fs: introduce unsetenv() to prepare for changing setenv(var, "") behavior

Currently, we treat setenv(var, "") and setenv(var, NULL) the same
and delete var, which is surprising and leads to subtle quirks:

 - setenv(var, "") is specified by POSIX to set var to an empty string,
   but barebox uses it to delete variables

 - nv.user= calls nv_set with NULL parameter, but nv user="" doesn't

Make the API more POSIX-like by providing unsetenv with the expected
semantics. Most user code can then use unsetenv without worrying about
whether "" or NULL is the magic deletion value.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/fs.c b/fs/fs.c
index f41e4b9b72..00b8645fb0 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -3066,7 +3066,7 @@ static int automount_mount(struct dentry *dentry)
 		setenv("automount_path", am->path);
 		export("automount_path");
 		ret = run_command(am->cmd);
-		setenv("automount_path", NULL);
+		unsetenv("automount_path");
 
 		if (ret) {
 			printf("running automount command '%s' failed\n",