packer-cn/provisioner/shell/unix_reader.go

66 lines
1.4 KiB
Go

package shell
import (
"bufio"
"io"
"sync"
)
// UnixReader is a Reader implementation that automatically converts
// Windows line endings to Unix line endings.
type UnixReader struct {
Reader io.Reader
buf []byte
once sync.Once
scanner *bufio.Scanner
}
func (r *UnixReader) Read(p []byte) (n int, err error) {
// Create the buffered reader once
r.once.Do(func() {
r.scanner = bufio.NewScanner(r.Reader)
r.scanner.Split(scanUnixLine)
})
// If we have no data in our buffer, scan to the next token
if len(r.buf) == 0 {
if !r.scanner.Scan() {
err = r.scanner.Err()
if err == nil {
err = io.EOF
}
return 0, err
}
r.buf = r.scanner.Bytes()
}
// Write out as much data as we can to the buffer, storing the rest
// for the next read.
n = len(p)
if n > len(r.buf) {
n = len(r.buf)
}
copy(p, r.buf)
r.buf = r.buf[n:]
return
}
// scanUnixLine is a bufio.Scanner SplitFunc. It tokenizes on lines, but
// only returns unix-style lines. So even if the line is "one\r\n", the
// token returned will be "one\n".
func scanUnixLine(data []byte, atEOF bool) (advance int, token []byte, err error) {
advance, token, err = bufio.ScanLines(data, atEOF)
if advance == 0 {
// If we reached the end of a line without a newline, then
// just return as it is. Otherwise the Scanner will keep trying
// to scan, blocking forever.
return
}
return advance, append(token, '\n'), err
}