uvol: fixes and adapt to in-tree ucode

Don't use features which are not yet present in the version of ucode
currently shipped with OpenWrt (such as `fs.access()` or assuming raw
mode by default).
Fix syntax error in main executable.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

utils/uvol/Makefile

@@ -32,7 +32,7 @@ define Package/uvol
 endef
 
 define Package/uvol/description
-  'uvol' is tool to automate storage volume handling on embedded
+  'uvol' is a tool to automate storage volume handling on embedded
   devices in a generic way.
   Depending on what is available, 'uvol' will use either UBI or LVM2
   as storage backends and transparently offer identical operations on

utils/uvol/files/blockdev_common.uc

@@ -108,6 +108,9 @@ let get_bootdev = function(void) {
 
 // adapted from /lib/upgrade/common.sh
 let get_partition = function(dev, num) {
+	if (!dev)
+		return null;
+
 	for (let bd in get_blockdevs()) {
 		let r = get_uevent_major_minor(sprintf("/sys/class/block/%s/uevent", bd));
 		if (r.major == dev.major && r.minor == dev.minor + num) {

utils/uvol/files/lvm.uc

@@ -50,6 +50,9 @@ function pvs() {
 	}
 	include("/usr/lib/uvol/blockdev_common.uc");
 	let rootdev = blockdev_common.get_partition(blockdev_common.get_bootdev(), 0);
+	if (!rootdev)
+		return null;
+
 	let tmp = lvm("pvs", "-o", "vg_name", "-S", sprintf("\"pv_name=~^/dev/%s.*\$\"", rootdev));
 	if (tmp.report.pv)
 		return tmp.report.pv[0].vg_name;
@@ -112,8 +115,8 @@ function getdev(lv) {
 function lvm_init(ctx) {
 	cursor = ctx.cursor;
 	fs = ctx.fs;
-	if (!fs.access(lvm_exec, "x"))
-		return false;
+//	if (!fs.access(lvm_exec, "x"))
+//		return false;
 
 	vg_name = pvs();
 	if (!vg_name)

utils/uvol/files/uvol

@@ -1,4 +1,4 @@
-#!/usr/bin/ucode
+#!/usr/bin/ucode -R
 // SPDX-License-Identifier: GPL-2.0-or-later
 // uvol - storage volume manager for OpenWrt
 //  (c) 2022 Daniel Golle <daniel@makrotopia.org>
@@ -25,11 +25,7 @@ commands:
                  1 - volume is not ready for use
                  2 - volume doesn'y exist
   write volname size		write to volume from stdin, size in bytes
-"
-
-function help() {
-	printf("%s", help_output);
-);
+";
 
 let fs = require("fs");
 let uci = require("uci");
@@ -71,7 +67,7 @@ if (!backend) {
 let cmd = shift(ARGV);
 
 if (!cmd || cmd == "-h" || cmd == "help") {
-	help();
+	printf("%s", help_output);
 	return cmd?0:22;
 }