memfd_secret: test case for memfd_secret

Adds a test case to test checkpoint and restore of a
memfd_secret fd containing process.

Signed-off-by: Dhanuka Warusadura <csx@tuta.io>

test/zdtm/static/Makefile

@@ -257,6 +257,7 @@ TST_NOFILE	:=				\
 		memfd02				\
 		memfd02-hugetlb			\
 		memfd03				\
+		memfd-secret00                  \
 		shmemfd				\
 		shmemfd-priv			\
 		time				\

test/zdtm/static/memfd-secret00.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "zdtmtst.h"
+
+#define SECRET "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+#define SIZE   26
+
+const char *test_doc = "memfd_secret file descriptor";
+const char *test_author = "Dhanuka Warusadura <csx@tuta.io>";
+
+static int _memfd_secret(unsigned int flags)
+{
+	return syscall(SYS_memfd_secret, flags);
+}
+
+static void *secret_init(size_t size)
+{
+	int fd;
+	void *secretmem = NULL;
+
+	fd = _memfd_secret(0);
+	if (fd < 0)
+		return secretmem;
+
+	if (ftruncate(fd, size) < 0) {
+		close(fd);
+		return secretmem;
+	}
+
+	secretmem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (secretmem == MAP_FAILED) {
+		close(fd);
+		return secretmem;
+	}
+
+	return secretmem;
+}
+
+static void secret_fini(void *mem, size_t size)
+{
+	munmap(mem, size);
+}
+
+int main(int argc, char *argv[])
+{
+	char *secretmem;
+
+	test_init(argc, argv);
+
+	secretmem = secret_init(SIZE);
+	if (!secretmem) {
+		fail("memfd_secret: not supported operation");
+		return 1;
+	}
+
+	for (int i = 0; i < SIZE; i++)
+		secretmem[i] = 'A' + i;
+
+	test_daemon();
+	test_waitsig();
+
+	if (strncmp(secretmem, SECRET, SIZE)) {
+		fail("secretmem content mismatch");
+		return 1;
+	}
+
+	secret_fini(secretmem, SIZE);
+
+	pass();
+
+	return 0;
+}