meson: Run patches on setup (#7)

* Add patching script with error checking+reporting
	new file:   patches/apply.sh

* Run patching script with run_command() at setup
and print the output with message() at the end
	modified:   meson.build

* Report on patch application failure and exit script with code 1
	modified:   patches/apply.sh

---------

Co-authored-by: Agent_00Ming <agent00ming9366@gmail.com>

meson.build

@@ -80,6 +80,8 @@ else
 	)
 endif
 
+patching = run_command('./patches/apply.sh', capture: true, check: true)
+
 features = {
 	'drm-backend': false,
 	'x11-backend': false,
@@ -204,3 +206,5 @@ pkgconfig.generate(
 	url: 'https://gitlab.freedesktop.org/wlroots/wlroots',
 	variables: wlr_vars,
 )
+
+message(patching.stdout().strip())

patches/apply.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# find all patches in patches/
+PATCHES=$(find patches/ -type f -name '*.patch')
+
+check () {
+	git apply --check -q -p1 $PATCH
+}
+
+apply () {
+	git apply -p1 $PATCH
+}
+
+check_applied () {
+	git apply --check --reverse -q -p1 $PATCH
+}
+
+fail () {
+	echo =======\> \'$PATCH\' was not applied && exit 1
+}
+
+if [[ -n "$PATCHES" ]];
+then
+	# check patch validity and apply, else check if already applied and report and exit on failure
+	echo 'Patches found. Applying...';
+	for PATCH in $PATCHES;
+	do
+		check && apply || check_applied || fail;
+	done
+else
+	echo 'No patches found.'
+fi