Move block device existence check

src/packages/sysquery-block-devices/index.js

@@ -4,6 +4,7 @@ const DataLoader = require("dataloader");
 const fs = require("fs").promises;
 const matchValue = require("match-value");
 const memoizee = require("memoizee");
+const { InvalidObject } = require("dlayer");
 const unreachable = require("@joepie91/unreachable")("@sysquery/block-devices");
 
 const dlayerSource = require("../dlayer-source");
@@ -13,6 +14,7 @@ const mapFromSource = require("../map-from-source");
 const treeMapAsync = require("../tree-map-async");
 const treeFind = require("../tree-find");
 
+
 function makePredicate({ path, name }) {
 	if (path != null) {
 		return (device) => device.path === path;
@@ -36,6 +38,7 @@ module.exports = {
 		});
 
 		return {
+			// FIXME: This is probably broken; {path,name} selectors are always unique keys!
 			lsblk: new DataLoader(async function (selectors) {
 				let blockDeviceTree = await lsblkOnce();
 		
@@ -50,7 +53,10 @@ module.exports = {
 		};
 	},
 	types: {
-		"sysquery.blockDevices.BlockDevice": function ({ name, path }) {
+		"sysquery.blockDevices.BlockDevice": async function ({ name, path }, { lsblk }) {
+			let entry = await lsblk.load({ name, path });
+
+			if (entry != null) {
 				return {
 					... dlayerSource("lsblk", {
 						[dlayerSource.ID]: { name, path },
@@ -71,25 +77,23 @@ module.exports = {
 						})
 					})
 				};
+			} else {
+				return InvalidObject;
+			}
 		}
 	},
 	extensions: {
 		"sysquery.mounts.Mount": {
-			sourceDevice: async function (_, { lsblk, $make, $getProperty }) {
+			sourceDevice: async function (_, { $make, $getProperty }) {
 				let sourceDevicePath = await $getProperty(this, "sourceDevicePath");
 
 				if (sourceDevicePath == null) {
 					// This occurs when the mount is not backed by a device, eg. an sshfs FUSE mount
 					return null;
 				} else {
-					let realSourcePath = await fs.realpath(sourceDevicePath);
-		
-					if (await lsblk.load({ path: realSourcePath }) != null) {
-						return $make("sysquery.blockDevices.BlockDevice", { path: realSourcePath });
-					} else {
-						// This occurs when the `sourceDevice` is a valid device, but it is not a *block* device, eg. `/dev/fuse`
-						return null;
-					}
+					return $make("sysquery.blockDevices.BlockDevice", {
+						path: await fs.realpath(sourceDevicePath)
+					});
 				}
 			}
 		}