int bufkeylen = -1;
+
+        slot->cache_fd = open(slot->cache_name, O_RDONLY);
+        if (slot->cache_fd == -1)
+                return errno;
+
+        if (fstat(slot->cache_fd, &slot->cache_st))
+                return errno;
+
+        slot->bufsize = read(slot->cache_fd, slot->buf, sizeof(slot->buf));
+        if (slot->bufsize == 0)
+                return errno;
+
+        bufz = memchr(slot->buf, 0, slot->bufsize);
+        if (bufz)
+                bufkeylen = bufz - slot->buf;
+
+        slot->match = bufkeylen == slot->keylen &&
+            !memcmp(slot->key, slot->buf, bufkeylen + 1);
+
+        return 0;
 }
 
-int cache_exist(struct cacheitem *item)
+/* Close the active cache slot */
+static void close_slot(struct cache_slot *slot)
 {
-        if (stat(item->name, &item->st)) {
-                item->st.st_mtime = 0;
-                return 0;
+        if (slot->cache_fd > 0) {
+                close(slot->cache_fd);
+                slot->cache_fd = -1;
         }
-        return 1;
 }
 
-int cache_create_dirs()
+/* Print the content of the active cache slot (but skip the key). */
+static int print_slot(struct cache_slot *slot)
 {
-        char *path;
+        ssize_t i, j = 0;
+
+        i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET);
+        if (i != slot->keylen + 1)
+                return errno;
 
-        path = fmt("%s", ctx.cfg.cache_root);
-        if (mkdir(path, S_IRWXU) && errno!=EEXIST)
+        while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0)
+                j = write(STDOUT_FILENO, slot->buf, i);
+
+        if (j < 0)
+                return errno;
+        else
                 return 0;
+}
 
-        if (!ctx.repo)
+/* Check if the slot has expired */
+static int is_expired(struct cache_slot *slot)
+{
+        if (slot->ttl < 0)
                 return 0;
+        else
+                return slot->cache_st.st_mtime + slot->ttl*60 < time(NULL);
+}
 
-        path = fmt("%s/%s", ctx.cfg.cache_root,
-                   cache_safe_filename(ctx.repo->url));
+/* Check if the slot has been modified since we opened it.
+ * NB: If stat() fails, we pretend the file is modified.
+ */
+static int is_modified(struct cache_slot *slot)
+{
+        struct stat st;
 
-        if (mkdir(path, S_IRWXU) && errno!=EEXIST)
-                return 0;
+        if (stat(slot->cache_name, &st))
+                return 1;
+        return (st.st_ino != slot->cache_st.st_ino ||
+                st.st_mtime != slot->cache_st.st_mtime ||
+                st.st_size != slot->cache_st.st_size);
+}
 
-        if (ctx.qry.page) {
-                path = fmt("%s/%s/%s", ctx.cfg.cache_root,
-                           cache_safe_filename(ctx.repo->url),
-                           ctx.qry.page);
-                if (mkdir(path, S_IRWXU) && errno!=EEXIST)
-                        return 0;
+/* Close an open lockfile */
+static void close_lock(struct cache_slot *slot)
+{
+        if (slot->lock_fd > 0) {
+                close(slot->lock_fd);
+                slot->lock_fd = -1;
         }
-        return 1;
 }
 
-int cache_refill_overdue(const char *lockfile)
+/* Create a lockfile used to store the generated content for a cache
+ * slot, and write the slot key + \0 into it.
+ * Returns 0 on success and errno otherwise.
+ */
+static int lock_slot(struct cache_slot *slot)
 {
-        struct stat st;
+        slot->lock_fd = open(slot->lock_name, O_RDWR|O_CREAT|O_EXCL,
+                             S_IRUSR|S_IWUSR);
+        if (slot->lock_fd == -1)
+                return errno;
+        write(slot->lock_fd, slot->key, slot->keylen + 1);
+        return 0;
+}
 
-        if (stat(lockfile, &st))
-                return 0;
+/* Release the current lockfile. If `replace_old_slot` is set the
+ * lockfile replaces the old cache slot, otherwise the lockfile is
+ * just deleted.
+ */
+static int unlock_slot(struct cache_slot *slot, int replace_old_slot)
+{
+        int err;
+
+        if (replace_old_slot)
+                err = rename(slot->lock_name, slot->cache_name);
         else
-                return (time(NULL) - st.st_mtime > ctx.cfg.cache_max_create_time);
+                err = unlink(slot->lock_name);
+        return err;
 }
 
-int cache_lock(struct cacheitem *item)
+/* Generate the content for the current cache slot by redirecting
+ * stdout to the lock-fd and invoking the callback function
+ */
+static int fill_slot(struct cache_slot *slot)
 {
-        int i = 0;
-        char *lockfile = xstrdup(fmt("%s.lock", item->name));
+        int tmp;
 
- top:
-        if (++i > ctx.cfg.max_lock_attempts)
+        /* Preserve stdout */
+        tmp = dup(STDOUT_FILENO);