add test cases

test/840/C840T02.c

@@ -0,0 +1,27 @@
+#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)
+{
+	pid_t pid;
+	int pfd[2];
+	char c;
+
+	pid = fork();
+	if (pid == 0) {
+		sleep(1);
+		kill(getppid(), SIGKILL);
+		exit(0);
+	}
+
+	pipe(pfd);
+	read(pfd[0], &c, 1);
+	exit(0);
+}