diff options
Diffstat (limited to 'pkg/sentry/fs/tty')
| -rw-r--r-- | pkg/sentry/fs/tty/line_discipline.go | 55 |
1 files changed, 24 insertions, 31 deletions
diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go index 31b6344f2..c4a364edb 100644 --- a/pkg/sentry/fs/tty/line_discipline.go +++ b/pkg/sentry/fs/tty/line_discipline.go @@ -280,10 +280,12 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte var ret int for len(buf) > 0 { - c, size := l.peekRune(buf) + size := l.peek(buf) + cBytes := append([]byte{}, buf[:size]...) ret += size buf = buf[size:] - switch c { + // We're guaranteed that cBytes has at least one element. + switch cBytes[0] { case '\n': if l.termios.OEnabled(linux.ONLRET) { l.column = 0 @@ -297,7 +299,7 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte continue } if l.termios.OEnabled(linux.OCRNL) { - c = '\n' + cBytes[0] = '\n' if l.termios.OEnabled(linux.ONLRET) { l.column = 0 } @@ -319,10 +321,7 @@ func (*outputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte default: l.column++ } - // The compiler optimizes this by growing readBuf without - // creating the intermediate slice. - q.readBuf = append(q.readBuf, make([]byte, size)...) - utf8.EncodeRune(q.readBuf[len(q.readBuf)-size:], c) + q.readBuf = append(q.readBuf, cBytes...) } if len(q.readBuf) > 0 { q.readable = true @@ -358,8 +357,10 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) var ret int for len(buf) > 0 && len(q.readBuf) < canonMaxBytes { - c, size := l.peekRune(buf) - switch c { + size := l.peek(buf) + cBytes := append([]byte{}, buf[:size]...) + // We're guaranteed that cBytes has at least one element. + switch cBytes[0] { case '\r': if l.termios.IEnabled(linux.IGNCR) { buf = buf[size:] @@ -367,17 +368,17 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) continue } if l.termios.IEnabled(linux.ICRNL) { - c = '\n' + cBytes[0] = '\n' } case '\n': if l.termios.IEnabled(linux.INLCR) { - c = '\r' + cBytes[0] = '\r' } } // In canonical mode, we discard non-terminating characters // after the first 4095. - if l.shouldDiscard(q, c) { + if l.shouldDiscard(q, cBytes) { buf = buf[size:] ret += size continue @@ -387,20 +388,16 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) if len(q.readBuf)+size > maxBytes { break } - cBytes := buf[:size] buf = buf[size:] ret += size // If we get EOF, make the buffer available for reading. - if l.termios.LEnabled(linux.ICANON) && l.termios.IsEOF(c) { + if l.termios.LEnabled(linux.ICANON) && l.termios.IsEOF(cBytes[0]) { q.readable = true break } - // The compiler optimizes this by growing readBuf without - // creating the intermediate slice. - q.readBuf = append(q.readBuf, make([]byte, size)...) - utf8.EncodeRune(q.readBuf[len(q.readBuf)-size:], c) + q.readBuf = append(q.readBuf, cBytes...) // Anything written to the readBuf will have to be echoed. if l.termios.LEnabled(linux.ECHO) { @@ -409,7 +406,7 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) } // If we finish a line, make it available for reading. - if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(c) { + if l.termios.LEnabled(linux.ICANON) && l.termios.IsTerminating(cBytes) { q.readable = true break } @@ -430,21 +427,17 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte) // Precondition: // * l.termiosMu must be held for reading. // * q.mu must be held. -func (l *lineDiscipline) shouldDiscard(q *queue, c rune) bool { - return l.termios.LEnabled(linux.ICANON) && len(q.readBuf)+utf8.RuneLen(c) >= canonMaxBytes && !l.termios.IsTerminating(c) +func (l *lineDiscipline) shouldDiscard(q *queue, cBytes []byte) bool { + return l.termios.LEnabled(linux.ICANON) && len(q.readBuf)+len(cBytes) >= canonMaxBytes && !l.termios.IsTerminating(cBytes) } -// peekRune returns the first rune from the byte array depending on whether -// UTF8 is enabled. -func (l *lineDiscipline) peekRune(b []byte) (rune, int) { - var c rune - var size int +// peek returns the size in bytes of the next character to process. As long as +// b isn't empty, peek returns a value of at least 1. +func (l *lineDiscipline) peek(b []byte) int { + size := 1 // If UTF-8 support is enabled, runes might be multiple bytes. if l.termios.IEnabled(linux.IUTF8) { - c, size = utf8.DecodeRune(b) - } else { - c = rune(b[0]) - size = 1 + _, size = utf8.DecodeRune(b) } - return c, size + return size } |