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- package iconv
-
- /*
- #cgo darwin LDFLAGS: -liconv
- #cgo freebsd LDFLAGS: -liconv
- #cgo windows LDFLAGS: -liconv
- #include <stdlib.h>
- #include <iconv.h>
- #include <locale.h>
-
- // As of GO 1.6 passing a pointer to Go pointer, will lead to panic
- // Therofore we use this wrapper function, to avoid passing **char directly from go
- size_t call_iconv(iconv_t ctx, char *in, size_t *size_in, char *out, size_t *size_out){
- return iconv(ctx, &in, size_in, &out, size_out);
- }
-
- */
- import "C"
- import "syscall"
- import "unsafe"
-
- type Converter struct {
- context C.iconv_t
- }
-
- // Initialize a new Converter. If fromEncoding or toEncoding are not supported by
- // iconv then an EINVAL error will be returned. An ENOMEM error maybe returned if
- // there is not enough memory to initialize an iconv descriptor
- func NewConverter(fromEncoding string, toEncoding string) (*Converter, error) {
- // convert to C strings
- toEncodingC := C.CString(toEncoding)
- fromEncodingC := C.CString(fromEncoding)
-
- // open an iconv descriptor
- context, err := C.iconv_open(toEncodingC, fromEncodingC)
-
- // free the C Strings
- C.free(unsafe.Pointer(toEncodingC))
- C.free(unsafe.Pointer(fromEncodingC))
-
- if err != nil {
- return nil, err
- }
-
- return &Converter{context}, nil
- }
-
- // Close a Converter's iconv descriptor explicitly
- func (converter *Converter) Close() error {
- _, err := C.iconv_close(converter.context)
- return err
- }
-
- // Reset state of iconv context
- func (converter *Converter) Reset() error {
- _, _, err := converter.Convert(nil, nil)
- return err
- }
-
- // Convert bytes from an input byte slice into a give output byte slice
- //
- // As many bytes that can converted and fit into the size of output will be
- // processed and the number of bytes read for input as well as the number of
- // bytes written to output will be returned. If not all converted bytes can fit
- // into output and E2BIG error will also be returned. If input contains an invalid
- // sequence of bytes for the Converter's fromEncoding an EILSEQ error will be returned
- //
- // For shift based output encodings, any end shift byte sequences can be generated by
- // passing a 0 length byte slice as input. Also passing a 0 length byte slice for output
- // will simply reset the iconv descriptor shift state without writing any bytes.
- func (converter *Converter) Convert(input []byte, output []byte) (bytesRead int, bytesWritten int, err error) {
- inputLeft := C.size_t(len(input))
- outputLeft := C.size_t(len(output))
-
- var inputPointer, outputPointer *C.char
-
- if inputLeft > 0 {
- inputPointer = (*C.char)(unsafe.Pointer(&input[0]))
- }
-
- if outputLeft > 0 {
- outputPointer = (*C.char)(unsafe.Pointer(&output[0]))
- }
-
- _, err = C.call_iconv(converter.context, inputPointer, &inputLeft, outputPointer, &outputLeft)
-
- bytesRead = len(input) - int(inputLeft)
- bytesWritten = len(output) - int(outputLeft)
-
- return bytesRead, bytesWritten, err
- }
-
- // Convert an input string
- //
- // EILSEQ error may be returned if input contains invalid bytes for the Converter's fromEncoding
- func (converter *Converter) ConvertString(input string) (output string, err error) {
- // construct the buffers
- inputBuffer := []byte(input)
- outputBuffer := make([]byte, len(inputBuffer)*2) // we use a larger buffer to help avoid resizing later
-
- // call Convert until all input bytes are read or an error occurs
- var bytesRead, totalBytesRead, bytesWritten, totalBytesWritten int
-
- for totalBytesRead < len(inputBuffer) && err == nil {
- // use the totals to create buffer slices
- bytesRead, bytesWritten, err = converter.Convert(inputBuffer[totalBytesRead:], outputBuffer[totalBytesWritten:])
-
- totalBytesRead += bytesRead
- totalBytesWritten += bytesWritten
-
- switch err {
- case syscall.E2BIG:
- // increase the size of the output buffer by another input length
- // first, create a new buffer
- tempBuffer := make([]byte, len(outputBuffer)+len(inputBuffer))
-
- // copy the existing data
- copy(tempBuffer, outputBuffer)
-
- // switch the buffers
- outputBuffer = tempBuffer
-
- // forget the error
- err = nil
- case syscall.EILSEQ, syscall.EINVAL:
- // iconv can still return these in cases where it still can proceed such as //IGNORE
- if bytesRead > 0 || bytesWritten > 0 {
- err = nil
- }
- }
- }
-
- if err == nil {
- // perform a final shift state reset
- _, bytesWritten, err = converter.Convert(nil, outputBuffer[totalBytesWritten:])
-
- // update total count
- totalBytesWritten += bytesWritten
- }
-
- // construct the final output string
- output = string(outputBuffer[:totalBytesWritten])
-
- return output, err
- }
-
- func finalizeConverter(converter *Converter) {
- converter.Close()
- }
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