work relatively to a root directory

Change-Id: I7cbb96bd3f699092ddfded8cc8893ec780a97d8c

1 files changed, 55 insertions, 0 deletions

diff --git a/wgt-rootdir.c b/wgt-rootdir.c
new file mode 100644
index 0000000..b7d9066
--- /dev/null
+++ b/wgt-rootdir.c
@@ -0,0 +1,55 @@
+/*
+ Copyright 2015 IoT.bzh
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+#define _GNU_SOURCE
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "wgt.h"
+
+
+static int rootfd = AT_FDCWD;
+
+int widget_set_rootdir(const char *pathname)
+{
+	int rfd;
+
+	if (!pathname)
+		rfd = AT_FDCWD;
+	else {
+		rfd = openat(AT_FDCWD, pathname, O_PATH|O_DIRECTORY);
+		if (rfd < 0)
+			return rfd;
+	}
+	if (rootfd >= 0)
+		close(rootfd);
+	rootfd = AT_FDCWD;
+	return 0;
+}
+
+int widget_has(const char *filename)
+{
+	return 0 == faccessat(rootfd, filename, F_OK, 0);
+}
+
+int widget_open_read(const char *filename)
+{
+	return openat(rootfd, filename, O_RDONLY);
+}
+