Our zlib ought to be read-only for now

1 files changed, 0 insertions, 194 deletions

diff --git a/internal/zlib/writer.go b/internal/zlib/writer.go
deleted file mode 100644
index bc468716..00000000
--- a/internal/zlib/writer.go
+++ /dev/null
@@ -1,194 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package zlib
-
-import (
-	"encoding/binary"
-	"fmt"
-	"hash"
-	"hash/adler32"
-	"io"
-
-	"git.sr.ht/~runxiyu/furgit/internal/flate"
-)
-
-// These constants are copied from the [flate] package, so that code that imports
-// [compress/zlib] does not also have to import [compress/flate].
-const (
-	NoCompression      = flate.NoCompression
-	BestSpeed          = flate.BestSpeed
-	BestCompression    = flate.BestCompression
-	DefaultCompression = flate.DefaultCompression
-	HuffmanOnly        = flate.HuffmanOnly
-)
-
-// A Writer takes data written to it and writes the compressed
-// form of that data to an underlying writer (see [NewWriter]).
-type Writer struct {
-	w           io.Writer
-	level       int
-	dict        []byte
-	compressor  *flate.Writer
-	digest      hash.Hash32
-	err         error
-	scratch     [4]byte
-	wroteHeader bool
-}
-
-// NewWriter creates a new [Writer].
-// Writes to the returned Writer are compressed and written to w.
-//
-// It is the caller's responsibility to call Close on the Writer when done.
-// Writes may be buffered and not flushed until Close.
-func NewWriter(w io.Writer) *Writer {
-	z, _ := NewWriterLevelDict(w, DefaultCompression, nil)
-	return z
-}
-
-// NewWriterLevel is like [NewWriter] but specifies the compression level instead
-// of assuming [DefaultCompression].
-//
-// The compression level can be [DefaultCompression], [NoCompression], [HuffmanOnly]
-// or any integer value between [BestSpeed] and [BestCompression] inclusive.
-// The error returned will be nil if the level is valid.
-func NewWriterLevel(w io.Writer, level int) (*Writer, error) {
-	return NewWriterLevelDict(w, level, nil)
-}
-
-// NewWriterLevelDict is like [NewWriterLevel] but specifies a dictionary to
-// compress with.
-//
-// The dictionary may be nil. If not, its contents should not be modified until
-// the Writer is closed.
-func NewWriterLevelDict(w io.Writer, level int, dict []byte) (*Writer, error) {
-	if level < HuffmanOnly || level > BestCompression {
-		return nil, fmt.Errorf("zlib: invalid compression level: %d", level)
-	}
-	return &Writer{
-		w:     w,
-		level: level,
-		dict:  dict,
-	}, nil
-}
-
-// Reset clears the state of the [Writer] z such that it is equivalent to its
-// initial state from [NewWriterLevel] or [NewWriterLevelDict], but instead writing
-// to w.
-func (z *Writer) Reset(w io.Writer) {
-	z.w = w
-	// z.level and z.dict left unchanged.
-	if z.compressor != nil {
-		z.compressor.Reset(w)
-	}
-	if z.digest != nil {
-		z.digest.Reset()
-	}
-	z.err = nil
-	z.scratch = [4]byte{}
-	z.wroteHeader = false
-}
-
-// writeHeader writes the ZLIB header.
-func (z *Writer) writeHeader() (err error) {
-	z.wroteHeader = true
-	// ZLIB has a two-byte header (as documented in RFC 1950).
-	// The first four bits is the CINFO (compression info), which is 7 for the default deflate window size.
-	// The next four bits is the CM (compression method), which is 8 for deflate.
-	z.scratch[0] = 0x78
-	// The next two bits is the FLEVEL (compression level). The four values are:
-	// 0=fastest, 1=fast, 2=default, 3=best.
-	// The next bit, FDICT, is set if a dictionary is given.
-	// The final five FCHECK bits form a mod-31 checksum.
-	switch z.level {
-	case -2, 0, 1:
-		z.scratch[1] = 0 << 6
-	case 2, 3, 4, 5:
-		z.scratch[1] = 1 << 6
-	case 6, -1:
-		z.scratch[1] = 2 << 6
-	case 7, 8, 9:
-		z.scratch[1] = 3 << 6
-	default:
-		panic("unreachable")
-	}
-	if z.dict != nil {
-		z.scratch[1] |= 1 << 5
-	}
-	z.scratch[1] += uint8(31 - binary.BigEndian.Uint16(z.scratch[:2])%31)
-	if _, err = z.w.Write(z.scratch[0:2]); err != nil {
-		return err
-	}
-	if z.dict != nil {
-		// The next four bytes are the Adler-32 checksum of the dictionary.
-		binary.BigEndian.PutUint32(z.scratch[:], adler32.Checksum(z.dict))
-		if _, err = z.w.Write(z.scratch[0:4]); err != nil {
-			return err
-		}
-	}
-	if z.compressor == nil {
-		// Initialize deflater unless the Writer is being reused
-		// after a Reset call.
-		z.compressor, err = flate.NewWriterDict(z.w, z.level, z.dict)
-		if err != nil {
-			return err
-		}
-		z.digest = adler32.New()
-	}
-	return nil
-}
-
-// Write writes a compressed form of p to the underlying [io.Writer]. The
-// compressed bytes are not necessarily flushed until the [Writer] is closed or
-// explicitly flushed.
-func (z *Writer) Write(p []byte) (n int, err error) {
-	if !z.wroteHeader {
-		z.err = z.writeHeader()
-	}
-	if z.err != nil {
-		return 0, z.err
-	}
-	if len(p) == 0 {
-		return 0, nil
-	}
-	n, err = z.compressor.Write(p)
-	if err != nil {
-		z.err = err
-		return
-	}
-	z.digest.Write(p)
-	return
-}
-
-// Flush flushes the Writer to its underlying [io.Writer].
-func (z *Writer) Flush() error {
-	if !z.wroteHeader {
-		z.err = z.writeHeader()
-	}
-	if z.err != nil {
-		return z.err
-	}
-	z.err = z.compressor.Flush()
-	return z.err
-}
-
-// Close closes the Writer, flushing any unwritten data to the underlying
-// [io.Writer], but does not close the underlying io.Writer.
-func (z *Writer) Close() error {
-	if !z.wroteHeader {
-		z.err = z.writeHeader()
-	}
-	if z.err != nil {
-		return z.err
-	}
-	z.err = z.compressor.Close()
-	if z.err != nil {
-		return z.err
-	}
-	checksum := z.digest.Sum32()
-	// ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
-	binary.BigEndian.PutUint32(z.scratch[:], checksum)
-	_, z.err = z.w.Write(z.scratch[0:4])
-	return z.err
-}