zdtm: Add tests for pidfd restore

Signed-off-by: Suraj Shirvankar <[email protected]>

test/zdtm/static/Makefile

@@ -268,6 +268,7 @@ TST_NOFILE	:=				\
 		sigtrap				\
 		sigtrap01			\
 		change_mnt_context		\
+		pidfd00                         \
 #		jobctl00			\
 
 PKG_CONFIG ?= pkg-config

test/zdtm/static/pidfd00.c

@@ -0,0 +1,64 @@
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <poll.h>
+
+#include "zdtmtst.h"
+
+static int pidfd_open(pid_t pid, unsigned int flags)
+{
+	return syscall(SYS_pidfd_open, pid, flags);
+}
+
+const char *test_doc = "Pidfd ";
+const char *test_author = "Suraj Shirvankar <[email protected]>";
+
+int main(int argc, char **argv)
+{
+	int pidfd, errcode = 42;
+	int status;
+	int ret;
+	struct pollfd pollfd;
+
+	test_init(argc, argv);
+
+	pidfd = pidfd_open(1, 0);
+	if (pidfd == -1) {
+		perror("Couldnt open pidfd");
+		exit(1);
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	pollfd.fd = pidfd;
+	pollfd.events = POLLIN;
+
+	ret = poll(&pollfd, 1, -1);
+	if (ret == -1) {
+		pr_perror("Poll error");
+		fail();
+	}
+
+	if (pollfd.revents & POLLIN) {
+		if (read(pidfd, &status, sizeof(status)) != sizeof(status)) {
+			fail("pidfd read error");
+		}
+		if (status == errcode) {
+			printf("Status code is %d", status);
+			pass();
+		} else {
+			fail("Exit code mismatch");
+		}
+	}
+
+	return 0;
+}