ubus: add request get_fd/set_fd methods

This can be used to send and receive file descriptors from within an object
method call.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 80 insertions, 11 deletions

diff --git a/lib/ubus.c b/lib/ubus.c
index b49a134..330ef5d 100644
--- a/lib/ubus.c
+++ b/lib/ubus.c
@@ -15,6 +15,7 @@
  */
 
 #include <unistd.h>
+#include <limits.h>
 #include <libubus.h>
 #include <libubox/blobmsg.h>
 
@@ -693,6 +694,34 @@ uc_ubus_have_uloop(void)
 	return active;
 }
 
+static int
+get_fd(uc_vm_t *vm, uc_value_t *val)
+{
+	uc_value_t *fn;
+	int64_t n;
+
+	fn = ucv_property_get(val, "fileno");
+	if (ucv_is_callable(fn)) {
+		uc_vm_stack_push(vm, ucv_get(val));
+		uc_vm_stack_push(vm, ucv_get(fn));
+
+		if (uc_vm_call(vm, true, 0) != EXCEPTION_NONE)
+			return -1;
+
+		val = uc_vm_stack_pop(vm);
+		n = ucv_int64_get(val);
+		ucv_put(val);
+	}
+	else {
+		n = ucv_int64_get(val);
+	}
+
+	if (errno || n < 0 || n > (int64_t)INT_MAX)
+		return -1;
+
+	return (int)n;
+}
+
 static uc_value_t *
 uc_ubus_call(uc_vm_t *vm, size_t nargs)
 {
@@ -815,6 +844,19 @@ uc_ubus_defer(uc_vm_t *vm, size_t nargs)
  */
 
 static void
+uc_ubus_request_finish_common(uc_ubus_request_t *callctx, int code)
+{
+	int fd;
+
+	fd = ubus_request_get_caller_fd(&callctx->req);
+	if (fd >= 0)
+		close(fd);
+
+	callctx->replied = true;
+	ubus_complete_deferred_request(callctx->ctx, &callctx->req, code);
+}
+
+static void
 uc_ubus_request_finish(uc_ubus_request_t *callctx, int code, uc_value_t *reply)
 {
 	if (callctx->replied)
@@ -826,9 +868,7 @@ uc_ubus_request_finish(uc_ubus_request_t *callctx, int code, uc_value_t *reply)
 		ubus_send_reply(callctx->ctx, &callctx->req, buf.head);
 	}
 
-	callctx->replied = true;
-
-	ubus_complete_deferred_request(callctx->ctx, &callctx->req, code);
+	uc_ubus_request_finish_common(callctx, code);
 	request_reg_clear(callctx->vm, callctx->registry_index);
 }
 
@@ -882,6 +922,34 @@ uc_ubus_request_defer(uc_vm_t *vm, size_t nargs)
 }
 
 static uc_value_t *
+uc_ubus_request_get_fd(uc_vm_t *vm, size_t nargs)
+{
+	uc_ubus_request_t *callctx = uc_fn_thisval("ubus.request");
+
+	if (!callctx)
+		return NULL;
+
+	return ucv_int64_new(ubus_request_get_caller_fd(&callctx->req));
+}
+
+static uc_value_t *
+uc_ubus_request_set_fd(uc_vm_t *vm, size_t nargs)
+{
+	uc_ubus_request_t *callctx = uc_fn_thisval("ubus.request");
+	int fd;
+
+	if (!callctx)
+		err_return(UBUS_STATUS_INVALID_ARGUMENT, "Invalid call context");
+
+	fd = get_fd(vm, uc_fn_arg(0));
+	if (fd < 0)
+		err_return(UBUS_STATUS_INVALID_ARGUMENT, "Invalid file descriptor");
+
+	ubus_request_set_fd(callctx->ctx, &callctx->req, fd);
+	return ucv_boolean_new(true);
+}
+
+static uc_value_t *
 uc_ubus_request_error(uc_vm_t *vm, size_t nargs)
 {
 	uc_ubus_request_t **callctx = uc_fn_this("ubus.request");
@@ -1251,6 +1319,9 @@ uc_ubus_handle_reply_common(struct ubus_context *ctx,
 
 	ubus_defer_request(ctx, req, &callctx->req);
 
+	/* fd is copied to deferred request. ensure it does not get closed early */
+	ubus_request_get_caller_fd(req);
+
 	/* create ucode request type object and set properties */
 	reqobj = uc_resource_new(request_type, callctx);
 
@@ -1285,8 +1356,7 @@ uc_ubus_handle_reply_common(struct ubus_context *ctx,
 			ucv_object_to_blob(res, &buf);
 			ubus_send_reply(ctx, &callctx->req, buf.head);
 
-			ubus_complete_deferred_request(ctx, &callctx->req, UBUS_STATUS_OK);
-			callctx->replied = true;
+			uc_ubus_request_finish_common(callctx, UBUS_STATUS_OK);
 		}
 
 		/* If neither a deferred ubus request, nor a plain object were
@@ -1302,8 +1372,7 @@ uc_ubus_handle_reply_common(struct ubus_context *ctx,
 					rv = UBUS_STATUS_UNKNOWN_ERROR;
 			}
 
-			ubus_complete_deferred_request(ctx, &callctx->req, rv);
-			callctx->replied = true;
+			uc_ubus_request_finish_common(callctx, rv);
 		}
 
 		ucv_put(res);
@@ -1317,15 +1386,13 @@ uc_ubus_handle_reply_common(struct ubus_context *ctx,
 		if (rv < UBUS_STATUS_OK || rv >= __UBUS_STATUS_LAST)
 			rv = UBUS_STATUS_UNKNOWN_ERROR;
 
-		ubus_complete_deferred_request(ctx, &callctx->req, rv);
-		callctx->replied = true;
+		uc_ubus_request_finish_common(callctx, rv);
 		break;
 
 	/* treat other exceptions as fatal and halt uloop */
 	default:
-		ubus_complete_deferred_request(ctx, &callctx->req, UBUS_STATUS_UNKNOWN_ERROR);
+		uc_ubus_request_finish_common(callctx, UBUS_STATUS_UNKNOWN_ERROR);
 		uloop_end();
-		callctx->replied = true;
 		break;
 	}
 
@@ -2064,6 +2131,8 @@ static const uc_function_list_t request_fns[] = {
 	{ "reply",			uc_ubus_request_reply },
 	{ "error",			uc_ubus_request_error },
 	{ "defer",			uc_ubus_request_defer },
+	{ "get_fd",			uc_ubus_request_get_fd },
+	{ "set_fd",			uc_ubus_request_set_fd },
 };
 
 static const uc_function_list_t notify_fns[] = {