cacert-gosigner/shared/io.go

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package shared
import (
"bytes"
"fmt"
"io"
"time"
log "github.com/sirupsen/logrus"
)
// receive at maximum the requested number of bytes from serial port and stop after the given timeout
func ReceiveBytes(port io.Reader, count int, timeout time.Duration) ([]byte, error) {
readCh := make(chan []byte, 1)
errCh := make(chan error, 1)
go func() {
buffer := bytes.NewBuffer([]byte{})
for remainder := count; remainder > 0; {
data := make([]byte, remainder)
if readBytes, err := port.Read(data); err != nil {
errCh <- err
return
} else if readBytes > 0 {
buffer.Write(data[0:readBytes])
remainder -= readBytes
log.Tracef("%d bytes read, remaining %d", readBytes, remainder)
}
}
readCh <- buffer.Bytes()
close(readCh)
}()
buffer := bytes.NewBuffer([]byte{})
select {
case <-time.After(timeout):
return nil, fmt.Errorf("timeout passed %v", timeout)
case err := <-errCh:
return nil, err
case data := <-readCh:
log.Tracef("received %d bytes from channel", len(data))
if data == nil {
break
}
buffer.Write(data)
}
return buffer.Bytes(), nil
}
func SendBytes(port io.Writer, data []byte) error {
if bytesWritten, err := port.Write(data); err != nil {
return err
} else {
log.Tracef("wrote %d bytes", bytesWritten)
}
return nil
}