rlog.go

/*
 * Copyright (C) 2017 Jianhui Zhao <jianhuizhao329@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

package main

import (
    "os"
    "fmt"
    "log"
    "github.com/mattn/go-isatty"
)

type RttyLog struct {
    file string
}

const LOG_FILE = "/var/log/rtty.log"

func (l *RttyLog) Write(b []byte) (n int, err error) {
    if isatty.IsTerminal(os.Stdout.Fd()) {
        fmt.Fprintf(os.Stderr, "%s", b)
        return 0, nil
    }

    if l.file == "" {
        return 0, nil
    }

    file, err := os.OpenFile(l.file, os.O_CREATE | os.O_WRONLY | os.O_APPEND, 0666)
    if err != nil {
        return 0, nil
    }

    st, _ := file.Stat()
    if st.Size() > 1024 * 1024 {
        file.Truncate(0)
    }

    defer file.Close()

    fmt.Fprintf(file, "%s", b)

    return 0, nil
}

var rlog = log.New(&RttyLog{file: LOG_FILE}, "", log.LstdFlags)