Define interface for IsoDataSource to access existent images.

src/data_source.c

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2007 Vreixo Formoso
+ * 
+ * This file is part of the libisofs project; you can redistribute it and/or 
+ * modify it under the terms of the GNU General Public License version 2 as 
+ * published by the Free Software Foundation. See COPYING file for details.
+ */
+
+#include "libisofs.h"
+#include "error.h"
+
+#include <stdlib.h>
+
+/**
+ * Increments the reference counting of the given IsoDataSource.
+ */
+void iso_data_source_ref(IsoDataSource *src)
+{
+    src->refcount++;
+}
+
+/**
+ * Decrements the reference counting of the given IsoDataSource, freeing it
+ * if refcount reach 0.
+ */
+void iso_data_source_unref(IsoDataSource *src)
+{
+    if (--src->refcount == 0) {
+        src->free_data(src);
+        free(src);
+    }
+}
+
+
+/**
+ * Create a new IsoDataSource from a local file. This is suitable for
+ * accessing regular .iso images, or to acces drives via its block device
+ * and standard POSIX I/O calls.
+ * 
+ * @param path
+ *     The path of the file
+ * @param src
+ *     Will be filled with the pointer to the newly created data source.
+ * @return
+ *    1 on success, < 0 on error.
+ */
+int iso_data_source_new_from_file(const char *path, IsoDataSource **src)
+{
+    
+    if (path == NULL || src == NULL) {
+        return ISO_MEM_ERROR;
+    }
+    
+    //TODO implement
+    return -1;
+}