diff -r fda83d91e600 -r ca75725e6849 librazor/root.c
--- a/librazor/root.c	Fri Jul 03 19:06:29 2009 +0100
+++ b/librazor/root.c	Wed Apr 28 11:59:02 2010 +0100
@@ -42,7 +42,14 @@
 #endif
 
 static const char system_repo_filename[] = "system.rzdb";
-static const char next_repo_filename[] = "system-next.rzdb";
+/*
+ * system_lock_filename is chosen to be the same as the pre v0.3
+ * next_repo_filename. This means that once a system has been
+ * updated by a v0.3+ copy of razor all pre v0.3 versions of razor
+ * will see the system as permenantly locked.
+ */
+static const char system_lock_filename[] = "system-next.rzdb";
+static const char system_tmp_filename[] = "system.tmp";
 #ifdef MSWIN_API
 #define RAZOR_ROOT_PATH	NULL
 #else
@@ -129,6 +136,7 @@
 razor_root_open(const char *root)
 {
 	struct razor_root *image;
+	char lock_path[PATH_MAX];
 
 	assert (root != NULL);
 
@@ -137,21 +145,28 @@
 	if (image == NULL)
 		return NULL;
 
-	/* Create the new next repo file up front to ensure exclusive
-	 * access. */
+	image->system = razor_set_create_without_root();
+	if (image->system == NULL) {
+		free(image);
+		return NULL;
+	}
+
+	snprintf(lock_path, sizeof lock_path,
+		 "%s%s/%s", root, razor_root_path, system_lock_filename);
+
+	if (razor_set_aquire_lock(image->system, lock_path, 1) < 0) {
+		razor_set_destroy(image->system);
+		free(image);
+		return NULL;
+	}
+
 	snprintf(image->new_path, sizeof image->new_path,
-		 "%s%s/%s", root, razor_root_path, next_repo_filename);
+		 "%s%s/%s", root, razor_root_path, system_tmp_filename);
 	image->fd = open(image->new_path,
-			 O_CREAT | O_WRONLY | O_TRUNC | O_EXCL | O_BINARY,
+			 O_CREAT | O_WRONLY | O_TRUNC | O_BINARY,
 			 0666);
 	if (image->fd < 0) {
-		fprintf(stderr, "failed to get lock file, "
-			"maybe previous operation crashed?\n");
-
-		/* FIXME: Use fcntl advisory locking on the system
-		 * package set file to figure out whether previous
-		 * operation crashed or is still in progress. */
-
+		razor_set_destroy(image->system);
 		free(image);
 		return NULL;
 	}
@@ -159,10 +174,10 @@
 	snprintf(image->path, sizeof image->path,
 		 "%s%s/%s", root, razor_root_path, system_repo_filename);
 
-	image->system = razor_set_open(image->path);
-	if (image->system == NULL) {
+	if (razor_set_bind_sections(image->system, image->path)) {
+		close(image->fd);
 		unlink(image->new_path);
-		close(image->fd);
+		razor_set_destroy(image->system);
 		free(image);
 		return NULL;
 	}
@@ -174,14 +189,31 @@
 razor_root_open_read_only(const char *root)
 {
 	char path[PATH_MAX];
+	struct razor_set *set;
 
 	assert (root != NULL);
 
 	razor_root_init();
+	set = razor_set_create_without_root();
+	if (set == NULL)
+		return NULL;
+
+	snprintf(path, sizeof path,
+		 "%s%s/%s", root, razor_root_path, system_lock_filename);
+	if (razor_set_aquire_lock(set, path, 0) < 0) {
+		razor_set_destroy(set);
+		return NULL;
+	}
+
 	snprintf(path, sizeof path, "%s%s/%s",
 		 root, razor_root_path, system_repo_filename);
 
-	return razor_set_open(path);
+	if (razor_set_bind_sections(set, path)) {
+		razor_set_destroy(set);
+		return NULL;
+	}
+
+	return set;
 }
 
 RAZOR_EXPORT struct razor_set *