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- package iconv
-
- import (
- "io"
- "syscall"
- )
-
- type Reader struct {
- source io.Reader
- converter *Converter
- buffer []byte
- readPos, writePos int
- err error
- }
-
- func NewReader(source io.Reader, fromEncoding string, toEncoding string) (*Reader, error) {
- // create a converter
- converter, err := NewConverter(fromEncoding, toEncoding)
-
- if err == nil {
- return NewReaderFromConverter(source, converter), err
- }
-
- // return the error
- return nil, err
- }
-
- func NewReaderFromConverter(source io.Reader, converter *Converter) (reader *Reader) {
- reader = new(Reader)
-
- // copy elements
- reader.source = source
- reader.converter = converter
-
- // create 8K buffers
- reader.buffer = make([]byte, 8*1024)
-
- return reader
- }
-
- func (this *Reader) fillBuffer() {
- // slide existing data to beginning
- if this.readPos > 0 {
- // copy current bytes - is this guaranteed safe?
- copy(this.buffer, this.buffer[this.readPos:this.writePos])
-
- // adjust positions
- this.writePos -= this.readPos
- this.readPos = 0
- }
-
- // read new data into buffer at write position
- bytesRead, err := this.source.Read(this.buffer[this.writePos:])
-
- // adjust write position
- this.writePos += bytesRead
-
- // track any reader error / EOF
- if err != nil {
- this.err = err
- }
- }
-
- // implement the io.Reader interface
- func (this *Reader) Read(p []byte) (n int, err error) {
- // checks for when we have no data
- for this.writePos == 0 || this.readPos == this.writePos {
- // if we have an error / EOF, just return it
- if this.err != nil {
- return n, this.err
- }
-
- // else, fill our buffer
- this.fillBuffer()
- }
-
- // TODO: checks for when we have less data than len(p)
-
- // we should have an appropriate amount of data, convert it into the given buffer
- bytesRead, bytesWritten, err := this.converter.Convert(this.buffer[this.readPos:this.writePos], p)
-
- // adjust byte counters
- this.readPos += bytesRead
- n += bytesWritten
-
- // if we experienced an iconv error, check it
- if err != nil {
- // E2BIG errors can be ignored (we'll get them often) as long
- // as at least 1 byte was written. If we experienced an E2BIG
- // and no bytes were written then the buffer is too small for
- // even the next character
- if err != syscall.E2BIG || bytesWritten == 0 {
- // track anything else
- this.err = err
- }
- }
-
- // return our results
- return n, this.err
- }
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