blob: e648eb81208fa4b86563545ea410fa8f0dac770c [file] [log] [blame]
package term
import (
"io"
)
// EscapeError is special error which returned by a TTY proxy reader's Read()
// method in case its detach escape sequence is read.
type EscapeError struct{}
func (EscapeError) Error() string {
return "read escape sequence"
}
// escapeProxy is used only for attaches with a TTY. It is used to proxy
// stdin keypresses from the underlying reader and look for the passed in
// escape key sequence to signal a detach.
type escapeProxy struct {
escapeKeys []byte
escapeKeyPos int
r io.Reader
}
// NewEscapeProxy returns a new TTY proxy reader which wraps the given reader
// and detects when the specified escape keys are read, in which case the Read
// method will return an error of type EscapeError.
func NewEscapeProxy(r io.Reader, escapeKeys []byte) io.Reader {
return &escapeProxy{
escapeKeys: escapeKeys,
r: r,
}
}
func (r *escapeProxy) Read(buf []byte) (int, error) {
nr, err := r.r.Read(buf)
preserve := func() {
// this preserves the original key presses in the passed in buffer
nr += r.escapeKeyPos
preserve := make([]byte, 0, r.escapeKeyPos+len(buf))
preserve = append(preserve, r.escapeKeys[:r.escapeKeyPos]...)
preserve = append(preserve, buf...)
r.escapeKeyPos = 0
copy(buf[0:nr], preserve)
}
if nr != 1 || err != nil {
if r.escapeKeyPos > 0 {
preserve()
}
return nr, err
}
if buf[0] != r.escapeKeys[r.escapeKeyPos] {
if r.escapeKeyPos > 0 {
preserve()
}
return nr, nil
}
if r.escapeKeyPos == len(r.escapeKeys)-1 {
return 0, EscapeError{}
}
// Looks like we've got an escape key, but we need to match again on the next
// read.
// Store the current escape key we found so we can look for the next one on
// the next read.
// Since this is an escape key, make sure we don't let the caller read it
// If later on we find that this is not the escape sequence, we'll add the
// keys back
r.escapeKeyPos++
return nr - r.escapeKeyPos, nil
}