cacert-gosigner/shared/io.go

package shared

import (
	"fmt"
	log "github.com/sirupsen/logrus"
	"io"
	"time"
)

// receive at maximum the requested number of bytes from serial port and stop after the given timeout
func ReceiveBytes(port *io.ReadWriteCloser, count int, timeout time.Duration) ([]byte, error) {
	readCh := make(chan []byte, 1)
	errCh := make(chan error, 1)
	go func() {
		data := make([]byte, count)
		if readBytes, err := (*port).Read(data); err != nil {
			errCh <- err
		} else if readBytes > 0 {
			log.Tracef("%d bytes read", readBytes)
			readCh <- data[0:readBytes]
		} else {
			readCh <- make([]byte, 0)
		}
		return
	}()
	select {
	case <-time.After(timeout):
		return nil, fmt.Errorf("timeout passed %v: %v", timeout)
	case err := <-errCh:
		return nil, err
	case data := <-readCh:
		return data, nil
	}
}

func SendByte(port *io.ReadWriteCloser, data byte) error {
	if bytesWritten, err := (*port).Write([]byte{data}); err != nil {
		return err
	} else {
		log.Tracef("wrote %d bytes of handshake info", bytesWritten)
	}
	return nil
}