Merge branch 'lh/cache'

* lh/cache:
  Add page 'ls_cache'
  Redesign the caching layer

7 files changed, 506 insertions, 216 deletions

diff --git a/cache.c b/cache.c
index 89f7ecd..b701e13 100644
--- a/cache.c
+++ b/cache.c
@@ -4,117 +4,408 @@
  *
  * 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)
 
-char *cache_safe_filename(const char *unsafe)
+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];
+};
+
+/* 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;
+
+	while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0)
+		j = write(STDOUT_FILENO, slot->buf, i);
 
-	path = fmt("%s", ctx.cfg.cache_root);
-	if (mkdir(path, S_IRWXU) && errno!=EEXIST)
+	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)
-		die("cache_lock: unable to lock %s: %s",
-		    item->name, strerror(errno));
+	/* Preserve stdout */
+	tmp = dup(STDOUT_FILENO);
+	if (tmp == -1)
+		return errno;
 
-       	item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
+	/* Redirect stdout to lockfile */
+	if (dup2(slot->lock_fd, STDOUT_FILENO) == -1)
+		return errno;
 
-	if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
-		goto top;
+	/* Generate cache content */
+	slot->fn(slot->cbdata);
 
-	if (item->fd == NOLOCK && errno == EEXIST &&
-	    cache_refill_overdue(lockfile) && !unlink(lockfile))
-			goto top;
+	/* Restore stdout */
+	if (dup2(tmp, STDOUT_FILENO) == -1)
+		return errno;
 
-	free(lockfile);
-	return (item->fd > 0);
+	/* Close the temporary filedescriptor */
+	close(tmp);
+	return 0;
 }
 
-int cache_unlock(struct cacheitem *item)
+/* Crude implementation of 32-bit FNV-1 hash algorithm,
+ * see http://www.isthe.com/chongo/tech/comp/fnv/ for details
+ * about the magic numbers.
+ */
+#define FNV_OFFSET 0x811c9dc5
+#define FNV_PRIME  0x01000193
+
+unsigned long hash_str(const char *str)
 {
-	close(item->fd);
-	return (rename(fmt("%s.lock", item->name), item->name) == 0);
+	unsigned long h = FNV_OFFSET;
+	unsigned char *s = (unsigned char *)str;
+
+	if (!s)
+		return h;
+
+	while(*s) {
+		h *= FNV_PRIME;
+		h ^= *s++;
+	}
+	return h;
 }
 
-int cache_cancel_lock(struct cacheitem *item)
+static int process_slot(struct cache_slot *slot)
 {
-	return (unlink(fmt("%s.lock", item->name)) == 0);
+	int err;
+
+	err = open_slot(slot);
+	if (!err && slot->match) {
+		if (is_expired(slot)) {
+			if (!lock_slot(slot)) {
+				/* If the cachefile has been replaced between
+				 * `open_slot` and `lock_slot`, we'll just
+				 * serve the stale content from the original
+				 * cachefile. This way we avoid pruning the
+				 * newly generated slot. The same code-path
+				 * is chosen if fill_slot() fails for some
+				 * reason.
+				 *
+				 * TODO? check if the new slot contains the
+				 * same key as the old one, since we would
+				 * prefer to serve the newest content.
+				 * This will require us to open yet another
+				 * file-descriptor and read and compare the
+				 * key from the new file, so for now we're
+				 * lazy and just ignore the new file.
+				 */
+				if (is_modified(slot) || fill_slot(slot)) {
+					unlock_slot(slot, 0);
+					close_lock(slot);
+				} else {
+					close_slot(slot);
+					unlock_slot(slot, 1);
+					slot->cache_fd = slot->lock_fd;
+				}
+			}
+		}
+		print_slot(slot);
+		close_slot(slot);
+		return 0;
+	}
+
+	/* If the cache slot does not exist (or its key doesn't match the
+	 * current key), lets try to create a new cache slot for this
+	 * request. If this fails (for whatever reason), lets just generate
+	 * the content without caching it and fool the caller to belive
+	 * everything worked out (but print a warning on stdout).
+	 */
+
+	close_slot(slot);
+	if ((err = lock_slot(slot)) != 0) {
+		cache_log("[cgit] Unable to lock slot %s: %s (%d)\n",
+			  slot->lock_name, strerror(err), err);
+		slot->fn(slot->cbdata);
+		return 0;
+	}
+
+	if ((err = fill_slot(slot)) != 0) {
+		cache_log("[cgit] Unable to fill slot %s: %s (%d)\n",
+			  slot->lock_name, strerror(err), err);
+		unlock_slot(slot, 0);
+		close_lock(slot);
+		slot->fn(slot->cbdata);
+		return 0;
+	}
+	// We've got a valid cache slot in the lock file, which
+	// is about to replace the old cache slot. But if we
+	// release the lockfile and then try to open the new cache
+	// slot, we might get a race condition with a concurrent
+	// writer for the same cache slot (with a different key).
+	// Lets avoid such a race by just printing the content of
+	// the lock file.
+	slot->cache_fd = slot->lock_fd;
+	unlock_slot(slot, 1);
+	err = print_slot(slot);
+	close_slot(slot);
+	return err;
 }
 
-int cache_expired(struct cacheitem *item)
+/* Print cached content to stdout, generate the content if necessary. */
+int cache_process(int size, const char *path, const char *key, int ttl,
+		  cache_fill_fn fn, void *cbdata)
 {
-	if (item->ttl < 0)
+	unsigned long hash;
+	int len, i;
+	char filename[1024];
+	char lockname[1024 + 5];  /* 5 = ".lock" */
+	struct cache_slot slot;
+
+	/* If the cache is disabled, just generate the content */
+	if (size <= 0) {
+		fn(cbdata);
+		return 0;
+	}
+
+	/* Verify input, calculate filenames */
+	if (!path) {
+		cache_log("[cgit] Cache path not specified, caching is disabled\n");
+		fn(cbdata);
 		return 0;
-	return item->st.st_mtime + item->ttl * 60 < time(NULL);
+	}
+	len = strlen(path);
+	if (len > sizeof(filename) - 10) { /* 10 = "/01234567\0" */
+		cache_log("[cgit] Cache path too long, caching is disabled: %s\n",
+			  path);
+		fn(cbdata);
+		return 0;
+	}
+	if (!key)
+		key = "";
+	hash = hash_str(key) % size;
+	strcpy(filename, path);
+	if (filename[len - 1] != '/')
+		filename[len++] = '/';
+	for(i = 0; i < 8; i++) {
+		sprintf(filename + len++, "%x",
+			(unsigned char)(hash & 0xf));
+		hash >>= 4;
+	}
+	filename[len] = '\0';
+	strcpy(lockname, filename);
+	strcpy(lockname + len, ".lock");
+	slot.fn = fn;
+	slot.cbdata = cbdata;
+	slot.ttl = ttl;
+	slot.cache_name = filename;
+	slot.lock_name = lockname;
+	slot.key = key;
+	slot.keylen = strlen(key);
+	return process_slot(&slot);
 }
+
+/* Return a strftime formatted date/time
+ * NB: the result from this function is to shared memory
+ */
+char *sprintftime(const char *format, time_t time)
+{
+	static char buf[64];
+	struct tm *tm;
+
+	if (!time)
+		return NULL;
+	tm = gmtime(&time);
+	strftime(buf, sizeof(buf)-1, format, tm);
+	return buf;
+}
+
+int cache_ls(const char *path)
+{
+	DIR *dir;
+	struct dirent *ent;
+	int err = 0;
+	struct cache_slot slot;
+	char fullname[1024];
+	char *name;
+
+	if (!path) {
+		cache_log("[cgit] cache path not specified\n");
+		return -1;
+	}
+	if (strlen(path) > 1024 - 10) {
+		cache_log("[cgit] cache path too long: %s\n",
+			  path);
+		return -1;
+	}
+	dir = opendir(path);
+	if (!dir) {
+		err = errno;
+		cache_log("[cgit] unable to open path %s: %s (%d)\n",
+			  path, strerror(err), err);
+		return err;
+	}
+	strcpy(fullname, path);
+	name = fullname + strlen(path);
+	if (*(name - 1) != '/') {
+		*name++ = '/';
+		*name = '\0';
+	}
+	slot.cache_name = fullname;
+	while((ent = readdir(dir)) != NULL) {
+		if (strlen(ent->d_name) != 8)
+			continue;
+		strcpy(name, ent->d_name);
+		if ((err = open_slot(&slot)) != 0) {
+			cache_log("[cgit] unable to open path %s: %s (%d)\n",
+				  fullname, strerror(err), err);
+			continue;
+		}
+		printf("%s %s %10lld %s\n",
+		       name,
+		       sprintftime("%Y-%m-%d %H:%M:%S",
+				   slot.cache_st.st_mtime),
+		       slot.cache_st.st_size,
+		       slot.buf);
+		close_slot(&slot);
+	}
+	closedir(dir);
+	return 0;
+}
+
+/* Print a message to stdout */
+void cache_log(const char *format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	vfprintf(stderr, format, args);
+	va_end(args);
+}
+
diff --git a/cache.h b/cache.h
index 4dcbea3..66cc41f 100644
--- a/cache.h
+++ b/cache.h
@@ -6,18 +6,30 @@
 #ifndef CGIT_CACHE_H
 #define CGIT_CACHE_H
 
-struct cacheitem {
-	char *name;
-	struct stat st;
-	int ttl;
-	int fd;
-};
-
-extern char *cache_safe_filename(const char *unsafe);
-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);
+typedef void (*cache_fill_fn)(void *cbdata);
+
+
+/* Print cached content to stdout, generate the content if necessary.
+ *
+ * Parameters
+ *   size    max number of cache files
+ *   path    directory used to store cache files
+ *   key     the key used to lookup cache files
+ *   ttl     max cache time in seconds for this key
+ *   fn      content generator function for this key
+ *   cbdata  user-supplied data to the content generator function
+ *
+ * Return value
+ *   0 indicates success, everyting else is an error
+ */
+extern int cache_process(int size, const char *path, const char *key, int ttl,
+			 cache_fill_fn fn, void *cbdata);
+
+
+/* List info about all cache entries on stdout */
+extern int cache_ls(const char *path);
+
+/* Print a message to stdout */
+extern void cache_log(const char *format, ...);
 
 #endif /* CGIT_CACHE_H */
diff --git a/cgit.c b/cgit.c
index a402758..ccd61f4 100644
--- a/cgit.c
+++ b/cgit.c
@@ -49,6 +49,8 @@ void config_cb(const char *name, const char *value)
 		ctx.cfg.enable_log_filecount = atoi(value);
 	else if (!strcmp(name, "enable-log-linecount"))
 		ctx.cfg.enable_log_linecount = atoi(value);
+	else if (!strcmp(name, "cache-size"))
+		ctx.cfg.cache_size = atoi(value);
 	else if (!strcmp(name, "cache-root"))
 		ctx.cfg.cache_root = xstrdup(value);
 	else if (!strcmp(name, "cache-root-ttl"))
@@ -147,6 +149,8 @@ static void prepare_context(struct cgit_context *ctx)
 {
 	memset(ctx, 0, sizeof(ctx));
 	ctx->cfg.agefile = "info/web/last-modified";
+	ctx->cfg.nocache = 0;
+	ctx->cfg.cache_size = 0;
 	ctx->cfg.cache_dynamic_ttl = 5;
 	ctx->cfg.cache_max_create_time = 5;
 	ctx->cfg.cache_repo_ttl = 5;
@@ -168,47 +172,8 @@ static void prepare_context(struct cgit_context *ctx)
 	ctx->page.mimetype = "text/html";
 	ctx->page.charset = PAGE_ENCODING;
 	ctx->page.filename = NULL;
-}
-
-static int cgit_prepare_cache(struct cacheitem *item)
-{
-	if (!ctx.repo && ctx.qry.repo) {
-		ctx.page.title = fmt("%s - %s", ctx.cfg.root_title,
-				      "Bad request");
-		cgit_print_http_headers(&ctx);
-		cgit_print_docstart(&ctx);
-		cgit_print_pageheader(&ctx);
-		cgit_print_error(fmt("Unknown repo: %s", ctx.qry.repo));
-		cgit_print_docend();
-		return 0;
-	}
-
-	if (!ctx.repo) {
-		item->name = xstrdup(fmt("%s/index.%s.html",
-					 ctx.cfg.cache_root,
-					 cache_safe_filename(ctx.qry.raw)));
-		item->ttl = ctx.cfg.cache_root_ttl;
-		return 1;
-	}
-
-	if (!ctx.qry.page) {
-		item->name = xstrdup(fmt("%s/%s/index.%s.html", ctx.cfg.cache_root,
-					 cache_safe_filename(ctx.repo->url),
-					 cache_safe_filename(ctx.qry.raw)));
-		item->ttl = ctx.cfg.cache_repo_ttl;
-	} else {
-		item->name = xstrdup(fmt("%s/%s/%s/%s.html", ctx.cfg.cache_root,
-					 cache_safe_filename(ctx.repo->url),
-					 ctx.qry.page,
-					 cache_safe_filename(ctx.qry.raw)));
-		if (ctx.qry.has_symref)
-			item->ttl = ctx.cfg.cache_dynamic_ttl;
-		else if (ctx.qry.has_sha1)
-			item->ttl = ctx.cfg.cache_static_ttl;
-		else
-			item->ttl = ctx.cfg.cache_repo_ttl;
-	}
-	return 1;
+	ctx->page.modified = time(NULL);
+	ctx->page.expires = ctx->page.modified;
 }
 
 struct refmatch {
@@ -293,8 +258,9 @@ static int prepare_repo_cmd(struct cgit_context *ctx)
 	return 0;
 }
 
-static void process_request(struct cgit_context *ctx)
+static void process_request(void *cbdata)
 {
+	struct cgit_context *ctx = cbdata;
 	struct cgit_cmd *cmd;
 
 	cmd = cgit_get_cmd(ctx);
@@ -333,82 +299,6 @@ static void process_request(struct cgit_context *ctx)
 		cgit_print_docend();
 }
 
-static long ttl_seconds(long ttl)
-{
-	if (ttl<0)
-		return 60 * 60 * 24 * 365;
-	else
-		return ttl * 60;
-}
-
-static void cgit_fill_cache(struct cacheitem *item, int use_cache)
-{
-	int stdout2;
-
-	if (use_cache) {
-		stdout2 = chk_positive(dup(STDOUT_FILENO),
-				       "Preserving STDOUT");
-		chk_zero(close(STDOUT_FILENO), "Closing STDOUT");
-		chk_positive(dup2(item->fd, STDOUT_FILENO), "Dup2(cachefile)");
-	}
-
-	ctx.page.modified = time(NULL);
-	ctx.page.expires = ctx.page.modified + ttl_seconds(item->ttl);
-	process_request(&ctx);
-
-	if (use_cache) {
-		chk_zero(close(STDOUT_FILENO), "Close redirected STDOUT");
-		chk_positive(dup2(stdout2, STDOUT_FILENO),
-			     "Restoring original STDOUT");
-		chk_zero(close(stdout2), "Closing temporary STDOUT");
-	}
-}
-
-static void cgit_check_cache(struct cacheitem *item)
-{
-	int i = 0;
-
- top:
-	if (++i > ctx.cfg.max_lock_attempts) {
-		die("cgit_refresh_cache: unable to lock %s: %s",
-		    item->name, strerror(errno));
-	}
-	if (!cache_exist(item)) {
-		if (!cache_lock(item)) {
-			sleep(1);
-			goto top;
-		}
-		if (!cache_exist(item)) {
-			cgit_fill_cache(item, 1);
-			cache_unlock(item);
-		} else {
-			cache_cancel_lock(item);
-		}
-	} else if (cache_expired(item) && cache_lock(item)) {
-		if (cache_expired(item)) {
-			cgit_fill_cache(item, 1);
-			cache_unlock(item);
-		} else {
-			cache_cancel_lock(item);
-		}
-	}
-}
-
-static void cgit_print_cache(struct cacheitem *item)
-{
-	static char buf[4096];
-	ssize_t i;
-
-	int fd = open(item->name, O_RDONLY);
-	if (fd<0)
-		die("Unable to open cached file %s", item->name);
-
-	while((i=read(fd, buf, sizeof(buf))) > 0)
-		write(STDOUT_FILENO, buf, i);
-
-	close(fd);
-}
-
 static void cgit_parse_args(int argc, const char **argv)
 {
 	int i;
@@ -443,13 +333,29 @@ static void cgit_parse_args(int argc, const char **argv)
 	}
 }
 
+static int calc_ttl()
+{
+	if (!ctx.repo)
+		return ctx.cfg.cache_root_ttl;
+
+	if (!ctx.qry.page)
+		return ctx.cfg.cache_repo_ttl;
+
+	if (ctx.qry.has_symref)
+		return ctx.cfg.cache_dynamic_ttl;
+
+	if (ctx.qry.has_sha1)
+		return ctx.cfg.cache_static_ttl;
+
+	return ctx.cfg.cache_repo_ttl;
+}
+
 int main(int argc, const char **argv)
 {
-	struct cacheitem item;
 	const char *cgit_config_env = getenv("CGIT_CONFIG");
+	int err, ttl;
 
 	prepare_context(&ctx);
-	item.st.st_mtime = time(NULL);
 	cgit_repolist.length = 0;
 	cgit_repolist.count = 0;
 	cgit_repolist.repos = NULL;
@@ -463,13 +369,15 @@ int main(int argc, const char **argv)
 		ctx.qry.raw = xstrdup(getenv("QUERY_STRING"));
 	cgit_parse_args(argc, argv);
 	http_parse_querystring(ctx.qry.raw, querystring_cb);
-	if (!cgit_prepare_cache(&item))
-		return 0;
-	if (ctx.cfg.nocache) {
-		cgit_fill_cache(&item, 0);
-	} else {
-		cgit_check_cache(&item);
-		cgit_print_cache(&item);
-	}
-	return 0;
+
+	ttl = calc_ttl();
+	ctx.page.expires += ttl*60;
+	if (ctx.cfg.nocache)
+		ctx.cfg.cache_size = 0;
+	err = cache_process(ctx.cfg.cache_size, ctx.cfg.cache_root,
+			    ctx.qry.raw, ttl, process_request, &ctx);
+	if (err)
+		cache_log("[cgit] error %d - %s\n",
+			  err, strerror(err));
+	return err;
 }
diff --git a/cgit.h b/cgit.h
index daebeff..bbb404e 100644
--- a/cgit.h
+++ b/cgit.h
@@ -136,6 +136,7 @@ struct cgit_config {
 	char *root_readme;
 	char *script_name;
 	char *virtual_root;
+	int cache_size;
 	int cache_dynamic_ttl;
 	int cache_max_create_time;
 	int cache_repo_ttl;
diff --git a/cmd.c b/cmd.c
index 6cc91e6..4edca6b 100644
--- a/cmd.c
+++ b/cmd.c
@@ -8,6 +8,8 @@
 
 #include "cgit.h"
 #include "cmd.h"
+#include "cache.h"
+#include "ui-shared.h"
 #include "ui-blob.h"
 #include "ui-commit.h"
 #include "ui-diff.h"
@@ -43,17 +45,25 @@ static void diff_fn(struct cgit_context *ctx)
 	cgit_print_diff(ctx->qry.sha1, ctx->qry.sha2, ctx->qry.path);
 }
 
-static void repolist_fn(struct cgit_context *ctx)
-{
-	cgit_print_repolist();
-}
-
 static void log_fn(struct cgit_context *ctx)
 {
 	cgit_print_log(ctx->qry.sha1, ctx->qry.ofs, ctx->cfg.max_commit_count,
 		       ctx->qry.grep, ctx->qry.search, ctx->qry.path, 1);
 }
 
+static void ls_cache_fn(struct cgit_context *ctx)
+{
+	ctx->page.mimetype = "text/plain";
+	ctx->page.filename = "ls-cache.txt";
+	cgit_print_http_headers(ctx);
+	cache_ls(ctx->cfg.cache_root);
+}
+
+static void repolist_fn(struct cgit_context *ctx)
+{
+	cgit_print_repolist();
+}
+
 static void patch_fn(struct cgit_context *ctx)
 {
 	cgit_print_patch(ctx->qry.sha1);
@@ -97,6 +107,7 @@ struct cgit_cmd *cgit_get_cmd(struct cgit_context *ctx)
 		def_cmd(commit, 1, 1),
 		def_cmd(diff, 1, 1),
 		def_cmd(log, 1, 1),
+		def_cmd(ls_cache, 0, 0),
 		def_cmd(patch, 1, 0),
 		def_cmd(refs, 1, 1),
 		def_cmd(repolist, 0, 0),
diff --git a/tests/setup.sh b/tests/setup.sh
index 66bf406..e37306e 100755
--- a/tests/setup.sh
+++ b/tests/setup.sh
@@ -44,7 +44,7 @@ setup_repos()
 virtual-root=/
 cache-root=$PWD/trash/cache
 
-nocache=0
+cache-size=1021
 snapshots=tar.gz tar.bz zip
 enable-log-filecount=1
 enable-log-linecount=1
diff --git a/tests/t0020-validate-cache.sh b/tests/t0020-validate-cache.sh
new file mode 100755
index 0000000..53ec2eb
--- /dev/null
+++ b/tests/t0020-validate-cache.sh
@@ -0,0 +1,67 @@
+#!/bin/sh
+
+. ./setup.sh
+
+prepare_tests 'Validate cache'
+
+run_test 'verify cache-size=0' '
+
+	rm -f trash/cache/* &&
+	sed -i -e "s/cache-size=1021$/cache-size=0/" trash/cgitrc &&
+	cgit_url "" &&
+	cgit_url "foo" &&
+	cgit_url "foo/refs" &&
+	cgit_url "foo/tree" &&
+	cgit_url "foo/log" &&
+	cgit_url "foo/diff" &&
+	cgit_url "foo/patch" &&
+	cgit_url "bar" &&
+	cgit_url "bar/refs" &&
+	cgit_url "bar/tree" &&
+	cgit_url "bar/log" &&
+	cgit_url "bar/diff" &&
+	cgit_url "bar/patch" &&
+	test 0 -eq $(ls trash/cache | wc -l)
+'
+
+run_test 'verify cache-size=1' '
+
+	rm -f trash/cache/* &&
+	sed -i -e "s/cache-size=0$/cache-size=1/" trash/cgitrc &&
+	cgit_url "" &&
+	cgit_url "foo" &&
+	cgit_url "foo/refs" &&
+	cgit_url "foo/tree" &&
+	cgit_url "foo/log" &&
+	cgit_url "foo/diff" &&
+	cgit_url "foo/patch" &&
+	cgit_url "bar" &&
+	cgit_url "bar/refs" &&
+	cgit_url "bar/tree" &&
+	cgit_url "bar/log" &&
+	cgit_url "bar/diff" &&
+	cgit_url "bar/patch" &&
+	test 1 -eq $(ls trash/cache | wc -l)
+'
+
+run_test 'verify cache-size=1021' '
+
+	rm -f trash/cache/* &&
+	sed -i -e "s/cache-size=1$/cache-size=1021/" trash/cgitrc &&
+	cgit_url "" &&
+	cgit_url "foo" &&
+	cgit_url "foo/refs" &&
+	cgit_url "foo/tree" &&
+	cgit_url "foo/log" &&
+	cgit_url "foo/diff" &&
+	cgit_url "foo/patch" &&
+	cgit_url "bar" &&
+	cgit_url "bar/refs" &&
+	cgit_url "bar/tree" &&
+	cgit_url "bar/log" &&
+	cgit_url "bar/diff" &&
+	cgit_url "bar/patch" &&
+	test 13 -eq $(ls trash/cache | wc -l)
+'
+
+tests_done