tests: add a ZDTM_NOREAP variable

We'll use this variable in the next test to make sure the test suite
doesn't accidentally reap the zombie we want to leave around for the actual
test.

This is kind of ugly and there might be a better way to pass information to
the test's init, I'm open for suggestions :)

CC: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/lib/ns.c

@@ -5,6 +5,7 @@
 #include <grp.h>
 #include <string.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -251,6 +252,7 @@ int ns_init(int argc, char **argv)
 	int ret, fd, status_pipe = STATUS_FD;
 	char buf[128], *x;
 	pid_t pid;
+	bool reap;
 
 	ret = fcntl(status_pipe, F_SETFD, FD_CLOEXEC);
 	if (ret == -1) {
@@ -258,9 +260,12 @@ int ns_init(int argc, char **argv)
 		exit(1);
 	}
 
+	reap = getenv("ZDTM_NOREAP") == NULL;
+
 	sigemptyset(&sa.sa_mask);
 	sigaddset(&sa.sa_mask, SIGTERM);
-	sigaddset(&sa.sa_mask, SIGCHLD);
+	if (reap)
+		sigaddset(&sa.sa_mask, SIGCHLD);
 
 	if (sigaction(SIGTERM, &sa, NULL)) {
 		fprintf(stderr, "Can't set SIGTERM handler: %m\n");
@@ -290,12 +295,12 @@ int ns_init(int argc, char **argv)
 
 	show_ps();
 
-	if (sigaction(SIGCHLD, &sa, NULL)) {
+	if (reap && sigaction(SIGCHLD, &sa, NULL)) {
 		fprintf(stderr, "Can't set SIGCHLD handler: %m\n");
 		exit(1);
 	}
 
-	while (1) {
+	while (reap && 1) {
 		int status;
 
 		pid = waitpid(-1, &status, WNOHANG);