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limbuffer.go
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limbuffer.go
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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2018 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package strutil
type LimitedBuffer struct {
buffer []byte
maxLines int
maxBytes int
}
func NewLimitedBuffer(maxLines, maxBytes int) *LimitedBuffer {
return &LimitedBuffer{
maxLines: maxLines,
maxBytes: maxBytes,
}
}
func (lb *LimitedBuffer) Write(data []byte) (int, error) {
drop := len(lb.buffer) + len(data) - lb.maxBytes
switch {
case drop < 0:
lb.buffer = append(lb.buffer, data...)
case drop > len(lb.buffer):
lb.buffer = append(lb.buffer[:0], data[drop-len(lb.buffer):]...)
default:
keep := copy(lb.buffer, lb.buffer[drop:])
lb.buffer = append(lb.buffer[:keep], data...)
}
return len(data), nil
}
func (lb *LimitedBuffer) Bytes() []byte {
return TruncateOutput(lb.buffer, lb.maxLines, lb.maxBytes)
}