cmd/dist: log OS version when testing

As a follow-up to https://golang.org/cl/371474, add the OS version to
the metadata printed for each test.

This is a redo of CL 371475. This version updates go.mod and conforms to
the changes made in the parent commit.

Fixes #50146.

Change-Id: Iba5541cc8dd2c85c1fa3a215e30c8c3f9b6aaaab
Reviewed-on: https://go-review.googlesource.com/c/go/+/378590
Reviewed-by: Austin Clements <austin@google.com>
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/go.mod

@@ -7,6 +7,7 @@ require (
 	golang.org/x/arch v0.0.0-20210923205945-b76863e36670
 	golang.org/x/mod v0.6.0-dev.0.20211102181907-3a5865c02020
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
+	golang.org/x/sys v0.0.0-20211205182925-97ca703d548d
 	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211
 	golang.org/x/tools v0.1.9-0.20220124164225-97de9ec46646
 )
@@ -14,6 +15,5 @@ require (
 require (
 	github.com/ianlancetaylor/demangle v0.0.0-20210905161508-09a460cdf81d // indirect
 	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 // indirect
-	golang.org/x/sys v0.0.0-20211205182925-97ca703d548d // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 )

src/cmd/internal/metadata/main.go

@@ -8,6 +8,7 @@
 package main
 
 import (
+	"cmd/internal/osinfo"
 	"fmt"
 	"internal/sysinfo"
 	"runtime"
@@ -16,4 +17,11 @@ import (
 func main() {
 	fmt.Printf("# GOARCH: %s\n", runtime.GOARCH)
 	fmt.Printf("# CPU: %s\n", sysinfo.CPU.Name())
+
+	fmt.Printf("# GOOS: %s\n", runtime.GOOS)
+	ver, err := osinfo.Version()
+	if err != nil {
+		ver = fmt.Sprintf("UNKNOWN: error determining OS version: %v", err)
+	}
+	fmt.Printf("# OS Version: %s\n", ver)
 }

src/cmd/internal/osinfo/doc.go

@@ -0,0 +1,6 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package osinfo provides OS metadata.
+package osinfo

src/cmd/internal/osinfo/os_js.go

@@ -0,0 +1,21 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build js
+
+package osinfo
+
+import (
+	"fmt"
+)
+
+// Version returns the OS version name/number.
+func Version() (string, error) {
+	// Version detection on wasm varies depending on the underlying runtime
+	// (browser, node, etc), nor is there a standard via something like
+	// WASI (see https://go.dev/issue/31105). We could attempt multiple
+	// combinations, but for now we leave this unimplemented for
+	// simplicity.
+	return "", fmt.Errorf("unimplemented")
+}

src/cmd/internal/osinfo/os_plan9.go

@@ -0,0 +1,21 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build plan9
+
+package osinfo
+
+import (
+	"os"
+)
+
+// Version returns the OS version name/number.
+func Version() (string, error) {
+	b, err := os.ReadFile("/dev/osversion")
+	if err != nil {
+		return "", err
+	}
+
+	return string(b), nil
+}

src/cmd/internal/osinfo/os_unix.go

@@ -0,0 +1,36 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+
+package osinfo
+
+import (
+	"bytes"
+
+	"golang.org/x/sys/unix"
+)
+
+func utsString(b []byte) string {
+	i := bytes.IndexByte(b, 0)
+	if i == -1 {
+		return string(b)
+	}
+	return string(b[:i])
+}
+
+// Version returns the OS version name/number.
+func Version() (string, error) {
+	var uts unix.Utsname
+	if err := unix.Uname(&uts); err != nil {
+		return "", err
+	}
+
+	sysname := utsString(uts.Sysname[:])
+	release := utsString(uts.Release[:])
+	version := utsString(uts.Version[:])
+	machine := utsString(uts.Machine[:])
+
+	return sysname + " " + release + " " + version + " " + machine, nil
+}

src/cmd/internal/osinfo/os_windows.go

@@ -0,0 +1,19 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package osinfo
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/windows"
+)
+
+// Version returns the OS version name/number.
+func Version() (string, error) {
+	major, minor, patch := windows.RtlGetNtVersionNumbers()
+	return fmt.Sprintf("%d.%d.%d", major, minor, patch), nil
+}