tst-syscall*: Add tests for syscall() with varargs

Add tests in preparation for genericizing some of the architecture
syscall() implementations.

This was noticed when testing OR1K and found it had a broken syscall
implementation.

These tests try to cover the libc syscall() lqyer which has the purpose
of passing the syscall number and arguments to the kernel.  The actual
kernel syscalls chosen have been selected for ease of testing.

Signed-off-by: Stafford Horne <shorne@gmail.com>

test/misc/tst-syscall0.c

@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+int main() {
+	int pid;
+
+	pid = syscall(SYS_getpid);
+   	if (pid > 0) {
+		printf("syscall(SYS_getpid) says %d\n", pid);
+     		return 0;
+	}
+
+	return 1;
+}

test/misc/tst-syscall1.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/utsname.h>
+
+int main() {
+	int ret;
+	struct utsname name;
+
+	ret = syscall(SYS_uname, &name);
+   	if (ret == 0) {
+		printf("syscall(SYS_uname) says %s-%s\n", name.sysname,
+			name.release);
+     		return 0;
+	}
+
+	return 1;
+}

test/misc/tst-syscall6.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/uio.h>
+#include <sys/types.h>
+#include <linux/fs.h> /* for RWF_HIPRI */
+
+int main()
+{
+	char tmp[] = "/tmp/tst-preadv2-XXXXXX";
+	int fd;
+	struct iovec iov[2];
+	char *str0 = "hello ";
+	char *str1 = "world\n";
+	char input[16];
+	int nio;
+
+	fd = mkstemp (tmp);
+	if (fd == -1) {
+		puts ("mkstemp failed");
+		return 1;
+	}
+
+	iov[0].iov_base = str0;
+	iov[0].iov_len = strlen(str0);
+	iov[1].iov_base = str1;
+	iov[1].iov_len = strlen(str1) + 1; /* null terminator */
+
+	nio = syscall(SYS_pwritev2, fd, iov, 2, 0, 0, RWF_DSYNC);
+
+	if (nio <= 0) {
+		puts ("failed to write to fd");
+		return 1;
+	}
+
+	/* Read in the second string into the first buffer */
+	iov[0].iov_base = input;
+	iov[0].iov_len = strlen(str1) + 1; /* null terminator */
+	nio = syscall(SYS_preadv2, fd, iov, 1, strlen(str0), 0, RWF_HIPRI);
+	if (nio <= 0) {
+		printf ("failed to read fd %d\n", nio);
+		return 1;
+	}
+
+	if (strncmp(iov[0].iov_base, iov[1].iov_base, strlen(str1)) == 0)
+		printf ("syscall(SYS_preadv2) read %s", (char *) iov[0].iov_base);
+
+	if (close(fd) != 0) {
+		puts ("failed to close read fd");
+		return 1;
+	}
+
+	if (unlink(tmp) != 0) {
+		puts ("failed to unlink file");
+		return 1;
+	}
+
+	return 0;
+}