refractor(build): move os logic to its own module.

pkg/os/os.go

@@ -0,0 +1,90 @@
+// apparmor.d - Full set of apparmor profiles
+// Copyright (C) 2023-2024 Alexandre Pujol <alexandre@pujol.io>
+// SPDX-License-Identifier: GPL-2.0-only
+
+package util
+
+import (
+	"os"
+	"slices"
+	"strings"
+
+	"github.com/arduino/go-paths-helper"
+)
+
+var (
+	Distribution = getDistribution()
+	Release      = getOSRelease()
+	Family       = getFamily()
+)
+
+var (
+	osReleaseFile  = "/etc/os-release"
+	supportedDists = map[string][]string{
+		"arch":     {},
+		"debian":   {},
+		"ubuntu":   {},
+		"opensuse": {"suse", "opensuse-tumbleweed"},
+		"whonix":   {},
+	}
+	famillyDists = map[string][]string{
+		"apt":    {"debian", "ubuntu", "whonix"},
+		"pacman": {"arch"},
+		"zypper": {"opensuse"},
+	}
+)
+
+func getOSRelease() map[string]string {
+	var lines []string
+	var err error
+	for _, name := range []string{osReleaseFile, "/usr/lib/os-release"} {
+		path := paths.New(name)
+		if path.Exist() {
+			lines, err = path.ReadFileAsLines()
+			if err != nil {
+				panic(err)
+			}
+			break
+		}
+	}
+	os := map[string]string{}
+	for _, line := range lines {
+		item := strings.Split(line, "=")
+		if len(item) == 2 {
+			os[item[0]] = strings.Trim(item[1], "\"")
+		}
+	}
+	return os
+}
+
+func getDistribution() string {
+	dist, present := os.LookupEnv("DISTRIBUTION")
+	if present {
+		return dist
+	}
+
+	id := Release["ID"]
+	if id == "ubuntu" {
+		return id
+	}
+	id_like := Release["ID_LIKE"]
+	for main, based := range supportedDists {
+		if main == id || main == id_like {
+			return main
+		} else if slices.Contains(based, id) {
+			return main
+		} else if slices.Contains(based, id_like) {
+			return main
+		}
+	}
+	return id
+}
+
+func getFamily() string {
+	for familly, dist := range famillyDists {
+		if slices.Contains(dist, Distribution) {
+			return familly
+		}
+	}
+	return ""
+}