cmd/mkinitfs: add --version option

Makefile

@@ -1,6 +1,7 @@
 .POSIX:
 .SUFFIXES: .1 .1.scd
 
+VERSION?=`git describe --tags --dirty 2>/dev/null || echo 0.0.0`
 VPATH=doc
 PREFIX?=/usr/local
 BINDIR?=$(PREFIX)/sbin
@@ -8,7 +9,7 @@ MANDIR?=$(PREFIX)/share/man
 SHAREDIR?=$(PREFIX)/share
 GO?=go
 GOFLAGS?=
-LDFLAGS+=-s -w
+LDFLAGS+=-s -w -X main.Version=$(VERSION)
 RM?=rm -f
 GOTEST=go test -count=1 -race
 

cmd/mkinitfs/main.go

@@ -6,6 +6,7 @@ package main
 import (
 	"errors"
 	"flag"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -26,7 +27,21 @@ import (
 	"gitlab.com/postmarketOS/postmarketos-mkinitfs/pkgs/deviceinfo"
 )
 
+// set at build time
+var Version string
+
 func main() {
+
+	outDir := flag.String("d", "/boot", "Directory to output initfs(-extra) and other boot files")
+	var showVersion bool
+	flag.BoolVar(&showVersion, "version", false, "Print version and quit.")
+	flag.Parse()
+
+	if showVersion {
+		fmt.Printf("%s - %s\n", filepath.Base(os.Args[0]), Version)
+		os.Exit(0)
+	}
+
 	deviceinfoFile := "/etc/deviceinfo"
 	if !misc.Exists(deviceinfoFile) {
 		log.Print("NOTE: deviceinfo (from device package) not installed yet, " +
@@ -40,9 +55,6 @@ func main() {
 		log.Fatal(err)
 	}
 
-	outDir := flag.String("d", "/boot", "Directory to output initfs(-extra) and other boot files")
-	flag.Parse()
-
 	defer misc.TimeFunc(time.Now(), "mkinitfs")
 
 	kernVer, err := misc.GetKernelVersion()