Fix execution of plugins on Windows

- syscall.Exec is not supported on Windows systems. Use the os/exec
  package instead.
- On windows the plugin executables should have the .exe filename
  extension in order to execute them.

Signed-off-by: Han Verstraete (OpenFaaS Ltd) <[email protected]>

commands/faas.go

@@ -4,9 +4,11 @@
 package commands
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"os"
+	"os/exec"
 	"path"
 	"runtime"
 	"strings"
@@ -88,21 +90,42 @@ func Execute(customArgs []string) {
 	}
 
 	if cmd1 != nil && len(args1) > 0 {
-
 		found := ""
 		for _, plugin := range plugins {
-			if path.Base(plugin) == args1[0] {
+			pluginName := args1[0]
+			if runtime.GOOS == "windows" {
+				pluginName = fmt.Sprintf("%s.exe", args1[0])
+			}
+
+			if path.Base(plugin) == pluginName {
 				found = plugin
 			}
 		}
 		if len(found) > 0 {
-
-			// if we have found the plugin then sysexec it by replacing current process.
-			if err := syscall.Exec(found, append([]string{found}, os.Args[2:]...), os.Environ()); err != nil {
-				fmt.Fprintf(os.Stderr, "Error from plugin: %v", err)
-				os.Exit(127)
+			// If we have found the plugin then sysexec it by replacing the current process.
+			// On Windows we use the os/exec package to run the plugins since replacing the current
+			// process with syscall.exec is not supported.
+			if runtime.GOOS == "windows" {
+				cmd := exec.Command(found, os.Args[2:]...)
+				cmd.Stdout = os.Stdout
+				cmd.Stderr = os.Stderr
+				if err := cmd.Run(); err != nil {
+					var exitErr *exec.ExitError
+					if errors.As(err, &exitErr) {
+						os.Exit(exitErr.ExitCode())
+					} else {
+						fmt.Println("Error from plugin", err)
+						os.Exit(127)
+					}
+				}
+				return
+			} else {
+				if err := syscall.Exec(found, append([]string{found}, os.Args[2:]...), os.Environ()); err != nil {
+					fmt.Fprintf(os.Stderr, "Error from plugin: %v", err)
+					os.Exit(127)
+				}
+				return
 			}
-			return
 		}
 	}
 

commands/plugin_get.go

@@ -132,6 +132,17 @@ func runPluginGetCmd(cmd *cobra.Command, args []string) error {
 	if err := archive.Untar(tarFile, pluginDir, gzipped, true); err != nil {
 		return fmt.Errorf("failed to untar %s: %w", tmpTar, err)
 	}
+
+	// Add the .exe filename extension to the plugin executable on windows.
+	// If the .exe extension is missing the plugin will not execute.
+	if runtime.GOOS == "windows" {
+		pluginPath := path.Join(pluginDir, pluginName)
+		err := os.Rename(pluginPath, fmt.Sprintf("%s.exe", pluginPath))
+		if err != nil {
+			return fmt.Errorf("failed to move plugin %w", err)
+		}
+	}
+
 	fmt.Printf("Downloaded in (%ds)\n\nUsage:\n  faas-cli %s\n", int(time.Since(st).Seconds()), pluginName)
 	return nil
 }