log: password prompt output fixed for unix - partially fixes #2220

fs/config/config.go

@@ -74,6 +74,9 @@ var (
 	// Key to use for password en/decryption.
 	// When nil, no encryption will be used for saving.
 	configKey []byte
+
+	// output of prompt for password
+	PasswordPromptOutput = os.Stderr
 )
 
 func init() {
@@ -287,9 +290,9 @@ func checkPassword(password string) (string, error) {
 
 // GetPassword asks the user for a password with the prompt given.
 func GetPassword(prompt string) string {
-	_, _ = fmt.Fprintln(os.Stderr, prompt)
+	_, _ = fmt.Fprintln(PasswordPromptOutput, prompt)
 	for {
-		_, _ = fmt.Fprint(os.Stderr, "password:")
+		_, _ = fmt.Fprint(PasswordPromptOutput, "password:")
 		password := ReadPassword()
 		password, err := checkPassword(password)
 		if err == nil {

fs/log/redirect_stderr_unix.go

@@ -8,12 +8,19 @@ import (
 	"log"
 	"os"
 
+	"github.com/ncw/rclone/fs/config"
+
 	"golang.org/x/sys/unix"
 )
 
 // redirectStderr to the file passed in
 func redirectStderr(f *os.File) {
-	err := unix.Dup2(int(f.Fd()), int(os.Stderr.Fd()))
+	passPromptFd, err := unix.Dup(int(os.Stderr.Fd()))
+	if err != nil {
+		log.Fatalf("Failed to duplicate stderr: %v", err)
+	}
+	config.PasswordPromptOutput = os.NewFile(uintptr(passPromptFd), "passPrompt")
+	err = unix.Dup2(int(f.Fd()), int(os.Stderr.Fd()))
 	if err != nil {
 		log.Fatalf("Failed to redirect stderr to file: %v", err)
 	}