Use temporary files, instead of stdin/stdout, when calling gpg

internal/chezmoi/gpgencryption.go

@@ -1,9 +1,10 @@
 package chezmoi
 
 import (
-	"bytes"
 	"os"
 	"os/exec"
+	"path/filepath"
+	"runtime"
 
 	"github.com/rs/zerolog/log"
 
@@ -21,69 +22,135 @@ type GPGEncryption struct {
 
 // Decrypt implements Encyrption.Decrypt.
 func (e *GPGEncryption) Decrypt(ciphertext []byte) ([]byte, error) {
-	args := append([]string{"--decrypt"}, e.Args...)
-	//nolint:gosec
-	cmd := exec.Command(e.Command, args...)
-	cmd.Stdin = bytes.NewReader(ciphertext)
-	cmd.Stderr = os.Stderr
-	return chezmoilog.LogCmdOutput(log.Logger, cmd)
+	var plaintext []byte
+	if err := withPrivateTempDir(func(tempDir string) error {
+		ciphertextFilename := filepath.Join(tempDir, "ciphertext"+e.EncryptedSuffix())
+		if err := os.WriteFile(ciphertextFilename, ciphertext, 0o600); err != nil {
+			return err
+		}
+		plaintextFilename := filepath.Join(tempDir, "plaintext")
+
+		args := e.decryptArgs(plaintextFilename, ciphertextFilename)
+		if err := e.run(args); err != nil {
+			return err
+		}
+
+		var err error
+		plaintext, err = os.ReadFile(plaintextFilename)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+	return plaintext, nil
 }
 
 // DecryptToFile implements Encryption.DecryptToFile.
 func (e *GPGEncryption) DecryptToFile(plaintextFilename string, ciphertext []byte) error {
-	args := append([]string{
-		"--decrypt",
-		"--output", plaintextFilename,
-		"--yes",
-	}, e.Args...)
-	//nolint:gosec
-	cmd := exec.Command(e.Command, args...)
-	cmd.Stdin = bytes.NewReader(ciphertext)
-	cmd.Stderr = os.Stderr
-	return chezmoilog.LogCmdRun(log.Logger, cmd)
+	return withPrivateTempDir(func(tempDir string) error {
+		ciphertextFilename := filepath.Join(tempDir, "ciphertext"+e.EncryptedSuffix())
+		if err := os.WriteFile(ciphertextFilename, ciphertext, 0o600); err != nil {
+			return err
+		}
+		args := e.decryptArgs(plaintextFilename, ciphertextFilename)
+		return e.run(args)
+	})
 }
 
 // Encrypt implements Encryption.Encrypt.
 func (e *GPGEncryption) Encrypt(plaintext []byte) ([]byte, error) {
-	args := append(e.encryptArgs(), e.Args...)
-	//nolint:gosec
-	cmd := exec.Command(e.Command, args...)
-	cmd.Stdin = bytes.NewReader(plaintext)
-	cmd.Stderr = os.Stderr
-	return chezmoilog.LogCmdOutput(log.Logger, cmd)
+	var ciphertext []byte
+	if err := withPrivateTempDir(func(tempDir string) error {
+		plaintextFilename := filepath.Join(tempDir, "plaintext")
+		if err := os.WriteFile(plaintextFilename, plaintext, 0o600); err != nil {
+			return err
+		}
+		ciphertextFilename := filepath.Join(tempDir, "ciphertext"+e.EncryptedSuffix())
+
+		args := e.encryptArgs(plaintextFilename, ciphertextFilename)
+		if err := e.run(args); err != nil {
+			return err
+		}
+
+		var err error
+		ciphertext, err = os.ReadFile(ciphertextFilename)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+	return ciphertext, nil
 }
 
 // EncryptFile implements Encryption.EncryptFile.
-func (e *GPGEncryption) EncryptFile(plaintextFilename string) (ciphertext []byte, err error) {
-	f, err := os.Open(plaintextFilename)
-	if err != nil {
+func (e *GPGEncryption) EncryptFile(plaintextFilename string) ([]byte, error) {
+	var ciphertext []byte
+	if err := withPrivateTempDir(func(tempDir string) error {
+		ciphertextFilename := filepath.Join(tempDir, "ciphertext"+e.EncryptedSuffix())
+
+		args := e.encryptArgs(plaintextFilename, ciphertextFilename)
+		if err := e.run(args); err != nil {
+			return err
+		}
+
+		var err error
+		ciphertext, err = os.ReadFile(ciphertextFilename)
+		return err
+	}); err != nil {
 		return nil, err
 	}
-	defer f.Close()
-	args := append(e.encryptArgs(), e.Args...)
-	//nolint:gosec
-	cmd := exec.Command(e.Command, args...)
-	cmd.Stdin = f
-	cmd.Stderr = os.Stderr
-	return chezmoilog.LogCmdOutput(log.Logger, cmd)
+	return ciphertext, nil
 }
 
 // EncryptedSuffix implements Encryption.EncryptedSuffix.
 func (e *GPGEncryption) EncryptedSuffix() string {
 	return e.Suffix
 }
 
-func (e *GPGEncryption) encryptArgs() []string {
+func (e *GPGEncryption) decryptArgs(plaintextFilename, ciphertextFilename string) []string {
+	args := []string{"--output", plaintextFilename}
+	args = append(args, e.Args...)
+	args = append(args, "--decrypt", ciphertextFilename)
+	return args
+}
+
+func (e *GPGEncryption) encryptArgs(plaintextFilename, ciphertextFilename string) []string {
 	args := []string{
 		"--armor",
+		"--output", ciphertextFilename,
 	}
 	if e.Symmetric {
 		args = append(args, "--symmetric")
-	} else {
+	} else if e.Recipient != "" {
+		args = append(args, "--recipient", e.Recipient)
+	}
+	args = append(args, e.Args...)
+	if !e.Symmetric {
 		args = append(args, "--encrypt")
-		if e.Recipient != "" {
-			args = append(args, "--recipient", e.Recipient)
-		}
 	}
+	args = append(args, plaintextFilename)
 	return args
 }
+
+func (e *GPGEncryption) run(args []string) error {
+	//nolint:gosec
+	cmd := exec.Command(e.Command, args...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return chezmoilog.LogCmdRun(log.Logger, cmd)
+}
+
+// withPrivateTempDir creates a private temporary and calls f.
+func withPrivateTempDir(f func(tempDir string) error) error {
+	tempDir, err := os.MkdirTemp("", "chezmoi-encryption")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tempDir)
+	if runtime.GOOS != "windows" {
+		if err := os.Chmod(tempDir, 0o700); err != nil {
+			return err
+		}
+	}
+
+	return f(tempDir)
+}