fix: Add ARM64 filter support

Author: bodgit

README.md

@@ -21,7 +21,7 @@ Current status:
 * Handles archives split into multiple volumes, (`7za a -v100m test.7z ...`).
 * Handles self-extracting archives, (`7za a -sfx archive.exe ...`).
 * Validates CRC values as it parses the file.
-* Supports ARM, BCJ, BCJ2, Brotli, Bzip2, Copy, Deflate, Delta, LZ4, LZMA, LZMA2, PPC, SPARC and Zstandard methods.
+* Supports ARM, ARM64, BCJ, BCJ2, Brotli, Bzip2, Copy, Deflate, Delta, LZ4, LZMA, LZMA2, PPC, SPARC and Zstandard methods.
 * Implements the `fs.FS` interface so you can treat an opened 7-zip archive like a filesystem.
 
 More examples of 7-zip archives are needed to test all of the different combinations/algorithms possible.

internal/bra/arm.go

@@ -19,26 +19,23 @@ func (c *arm) Convert(b []byte, encoding bool) int {
 	}
 
 	if c.ip == 0 {
-		c.ip += armAlignment
+		c.ip = armAlignment
 	}
 
 	var i int
 
 	for i = 0; i < len(b) & ^(armAlignment-1); i += armAlignment {
 		v := binary.LittleEndian.Uint32(b[i:])
 
-		c.ip += uint32(armAlignment)
+		c.ip += armAlignment
 
 		if b[i+3] == 0xeb {
-			v <<= 2
-
 			if encoding {
-				v += c.ip
+				v += c.ip >> 2
 			} else {
-				v -= c.ip
+				v -= c.ip >> 2
 			}
 
-			v >>= 2
 			v &= 0x00ffffff
 			v |= 0xeb000000
 		}

internal/bra/arm64.go

@@ -0,0 +1,78 @@
+package bra
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+const arm64Alignment = 4
+
+type arm64 struct {
+	ip uint32
+}
+
+func (c *arm64) Size() int { return arm64Alignment }
+
+func (c *arm64) Convert(b []byte, encoding bool) int {
+	if len(b) < c.Size() {
+		return 0
+	}
+
+	var i int
+
+	for i = 0; i < len(b) & ^(arm64Alignment-1); i, c.ip = i+arm64Alignment, c.ip+arm64Alignment {
+		v := binary.LittleEndian.Uint32(b[i:])
+
+		if (v-0x94000000)&0xfc000000 == 0 {
+			if encoding {
+				v += c.ip >> 2
+			} else {
+				v -= c.ip >> 2
+			}
+
+			v &= 0x03ffffff
+			v |= 0x94000000
+
+			binary.LittleEndian.PutUint32(b[i:], v)
+
+			continue
+		}
+
+		v -= 0x90000000
+
+		if v&0x9f000000 == 0 {
+			const (
+				flag = uint32(1) << (24 - 4)
+				mask = uint32(1)<<24 - flag<<1
+			)
+
+			v += flag
+
+			if v&mask > 0 {
+				continue
+			}
+
+			z, ip := v&0xffffffe0|v>>26, (c.ip>>(12-3)) & ^uint32(7)
+
+			if encoding {
+				z += ip
+			} else {
+				z -= ip
+			}
+
+			v &= 0x1f
+			v |= 0x90000000
+			v |= z << 26
+			v |= 0x00ffffe0 & ((z & (flag<<1 - 1)) - flag)
+
+			binary.LittleEndian.PutUint32(b[i:], v)
+		}
+	}
+
+	return i
+}
+
+// NewARM64Reader returns a new ARM64 io.ReadCloser.
+func NewARM64Reader(_ []byte, _ uint64, readers []io.ReadCloser) (io.ReadCloser, error) {
+	return newReader(readers, new(arm64))
+}

internal/bra/ppc.go

@@ -20,7 +20,7 @@ func (c *ppc) Convert(b []byte, encoding bool) int {
 
 	var i int
 
-	for i = 0; i < len(b) & ^(ppcAlignment-1); i += ppcAlignment {
+	for i = 0; i < len(b) & ^(ppcAlignment-1); i, c.ip = i+ppcAlignment, c.ip+ppcAlignment {
 		v := binary.BigEndian.Uint32(b[i:])
 
 		if b[i+0]&0xfc == 0x48 && b[i+3]&3 == 1 {
@@ -34,8 +34,6 @@ func (c *ppc) Convert(b []byte, encoding bool) int {
 			v |= 0x48000000
 		}
 
-		c.ip += uint32(ppcAlignment)
-
 		binary.BigEndian.PutUint32(b[i:], v)
 	}
 

internal/bra/sparc.go

@@ -20,10 +20,12 @@ func (c *sparc) Convert(b []byte, encoding bool) int {
 
 	var i int
 
-	for i = 0; i < len(b) & ^(sparcAlignment-1); i += sparcAlignment {
+	for i = 0; i < len(b) & ^(sparcAlignment-1); i, c.ip = i+sparcAlignment, c.ip+sparcAlignment {
 		v := binary.BigEndian.Uint32(b[i:])
 
 		if (b[i+0] == 0x40 && b[i+1]&0xc0 == 0) || (b[i+0] == 0x7f && b[i+1] >= 0xc0) {
+			const flag = uint32(1) << 24
+
 			v <<= 2
 
 			if encoding {
@@ -33,14 +35,12 @@ func (c *sparc) Convert(b []byte, encoding bool) int {
 			}
 
 			v &= 0x01ffffff
-			v -= uint32(1) << 24
+			v -= flag
 			v ^= 0xff000000
 			v >>= 2
 			v |= 0x40000000
 		}
 
-		c.ip += uint32(sparcAlignment)
-
 		binary.BigEndian.PutUint32(b[i:], v)
 	}
 

reader_test.go

@@ -197,6 +197,10 @@ func TestOpenReader(t *testing.T) {
 			file: "COMPRESS-492.7z",
 			err:  sevenzip.ErrMissingUnpackInfo,
 		},
+		{
+			name: "arm64",
+			file: "arm64.7z",
+		},
 	}
 
 	for _, table := range tables {
@@ -657,3 +661,7 @@ func BenchmarkARM(b *testing.B) {
 func BenchmarkSPARC(b *testing.B) {
 	benchmarkArchive(b, "sparc.7z", "", true)
 }
+
+func BenchmarkARM64(b *testing.B) {
+	benchmarkArchive(b, "arm64.7z", "", true)
+}

register.go

@@ -69,6 +69,8 @@ func init() {
 	RegisterDecompressor([]byte{0x04, 0xf7, 0x11, 0x04}, Decompressor(lz4.NewReader))
 	// AES-CBC-256 & SHA-256
 	RegisterDecompressor([]byte{0x06, 0xf1, 0x07, 0x01}, Decompressor(aes7z.NewReader))
+	// ARM64
+	RegisterDecompressor([]byte{0x0a}, Decompressor(bra.NewARM64Reader))
 	// LZMA2
 	RegisterDecompressor([]byte{0x21}, Decompressor(lzma2.NewReader))
 }