add test cases

test/840/C840T04.c

@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+
+int
+main(int argc, char **argv)
+{
+	int fd;
+	void *p;
+	long l;
+
+	fd = open("rpf.data", O_RDONLY);
+	if (fd == -1) {
+		perror("open(rpf.data)");
+		exit(1);
+	}
+	p = mmap(NULL, 512*1024*1024, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (p == (void *)-1) {
+		perror("mmap");
+		exit(1);
+	}
+	close(fd);
+	fd = open("rpf.out", O_WRONLY|O_CREAT|O_TRUNC, 0600);
+	if (fd == -1) {
+		perror("open(fpt.out)");
+		exit(1);
+	}
+	l = write(fd, p, 512*1024*1024);
+	printf("write=%ld\n", l);
+	close(fd);
+	munmap(p, 512*1024*1024);
+	exit(0);
+}