Change errors to include details

CHANGELOG.adoc

@@ -14,6 +14,12 @@ All notable changes to this project will be documented in this file.
 The format is based on https://keepachangelog.com/[Keep a Changelog], and this
 project adheres to https://semver.org/[Semantic Versioning].
 
+== {compare-url}/v0.2.0\...HEAD[Unreleased]
+
+=== Changed
+
+* Change errors to include details ({pull-request-url}/8[#8])
+
 == {compare-url}/v0.1.0\...v0.2.0[0.2.0] - 2024-04-05
 
 === Added

error.go

@@ -6,43 +6,86 @@ package lzip
 
 import "errors"
 
-var (
-	// ErrInvalidMagic represents an error due to the magic number was
-	// invalid.
-	ErrInvalidMagic = errors.New("lzip: invalid magic number")
-
-	// ErrUnsupportedVersion represents an error due to the version number
-	// stored in the header indicated the lzip format which is not
-	// supported by this package.
-	ErrUnsupportedVersion = errors.New("lzip: unsupported version number")
-
-	// ErrUnknownVersion represents an error due to the version number
-	// stored in the header was not recognized by this package.
-	ErrUnknownVersion = errors.New("lzip: unknown version number")
-
-	// ErrDictSizeTooSmall represents an error due to the dictionary size
-	// was smaller than 4 KiB.
-	ErrDictSizeTooSmall = errors.New("lzip: dictionary size is too small")
-
-	// ErrDictSizeTooLarge represents an error due to the dictionary size
-	// was larger than 512 MiB.
-	ErrDictSizeTooLarge = errors.New("lzip: dictionary size is too large")
-
-	// ErrInvalidCRC represents an error due to a CRC of the original
-	// uncompressed data mismatched.
-	ErrInvalidCRC = errors.New("lzip: CRC mismatch")
-
-	// ErrInvalidDataSize represents an error due to the size of the
-	// original uncompressed data stored in the trailer and the actual size
-	// of it mismatched.
-	ErrInvalidDataSize = errors.New("lzip: data size mismatch")
-
-	// ErrInvalidMemberSize represents an error due to the total size of
-	// the member stored in the trailer and the actual total size of it
-	// mismatched.
-	ErrInvalidMemberSize = errors.New("lzip: member size mismatch")
-
-	// ErrDictSizeTooLarge represents an error due to the member size was
-	// larger than 2 PiB.
-	ErrMemberSizeTooLarge = errors.New("lzip: member size is too large")
-)
+// ErrInvalidMagic represents an error due to the magic number was invalid.
+var ErrInvalidMagic = errors.New("lzip: invalid magic number")
+
+// UnsupportedVersionError represents an error due to the version number stored
+// in the header indicated the lzip format which is not supported by this
+// package.
+type UnsupportedVersionError struct {
+	Version uint8
+}
+
+func (e *UnsupportedVersionError) Error() string {
+	return "lzip: unsupported version number"
+}
+
+// UnknownVersionError represents an error due to the version number stored in
+// the header was not recognized by this package.
+type UnknownVersionError struct {
+	Version uint8
+}
+
+func (e *UnknownVersionError) Error() string {
+	return "lzip: unknown version number"
+}
+
+// DictSizeTooSmallError represents an error due to the dictionary size was
+// smaller than 4 KiB.
+type DictSizeTooSmallError struct {
+	DictSize uint32
+}
+
+func (e *DictSizeTooSmallError) Error() string {
+	return "lzip: dictionary size is too small"
+}
+
+// DictSizeTooLargeError represents an error due to the dictionary size was
+// larger than 512 MiB.
+type DictSizeTooLargeError struct {
+	DictSize uint32
+}
+
+func (e *DictSizeTooLargeError) Error() string {
+	return "lzip: dictionary size is too large"
+}
+
+// InvalidCRCError represents an error due to a CRC of the original
+// uncompressed data mismatched.
+type InvalidCRCError struct {
+	CRC uint32
+}
+
+func (e *InvalidCRCError) Error() string {
+	return "lzip: CRC mismatch"
+}
+
+// InvalidDataSizeError represents an error due to the size of the original
+// uncompressed data stored in the trailer and the actual size of it mismatched.
+type InvalidDataSizeError struct {
+	DataSize uint64
+}
+
+func (e *InvalidDataSizeError) Error() string {
+	return "lzip: data size mismatch"
+}
+
+// InvalidMemberSizeError represents an error due to the total size of the
+// member stored in the trailer and the actual total size of it mismatched.
+type InvalidMemberSizeError struct {
+	MemberSize uint64
+}
+
+func (e *InvalidMemberSizeError) Error() string {
+	return "lzip: member size mismatch"
+}
+
+// MemberSizeTooLargeError represents an error due to the member size was
+// larger than 2 PiB.
+type MemberSizeTooLargeError struct {
+	MemberSize uint64
+}
+
+func (e *MemberSizeTooLargeError) Error() string {
+	return "lzip: member size is too large"
+}

error_test.go

@@ -5,6 +5,7 @@
 package lzip_test
 
 import (
+	"math"
 	"testing"
 
 	"github.com/sorairolake/lzip-go"
@@ -21,90 +22,122 @@ func TestErrInvalidMagic(t *testing.T) {
 	}
 }
 
-func TestErrUnsupportedVersion(t *testing.T) {
+func TestUnsupportedVersionError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrUnsupportedVersion
+	err := lzip.UnsupportedVersionError{0}
 	expected := "lzip: unsupported version number"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if v := err.Version; v != 0 {
+		t.Errorf("expected unsupported version number `%v`, got `%v`", 0, v)
+	}
 }
 
-func TestErrUnknownVersion(t *testing.T) {
+func TestUnknownVersionError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrUnknownVersion
+	err := lzip.UnknownVersionError{math.MaxUint8}
 	expected := "lzip: unknown version number"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if v := err.Version; v != math.MaxUint8 {
+		t.Errorf("expected unknown version number `%v`, got `%v`", math.MaxUint8, v)
+	}
 }
 
-func TestErrDictSizeTooSmall(t *testing.T) {
+func TestDictSizeTooSmallError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrDictSizeTooSmall
+	err := lzip.DictSizeTooSmallError{lzip.MinDictSize - 1}
 	expected := "lzip: dictionary size is too small"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if size := err.DictSize; size != (lzip.MinDictSize - 1) {
+		t.Errorf("expected too small dictionary size `%v`, got `%v`", lzip.MinDictSize-1, size)
+	}
 }
 
-func TestErrDictSizeTooLarge(t *testing.T) {
+func TestDictSizeTooLargeError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrDictSizeTooLarge
+	err := lzip.DictSizeTooLargeError{lzip.MaxDictSize + 1}
 	expected := "lzip: dictionary size is too large"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if size := err.DictSize; size != (lzip.MaxDictSize + 1) {
+		t.Errorf("expected too large dictionary size `%v`, got `%v`", lzip.MaxDictSize+1, size)
+	}
 }
 
-func TestErrInvalidCRC(t *testing.T) {
+func TestInvalidCRCError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrInvalidCRC
+	err := lzip.InvalidCRCError{0}
 	expected := "lzip: CRC mismatch"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if crc := err.CRC; crc != 0 {
+		t.Errorf("expected invalid CRC `%v`, got `%v`", 0, crc)
+	}
 }
 
-func TestErrInvalidDataSize(t *testing.T) {
+func TestInvalidDataSizeError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrInvalidDataSize
+	err := lzip.InvalidDataSizeError{0}
 	expected := "lzip: data size mismatch"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if size := err.DataSize; size != 0 {
+		t.Errorf("expected invalid data size `%v`, got `%v`", 0, size)
+	}
 }
 
-func TestErrInvalidMemberSize(t *testing.T) {
+func TestInvalidMemberSizeError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrInvalidMemberSize
+	err := lzip.InvalidMemberSizeError{0}
 	expected := "lzip: member size mismatch"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if size := err.MemberSize; size != 0 {
+		t.Errorf("expected invalid member size `%v`, got `%v`", 0, size)
+	}
 }
 
-func TestErrMemberSizeTooLarge(t *testing.T) {
+func TestMemberSizeTooLargeError(t *testing.T) {
 	t.Parallel()
 
-	err := lzip.ErrMemberSizeTooLarge
+	err := lzip.MemberSizeTooLargeError{lzip.MaxMemberSize + 1}
 	expected := "lzip: member size is too large"
 
 	if err.Error() != expected {
 		t.Error("unexpected error message")
 	}
+
+	if size := err.MemberSize; size != (lzip.MaxMemberSize + 1) {
+		t.Errorf("expected too large member size `%v`, got `%v`", lzip.MaxMemberSize+1, size)
+	}
 }

reader.go

@@ -38,20 +38,20 @@ func NewReader(r io.Reader) (*Reader, error) {
 
 	switch v := header[4]; v {
 	case 0:
-		return nil, ErrUnsupportedVersion
+		return nil, &UnsupportedVersionError{v}
 	case 1:
 	default:
-		return nil, ErrUnknownVersion
+		return nil, &UnknownVersionError{v}
 	}
 
 	dictSize := uint32(1 << (header[5] & 0x1f))
 	dictSize -= (dictSize / 16) * uint32((header[5]>>5)&0x07)
 
 	switch {
 	case dictSize < MinDictSize:
-		return nil, ErrDictSizeTooSmall
+		return nil, &DictSizeTooSmallError{dictSize}
 	case dictSize > MaxDictSize:
-		return nil, ErrDictSizeTooLarge
+		return nil, &DictSizeTooLargeError{dictSize}
 	}
 
 	rb, err := io.ReadAll(r)
@@ -66,8 +66,8 @@ func NewReader(r io.Reader) (*Reader, error) {
 	copy(lzmaHeader[5:], rb[len(rb)-16:len(rb)-8])
 
 	z.trailer.memberSize = uint64(headerSize + len(rb))
-	if z.trailer.memberSize > MaxMemberSize {
-		return nil, ErrMemberSizeTooLarge
+	if memberSize := z.trailer.memberSize; memberSize > MaxMemberSize {
+		return nil, &MemberSizeTooLargeError{memberSize}
 	}
 
 	rb = slices.Concat(lzmaHeader[:], rb)
@@ -106,17 +106,17 @@ func (z *Reader) Read(p []byte) (n int, err error) {
 
 		crc := binary.LittleEndian.Uint32(trailer[:4])
 		if crc != z.trailer.crc {
-			return n, ErrInvalidCRC
+			return n, &InvalidCRCError{crc}
 		}
 
 		dataSize := binary.LittleEndian.Uint64(trailer[4:12])
 		if dataSize != z.trailer.dataSize {
-			return n, ErrInvalidDataSize
+			return n, &InvalidDataSizeError{dataSize}
 		}
 
 		memberSize := binary.LittleEndian.Uint64(trailer[12:])
 		if memberSize != z.trailer.memberSize {
-			return n, ErrInvalidMemberSize
+			return n, &InvalidMemberSizeError{memberSize}
 		}
 	}
 

reader_test.go

@@ -63,8 +63,20 @@ func TestReaderUnknownVersion(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if _, err := lzip.NewReader(file); !errors.Is(err, lzip.ErrUnknownVersion) {
-		t.Error("unexpected error type")
+	_, err = lzip.NewReader(file)
+	if err == nil {
+		t.Fatal("unexpected success")
+	}
+
+	var unknownVersionError *lzip.UnknownVersionError
+	if !errors.As(err, &unknownVersionError) {
+		t.Fatal("unexpected error type")
+	}
+
+	const expected = 2
+
+	if v := unknownVersionError.Version; v != expected {
+		t.Errorf("expected unrecognized version number `%v`, got `%v`", expected, v)
 	}
 }
 
@@ -76,7 +88,19 @@ func TestReaderDictSizeTooSmall(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if _, err := lzip.NewReader(file); !errors.Is(err, lzip.ErrDictSizeTooSmall) {
-		t.Error("unexpected error type")
+	_, err = lzip.NewReader(file)
+	if err == nil {
+		t.Fatal("unexpected success")
+	}
+
+	var dictSizeTooSmallError *lzip.DictSizeTooSmallError
+	if !errors.As(err, &dictSizeTooSmallError) {
+		t.Fatal("unexpected error type")
+	}
+
+	const expected = 1 << 11
+
+	if size := dictSizeTooSmallError.DictSize; size != expected {
+		t.Errorf("expected too small dictionary size `%v`, got `%v`", expected, size)
 	}
 }