[LTP] [PATCH V2 2/2] setpgid03: use SIGUSR1 instead of sleep

[Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>]

I came accross the following rare issue:

setpgid03    1  TPASS  :  setpgid SUCCESS to set errno to EPERM
setpgid03    2  TFAIL  :  setpgid FAILED, expect EACCES got 1

I suppose It may happen if the test host is under stress.

To prevent this It would be better to use SIGUSR1 for parent-child
synchronisations.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
---
 testcases/kernel/syscalls/setpgid/setpgid03.c |  123 +++++++++++++++++++++++--
 1 files changed, 115 insertions(+), 8 deletions(-)

diff --git a/testcases/kernel/syscalls/setpgid/setpgid03.c b/testcases/kernel/syscalls/setpgid/setpgid03.c
index 2c47bc4..34975b7 100644
--- a/testcases/kernel/syscalls/setpgid/setpgid03.c
+++ b/testcases/kernel/syscalls/setpgid/setpgid03.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) International Business Machines  Corp., 2001
+ * Copyright (c) 2013 Oracle and/or its affiliates. All Rights Reserved.
  *
  * This program is free software;  you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -34,15 +35,20 @@
 char *TCID = "setpgid03";
 int TST_TOTAL = 1;
 
+static pid_t pid = -1;
+
 static void do_child(void);
+static void sigusr_handler(int signum);
+static void term_handler(int signum);
 static void setup(void);
 static void cleanup(void);
 
 int main(int ac, char **av)
 {
-	int pid;
 	int rval;
 	int status;
+	sigset_t sig_set;
+	struct sigaction sa;
 
 	int lc;
 	char *msg;
@@ -56,12 +62,42 @@ int main(int ac, char **av)
 
 	setup();
 
+	/* We need to block these signals before fork()
+	 * because our children may terminate either
+	 * normally (parent receives both SIGUSR1 and SIGCHLD) or
+	 * abnormally (parent receives SIGCHLD only)
+	 */
+	sigemptyset(&sig_set);
+	sigaddset(&sig_set, SIGUSR1);
+	sigaddset(&sig_set, SIGCHLD);
+
+	/* Since we use SIGUSR1 as a control signal It should not
+	 * be an "unexpected" one
+	 */
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = sigusr_handler;
+	if (sigaction(SIGUSR1, &sa, NULL) < 0)
+		tst_brkm(TFAIL | TERRNO, cleanup, "sigaction(SIGUSR1) failed");
+
+	/* But for SIGINT, SIGTERM we should kill our children */
+	sa.sa_handler = term_handler;
+	if (sigaction(SIGTERM, &sa, NULL) < 0)
+		tst_brkm(TFAIL | TERRNO, cleanup, "sigaction(SIGTERM) failed");
+	if (sigaction(SIGINT, &sa, NULL) < 0)
+		tst_brkm(TFAIL | TERRNO, cleanup, "sigaction(SIGINT) failed");
+
 	for (lc = 0; TEST_LOOPING(lc); lc++) {
 
 		tst_count = 0;
 
 //test1:
 		/* sid of the calling process is not same */
+
+		if (sigprocmask(SIG_BLOCK, &sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigprocmask(SIG_BLOCK) in test 1 failed");
+
+
 		if ((pid = FORK_OR_VFORK()) == -1) {
 			tst_brkm(TBROK, cleanup, "fork() failed");
 		}
@@ -76,7 +112,14 @@ int main(int ac, char **av)
 #endif
 		}
 
-		sleep(1);
+		if (sigwaitinfo(&sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigwaitinfo() failed");
+
+		if (sigprocmask(SIG_UNBLOCK, &sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigprocmask(SIG_UNBLOCK) in test 2 failed");
+
 		rval = setpgid(pid, getppid());
 		if (errno == EPERM) {
 			tst_resm(TPASS,
@@ -86,11 +129,14 @@ int main(int ac, char **av)
 				"setpgid FAILED, expect %d, return %d",
 				EPERM, errno);
 		}
-		sleep(1);
+
+		kill(pid, SIGUSR1);
 
 		if (wait(&status) < 0)
 			tst_resm(TFAIL | TERRNO, "wait() for child 1 failed");
 
+		pid = -1;
+
 		if (!(WIFEXITED(status)) || (WEXITSTATUS(status) != 0))
 			tst_resm(TFAIL, "child 1 failed with status %d",
 				WEXITSTATUS(status));
@@ -100,18 +146,47 @@ int main(int ac, char **av)
 		 * Value of pid matches the pid of the child process and
 		 * the child process has exec successfully. Error
 		 */
+
+		if (sigprocmask(SIG_BLOCK, &sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigprocmask(SIG_BLOCK) in test 2 failed");
+
 		if ((pid = FORK_OR_VFORK()) == -1) {
 			tst_resm(TFAIL, "Fork failed");
 
 		}
 		if (pid == 0) {
-			if (execlp("sleep", "sleep", "3", NULL) < 0) {
-				perror("exec failed");
+			char buf[10];
+			int ret;
+
+			ret = snprintf(buf, 10, "%d", getppid());
+			if ((ret >= 10) || (ret <= 0)) {
+				printf("snprintf() failed\n");
+
+				exit(126);
 			}
+
+			const char *args[4 + 1];
+			args[0] = "kill";
+			args[1] = "-s";
+			args[2] = "SIGUSR1";
+			args[3] = buf;
+			args[4] = NULL;
+
+			if (execvp(args[0], (char *const *)args) < 0)
+				perror("execvp() failed\n");
+
 			exit(127);
 		}
 
-		sleep(1);
+		if (sigwaitinfo(&sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigwaitinfo() failed");
+
+		if (sigprocmask(SIG_UNBLOCK, &sig_set, NULL) < 0)
+			tst_brkm(TFAIL | TERRNO, cleanup,
+				"sigprocmask(SIG_UNBLOCK) in test 2 failed");
+
 		rval = setpgid(pid, getppid());
 		if (errno == EACCES) {
 			tst_resm(TPASS,
@@ -124,6 +199,8 @@ int main(int ac, char **av)
 		if (wait(&status) < 0)
 			tst_resm(TFAIL | TERRNO, "wait() for child 2 failed");
 
+		pid = -1;
+
 		if (!(WIFEXITED(status)) || (WEXITSTATUS(status) != 0))
 			tst_resm(TFAIL, "child 2 failed with status %d",
 				WEXITSTATUS(status));
@@ -136,18 +213,48 @@ int main(int ac, char **av)
 static void do_child(void)
 {
 	int exno = 0;
+	sigset_t set;
 
 	if (setsid() < 0) {
 		printf("setsid() failed, errno: %d\n", errno);
 		exno = 1;
 	}
-	sleep(2);
+
+	kill(getppid(), SIGUSR1);
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGUSR1);
+	if (sigprocmask(SIG_UNBLOCK, &set, NULL) < 0) {
+		printf("sigprocmask() in child failed: %d\n", errno);
+
+		exit(1);
+	}
+
+	pause();
+
 	exit(exno);
 }
 
-static void setup(void)
+static void sigusr_handler(int signum)
 {
+}
+
+static void term_handler(int signum)
+{
+	if (pid == 0) {
+		printf("Child received signal %d\n", signum);
 
+		exit(1);
+	} else {
+		if (pid > 0)
+			kill(pid, signum);
+
+		tst_brkm(TFAIL, cleanup, "Signal %d received. Exiting", signum);
+	}
+}
+
+static void setup(void)
+{
 	tst_sig(FORK, DEF_HANDLER, cleanup);
 
 	umask(0);
-- 
1.7.1


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