From 3a616ae8aca1d2b24bea5d17dab7c7ba5f0b417d Mon Sep 17 00:00:00 2001
From: Matthias Kruk <m@m10k.eu>
Date: Fri, 14 Jan 2022 21:20:44 +0900
Subject: [PATCH] buildbot: Prepend an entry to the changelog of unstable
 builds

Unstable branches are built automatically, but the changelog is not
changed everytime the unstable branch is updated, causing the built
packages to have the same version and release.

This commit modifies buildbot so that it prepends an entry to the
debian changelog of unstable builds, causing the package version and
release to be increased.
---
 buildbot.sh | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 103 insertions(+), 3 deletions(-)

diff --git a/buildbot.sh b/buildbot.sh
index 5c03e76..2a5658f 100755
--- a/buildbot.sh
+++ b/buildbot.sh
@@ -16,11 +16,102 @@ store_packages() {
 	return 0
 }
 
+increase_version() {
+	local verrel="$1"
+
+	local version
+	local version_prefix
+	local version_suffix
+	local unixtime
+
+	version="${verrel%-*}"
+
+	version_prefix="${version%.*}"
+	version_suffix="${version##*.}"
+
+	if ! is_digits "$version_suffix"; then
+		return 1
+	fi
+
+	(( version_suffix++ ))
+
+	if ! unixtime=$(date +"%s"); then
+		return 1
+	fi
+
+	echo "$version_prefix.$version_suffix-$unixtime"
+	return 0
+}
+
+make_changelog_entry() {
+	local package="$1"
+	local version="$2"
+	local branch="$3"
+	local ref="$4"
+
+	local datetime
+
+	if ! datetime=$(date -R); then
+		return 1
+	fi
+
+	cat <<EOF
+$package ($version) unstable; urgency=medium
+
+  * Automatic build from $branch branch [$ref]
+
+ -- Build Bot <buildbot@m10k.eu>  $datetime
+EOF
+
+    return 0
+}
+
+prepend_changelog() {
+	local changelog="$1"
+	local branch="$2"
+	local ref="$3"
+
+	local package
+	local prev_version
+	local next_version
+	local prev_changelog
+	local updated_changelog
+
+	if ! prev_changelog=$(< "$changelog"); then
+		log_error "Could not read changelog"
+
+	elif ! package=$(grep -m 1 -oP '^\K[^ ]+' <<< "$prev_changelog"); then
+		log_error "Could not parse package name from changelog"
+
+	elif ! prev_version=$(grep -m 1 -oP '^[^ ]+ \(\K[^\)]+' <<< "$prev_changelog"); then
+		log_error "Could not parse previous version from changelog"
+
+	elif ! next_version=$(increase_version "$prev_version"); then
+		log_error "Could not increase version"
+
+	elif ! updated_changelog=$(make_changelog_entry "$package"      \
+	                                                "$next_version" \
+	                                                "$branch"       \
+	                                                "$ref"); then
+		log_error "Could not make changlog entry"
+
+	elif ! printf '%s\n\n\n%s\n' "$updated_changelog" \
+	                             "$prev_changelog" > "$changelog"; then
+		log_error "Could not write to changelog"
+
+	else
+		return 0
+	fi
+
+	return 1
+}
+
 build() {
 	local context="$1"
 	local repository="$2"
 	local branch="$3"
-	local builddir="$4"
+	local ref="$4"
+	local builddir="$5"
 
 	local output
 	local err
@@ -41,7 +132,16 @@ build() {
 		return 1
 	fi
 
-	if ! output=$(cd "$builddir/sources" && dpkg-buildpackage --no-sign 2>&1); then
+	if [[ "$branch" == "unstable" ]]; then
+		if ! prepend_changelog "$builddir/sources/debian/changelog" \
+		                       "$branch"                            \
+		                       "$ref"; then
+			log_error "Could not add entry to $builddir/sources/debian/changelog"
+			return 1
+		fi
+	fi
+
+	if ! output=$(cd "$builddir/sources" && dpkg-buildpackage -us -uc 2>&1); then
 		err=1
 	fi
 
@@ -154,7 +254,7 @@ handle_commit_message() {
 	fi
 
 	log_info "Building $context in $builddir"
-	if ! build "$context" "$repository" "$ref" "$builddir"; then
+	if ! build "$context" "$repository" "$branch" "$ref" "$builddir"; then
 		result=1
 	fi
 
-- 
2.47.3