Pointer map for callbacks, make go1.6 happy
Go 1.6 does not allow us to pass go pointers into C that will be stored and¬ used in callbacks and suggests we use a value lookup for pointer callbacks.¬ https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md¬ Fixes 'panic: runtime error: cgo argument has Go pointer to Go' in tests.
This commit is contained in:
Mark Pitchless
parent
f3b772e34d
commit
6225341041
85
libflac.go
85
libflac.go
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@ -11,6 +11,7 @@ import (
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"io"
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"reflect"
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"runtime"
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"sync"
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"unsafe"
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)
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@ -80,6 +81,64 @@ get_audio_samples(int32_t *output, const FLAC__int32 **input,
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*/
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import "C"
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// Go 1.6 does not allow us to pass go pointers into C that will be stored and
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// used in callbacks and suggests we use a value lookup for pointer callbacks.
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// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
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// Concurrent safe map for mapping pointers between C and Go.
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type decoderPtrMap struct {
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sync.RWMutex
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ptrs map[uintptr]*Decoder
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}
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func (m decoderPtrMap) get(d *C.FLAC__StreamDecoder) *Decoder {
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ptr := uintptr(unsafe.Pointer(d))
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m.RLock()
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defer m.RUnlock()
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return m.ptrs[ptr]
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}
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func (m decoderPtrMap) add(d *Decoder) {
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m.Lock()
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defer m.Unlock()
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m.ptrs[uintptr(unsafe.Pointer(d.d))] = d
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}
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func (m decoderPtrMap) del(d *Decoder) {
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m.Lock()
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defer m.Unlock()
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delete(m.ptrs, uintptr(unsafe.Pointer(d.d)))
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}
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var decoderPtrs = decoderPtrMap{ptrs: make(map[uintptr]*Decoder)}
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// Concurrent safe map for mapping pointers between C and Go.
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type encoderPtrMap struct {
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sync.RWMutex
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ptrs map[uintptr]*Encoder
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}
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func (m encoderPtrMap) get(e *C.FLAC__StreamEncoder) *Encoder {
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ptr := uintptr(unsafe.Pointer(e))
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m.RLock()
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defer m.RUnlock()
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return m.ptrs[ptr]
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}
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func (m encoderPtrMap) add(e *Encoder) {
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m.Lock()
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defer m.Unlock()
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m.ptrs[uintptr(unsafe.Pointer(e.e))] = e
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}
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func (m encoderPtrMap) del(e *Encoder) {
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m.Lock()
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defer m.Unlock()
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delete(m.ptrs, uintptr(unsafe.Pointer(e.e)))
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}
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var encoderPtrs = encoderPtrMap{ptrs: make(map[uintptr]*Encoder)}
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type FlacWriter interface {
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io.Writer
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io.Closer
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@ -117,14 +176,14 @@ type Encoder struct {
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//export decoderErrorCallback
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func decoderErrorCallback(d *C.FLAC__StreamDecoder, status C.FLAC__StreamDecoderErrorStatus, data unsafe.Pointer) {
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decoder := (*Decoder)(data)
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decoder := decoderPtrs.get(d)
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decoder.error = true
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decoder.errorStr = C.GoString(C.get_decoder_error_str(status))
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}
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//export decoderMetadataCallback
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func decoderMetadataCallback(d *C.FLAC__StreamDecoder, metadata *C.FLAC__StreamMetadata, data unsafe.Pointer) {
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decoder := (*Decoder)(data)
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decoder := decoderPtrs.get(d)
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if metadata._type == C.FLAC__METADATA_TYPE_STREAMINFO {
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decoder.Channels = int(C.get_decoder_channels(metadata))
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decoder.Depth = int(C.get_decoder_depth(metadata))
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@ -134,7 +193,7 @@ func decoderMetadataCallback(d *C.FLAC__StreamDecoder, metadata *C.FLAC__StreamM
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//export decoderWriteCallback
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func decoderWriteCallback(d *C.FLAC__StreamDecoder, frame *C.FLAC__Frame, buffer **C.FLAC__int32, data unsafe.Pointer) C.FLAC__StreamDecoderWriteStatus {
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decoder := (*Decoder)(data)
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decoder := decoderPtrs.get(d)
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blocksize := int(frame.header.blocksize)
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decoder.frame = new(Frame)
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f := decoder.frame
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@ -148,7 +207,7 @@ func decoderWriteCallback(d *C.FLAC__StreamDecoder, frame *C.FLAC__Frame, buffer
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//export decoderReadCallback
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func decoderReadCallback(d *C.FLAC__StreamDecoder, buffer *C.FLAC__byte, bytes *C.size_t, data unsafe.Pointer) C.FLAC__StreamDecoderReadStatus {
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decoder := (*Decoder)(data)
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decoder := decoderPtrs.get(d)
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numBytes := int(*bytes)
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if numBytes <= 0 {
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return C.FLAC__STREAM_DECODER_READ_STATUS_ABORT
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@ -183,10 +242,11 @@ func NewDecoder(name string) (d *Decoder, err error) {
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(C.FLAC__StreamDecoderWriteCallback)(unsafe.Pointer(C.decoderWriteCallback_cgo)),
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(C.FLAC__StreamDecoderMetadataCallback)(unsafe.Pointer(C.decoderMetadataCallback_cgo)),
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(C.FLAC__StreamDecoderErrorCallback)(unsafe.Pointer(C.decoderErrorCallback_cgo)),
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unsafe.Pointer(d))
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nil)
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if status != C.FLAC__STREAM_DECODER_INIT_STATUS_OK {
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return nil, errors.New("failed to open file")
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}
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decoderPtrs.add(d)
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ret := C.FLAC__stream_decoder_process_until_end_of_metadata(d.d)
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if ret == 0 || d.error == true || d.Channels == 0 {
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return nil, fmt.Errorf("failed to process metadata %s", d.errorStr)
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@ -209,10 +269,11 @@ func NewDecoderReader(reader io.ReadCloser) (d *Decoder, err error) {
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(C.FLAC__StreamDecoderWriteCallback)(unsafe.Pointer(C.decoderWriteCallback_cgo)),
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(C.FLAC__StreamDecoderMetadataCallback)(unsafe.Pointer(C.decoderMetadataCallback_cgo)),
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(C.FLAC__StreamDecoderErrorCallback)(unsafe.Pointer(C.decoderErrorCallback_cgo)),
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unsafe.Pointer(d))
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nil)
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if status != C.FLAC__STREAM_DECODER_INIT_STATUS_OK {
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return nil, errors.New("failed to open stream")
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}
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decoderPtrs.add(d)
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ret := C.FLAC__stream_decoder_process_until_end_of_metadata(d.d)
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if ret == 0 || d.error == true || d.Channels == 0 {
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return nil, fmt.Errorf("failed to process metadata %s", d.errorStr)
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@ -225,6 +286,7 @@ func (d *Decoder) Close() {
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if d.d != nil {
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C.FLAC__stream_decoder_delete(d.d)
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d.d = nil
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decoderPtrs.del(d)
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}
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if d.reader != nil {
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d.reader.Close()
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@ -260,6 +322,7 @@ func NewEncoder(name string, channels int, depth int, rate int) (e *Encoder, err
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if e.e == nil {
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return nil, errors.New("failed to create decoder")
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}
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encoderPtrs.add(e)
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c := C.CString(name)
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defer C.free(unsafe.Pointer(c))
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runtime.SetFinalizer(e, (*Encoder).Close)
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@ -278,7 +341,7 @@ func NewEncoder(name string, channels int, depth int, rate int) (e *Encoder, err
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//export encoderWriteCallback
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func encoderWriteCallback(e *C.FLAC__StreamEncoder, buffer *C.FLAC__byte, bytes C.size_t, samples, current_frame C.unsigned, data unsafe.Pointer) C.FLAC__StreamEncoderWriteStatus {
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encoder := (*Encoder)(data)
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encoder := encoderPtrs.get(e)
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numBytes := int(bytes)
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if numBytes <= 0 {
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return C.FLAC__STREAM_DECODER_READ_STATUS_ABORT
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@ -298,7 +361,7 @@ func encoderWriteCallback(e *C.FLAC__StreamEncoder, buffer *C.FLAC__byte, bytes
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//export encoderSeekCallback
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func encoderSeekCallback(e *C.FLAC__StreamEncoder, absPos C.FLAC__uint64, data unsafe.Pointer) C.FLAC__StreamEncoderWriteStatus {
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encoder := (*Encoder)(data)
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encoder := encoderPtrs.get(e)
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_, err := encoder.writer.Seek(int64(absPos), 0)
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if err != nil {
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return C.FLAC__STREAM_ENCODER_SEEK_STATUS_ERROR
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@ -308,7 +371,7 @@ func encoderSeekCallback(e *C.FLAC__StreamEncoder, absPos C.FLAC__uint64, data u
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//export encoderTellCallback
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func encoderTellCallback(e *C.FLAC__StreamEncoder, absPos *C.FLAC__uint64, data unsafe.Pointer) C.FLAC__StreamEncoderWriteStatus {
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encoder := (*Encoder)(data)
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encoder := encoderPtrs.get(e)
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newPos, err := encoder.writer.Seek(0, 1)
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if err != nil {
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return C.FLAC__STREAM_ENCODER_TELL_STATUS_ERROR
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@ -330,6 +393,7 @@ func NewEncoderWriter(writer FlacWriter, channels int, depth int, rate int) (e *
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if e.e == nil {
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return nil, errors.New("failed to create decoder")
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}
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encoderPtrs.add(e)
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e.writer = writer
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runtime.SetFinalizer(e, (*Encoder).Close)
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C.FLAC__stream_encoder_set_channels(e.e, C.uint(channels))
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@ -339,7 +403,7 @@ func NewEncoderWriter(writer FlacWriter, channels int, depth int, rate int) (e *
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(C.FLAC__StreamEncoderWriteCallback)(unsafe.Pointer(C.encoderWriteCallback_cgo)),
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(C.FLAC__StreamEncoderSeekCallback)(unsafe.Pointer(C.encoderSeekCallback_cgo)),
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(C.FLAC__StreamEncoderTellCallback)(unsafe.Pointer(C.encoderTellCallback_cgo)),
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nil, unsafe.Pointer(e))
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nil, nil)
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if status != C.FLAC__STREAM_ENCODER_INIT_STATUS_OK {
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return nil, errors.New("failed to open file")
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}
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@ -369,6 +433,7 @@ func (e *Encoder) Close() {
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if e.e != nil {
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C.FLAC__stream_encoder_finish(e.e)
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e.e = nil
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encoderPtrs.del(e)
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}
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if e.writer != nil {
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e.writer.Close()
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