age: wrap decryption errors through and add armor.Error

age.go

@@ -179,7 +179,7 @@ func Decrypt(src io.Reader, identities ...Identity) (io.Reader, error) {
 
 	hdr, payload, err := format.Parse(src)
 	if err != nil {
-		return nil, fmt.Errorf("failed to read header: %v", err)
+		return nil, fmt.Errorf("failed to read header: %w", err)
 	}
 
 	stanzas := make([]*Stanza, 0, len(hdr.Recipients))
@@ -212,7 +212,7 @@ func Decrypt(src io.Reader, identities ...Identity) (io.Reader, error) {
 
 	nonce := make([]byte, streamNonceSize)
 	if _, err := io.ReadFull(payload, nonce); err != nil {
-		return nil, fmt.Errorf("failed to read nonce: %v", err)
+		return nil, fmt.Errorf("failed to read nonce: %w", err)
 	}
 
 	return stream.NewReader(streamKey(fileKey, nonce), payload)

armor/armor.go

@@ -14,6 +14,7 @@ import (
 	"bytes"
 	"encoding/base64"
 	"errors"
+	"fmt"
 	"io"
 
 	"filippo.io/age/internal/format"
@@ -90,7 +91,7 @@ func (r *armoredReader) Read(p []byte) (int, error) {
 		line, err := r.r.ReadBytes('\n')
 		if err != nil && len(line) == 0 {
 			if err == io.EOF {
-				err = errors.New("invalid armor: unexpected EOF")
+				err = io.ErrUnexpectedEOF
 			}
 			return nil, err
 		}
@@ -103,7 +104,7 @@ func (r *armoredReader) Read(p []byte) (int, error) {
 			return 0, r.setErr(err)
 		}
 		if string(line) != Header {
-			return 0, r.setErr(errors.New("invalid armor first line: " + string(line)))
+			return 0, r.setErr(fmt.Errorf("invalid first line: %q", line))
 		}
 		r.started = true
 	}
@@ -115,12 +116,12 @@ func (r *armoredReader) Read(p []byte) (int, error) {
 		return 0, r.setErr(io.EOF)
 	}
 	if len(line) > format.ColumnsPerLine {
-		return 0, r.setErr(errors.New("invalid armor: column limit exceeded"))
+		return 0, r.setErr(errors.New("column limit exceeded"))
 	}
 	r.unread = r.buf[:]
 	n, err := base64.StdEncoding.Strict().Decode(r.unread, line)
 	if err != nil {
-		return 0, r.setErr(errors.New("invalid armor: " + err.Error()))
+		return 0, r.setErr(err)
 	}
 	r.unread = r.unread[:n]
 
@@ -130,7 +131,7 @@ func (r *armoredReader) Read(p []byte) (int, error) {
 			return 0, r.setErr(err)
 		}
 		if string(line) != Footer {
-			return 0, r.setErr(errors.New("invalid armor closing line: " + string(line)))
+			return 0, r.setErr(fmt.Errorf("invalid closing line: %q", line))
 		}
 		r.err = io.EOF
 	}
@@ -140,7 +141,22 @@ func (r *armoredReader) Read(p []byte) (int, error) {
 	return nn, nil
 }
 
+type Error struct {
+	err error
+}
+
+func (e *Error) Error() string {
+	return "invalid armor: " + e.err.Error()
+}
+
+func (e *Error) Unwrap() error {
+	return e.err
+}
+
 func (r *armoredReader) setErr(err error) error {
+	if err != io.EOF {
+		err = &Error{err}
+	}
 	r.err = err
 	return err
 }

internal/format/format.go

@@ -175,7 +175,7 @@ func (r *StanzaReader) ReadStanza() (s *Stanza, err error) {
 
 	line, err := r.r.ReadBytes('\n')
 	if err != nil {
-		return nil, fmt.Errorf("failed to read line: %v", err)
+		return nil, fmt.Errorf("failed to read line: %w", err)
 	}
 	if !bytes.HasPrefix(line, stanzaPrefix) {
 		return nil, fmt.Errorf("malformed stanza opening line: %q", line)
@@ -195,7 +195,7 @@ func (r *StanzaReader) ReadStanza() (s *Stanza, err error) {
 	for {
 		line, err := r.r.ReadBytes('\n')
 		if err != nil {
-			return nil, fmt.Errorf("failed to read line: %v", err)
+			return nil, fmt.Errorf("failed to read line: %w", err)
 		}
 
 		b, err := DecodeString(strings.TrimSuffix(string(line), "\n"))
@@ -216,14 +216,20 @@ func (r *StanzaReader) ReadStanza() (s *Stanza, err error) {
 	}
 }
 
-type ParseError string
+type ParseError struct {
+	err error
+}
 
-func (e ParseError) Error() string {
-	return "parsing age header: " + string(e)
+func (e *ParseError) Error() string {
+	return "parsing age header: " + e.err.Error()
+}
+
+func (e *ParseError) Unwrap() error {
+	return e.err
 }
 
 func errorf(format string, a ...interface{}) error {
-	return ParseError(fmt.Sprintf(format, a...))
+	return &ParseError{fmt.Errorf(format, a...)}
 }
 
 // Parse returns the header and a Reader that begins at the start of the
@@ -234,7 +240,7 @@ func Parse(input io.Reader) (*Header, io.Reader, error) {
 
 	line, err := rr.ReadString('\n')
 	if err != nil {
-		return nil, nil, errorf("failed to read intro: %v", err)
+		return nil, nil, errorf("failed to read intro: %w", err)
 	}
 	if line != intro {
 		return nil, nil, errorf("unexpected intro: %q", line)
@@ -244,13 +250,13 @@ func Parse(input io.Reader) (*Header, io.Reader, error) {
 	for {
 		peek, err := rr.Peek(len(footerPrefix))
 		if err != nil {
-			return nil, nil, errorf("failed to read header: %v", err)
+			return nil, nil, errorf("failed to read header: %w", err)
 		}
 
 		if bytes.Equal(peek, footerPrefix) {
 			line, err := rr.ReadBytes('\n')
 			if err != nil {
-				return nil, nil, fmt.Errorf("failed to read header: %v", err)
+				return nil, nil, fmt.Errorf("failed to read header: %w", err)
 			}
 
 			prefix, args := splitArgs(line)
@@ -266,7 +272,7 @@ func Parse(input io.Reader) (*Header, io.Reader, error) {
 
 		s, err := sr.ReadStanza()
 		if err != nil {
-			return nil, nil, fmt.Errorf("failed to parse header: %v", err)
+			return nil, nil, fmt.Errorf("failed to parse header: %w", err)
 		}
 		h.Recipients = append(h.Recipients, s)
 	}