test: add a test for remap_dead_pid

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -179,6 +179,7 @@ static/cgroup00
 static/cgroup01
 static/cgroup02
 ns/static/clean_mntns
+static/remap_dead_pid
 "
 
 TEST_CR_KERNEL="

test/zdtm/.gitignore

@@ -90,6 +90,7 @@
 /live/static/pty02
 /live/static/pty03
 /live/static/pty04
+/live/static/remap_dead_pid
 /live/static/rlimits00
 /live/static/rmdir_open
 /live/static/rtc

test/zdtm/live/static/Makefile

@@ -113,6 +113,7 @@ TST_NOFILE	=				\
 		clean_mntns			\
 		dumpable01			\
 		dumpable02			\
+		remap_dead_pid			\
 #		jobctl00			\
 
 TST_FILE	=				\

test/zdtm/live/static/remap_dead_pid.c

@@ -0,0 +1,74 @@
+#define _GNU_SOURCE
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <limits.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "zdtmtst.h"
+
+#ifndef CLONE_NEWNS
+#define CLONE_NEWNS     0x00020000
+#endif
+
+const char *test_doc	= "Check that dead pid's /proc entries are remapped correctly";
+const char *test_author	= "Tycho Andersen <tycho.andersen@canonical.com>";
+
+int main(int argc, char **argv)
+{
+	pid_t pid;
+
+	test_init(argc, argv);
+
+	pid = fork();
+	if (pid < 0) {
+		fail("fork() failed");
+		return -1;
+	}
+
+	if (pid == 0) {
+		test_msg("child is %d\n", pid);
+		/* Child process just sleeps until it is killed. All we need
+		 * here is a process to open the mountinfo of. */
+		while(1)
+			sleep(10);
+	} else {
+		int fd, ret;
+		char path[PATH_MAX];
+		pid_t result;
+
+		sprintf(path, "/proc/%d/mountinfo", pid);
+
+		fd = open(path, O_RDONLY);
+
+		/* no matter what, we should kill the child */
+		kill(pid, SIGINT);
+		result = waitpid(pid, NULL, 0);
+		if (result < 0) {
+			fail("failed waitpid()");
+			return -1;
+		}
+
+		if (fd < 0) {
+			fail("failed opening %s", path);
+			return -1;
+		}
+
+		test_daemon();
+		test_waitsig();
+
+		ret = fcntl(fd, F_GETFD);
+		close(fd);
+
+		if (ret) {
+			fail("bad fd after restore");
+			return -1;
+		}
+	}
+
+	pass();
+	return 0;
+}