cmd: test: fix handling of single-argument form of test

POSIX states that

  0 arguments:
      Exit false (1).
  1 argument:
      Exit true (0) if $1 is not null; otherwise, exit false.

and at least bash and busybox sh behave that way.

The current 'argc < 3' does the right thing for a non-existing or
empty argv[1], but not for a non-empty argv[1]. Fix that and add
corresponding test cases.

Signed-off-by: Rasmus Villemoes <[email protected]>
Tested-by: Anshul Dalal <[email protected]>

1 files changed, 9 insertions, 2 deletions

diff --git a/cmd/test.c b/cmd/test.c
index f0645ef98f1..0d0f090386c 100644
--- a/cmd/test.c
+++ b/cmd/test.c
@@ -71,10 +71,17 @@ static int do_test(struct cmd_tbl *cmdtp, int flag, int argc,
 		argc--;
 	}
 
-	/* args? */
-	if (argc < 3)
+	/*
+	 * Per POSIX, 'test' with 0 arguments should return 1, while
+	 * 'test <arg>' should be equivalent to 'test -n <arg>',
+	 * i.e. true if and only if <arg> is not empty.
+	 */
+	if (argc < 2)
 		return 1;
 
+	if (argc == 2)
+		return !strcmp(argv[1], "");
+
 #ifdef DEBUG
 	{
 		debug("test(%d):", argc);