forked from chai2010/webp
/
cbuffer.go
146 lines (128 loc) · 2.85 KB
/
cbuffer.go
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// Copyright 2015 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package webp
//#include "webp.h"
import "C"
import (
"errors"
"io"
"reflect"
"runtime"
"unsafe"
)
var (
_ CBuffer = (*cBuffer)(nil)
)
type CBuffer interface {
CBufMagic() string
CanResize() bool
Resize(size int) error
CData() []byte
Own(d []byte) bool
io.Closer
}
type cBuffer struct {
*innerCBuffer
}
func newCBufferFrom(cptr unsafe.Pointer, size int, dontResize ...bool) CBuffer {
p := &cBuffer{
innerCBuffer: newInnerCBufferFrom(cptr, size, dontResize...),
}
runtime.SetFinalizer(p.innerCBuffer, (*innerCBuffer).Close)
return p
}
func NewCBuffer(size int, dontResize ...bool) CBuffer {
p := &cBuffer{
innerCBuffer: newInnerCBuffer(size, dontResize...),
}
runtime.SetFinalizer(p.innerCBuffer, (*innerCBuffer).Close)
return p
}
func (p *cBuffer) Close() error {
var err error
if p.innerCBuffer != nil {
err = p.innerCBuffer.Close()
}
*p = cBuffer{}
return err
}
type innerCBuffer struct {
dontResize bool
cptr unsafe.Pointer
data []byte
}
func newInnerCBufferFrom(cptr unsafe.Pointer, size int, dontResize ...bool) *innerCBuffer {
p := new(innerCBuffer)
if cptr != nil && size > 0 {
p.cptr = cptr
p.data = (*[1 << 30]byte)(p.cptr)[0:size:size]
}
if len(dontResize) > 0 {
p.dontResize = dontResize[0]
}
return p
}
func newInnerCBuffer(size int, dontResize ...bool) *innerCBuffer {
p := new(innerCBuffer)
if size > 0 {
p.cptr = C.webpMalloc(C.size_t(size))
p.data = (*[1 << 30]byte)(p.cptr)[0:size:size]
}
if len(dontResize) > 0 {
p.dontResize = dontResize[0]
}
return p
}
func (p *innerCBuffer) CBufMagic() string {
return "CBufMagic"
}
func (p *innerCBuffer) Close() error {
if p.cptr != nil {
C.webpFree(p.cptr)
}
*p = innerCBuffer{}
// no need for a finalizer anymore
runtime.SetFinalizer(p, nil)
return nil
}
func (p *innerCBuffer) CanResize() bool {
return !p.dontResize
}
func (p *innerCBuffer) Resize(size int) error {
if size < 0 {
return errors.New("webp: cBuffer.Resize, bad size!")
}
if p.dontResize {
return errors.New("webp: cBuffer.Resize, donot resize!")
}
if n := len(p.data); n > 0 && n != size {
C.webpFree(p.cptr)
p.cptr = nil
p.data = nil
}
p.Close()
if size > 0 {
p.cptr = C.webpMalloc(C.size_t(size))
p.data = (*[1 << 30]byte)(p.cptr)[0:size:size]
}
return nil
}
func (p *innerCBuffer) CData() []byte {
return p.data
}
func (p *innerCBuffer) Own(d []byte) bool {
if cap(d) == 0 || p.cptr == nil {
return false
}
min := uintptr(p.cptr)
max := uintptr(p.cptr) + uintptr(len(p.data)-1)
hdr := (*reflect.SliceHeader)(unsafe.Pointer(&d))
if x := hdr.Data; x < min || x > max {
return false
}
if x := hdr.Data + uintptr(hdr.Cap-1); x < min || x > max {
return false
}
return true
}