From 2072dcc1270ed9caf8788700f4872a18f110ba25 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Thu, 30 Jul 2020 07:59:43 -0700
Subject: [PATCH] version: revert the filepath change from earlier commit

f81233524fddeec450940af8dc1a0dd8841bf28c changed a use of package 'path' to 'filepath'.
Restore it back to 'path', with a comment.

Also, use the os.Executable-based fallback name in the case where the
binary itself doesn't have Go module information. That was overlooked in
the original code.
---
 version/cmdname.go | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/version/cmdname.go b/version/cmdname.go
index a72eb9c21..a7899ed9f 100644
--- a/version/cmdname.go
+++ b/version/cmdname.go
@@ -8,6 +8,7 @@ package version
 
 import (
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 
@@ -22,23 +23,27 @@ func CmdName() string {
 	if err != nil {
 		return "cmd"
 	}
+
+	// fallbackName, the lowercase basename of the executable, is what we return if
+	// we can't find the Go module metadata embedded in the file.
+	fallbackName := filepath.Base(strings.TrimSuffix(strings.ToLower(e), ".exe"))
+
 	var ret string
 	v, err := version.ReadExe(e)
 	if err != nil {
-		ret = strings.TrimSuffix(strings.ToLower(e), ".exe")
-		ret = filepath.Base(ret)
-	} else {
-		// v is like:
-		// "path\ttailscale.com/cmd/tailscale\nmod\ttailscale.com\t(devel)\t\ndep\tgithub.com/apenwarr/fixconsole\tv0.0.0-20191012055117-5a9f6489cc29\th1:muXWUcay7DDy1/hEQWrYlBy+g0EuwT70sBHg65SeUc4=\ndep\tgithub....
-		for _, line := range strings.Split(v.ModuleInfo, "\n") {
-			if strings.HasPrefix(line, "path\t") {
-				ret = filepath.Base(strings.TrimPrefix(line, "path\t"))
-				break
-			}
+		return fallbackName
+	}
+	// v is like:
+	// "path\ttailscale.com/cmd/tailscale\nmod\ttailscale.com\t(devel)\t\ndep\tgithub.com/apenwarr/fixconsole\tv0.0.0-20191012055117-5a9f6489cc29\th1:muXWUcay7DDy1/hEQWrYlBy+g0EuwT70sBHg65SeUc4=\ndep\tgithub....
+	for _, line := range strings.Split(v.ModuleInfo, "\n") {
+		if strings.HasPrefix(line, "path\t") {
+			goPkg := strings.TrimPrefix(line, "path\t") // like "tailscale.com/cmd/tailscale"
+			ret = path.Base(goPkg)                      // goPkg is always forward slashes; use path, not filepath
+			break
 		}
 	}
 	if ret == "" {
-		return "cmd"
+		return fallbackName
 	}
 	return ret
 }