Add release asset builder

scripts/build-release-assets.sh

@@ -0,0 +1,93 @@
+#!/bin/sh
+set -eu
+
+script_dir=$(CDPATH= cd "$(dirname "$0")" && pwd -P)
+# shellcheck source=release-lib.sh
+. "$script_dir/release-lib.sh"
+
+tool_name=build-release-assets
+
+if [ "$#" -ne 2 ]; then
+	narratio_release_fail "$tool_name" 'usage: scripts/build-release-assets.sh VERSION OUTPUT_DIR'
+fi
+
+release_version=$1
+output_dir=$2
+if ! narratio_release_validate_version "$release_version"; then
+	narratio_release_fail "$tool_name" "invalid stable version: $release_version"
+fi
+
+case $output_dir in
+	/*) ;;
+	*) narratio_release_fail "$tool_name" "output directory must be absolute: $output_dir" ;;
+esac
+
+repo_root=$(narratio_release_repo_root "$0") || narratio_release_fail "$tool_name" 'cannot locate repository root'
+if ! cd "$repo_root"; then
+	narratio_release_fail "$tool_name" "cannot enter repository root: $repo_root"
+fi
+if [ "$output_dir" = / ]; then
+	narratio_release_fail "$tool_name" 'output directory must not be /'
+fi
+if [ -L "$output_dir" ]; then
+	narratio_release_fail "$tool_name" "output directory must not be a symlink: $output_dir"
+fi
+if [ -e "$output_dir" ]; then
+	if [ ! -d "$output_dir" ]; then
+		narratio_release_fail "$tool_name" "output path must be a directory: $output_dir"
+	fi
+	resolved_output_dir=$(CDPATH= cd "$output_dir" && pwd -P) || narratio_release_fail "$tool_name" "cannot access output directory: $output_dir"
+	if [ "$resolved_output_dir" = "$repo_root" ]; then
+		narratio_release_fail "$tool_name" 'output directory must not be the repository root'
+	fi
+	for existing_entry in "$output_dir"/* "$output_dir"/.[!.]* "$output_dir"/..?*; do
+		if [ -e "$existing_entry" ] || [ -L "$existing_entry" ]; then
+			narratio_release_fail "$tool_name" "output directory must be empty: $output_dir"
+		fi
+	done
+else
+	if ! mkdir "$output_dir"; then
+		narratio_release_fail "$tool_name" "cannot create output directory: $output_dir"
+	fi
+fi
+
+temporary_smoke_binary=
+cleanup_temporary_smoke_binary() {
+	if [ -n "$temporary_smoke_binary" ]; then
+		rm -f "$temporary_smoke_binary"
+	fi
+}
+trap cleanup_temporary_smoke_binary 0 HUP INT TERM
+
+build_flags="-s -w -X gitea.maximumdirect.net/eric/narratio/internal/buildinfo.Version=$release_version"
+host_os=$(go env GOOS)
+host_arch=$(go env GOARCH)
+host_asset=
+
+for target in linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64; do
+	target_os=${target%%/*}
+	target_arch=${target#*/}
+	suffix=
+	if [ "$target_os" = windows ]; then
+		suffix=.exe
+	fi
+	asset_path="$output_dir/narratio-$release_version-$target_os-$target_arch$suffix"
+	CGO_ENABLED=0 GOOS="$target_os" GOARCH="$target_arch" go build -trimpath -ldflags "$build_flags" -o "$asset_path" ./cmd/narratio
+	if [ "$target_os" = "$host_os" ] && [ "$target_arch" = "$host_arch" ]; then
+		host_asset=$asset_path
+	fi
+done
+
+if [ -z "$host_asset" ]; then
+	temporary_smoke_binary="$output_dir/.narratio-release-version-smoke"
+	CGO_ENABLED=0 go build -trimpath -ldflags "$build_flags" -o "$temporary_smoke_binary" ./cmd/narratio
+	host_asset=$temporary_smoke_binary
+fi
+
+reported_version=$("$host_asset" version)
+if [ "$reported_version" != "narratio $release_version" ]; then
+	narratio_release_fail "$tool_name" "release binary reported unexpected version: $reported_version"
+fi
+
+cleanup_temporary_smoke_binary
+temporary_smoke_binary=