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// 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 (
"bufio"
"encoding/binary"
"errors"
"io"
"codeberg.org/lindenii/furgit/internal/adler32"
"codeberg.org/lindenii/furgit/internal/compress/flate"
"codeberg.org/lindenii/furgit/internal/intconv"
)
// reset resets receiver to read a new zlib stream.
func (z *Reader) reset(r io.Reader, dict []byte) error {
*z = Reader{decompressor: z.decompressor}
var input flate.Reader
if fr, ok := r.(flate.Reader); ok {
input = fr
} else {
input = bufio.NewReader(r)
}
z.r = input
// Read the header (RFC 1950 section 2.2.).
readN, err := io.ReadFull(z.r, z.scratch[0:2])
readNUint64, convErr := intconv.IntToUint64(readN)
if convErr != nil {
z.err = convErr
return z.err
}
z.headerRead += readNUint64
z.err = err
if z.err != nil {
if errors.Is(z.err, io.EOF) {
z.err = io.ErrUnexpectedEOF
}
return z.err
}
h := binary.BigEndian.Uint16(z.scratch[:2])
if (z.scratch[0]&0x0f != zlibDeflate) || (z.scratch[0]>>4 > zlibMaxWindow) || (h%31 != 0) {
z.err = ErrHeader
return z.err
}
haveDict := z.scratch[1]&0x20 != 0
if haveDict { //nolint:nestif
readN, z.err = io.ReadFull(z.r, z.scratch[0:4])
readNUint64, err := intconv.IntToUint64(readN)
if err != nil {
z.err = err
return z.err
}
z.headerRead += readNUint64
if z.err != nil {
if errors.Is(z.err, io.EOF) {
z.err = io.ErrUnexpectedEOF
}
return z.err
}
checksum := binary.BigEndian.Uint32(z.scratch[:4])
if checksum != adler32.Checksum(dict) {
z.err = ErrDictionary
return z.err
}
}
if z.decompressor != nil {
resetter, ok := z.decompressor.(flate.Resetter)
if !ok {
panic("zlib: pooled decompressor does not implement flate.Resetter")
}
z.err = resetter.Reset(z.r, dict)
if z.err != nil {
return z.err
}
progress, ok := z.decompressor.(flate.InputProgress)
if !ok {
panic("zlib: pooled decompressor does not implement flate.InputProgress")
}
z.progress = progress
z.digest = adler32.New()
return nil
}
if haveDict {
z.decompressor = flate.NewReaderDict(z.r, dict)
} else {
z.decompressor = flate.NewReader(z.r)
}
progress, ok := z.decompressor.(flate.InputProgress)
if !ok {
panic("zlib: decompressor does not implement flate.InputProgress")
}
z.progress = progress
z.digest = adler32.New()
return nil
}
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