main/postmarketos-duranium: add script to set image channel

This adds a script that can be used to set the "channel" for images to
"staging" or "main." "Staging" will come from a separate pipeline in the
duranium mkosi config repo, it may build images with patches or whatever
for testing, and won't be available to users running the "main" channel.

Signed-off-by: Clayton Craft <craftyguy@postmarketos.org>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8330>

main/postmarketos-duranium/APKBUILD

@@ -52,6 +52,7 @@ _source644="
 "
 
 _source755="
+	usr/bin/duranium-set-channel
 	etc/profile.d/99-local-bin.sh
 	usr/libexec/duranium/first-boot
 	usr/libexec/duranium/mount-subpartitions
@@ -157,6 +158,7 @@ fa1c3dd727fd20d16d18695d58dd10ec335d64ece00152346c84ae750ed5ade8faf5ba11747135d7
 7d98cb314472d7db64599c8abfc2e21ef6437b0c5bf407f0c21a42ec2f14f660fb3aef64c99a13aada124a822a85d8e4a6674838d1fe07719774331121d5414b  rootfs-usr-lib-tmpfiles.d-var.conf
 ede57bf8696dce4ee295dc2a1dfe31dec415e7ce994600ce3bf7386ac1ad63797a6c5a88434ca0cc854cdad6618647845126b1f8757c48f83ce308d394b8c68d  rootfs-usr-lib-udev-rules.d-90-udisks-ignore-verity-hack.rules
 7f2b98edc7b485129ea862c5c852422e8996ffe0a2bdae3160b6c94667b4e345a1792164e3143d58cb1a51c3c6981381ad7610d709aba210bb61a0c883455476  rootfs-usr-share-duranium-f0rmz-firstboot.conf
+619368ffc9dd1fd9c0f662c0bb8f407a6514c8b12611511d715f705874e3be24201b5046e631c476bd70d661ca45576df8fb10aa86cf11a7de9a79289b7a7806  rootfs-usr-bin-duranium-set-channel
 765797421f9123cdcf85e1496d01884cce1c8c304d15369b7eee32a8fc5abcd860dc5856c0d493f1cd3c6ad2a0ccdc4d6ba7d2ae356f0fc824dc16cdb84ebf37  rootfs-etc-profile.d-99-local-bin.sh
 6661a981a3c2e549f0f1a12d4777f662eb88aa581608529f6e75a5d448b78fcb709812a4291d5708da840ba72d6cbf48375485d3ecd900d252efd2eb4a9e170c  rootfs-usr-libexec-duranium-first-boot
 bb3ec1693f88a61563876cd069b49351861a31c15b1795702031e5beb4e89cefe302644c1ea9d0bb74746aa97007664c1782857900e2b85dd71182e95efd66ae  rootfs-usr-libexec-duranium-mount-subpartitions

main/postmarketos-duranium/rootfs-usr-bin-duranium-set-channel

@@ -0,0 +1,74 @@
+#!/bin/sh
+# switch the sysupdate channel between main (production) and staging.
+set -eu
+
+SYSUPDATE_DIR=/usr/lib/sysupdate.d
+OVERRIDE_DIR=/etc/sysupdate.d
+BASE_URL="https://duranium.postmarketos.org/images/"
+
+usage() {
+	echo "Usage: $0 [-h|--help] [main|staging]"
+	echo "With no arguments, print the current channel."
+}
+
+case "${1:-}" in
+	-h|--help)
+		usage
+		exit 0
+		;;
+	""|main|staging)
+		;;
+	*)
+		usage >&2
+		exit 1
+		;;
+esac
+
+get_channel() {
+	for f in "$OVERRIDE_DIR"/*.transfer; do
+		[ -f "$f" ] || continue
+		if grep -q '/images/staging/' "$f"; then
+			echo "staging"
+			return
+		fi
+	done
+	echo "main"
+}
+
+if [ -z "${1:-}" ]; then
+	get_channel
+	exit 0
+fi
+
+if [ "$(id -u)" -ne 0 ]; then
+	echo "error: changing channel requires root" >&2
+	exit 1
+fi
+
+channel="$1"
+
+if [ "$channel" = "main" ]; then
+	for f in "$OVERRIDE_DIR"/*.transfer; do
+		[ -f "$f" ] || continue
+		if grep -q '/images/staging/' "$f"; then
+			rm "$f"
+		fi
+	done
+	echo "Switched to main"
+	exit 0
+fi
+
+# staging
+mkdir -p "$OVERRIDE_DIR"
+for transfer in "$SYSUPDATE_DIR"/*.transfer; do
+	[ -f "$transfer" ] || continue
+
+	grep -q "^Path=.*$BASE_URL" "$transfer" || continue
+
+	name=$(basename "$transfer")
+	# NOTE: if there are changes to .transfer files in the image, the changes won't
+	# make it into the override...
+	sed 's|/images/|/images/staging/|' "$transfer" > "$OVERRIDE_DIR/$name"
+done
+
+echo "Switched to staging"