/
lzma.go
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/
lzma.go
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// Copyright 2016, Joe Tsai. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE.md file.
// +build cgo
// Package lzma implements the LZMA2 compressed data format using C wrappers.
package lzma
/*
#cgo LDFLAGS: -llzma
#include <assert.h>
#include <stdlib.h>
#include "lzma.h"
// zlState is a tuple of C allocated data structures.
//
// The liblzma documentation is not clear about whether the filters struct must
// stay live past calls to lzma_raw_encoder and lzma_raw_decoder.
// To be on the safe side, we allocate them and keep them around until the end.
typedef struct {
lzma_stream stream;
lzma_filter filters[2];
lzma_options_lzma options;
} zlState;
zlState* zlDecCreate() {
zlState* state = calloc(1, sizeof(zlState));
state->filters[0].id = LZMA_FILTER_LZMA2;
state->filters[0].options = &state->options;
state->filters[1].id = LZMA_VLI_UNKNOWN;
state->options.dict_size = LZMA_DICT_SIZE_DEFAULT;
assert(lzma_raw_decoder(&state->stream, state->filters) == LZMA_OK);
return state;
}
zlState* zlEncCreate(int level) {
zlState* state = calloc(1, sizeof(zlState));
state->filters[0].id = LZMA_FILTER_LZMA2;
state->filters[0].options = &state->options;
state->filters[1].id = LZMA_VLI_UNKNOWN;
assert(!lzma_lzma_preset(&state->options, level));
assert(lzma_raw_encoder(&state->stream, state->filters) == LZMA_OK);
return state;
}
lzma_ret zlStream(
lzma_stream* strm, lzma_action action,
size_t* avail_in, uint8_t* next_in,
size_t* avail_out, uint8_t* next_out
) {
strm->avail_in = *avail_in;
strm->avail_out = *avail_out;
strm->next_in = next_in;
strm->next_out = next_out;
lzma_ret ret = lzma_code(strm, action);
*avail_in = strm->avail_in;
*avail_out = strm->avail_out;
strm->next_in = NULL;
strm->next_out = NULL;
return ret;
}
void zlDestroy(zlState* state) {
lzma_end(&state->stream);
free(state);
}
*/
import "C"
import (
"errors"
"io"
"unsafe"
)
type reader struct {
r io.Reader
err error
state *C.zlState
buf []byte
arr [1 << 14]byte
}
func NewReader(r io.Reader) io.ReadCloser {
zr := &reader{r: r, state: C.zlDecCreate()}
if zr.state == nil {
panic("lzma: could not allocate decoder state")
}
return zr
}
func (zr *reader) Read(buf []byte) (int, error) {
if zr.state == nil {
return 0, io.ErrClosedPipe
}
var n int
for zr.err == nil && (len(buf) > 0 && n == 0) {
availIn, availOut, ptrIn, ptrOut := sizePtrs(zr.buf, buf)
ret := C.zlStream(&zr.state.stream, 0, &availIn, ptrIn, &availOut, ptrOut)
n += len(buf) - int(availOut)
buf = buf[len(buf)-int(availOut):]
zr.buf = zr.buf[len(zr.buf)-int(availIn):]
switch ret {
case C.LZMA_OK:
return n, nil
case C.LZMA_BUF_ERROR:
if len(zr.buf) == 0 {
n1, err := zr.r.Read(zr.arr[:])
if n1 > 0 {
zr.buf = zr.arr[:n1]
} else if err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
zr.err = err
}
}
case C.LZMA_STREAM_END:
return n, io.EOF
default:
zr.err = errors.New("lzma: corrupted input")
}
}
return n, zr.err
}
func (zr *reader) Close() error {
if zr.state != nil {
defer func() {
C.zlDestroy(zr.state)
zr.state = nil
}()
}
return zr.err
}
type writer struct {
w io.Writer
err error
state *C.zlState
buf []byte
arr [1 << 14]byte
}
func NewWriter(w io.Writer, level int) io.WriteCloser {
if level < 0 || level > 9 {
panic("lzma: invalid compression level")
}
zw := &writer{w: w, state: C.zlEncCreate(C.int(level))}
if zw.state == nil {
panic("lzma: could not allocate encoder state")
}
return zw
}
func (zw *writer) Write(buf []byte) (int, error) {
return zw.write(buf, C.LZMA_RUN)
}
func (zw *writer) write(buf []byte, op C.lzma_action) (int, error) {
if zw.state == nil {
return 0, io.ErrClosedPipe
}
var n int
flush := op != C.LZMA_RUN
for zw.err == nil && (len(buf) > 0 || flush) {
availIn, availOut, ptrIn, ptrOut := sizePtrs(buf, zw.arr[:])
ret := C.zlStream(&zw.state.stream, op, &availIn, ptrIn, &availOut, ptrOut)
n += len(buf) - int(availIn)
buf = buf[len(buf)-int(availIn):]
zw.buf = zw.arr[:len(zw.arr)-int(availOut)]
if len(zw.buf) > 0 {
if _, err := zw.w.Write(zw.buf); err != nil {
zw.err = err
}
}
switch ret {
case C.LZMA_OK, C.LZMA_BUF_ERROR:
continue // Do nothing
case C.LZMA_STREAM_END:
return n, zw.err
default:
zw.err = errors.New("lzma: compression error")
}
}
return n, zw.err
}
func (zw *writer) Close() error {
if zw.state != nil {
defer func() {
C.zlDestroy(zw.state)
zw.state = nil
}()
zw.write(nil, C.LZMA_FINISH)
}
return zw.err
}
func sizePtrs(in, out []byte) (sizeIn, sizeOut C.size_t, ptrIn, ptrOut *C.uint8_t) {
sizeIn = C.size_t(len(in))
sizeOut = C.size_t(len(out))
if len(in) > 0 {
ptrIn = (*C.uint8_t)(unsafe.Pointer(&in[0]))
}
if len(out) > 0 {
ptrOut = (*C.uint8_t)(unsafe.Pointer(&out[0]))
}
return
}