Re: [PATCH v2 03/27] parse_arg(): Really test that argument is properly terminated

Test that the argument is properly terminated by either whitespace or
a NUL character, even if it is quoted, to be consistent with the
non-quoted case.  Adjust the tests to expect the new error message.
Add a docstring to the function, incorporating the comments that were
formerly within the function plus some added information.

Signed-off-by: Michael Haggerty <redacted>
---
 builtin/update-ref.c  | 20 +++++++++++++++-----
 t/t1400-update-ref.sh |  4 ++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 1292cfe..02b5f95 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c

@@ -62,16 +62,26 @@ static void update_store_old_sha1(struct ref_update *update,
 	update->have_old = *oldvalue || line_termination;
 }
 
+/*
+ * Parse one whitespace- or NUL-terminated, possibly C-quoted argument
+ * and append the result to arg.  Return a pointer to the terminator.
+ * Die if there is an error in how the argument is C-quoted.  This
+ * function is only used if not -z.
+ */
 static const char *parse_arg(const char *next, struct strbuf *arg)
 {
-	/* Parse SP-terminated, possibly C-quoted argument */
-	if (*next != '"')
+	if (*next == '"') {
+		const char *orig = next;
+
+		if (unquote_c_style(arg, next, &next))
+			die("badly quoted argument: %s", orig);
+		if (*next && !isspace(*next))
+			die("unexpected character after quoted argument: %s", orig);
+	} else {
 		while (*next && !isspace(*next))
 			strbuf_addch(arg, *next++);
-	else if (unquote_c_style(arg, next, &next))
-		die("badly quoted argument: %s", next);
+	}
 
-	/* Return position after the argument */
 	return next;
 }
 

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 29391c6..774f8c5 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh

@@ -356,10 +356,10 @@ test_expect_success 'stdin fails on badly quoted input' '
 	grep "fatal: badly quoted argument: \\\"master" err
 '
 
-test_expect_success 'stdin fails on arguments not separated by space' '
+test_expect_success 'stdin fails on junk after quoted argument' '
 	echo "create \"$a\"master" >stdin &&
 	test_must_fail git update-ref --stdin <stdin 2>err &&
-	grep "fatal: expected SP but got: master" err
+	grep "fatal: unexpected character after quoted argument: \\\"$a\\\"master" err
 '