/usr/share/gocode/src/github.com/jrick/logrotate/rotator/rotator.go is in golang-github-jrick-logrotate-dev 0.0~git20170628.a93b200-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Copyright (c) 2017, Josh Rickmar <jrick@devio.us>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Package rotator implements a simple logfile rotator. Logs are read from an
// io.Reader and are written to a file until they reach a specified size. The
// log is then gzipped to another file and truncated.
package rotator
import (
"bufio"
"compress/gzip"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
)
// nl is a byte slice containing a newline byte. It is used to avoid creating
// additional allocations when writing newlines to the log file.
var nl = []byte{'\n'}
// A Rotator writes input to a file, splitting it up into gzipped chunks once
// the filesize reaches a certain threshold.
type Rotator struct {
size int64
threshold int64
maxRolls int
filename string
out *os.File
tee bool
wg sync.WaitGroup
}
// New returns a new Rotator. The rotator can be used either by reading input
// from an io.Reader by calling Run, or writing directly to the Rotator with
// Write.
func New(filename string, thresholdKB int64, tee bool, maxRolls int) (*Rotator, error) {
f, err := os.OpenFile(filename, os.O_CREATE|os.O_APPEND|os.O_RDWR, 0644)
if err != nil {
return nil, err
}
stat, err := f.Stat()
if err != nil {
return nil, err
}
return &Rotator{
size: stat.Size(),
threshold: 1000 * thresholdKB,
maxRolls: maxRolls,
filename: filename,
out: f,
tee: tee,
}, nil
}
// Run begins reading lines from the reader and rotating logs as necessary. Run
// should not be called concurrently with Write.
//
// Prefer to use Rotator as a writer instead to avoid unnecessary scanning of
// input, as this job is better handled using io.Pipe.
func (r *Rotator) Run(reader io.Reader) error {
in := bufio.NewReader(reader)
// Rotate file immediately if it is already over the size limit.
if r.size >= r.threshold {
if err := r.rotate(); err != nil {
return err
}
r.size = 0
}
for {
line, isPrefix, err := in.ReadLine()
if err != nil {
return err
}
n, _ := r.out.Write(line)
r.size += int64(n)
if r.tee {
os.Stdout.Write(line)
}
if isPrefix {
continue
}
m, _ := r.out.Write(nl)
if r.tee {
os.Stdout.Write(nl)
}
r.size += int64(m)
if r.size >= r.threshold {
err := r.rotate()
if err != nil {
return err
}
r.size = 0
}
}
}
// Write implements the io.Writer interface for Rotator. If p ends in a newline
// and the file has exceeded the threshold size, the file is rotated.
func (r *Rotator) Write(p []byte) (n int, err error) {
n, _ = r.out.Write(p)
r.size += int64(n)
if r.size >= r.threshold && len(p) > 0 && p[len(p)-1] == '\n' {
err := r.rotate()
if err != nil {
return 0, err
}
r.size = 0
}
return n, nil
}
// Close closes the output logfile.
func (r *Rotator) Close() error {
err := r.out.Close()
r.wg.Wait()
return err
}
func (r *Rotator) rotate() error {
dir := filepath.Dir(r.filename)
glob := filepath.Join(dir, filepath.Base(r.filename)+".*")
existing, err := filepath.Glob(glob)
if err != nil {
return err
}
maxNum := 0
for _, name := range existing {
parts := strings.Split(name, ".")
if len(parts) < 2 {
continue
}
numIdx := len(parts) - 1
if parts[numIdx] == "gz" {
numIdx--
}
num, err := strconv.Atoi(parts[numIdx])
if err != nil {
continue
}
if num > maxNum {
maxNum = num
}
}
err = r.out.Close()
if err != nil {
return err
}
rotname := fmt.Sprintf("%s.%d", r.filename, maxNum+1)
err = os.Rename(r.filename, rotname)
if err != nil {
return err
}
if r.maxRolls > 0 {
for n := maxNum + 1 - r.maxRolls; ; n-- {
err := os.Remove(fmt.Sprintf("%s.%d.gz", r.filename, n))
if err != nil {
break
}
}
}
r.out, err = os.OpenFile(r.filename, os.O_CREATE|os.O_RDWR, 0644)
if err != nil {
return err
}
r.wg.Add(1)
go func() {
err := compress(rotname)
if err == nil {
os.Remove(rotname)
}
r.wg.Done()
}()
return nil
}
func compress(name string) (err error) {
f, err := os.Open(name)
if err != nil {
return err
}
defer f.Close()
arc, err := os.OpenFile(name+".gz", os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644)
if err != nil {
return err
}
z := gzip.NewWriter(arc)
if _, err = io.Copy(z, f); err != nil {
return err
}
if err = z.Close(); err != nil {
return err
}
return arc.Close()
}
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