diff options
Diffstat (limited to 'vendor/github.com/ulikunitz/xz/lzma/writer.go')
-rw-r--r-- | vendor/github.com/ulikunitz/xz/lzma/writer.go | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/vendor/github.com/ulikunitz/xz/lzma/writer.go b/vendor/github.com/ulikunitz/xz/lzma/writer.go new file mode 100644 index 000000000..efe34fb6b --- /dev/null +++ b/vendor/github.com/ulikunitz/xz/lzma/writer.go @@ -0,0 +1,209 @@ +// Copyright 2014-2017 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 lzma + +import ( + "bufio" + "errors" + "io" +) + +// MinDictCap and MaxDictCap provide the range of supported dictionary +// capacities. +const ( + MinDictCap = 1 << 12 + MaxDictCap = 1<<32 - 1 +) + +// WriterConfig defines the configuration parameter for a writer. +type WriterConfig struct { + // Properties for the encoding. If the it is nil the value + // {LC: 3, LP: 0, PB: 2} will be chosen. + Properties *Properties + // The capacity of the dictionary. If DictCap is zero, the value + // 8 MiB will be chosen. + DictCap int + // Size of the lookahead buffer; value 0 indicates default size + // 4096 + BufSize int + // Match algorithm + Matcher MatchAlgorithm + // SizeInHeader indicates that the header will contain an + // explicit size. + SizeInHeader bool + // Size of the data to be encoded. A positive value will imply + // than an explicit size will be set in the header. + Size int64 + // EOSMarker requests whether the EOSMarker needs to be written. + // If no explicit size is been given the EOSMarker will be + // set automatically. + EOSMarker bool +} + +// fill converts zero-value fields to their explicit default values. +func (c *WriterConfig) fill() { + if c.Properties == nil { + c.Properties = &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.Size > 0 { + c.SizeInHeader = true + } + if !c.SizeInHeader { + c.EOSMarker = true + } +} + +// Verify checks WriterConfig for errors. Verify will replace zero +// values with default values. +func (c *WriterConfig) Verify() error { + c.fill() + var err error + if c == nil { + return errors.New("lzma: WriterConfig is nil") + } + if c.Properties == nil { + return errors.New("lzma: WriterConfig has no Properties set") + } + if err = c.Properties.verify(); err != nil { + return err + } + if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) { + return errors.New("lzma: dictionary capacity is out of range") + } + if !(maxMatchLen <= c.BufSize) { + return errors.New("lzma: lookahead buffer size too small") + } + if c.SizeInHeader { + if c.Size < 0 { + return errors.New("lzma: negative size not supported") + } + } else if !c.EOSMarker { + return errors.New("lzma: EOS marker is required") + } + if err = c.Matcher.verify(); err != nil { + return err + } + + return nil +} + +// header returns the header structure for this configuration. +func (c *WriterConfig) header() header { + h := header{ + properties: *c.Properties, + dictCap: c.DictCap, + size: -1, + } + if c.SizeInHeader { + h.size = c.Size + } + return h +} + +// Writer writes an LZMA stream in the classic format. +type Writer struct { + h header + bw io.ByteWriter + buf *bufio.Writer + e *encoder +} + +// NewWriter creates a new LZMA writer for the classic format. The +// method will write the header to the underlying stream. +func (c WriterConfig) NewWriter(lzma io.Writer) (w *Writer, err error) { + if err = c.Verify(); err != nil { + return nil, err + } + w = &Writer{h: c.header()} + + var ok bool + w.bw, ok = lzma.(io.ByteWriter) + if !ok { + w.buf = bufio.NewWriter(lzma) + w.bw = w.buf + } + state := newState(w.h.properties) + m, err := c.Matcher.new(w.h.dictCap) + if err != nil { + return nil, err + } + dict, err := newEncoderDict(w.h.dictCap, c.BufSize, m) + if err != nil { + return nil, err + } + var flags encoderFlags + if c.EOSMarker { + flags = eosMarker + } + if w.e, err = newEncoder(w.bw, state, dict, flags); err != nil { + return nil, err + } + + if err = w.writeHeader(); err != nil { + return nil, err + } + return w, nil +} + +// NewWriter creates a new LZMA writer using the classic format. The +// function writes the header to the underlying stream. +func NewWriter(lzma io.Writer) (w *Writer, err error) { + return WriterConfig{}.NewWriter(lzma) +} + +// writeHeader writes the LZMA header into the stream. +func (w *Writer) writeHeader() error { + data, err := w.h.marshalBinary() + if err != nil { + return err + } + _, err = w.bw.(io.Writer).Write(data) + return err +} + +// Write puts data into the Writer. +func (w *Writer) Write(p []byte) (n int, err error) { + if w.h.size >= 0 { + m := w.h.size + m -= w.e.Compressed() + int64(w.e.dict.Buffered()) + if m < 0 { + m = 0 + } + if m < int64(len(p)) { + p = p[:m] + err = ErrNoSpace + } + } + var werr error + if n, werr = w.e.Write(p); werr != nil { + err = werr + } + return n, err +} + +// Close closes the writer stream. It ensures that all data from the +// buffer will be compressed and the LZMA stream will be finished. +func (w *Writer) Close() error { + if w.h.size >= 0 { + n := w.e.Compressed() + int64(w.e.dict.Buffered()) + if n != w.h.size { + return errSize + } + } + err := w.e.Close() + if w.buf != nil { + ferr := w.buf.Flush() + if err == nil { + err = ferr + } + } + return err +} |