[LTP] [PATCH v3] setpriority01: Skip only PRIO_USER when unable to add test user

[Saravana Kannan]

We don't need to skip all the tests just because we are unable to add
a test user. Not having a test user only affects PRIO_USER test case.
So just skip that one and continue running the rest of the tests when
useradd is not available or can't write to /etc/passwd (Eg: read-only
filesystem)

If useradd is present and it still fails for other reasons, then
consider it an error in the test preparation phase.

This also allows this test case to be built and run on Android.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---

v1:
- Skip only PRIO_USER test when unable to add user for any reason.

v2:
- Skip only PRIO_USER test when useradd isn't present
- Fail entire test with TBROK for all other cases where user can't be
  added

v3:
- Skip only PRIO_USER test when useradd isn't present or can't write
  to /etc/passwd
- Fail entire test with TBROK for all other failures of useradd

 .../kernel/syscalls/setpriority/Makefile      |  5 ----
 .../syscalls/setpriority/setpriority01.c      | 30 +++++++++++++------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/testcases/kernel/syscalls/setpriority/Makefile b/testcases/kernel/syscalls/setpriority/Makefile
index 5d00984ea..7a1a87a28 100644
--- a/testcases/kernel/syscalls/setpriority/Makefile
+++ b/testcases/kernel/syscalls/setpriority/Makefile
@@ -19,9 +19,4 @@
 top_srcdir		?= ../../../..
 
 include $(top_srcdir)/include/mk/testcases.mk
-
-ifeq ($(ANDROID), 1)
-FILTER_OUT_MAKE_TARGETS	+= setpriority01
-endif
-
 include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/setpriority/setpriority01.c b/testcases/kernel/syscalls/setpriority/setpriority01.c
index 38b77b77f..b93a42aa6 100644
--- a/testcases/kernel/syscalls/setpriority/setpriority01.c
+++ b/testcases/kernel/syscalls/setpriority/setpriority01.c
@@ -92,9 +92,16 @@ static void verify_setpriority(unsigned int n)
 {
 	struct tcase *tc = &tcases[n];
 
+	if (tc->which == PRIO_USER && !user_added) {
+		tst_res(TCONF, "setpriority(%s(%d), %d, -20..19) skipped - Can't add user",
+			str_which(tc->which), tc->which, *tc->who);
+		return;
+	}
+
 	pid = SAFE_FORK();
 	if (pid == 0) {
-		SAFE_SETUID(uid);
+		if (user_added)
+			SAFE_SETUID(uid);
 		SAFE_SETPGID(0, 0);
 
 		TST_CHECKPOINT_WAKE_AND_WAIT(0);
@@ -115,15 +122,20 @@ static void setup(void)
 {
 	const char *const cmd_useradd[] = {"useradd", username, NULL};
 	struct passwd *ltpuser;
+	int rc;
 
-	if (eaccess("/etc/passwd", W_OK))
-		tst_brk(TCONF, "/etc/passwd is not accessible");
-
-	tst_run_cmd(cmd_useradd, NULL, NULL, 0);
-	user_added = 1;
-
-	ltpuser = SAFE_GETPWNAM(username);
-	uid = ltpuser->pw_uid;
+	switch ((rc = tst_run_cmd(cmd_useradd, NULL, NULL, 1))) {
+	case 0:
+		user_added = 1;
+		ltpuser = SAFE_GETPWNAM(username);
+		uid = ltpuser->pw_uid;
+		return;
+	case 1:
+	case 255:
+		return;
+	default:
+		tst_brk(TBROK, "Useradd failed (%d)", rc);
+	}
 }
 
 static void cleanup(void)
-- 
2.21.0.225.g810b269d1ac-goog