commands: LXC_CMD_GET_INIT_PIDFD

src/lxc/commands.c

@@ -83,6 +83,7 @@ static const char *lxc_cmd_str(lxc_cmd_t cmd)
 		[LXC_CMD_FREEZE]			= "freeze",
 		[LXC_CMD_UNFREEZE]			= "unfreeze",
 		[LXC_CMD_GET_CGROUP2_FD]		= "get_cgroup2_fd",
+		[LXC_CMD_GET_INIT_PIDFD]        	= "get_init_pidfd",
 	};
 
 	if (cmd >= LXC_CMD_MAX)
@@ -146,6 +147,11 @@ static int lxc_cmd_rsp_recv(int sock, struct lxc_cmd_rr *cmd)
 		rsp->data = INT_TO_PTR(cgroup2_fd);
 	}
 
+	if (cmd->req.cmd == LXC_CMD_GET_INIT_PIDFD) {
+		int init_pidfd = move_fd(fd_rsp);
+		rsp->data = INT_TO_PTR(init_pidfd);
+	}
+
 	if (rsp->datalen == 0)
 		return log_debug(ret,
 				 "Response data length for command \"%s\" is 0",
@@ -372,6 +378,43 @@ static int lxc_cmd_get_init_pid_callback(int fd, struct lxc_cmd_req *req,
 	return 0;
 }
 
+int lxc_cmd_get_init_pidfd(const char *name, const char *lxcpath)
+{
+	int ret, stopped;
+	struct lxc_cmd_rr cmd = {
+		.req = {
+			.cmd = LXC_CMD_GET_INIT_PIDFD,
+		},
+	};
+
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
+	if (ret < 0)
+		return log_debug_errno(-1, errno, "Failed to process init pidfd command");
+
+	if (cmd.rsp.ret < 0)
+		return log_debug_errno(-EBADF, errno, "Failed to receive init pidfd");
+
+	return PTR_TO_INT(cmd.rsp.data);
+}
+
+static int lxc_cmd_get_init_pidfd_callback(int fd, struct lxc_cmd_req *req,
+					   struct lxc_handler *handler,
+					   struct lxc_epoll_descr *descr)
+{
+	struct lxc_cmd_rsp rsp = {
+		.ret = 0,
+	};
+	int ret;
+
+	if (handler->pidfd < 0)
+		rsp.ret = -EBADF;
+	ret = lxc_abstract_unix_send_fds(fd, &handler->pidfd, 1, &rsp, sizeof(rsp));
+	if (ret < 0)
+		return log_error(LXC_CMD_REAP_CLIENT_FD, "Failed to send init pidfd");
+
+	return 0;
+}
+
 /*
  * lxc_cmd_get_clone_flags: Get clone flags container was spawned with
  *
@@ -1329,6 +1372,7 @@ static int lxc_cmd_process(int fd, struct lxc_cmd_req *req,
 		[LXC_CMD_FREEZE]			= lxc_cmd_freeze_callback,
 		[LXC_CMD_UNFREEZE]			= lxc_cmd_unfreeze_callback,
 		[LXC_CMD_GET_CGROUP2_FD]		= lxc_cmd_get_cgroup2_fd_callback,
+		[LXC_CMD_GET_INIT_PIDFD]                = lxc_cmd_get_init_pidfd_callback,
 	};
 
 	if (req->cmd >= LXC_CMD_MAX)

src/lxc/commands.h

@@ -37,6 +37,7 @@ typedef enum {
 	LXC_CMD_FREEZE,
 	LXC_CMD_UNFREEZE,
 	LXC_CMD_GET_CGROUP2_FD,
+	LXC_CMD_GET_INIT_PIDFD,
 	LXC_CMD_MAX,
 } lxc_cmd_t;
 
@@ -84,6 +85,7 @@ extern char *lxc_cmd_get_config_item(const char *name, const char *item, const c
 extern char *lxc_cmd_get_name(const char *hashed_sock);
 extern char *lxc_cmd_get_lxcpath(const char *hashed_sock);
 extern pid_t lxc_cmd_get_init_pid(const char *name, const char *lxcpath);
+extern int lxc_cmd_get_init_pidfd(const char *name, const char *lxcpath);
 extern int lxc_cmd_get_state(const char *name, const char *lxcpath);
 extern int lxc_cmd_stop(const char *name, const char *lxcpath);