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gitea/vendor/github.com/ulikunitz/xz/writer.go

400 lines
8.7 KiB
Go

// Copyright 2014-2021 Ulrich Kunitz. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package xz
import (
"errors"
"fmt"
"hash"
"io"
"github.com/ulikunitz/xz/lzma"
)
// WriterConfig describe the parameters for an xz writer.
type WriterConfig struct {
Properties *lzma.Properties
DictCap int
BufSize int
BlockSize int64
// checksum method: CRC32, CRC64 or SHA256 (default: CRC64)
CheckSum byte
// Forces NoChecksum (default: false)
NoCheckSum bool
// match algorithm
Matcher lzma.MatchAlgorithm
}
// fill replaces zero values with default values.
func (c *WriterConfig) fill() {
if c.Properties == nil {
c.Properties = &lzma.Properties{LC: 3, LP: 0, PB: 2}
}
if c.DictCap == 0 {
c.DictCap = 8 * 1024 * 1024
}
if c.BufSize == 0 {
c.BufSize = 4096
}
if c.BlockSize == 0 {
c.BlockSize = maxInt64
}
if c.CheckSum == 0 {
c.CheckSum = CRC64
}
if c.NoCheckSum {
c.CheckSum = None
}
}
// Verify checks the configuration for errors. Zero values will be
// replaced by default values.
func (c *WriterConfig) Verify() error {
if c == nil {
return errors.New("xz: writer configuration is nil")
}
c.fill()
lc := lzma.Writer2Config{
Properties: c.Properties,
DictCap: c.DictCap,
BufSize: c.BufSize,
Matcher: c.Matcher,
}
if err := lc.Verify(); err != nil {
return err
}
if c.BlockSize <= 0 {
return errors.New("xz: block size out of range")
}
if err := verifyFlags(c.CheckSum); err != nil {
return err
}
return nil
}
// filters creates the filter list for the given parameters.
func (c *WriterConfig) filters() []filter {
return []filter{&lzmaFilter{int64(c.DictCap)}}
}
// maxInt64 defines the maximum 64-bit signed integer.
const maxInt64 = 1<<63 - 1
// verifyFilters checks the filter list for the length and the right
// sequence of filters.
func verifyFilters(f []filter) error {
if len(f) == 0 {
return errors.New("xz: no filters")
}
if len(f) > 4 {
return errors.New("xz: more than four filters")
}
for _, g := range f[:len(f)-1] {
if g.last() {
return errors.New("xz: last filter is not last")
}
}
if !f[len(f)-1].last() {
return errors.New("xz: wrong last filter")
}
return nil
}
// newFilterWriteCloser converts a filter list into a WriteCloser that
// can be used by a blockWriter.
func (c *WriterConfig) newFilterWriteCloser(w io.Writer, f []filter) (fw io.WriteCloser, err error) {
if err = verifyFilters(f); err != nil {
return nil, err
}
fw = nopWriteCloser(w)
for i := len(f) - 1; i >= 0; i-- {
fw, err = f[i].writeCloser(fw, c)
if err != nil {
return nil, err
}
}
return fw, nil
}
// nopWCloser implements a WriteCloser with a Close method not doing
// anything.
type nopWCloser struct {
io.Writer
}
// Close returns nil and doesn't do anything else.
func (c nopWCloser) Close() error {
return nil
}
// nopWriteCloser converts the Writer into a WriteCloser with a Close
// function that does nothing beside returning nil.
func nopWriteCloser(w io.Writer) io.WriteCloser {
return nopWCloser{w}
}
// Writer compresses data written to it. It is an io.WriteCloser.
type Writer struct {
WriterConfig
xz io.Writer
bw *blockWriter
newHash func() hash.Hash
h header
index []record
closed bool
}
// newBlockWriter creates a new block writer writes the header out.
func (w *Writer) newBlockWriter() error {
var err error
w.bw, err = w.WriterConfig.newBlockWriter(w.xz, w.newHash())
if err != nil {
return err
}
if err = w.bw.writeHeader(w.xz); err != nil {
return err
}
return nil
}
// closeBlockWriter closes a block writer and records the sizes in the
// index.
func (w *Writer) closeBlockWriter() error {
var err error
if err = w.bw.Close(); err != nil {
return err
}
w.index = append(w.index, w.bw.record())
return nil
}
// NewWriter creates a new xz writer using default parameters.
func NewWriter(xz io.Writer) (w *Writer, err error) {
return WriterConfig{}.NewWriter(xz)
}
// NewWriter creates a new Writer using the given configuration parameters.
func (c WriterConfig) NewWriter(xz io.Writer) (w *Writer, err error) {
if err = c.Verify(); err != nil {
return nil, err
}
w = &Writer{
WriterConfig: c,
xz: xz,
h: header{c.CheckSum},
index: make([]record, 0, 4),
}
if w.newHash, err = newHashFunc(c.CheckSum); err != nil {
return nil, err
}
data, err := w.h.MarshalBinary()
if err != nil {
return nil, fmt.Errorf("w.h.MarshalBinary(): error %w", err)
}
if _, err = xz.Write(data); err != nil {
return nil, err
}
if err = w.newBlockWriter(); err != nil {
return nil, err
}
return w, nil
}
// Write compresses the uncompressed data provided.
func (w *Writer) Write(p []byte) (n int, err error) {
if w.closed {
return 0, errClosed
}
for {
k, err := w.bw.Write(p[n:])
n += k
if err != errNoSpace {
return n, err
}
if err = w.closeBlockWriter(); err != nil {
return n, err
}
if err = w.newBlockWriter(); err != nil {
return n, err
}
}
}
// Close closes the writer and adds the footer to the Writer. Close
// doesn't close the underlying writer.
func (w *Writer) Close() error {
if w.closed {
return errClosed
}
w.closed = true
var err error
if err = w.closeBlockWriter(); err != nil {
return err
}
f := footer{flags: w.h.flags}
if f.indexSize, err = writeIndex(w.xz, w.index); err != nil {
return err
}
data, err := f.MarshalBinary()
if err != nil {
return err
}
if _, err = w.xz.Write(data); err != nil {
return err
}
return nil
}
// countingWriter is a writer that counts all data written to it.
type countingWriter struct {
w io.Writer
n int64
}
// Write writes data to the countingWriter.
func (cw *countingWriter) Write(p []byte) (n int, err error) {
n, err = cw.w.Write(p)
cw.n += int64(n)
if err == nil && cw.n < 0 {
return n, errors.New("xz: counter overflow")
}
return
}
// blockWriter is writes a single block.
type blockWriter struct {
cxz countingWriter
// mw combines io.WriteCloser w and the hash.
mw io.Writer
w io.WriteCloser
n int64
blockSize int64
closed bool
headerLen int
filters []filter
hash hash.Hash
}
// newBlockWriter creates a new block writer.
func (c *WriterConfig) newBlockWriter(xz io.Writer, hash hash.Hash) (bw *blockWriter, err error) {
bw = &blockWriter{
cxz: countingWriter{w: xz},
blockSize: c.BlockSize,
filters: c.filters(),
hash: hash,
}
bw.w, err = c.newFilterWriteCloser(&bw.cxz, bw.filters)
if err != nil {
return nil, err
}
if bw.hash.Size() != 0 {
bw.mw = io.MultiWriter(bw.w, bw.hash)
} else {
bw.mw = bw.w
}
return bw, nil
}
// writeHeader writes the header. If the function is called after Close
// the commpressedSize and uncompressedSize fields will be filled.
func (bw *blockWriter) writeHeader(w io.Writer) error {
h := blockHeader{
compressedSize: -1,
uncompressedSize: -1,
filters: bw.filters,
}
if bw.closed {
h.compressedSize = bw.compressedSize()
h.uncompressedSize = bw.uncompressedSize()
}
data, err := h.MarshalBinary()
if err != nil {
return err
}
if _, err = w.Write(data); err != nil {
return err
}
bw.headerLen = len(data)
return nil
}
// compressed size returns the amount of data written to the underlying
// stream.
func (bw *blockWriter) compressedSize() int64 {
return bw.cxz.n
}
// uncompressedSize returns the number of data written to the
// blockWriter
func (bw *blockWriter) uncompressedSize() int64 {
return bw.n
}
// unpaddedSize returns the sum of the header length, the uncompressed
// size of the block and the hash size.
func (bw *blockWriter) unpaddedSize() int64 {
if bw.headerLen <= 0 {
panic("xz: block header not written")
}
n := int64(bw.headerLen)
n += bw.compressedSize()
n += int64(bw.hash.Size())
return n
}
// record returns the record for the current stream. Call Close before
// calling this method.
func (bw *blockWriter) record() record {
return record{bw.unpaddedSize(), bw.uncompressedSize()}
}
var errClosed = errors.New("xz: writer already closed")
var errNoSpace = errors.New("xz: no space")
// Write writes uncompressed data to the block writer.
func (bw *blockWriter) Write(p []byte) (n int, err error) {
if bw.closed {
return 0, errClosed
}
t := bw.blockSize - bw.n
if int64(len(p)) > t {
err = errNoSpace
p = p[:t]
}
var werr error
n, werr = bw.mw.Write(p)
bw.n += int64(n)
if werr != nil {
return n, werr
}
return n, err
}
// Close closes the writer.
func (bw *blockWriter) Close() error {
if bw.closed {
return errClosed
}
bw.closed = true
if err := bw.w.Close(); err != nil {
return err
}
s := bw.hash.Size()
k := padLen(bw.cxz.n)
p := make([]byte, k+s)
bw.hash.Sum(p[k:k])
if _, err := bw.cxz.w.Write(p); err != nil {
return err
}
return nil
}