dup02.c: Simplify using TST_EXP macro and doc rewording

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Avinesh Kumar <akumar@suse.de>
Signed-off-by: Petr Vorel <pvorel@suse.cz>

Author: Avinesh

testcases/kernel/syscalls/dup/dup02.c

@@ -2,24 +2,21 @@
 /*
  * Copyright (c) 2000 Silicon Graphics, Inc.  All Rights Reserved.
  * Copyright (c) 2020 SUSE LLC
- *
  * 03/30/1992 AUTHOR: Richard Logan CO-PILOT: William Roske
- *
  */
+
 /*\
  * [Description]
- * Negative test for dup(2) with bad fds.
  *
- * [Algorithm]
- * Call dup(2) with invalid argument and make sure it returns -1 with errno set
- * to EBADF.
+ * Verify that dup(2) syscall fails with errno EBADF when called with
+ * invalid value for oldfd argument.
  */
 
 #include "tst_test.h"
 
 static struct tcase {
 	int fd;
-	int expected_errno;
+	int exp_err;
 } tcases[] = {
 	{-1, EBADF},
 	{1500, EBADF},
@@ -29,27 +26,10 @@ static void run(unsigned int n)
 {
 	struct tcase *tc = &tcases[n];
 
-	TEST(dup(tc->fd));
-
-	if (TST_RET < -1) {
-		tst_res(TFAIL | TTERRNO, "Invalid dup() return value %ld",
-			TST_RET);
-		return;
-	}
-
-	if (TST_RET == -1) {
-		if (tc->expected_errno == TST_ERR) {
-			tst_res(TPASS | TTERRNO, "dup(%d) failed as expected",
-				tc->fd);
-		} else {
-			tst_res(TFAIL | TTERRNO, "dup(%d) failed unexpectedly",
-				tc->fd);
-		}
-		return;
-	}
+	TST_EXP_FAIL2(dup(tc->fd), tc->exp_err, "dup(%d)", tc->fd);
 
-	tst_res(TFAIL, "dup(%d) succeeded unexpectedly", tc->fd);
-	SAFE_CLOSE(TST_RET);
+	if (TST_RET != -1)
+		SAFE_CLOSE(TST_RET);
 }
 
 static struct tst_test test = {