Refactor password resolving.

Instead of determining the password lazily during ReadPassword(), do so now in
cobra.PersistentPreRunE() so we can store the result in the globalOptions and
reuse/override when applicable without having to worry about the environment
or flag options interfering.

cmd/restic/cmd_key.go

@@ -3,7 +3,6 @@ package main
 import (
 	"context"
 	"fmt"
-	"os"
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/repository"
@@ -60,14 +59,10 @@ func getNewPassword(gopts GlobalOptions) (string, error) {
 		return testKeyNewPassword, nil
 	}
 
-	// Since we already have an open repository, temporary remove the overrides
-	// to prompt the user for their passwd
-	oldPasswd := os.Getenv("RESTIC_PASSWORD")
-	defer func() { os.Setenv("RESTIC_PASSWORD", oldPasswd) }()
-	os.Unsetenv("RESTIC_PASSWORD")
+	// Since we already have an open repository, temporary remove the password
+	// to prompt the user for the passwd.
 	newopts := gopts
 	newopts.password = ""
-	newopts.PasswordFile = ""
 
 	return ReadPasswordTwice(newopts,
 		"enter password for new key: ",

cmd/restic/global.go

@@ -53,11 +53,6 @@ var globalOptions = GlobalOptions{
 }
 
 func init() {
-	pw := os.Getenv("RESTIC_PASSWORD")
-	if pw != "" {
-		globalOptions.password = pw
-	}
-
 	var cancel context.CancelFunc
 	globalOptions.ctx, cancel = context.WithCancel(context.Background())
 	AddCleanupHandler(func() error {
@@ -207,6 +202,20 @@ func Exitf(exitcode int, format string, args ...interface{}) {
 	Exit(exitcode)
 }
 
+// resolvePassword determines the password to be used for opening the repository.
+func resolvePassword(opts GlobalOptions, env string) (string, error) {
+	if opts.PasswordFile != "" {
+		s, err := ioutil.ReadFile(opts.PasswordFile)
+		return strings.TrimSpace(string(s)), errors.Wrap(err, "Readfile")
+	}
+
+	if pwd := os.Getenv(env); pwd != "" {
+		return pwd, nil
+	}
+
+	return "", nil
+}
+
 // readPassword reads the password from the given reader directly.
 func readPassword(in io.Reader) (password string, err error) {
 	buf := make([]byte, 1000)
@@ -238,13 +247,8 @@ func readPasswordTerminal(in *os.File, out io.Writer, prompt string) (password s
 // ReadPassword reads the password from a password file, the environment
 // variable RESTIC_PASSWORD or prompts the user.
 func ReadPassword(opts GlobalOptions, prompt string) (string, error) {
-	if opts.PasswordFile != "" {
-		s, err := ioutil.ReadFile(opts.PasswordFile)
-		return strings.TrimSpace(string(s)), errors.Wrap(err, "Readfile")
-	}
-
-	if pwd := os.Getenv("RESTIC_PASSWORD"); pwd != "" {
-		return pwd, nil
+	if opts.password != "" {
+		return opts.password, nil
 	}
 
 	var (

cmd/restic/main.go

@@ -36,6 +36,13 @@ directories in an encrypted repository stored on different backends.
 		}
 		globalOptions.extended = opts
 
+		pwd, err := resolvePassword(globalOptions, "RESTIC_PASSWORD")
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Resolving password failed: %v\n", err)
+			Exit(1)
+		}
+		globalOptions.password = pwd
+
 		// run the debug functions for all subcommands (if build tag "debug" is
 		// enabled)
 		if err := runDebug(); err != nil {