cmd,extra: restore the Version link-time variable

We don't need it in our builds, but it's useful for downstream packagers.

Fixes #671
Updates NixOS/nixpkgs#474666
Updates golang/go#77020

cmd/age-inspect/inspect.go

@@ -24,6 +24,10 @@ Options:
 INPUT defaults to standard input. "-" may be used as INPUT to explicitly
 read from standard input.`
 
+// Version can be set at link time to override debug.BuildInfo.Main.Version when
+// building manually without git history. It should look like "v1.2.3".
+var Version string
+
 func main() {
 	flag.Usage = func() { fmt.Fprintf(os.Stderr, "%s\n", usage) }
 
@@ -37,11 +41,10 @@ func main() {
 	flag.Parse()
 
 	if versionFlag {
-		if buildInfo, ok := debug.ReadBuildInfo(); ok {
-			fmt.Println(buildInfo.Main.Version)
-			return
+		if buildInfo, ok := debug.ReadBuildInfo(); ok && Version == "" {
+			Version = buildInfo.Main.Version
 		}
-		fmt.Println("(unknown)")
+		fmt.Println(Version)
 		return
 	}
 

cmd/age-keygen/keygen.go

@@ -56,6 +56,10 @@ Examples:
     $ age-keygen -y key.txt
     age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p`
 
+// Version can be set at link time to override debug.BuildInfo.Main.Version when
+// building manually without git history. It should look like "v1.2.3".
+var Version string
+
 func main() {
 	log.SetFlags(0)
 	flag.Usage = func() { fmt.Fprintf(os.Stderr, "%s\n", usage) }
@@ -69,6 +73,15 @@ func main() {
 	flag.StringVar(&outFlag, "o", "", "output to `FILE` (default stdout)")
 	flag.StringVar(&outFlag, "output", "", "output to `FILE` (default stdout)")
 	flag.Parse()
+
+	if versionFlag {
+		if buildInfo, ok := debug.ReadBuildInfo(); ok && Version == "" {
+			Version = buildInfo.Main.Version
+		}
+		fmt.Println(Version)
+		return
+	}
+
 	if len(flag.Args()) != 0 && !convertFlag {
 		errorf("too many arguments")
 	}
@@ -78,14 +91,6 @@ func main() {
 	if pqFlag && convertFlag {
 		errorf("-pq cannot be used with -y")
 	}
-	if versionFlag {
-		if buildInfo, ok := debug.ReadBuildInfo(); ok {
-			fmt.Println(buildInfo.Main.Version)
-			return
-		}
-		fmt.Println("(unknown)")
-		return
-	}
 
 	out := os.Stdout
 	if outFlag != "" {

cmd/age-plugin-batchpass/plugin-batchpass.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"log"
 	"os"
+	"runtime/debug"
 	"strconv"
 	"strings"
 
@@ -73,6 +74,10 @@ When decrypting, you can set AGE_PASSPHRASE_MAX_WORK_FACTOR to limit the
 maximum scrypt work factor accepted (between 1 and 30, default 30). This can
 be used to avoid very slow decryptions.`
 
+// Version can be set at link time to override debug.BuildInfo.Main.Version when
+// building manually without git history. It should look like "v1.2.3".
+var Version string
+
 func main() {
 	flag.Usage = func() { fmt.Fprintf(os.Stderr, "%s\n", usage) }
 
@@ -80,6 +85,19 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
+	p.RegisterFlags(nil)
+
+	versionFlag := flag.Bool("version", false, "print the version")
+	flag.Parse()
+
+	if *versionFlag {
+		if buildInfo, ok := debug.ReadBuildInfo(); ok && Version == "" {
+			Version = buildInfo.Main.Version
+		}
+		fmt.Println(Version)
+		return
+	}
+
 	p.HandleIdentityAsRecipient(func(data []byte) (age.Recipient, error) {
 		if len(data) != 0 {
 			return nil, fmt.Errorf("batchpass identity does not take any payload")

cmd/age/age.go

@@ -98,6 +98,10 @@ func (f *identityFlags) addPluginFlag(value string) error {
 	return nil
 }
 
+// Version can be set at link time to override debug.BuildInfo.Main.Version when
+// building manually without git history. It should look like "v1.2.3".
+var Version string
+
 func main() {
 	flag.Usage = func() { fmt.Fprintf(os.Stderr, "%s\n", usage) }
 
@@ -136,13 +140,10 @@ func main() {
 	flag.Parse()
 
 	if versionFlag {
-		if buildInfo, ok := debug.ReadBuildInfo(); ok {
-			// TODO: use buildInfo.Settings to prepare a pseudoversion such as
-			// v0.0.0-20210817164053-32db794688a5+dirty on Go 1.18+.
-			fmt.Println(buildInfo.Main.Version)
-			return
+		if buildInfo, ok := debug.ReadBuildInfo(); ok && Version == "" {
+			Version = buildInfo.Main.Version
 		}
-		fmt.Println("(unknown)")
+		fmt.Println(Version)
 		return
 	}