Add zstd decompression for .tar.zst

README.md

@@ -1,6 +1,6 @@
 # archives
 
-A Go library for reading and browsing archive files in memory. Supports ZIP, TAR (with gzip, bzip2, xz compression), and Ruby gem formats.
+A Go library for reading and browsing archive files in memory. Supports ZIP, TAR (with gzip, bzip2, xz, zstd compression), and Ruby gem formats.
 
 ## Installation
 
@@ -67,7 +67,7 @@ reader, _ := archives.OpenBytes("pkg.tgz", data)
 ```
 
 Filename mappings are used first. When a name has no supported extension,
-`Open` and `OpenBytes` detect ZIP, TAR, gzip, bzip2, and xz from the content.
+`Open` and `OpenBytes` detect ZIP, TAR, gzip, bzip2, xz, and zstd from the content.
 Compressed content is opened as TAR and returns a parser error when it does not
 contain a TAR archive. `Open` reads at most 512 bytes before rejecting an
 unsupported stream with no recognised extension.
@@ -115,11 +115,11 @@ for _, f := range result.Files {
 ## Supported formats
 
 - `.zip`, `.jar`, `.whl`, `.nupkg`, `.egg`, `.vsix` (ZIP-based)
-- `.tar`, `.tar.gz`, `.tgz`, `.crate`, `.tar.bz2`, `.tar.xz`
+- `.tar`, `.tar.gz`, `.tgz`, `.crate`, `.tar.bz2`, `.tar.xz`, `.tar.zst`
 - `.gem` (Ruby gems with nested data.tar.gz)
 - `.apk` (routed by content: Android packages open as ZIP, Alpine packages open as gzipped tar)
 
-Filenames without a recognised extension are opened by inspecting the first bytes for a ZIP, tar, gzip, bzip2, or xz signature.
+Filenames without a recognised extension are opened by inspecting the first bytes for a ZIP, tar, gzip, bzip2, xz, or zstd signature.
 
 ## License
 

archives.go

@@ -2,7 +2,7 @@
 //
 // It supports multiple archive formats including:
 //   - ZIP (.zip, .jar, .whl, .nupkg, .egg, .vsix)
-//   - TAR (.tar, .tar.gz, .tgz, .crate, .tar.bz2, .tar.xz)
+//   - TAR (.tar, .tar.gz, .tgz, .crate, .tar.bz2, .tar.xz, .tar.zst)
 //   - GEM (.gem - Ruby gems with nested tar structure)
 //
 // The .apk extension is routed by content since Android packages are ZIP
@@ -31,6 +31,7 @@ const (
 	formatTGZ        = "tgz"
 	formatTarBzip2   = "tar.bz2"
 	formatTarXZ      = "tar.xz"
+	formatTarZstd    = "tar.zst"
 	formatGem        = "gem"
 	contentSniffSize = 512
 )
@@ -130,6 +131,8 @@ func openRaw(format string, raw []byte) (Reader, error) {
 		return openTar(raw, "bzip2")
 	case formatTarXZ:
 		return openTar(raw, "xz")
+	case formatTarZstd:
+		return openTar(raw, "zstd")
 	case formatGem:
 		return openGem(raw)
 	default:
@@ -157,6 +160,8 @@ func archiveFormat(detected string) string {
 		return formatTarBzip2
 	case "xz":
 		return formatTarXZ
+	case "zstd":
+		return formatTarZstd
 	default:
 		return ""
 	}
@@ -209,6 +214,9 @@ func detectFormat(filename string) string {
 	if strings.HasSuffix(filename, ".tar.xz") {
 		return formatTarXZ
 	}
+	if strings.HasSuffix(filename, ".tar.zst") {
+		return formatTarZstd
+	}
 
 	// Check simple extensions. .apk is deliberately absent: Alpine packages
 	// are gzipped tarballs and Android packages are zips, so it falls

archives_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/klauspost/compress/zstd"
 	"github.com/ulikunitz/xz"
 )
 
@@ -31,6 +32,7 @@ func TestDetectFormat(t *testing.T) {
 		{"package.tgz", "tgz"},
 		{"package.tar.bz2", "tar.bz2"},
 		{"package.tar.xz", "tar.xz"},
+		{"package.tar.zst", "tar.zst"},
 		{"package.gem", "gem"},
 		{"package.vsix", "zip"},
 		{"package.crate", "tgz"},
@@ -237,6 +239,22 @@ func createTestTarBz2(t *testing.T) []byte {
 	return data
 }
 
+func createTestTarZst(t *testing.T) []byte {
+	t.Helper()
+	buf := new(bytes.Buffer)
+	w, err := zstd.NewWriter(buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := w.Write(createTestTar()); err != nil {
+		t.Fatal(err)
+	}
+	if err := w.Close(); err != nil {
+		t.Fatal(err)
+	}
+	return buf.Bytes()
+}
+
 func createTestTarXz(t *testing.T) []byte {
 	t.Helper()
 	buf := new(bytes.Buffer)
@@ -326,6 +344,7 @@ func TestOpenDetectsExtensionlessArchives(t *testing.T) {
 		{"gzip", createTestTarGz()},
 		{"bzip2", createTestTarBz2(t)},
 		{"xz", createTestTarXz(t)},
+		{"zstd", createTestTarZst(t)},
 	}
 	for _, test := range tests {
 		t.Run(test.name+"/Open", func(t *testing.T) {

go.mod

@@ -4,5 +4,6 @@ go 1.25.6
 
 require (
 	github.com/git-pkgs/magic v0.2.0
+	github.com/klauspost/compress v1.19.2
 	github.com/ulikunitz/xz v0.5.16
 )

go.sum

@@ -1,4 +1,6 @@
 github.com/git-pkgs/magic v0.2.0 h1:c7HqVxnP8c88EaVMH0/KraDFVTcmiXckRiSvNZEnvMQ=
 github.com/git-pkgs/magic v0.2.0/go.mod h1:3ndidt+yvFaI1M0aEkkzkOlFnLPkeVQASIUojazcxCI=
+github.com/klauspost/compress v1.19.2 h1:hMRETovs/pu/dVWN7zIT1PGG8t509MwT6bO7XSi26R8=
+github.com/klauspost/compress v1.19.2/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
 github.com/ulikunitz/xz v0.5.16 h1:ld6NyySjx5lowVKwJvMRLnW5nxKX/xnpSiFYZ/Lxur0=
 github.com/ulikunitz/xz v0.5.16/go.mod h1:H9Rt/W6/Qj27PGauhQc6nfCDy7vHpzsOThBSaYDoEhw=

tar.go

@@ -11,6 +11,7 @@ import (
 	"io/fs"
 	"strings"
 
+	"github.com/klauspost/compress/zstd"
 	"github.com/ulikunitz/xz"
 )
 
@@ -49,6 +50,13 @@ func openTar(raw []byte, compression string) (*tarReader, error) {
 			return nil, fmt.Errorf("opening xz: %w", err)
 		}
 		r = xzReader
+	case "zstd":
+		dec, err := zstd.NewReader(content, zstd.WithDecoderConcurrency(1))
+		if err != nil {
+			return nil, fmt.Errorf("opening zstd: %w", err)
+		}
+		defer dec.Close()
+		r = dec
 	}
 
 	tr := tar.NewReader(r)