--- a/src/lib/cache.h	Sun Dec 27 22:01:17 2009 +0200
+++ b/src/lib/cache.h	Sun Dec 27 23:14:10 2009 +0200
@@ -8,14 +8,37 @@
  */
 #include "image.h"
 
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <png.h>
+
 /**
  * State for cache access
  */
 struct pt_cache {
+    /** Filesystem path to cache file */
+    char *path;
 
+    /** The mode we are operating in, bitmask of PT_IMG_* */
+    int mode;
+    
+    /** Opened file */
+    int fd;
+
+    /** Memory-mapped file data, from the second page on */
+    uint8_t *mmap;
+
+    /** Size of the mmap'd segment in bytes */
+    size_t size;
 };
 
 /**
+ * Size of a cache file page in bytes
+ */
+#define PT_CACHE_PAGE 4096
+
+/**
  * On-disk header
  */
 struct pt_cache_header {
@@ -32,16 +55,21 @@
 /**
  * Construct the image cache info object associated with the given image.
  */
-int pt_cache_open (struct pt_cache **cache_ptr, struct pt_image *img, int mode);
+int pt_cache_open (struct pt_cache **cache_ptr, const char *path, int mode);
 
 /**
- * Verify if the cached data is still fresh compared to the original.
+ * Verify if the cached data has become stale compared to the given original file.
  */
-bool pt_cache_fresh (struct pt_cache *cache);
+int pt_cache_stale (struct pt_cache *cache, const char *orig_path);
 
 /**
  * Update the cache data from the given PNG image.
  */
 int pt_cache_update_png (struct pt_cache *cache, png_structp png, png_infop info);
 
+/**
+ * Release all resources associated with the given cache object without any cleanup.
+ */
+void pt_cache_destroy (struct pt_cache *cache);
+
 #endif