namespace: support CLONE_PIDFD with lxc_clone()

src/lxc/conf.c

@@ -4348,7 +4348,7 @@ int userns_exec_full(struct lxc_conf *conf, int (*fn)(void *), void *data,
 	d.p[1] = p[1];
 
 	/* Clone child in new user namespace. */
-	pid = lxc_clone(run_userns_fn, &d, CLONE_NEWUSER);
+	pid = lxc_clone(run_userns_fn, &d, CLONE_NEWUSER, NULL);
 	if (pid < 0) {
 		ERROR("Failed to clone process in new user namespace");
 		goto on_error;

src/lxc/namespace.c

@@ -54,7 +54,7 @@ static int do_clone(void *arg)
 }
 
 #define __LXC_STACK_SIZE 4096
-pid_t lxc_clone(int (*fn)(void *), void *arg, int flags)
+pid_t lxc_clone(int (*fn)(void *), void *arg, int flags, int *pidfd)
 {
 	size_t stack_size;
 	pid_t ret;
@@ -66,9 +66,9 @@ pid_t lxc_clone(int (*fn)(void *), void *arg, int flags)
 	stack_size = __LXC_STACK_SIZE;
 
 #ifdef __ia64__
-	ret = __clone2(do_clone, stack, stack_size, flags | SIGCHLD, &clone_arg);
+	ret = __clone2(do_clone, stack, stack_size, flags | SIGCHLD, &clone_arg, pidfd);
 #else
-	ret = clone(do_clone, stack + stack_size, flags | SIGCHLD, &clone_arg);
+	ret = clone(do_clone, stack + stack_size, flags | SIGCHLD, &clone_arg, pidfd);
 #endif
 	if (ret < 0)
 		SYSERROR("Failed to clone (%#x)", flags);

src/lxc/namespace.h

@@ -133,7 +133,7 @@ int clone(int (*fn)(void *), void *child_stack,
  * - should call lxc_raw_getpid():
  *   The child should use lxc_raw_getpid() to retrieve its pid.
  */
-extern pid_t lxc_clone(int (*fn)(void *), void *arg, int flags);
+extern pid_t lxc_clone(int (*fn)(void *), void *arg, int flags, int *pidfd);
 
 extern int lxc_namespace_2_cloneflag(const char *namespace);
 extern int lxc_namespace_2_ns_idx(const char *namespace);

src/lxc/start.c

@@ -1705,7 +1705,7 @@ static int lxc_spawn(struct lxc_handler *handler)
 		pid_t attacher_pid;
 
 		attacher_pid = lxc_clone(do_share_ns, handler,
-					 CLONE_VFORK | CLONE_VM | CLONE_FILES);
+					 CLONE_VFORK | CLONE_VM | CLONE_FILES, NULL);
 		if (attacher_pid < 0) {
 			SYSERROR(LXC_CLONE_ERROR);
 			goto out_delete_net;

src/lxc/storage/nbd.c

@@ -266,7 +266,7 @@ static bool clone_attach_nbd(const char *nbd, const char *path)
 	data.nbd = nbd;
 	data.path = path;
 
-	pid = lxc_clone(do_attach_nbd, &data, CLONE_NEWPID);
+	pid = lxc_clone(do_attach_nbd, &data, CLONE_NEWPID, NULL);
 	if (pid < 0)
 		return false;
 

src/lxc/tools/lxc_unshare.c

@@ -388,7 +388,7 @@ int main(int argc, char *argv[])
 	start_arg.want_hostname = my_args.want_hostname;
 	start_arg.want_default_mounts = my_args.want_default_mounts;
 
-	pid = lxc_clone(do_start, &start_arg, my_args.flags);
+	pid = lxc_clone(do_start, &start_arg, my_args.flags, NULL);
 	if (pid < 0) {
 		ERROR("Failed to clone");
 		free_ifname_list();