[PATCH 2/4] signaltest: properly test return value from system()

[Henrik Austad <haustad@cisco.com>]

signaltest writes to several /proc/sys/kernel attributes without testing
if the system() call succeeds or not. We expect the writes from echo to
suceed (i.e. yield '0' in return), so we test explicitly for that.

Signed-off-by: Henrik Austad <haustad@cisco.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
---
 src/signaltest/signaltest.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/signaltest/signaltest.c b/src/signaltest/signaltest.c
index b80969b..8074b68 100644
--- a/src/signaltest/signaltest.c
+++ b/src/signaltest/signaltest.c
@@ -65,6 +65,11 @@ struct thread_stat {
 	int threadstarted;
 	int tid;
 };
+#define SYSTEM_W(x)				\
+	if (system((x)) != 0) {			\
+		fprintf(stderr, "Trouble running %s\n", (x));	\
+		return NULL;					\
+	}							\
 
 static int shutdown;
 static int tracelimit = 0;
@@ -102,16 +107,16 @@ void *signalthread(void *param)
 	int first = 1;
 
 	if (tracelimit) {
-		system("echo 1 > /proc/sys/kernel/trace_all_cpus");
-		system("echo 1 > /proc/sys/kernel/trace_enabled");
-		system("echo 1 > /proc/sys/kernel/trace_freerunning");
-		system("echo 0 > /proc/sys/kernel/trace_print_at_crash");
-		system("echo 1 > /proc/sys/kernel/trace_user_triggered");
-		system("echo -1 > /proc/sys/kernel/trace_user_trigger_irq");
-		system("echo 0 > /proc/sys/kernel/trace_verbose");
-		system("echo 0 > /proc/sys/kernel/preempt_thresh");
-		system("echo 0 > /proc/sys/kernel/wakeup_timing");
-		system("echo 0 > /proc/sys/kernel/preempt_max_latency");
+		SYSTEM_W("echo 1 > /proc/sys/kernel/trace_all_cpus");
+		SYSTEM_W("echo 1 > /proc/sys/kernel/trace_enabled");
+		SYSTEM_W("echo 1 > /proc/sys/kernel/trace_freerunning");
+		SYSTEM_W("echo 0 > /proc/sys/kernel/trace_print_at_crash");
+		SYSTEM_W("echo 1 > /proc/sys/kernel/trace_user_triggered");
+		SYSTEM_W("echo -1 > /proc/sys/kernel/trace_user_trigger_irq");
+		SYSTEM_W("echo 0 > /proc/sys/kernel/trace_verbose");
+		SYSTEM_W("echo 0 > /proc/sys/kernel/preempt_thresh");
+		SYSTEM_W("echo 0 > /proc/sys/kernel/wakeup_timing");
+		SYSTEM_W("echo 0 > /proc/sys/kernel/preempt_max_latency");
 	}
 
 	stat->tid = gettid();
-- 
1.9.1