fs: implement pushd/popd chdir wrappers

We don't have dirfd's, so running operations relative to the current
working directory always involves some allocation/freeing boilerplate.

Add pushd/popd helpers to move the boilerplate out of the callsites.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20220108171555.588426-1-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 30 insertions, 0 deletions

diff --git a/fs/fs.c b/fs/fs.c
index 7da3a050c1..60fdb29078 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -2846,6 +2846,36 @@ out:
 }
 EXPORT_SYMBOL(chdir);
 
+char *pushd(const char *dir)
+{
+	char *oldcwd;
+	int ret;
+
+	oldcwd = strdup(getcwd());
+	if (!oldcwd)
+		return NULL;
+
+	ret = chdir(dir);
+	if (ret) {
+		free(oldcwd);
+		return NULL;
+	}
+
+	return oldcwd;
+}
+
+int popd(char *oldcwd)
+{
+	int ret;
+
+	if (!oldcwd)
+		return 0;
+
+	ret = chdir(oldcwd);
+	free(oldcwd);
+	return ret;
+}
+
 static char *get_linux_mmcblkdev(struct fs_device_d *fsdev)
 {
 	struct cdev *cdevm, *cdev;