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// SPDX-License-Identifier: GPL-3.0-or-later
package logs
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sort"
"github.com/netdata/netdata/go/go.d.plugin/logger"
)
const (
maxEOF = 60
)
var (
ErrNoMatchedFile = errors.New("no matched files")
)
// Reader is a log rotate aware Reader
// TODO: better reopen algorithm
// TODO: handle truncate
type Reader struct {
file *os.File
path string
excludePath string
eofCounter int
continuousEOF int
log *logger.Logger
}
// Open a file and seek to end of the file.
// path: the shell file name pattern
// excludePath: the shell file name pattern
func Open(path string, excludePath string, log *logger.Logger) (*Reader, error) {
var err error
if path, err = filepath.Abs(path); err != nil {
return nil, err
}
if _, err = filepath.Match(path, "/"); err != nil {
return nil, fmt.Errorf("bad path syntax: %q", path)
}
if _, err = filepath.Match(excludePath, "/"); err != nil {
return nil, fmt.Errorf("bad exclude_path syntax: %q", path)
}
r := &Reader{
path: path,
excludePath: excludePath,
log: log,
}
if err = r.open(); err != nil {
return nil, err
}
return r, nil
}
// CurrentFilename get current opened file name
func (r *Reader) CurrentFilename() string {
return r.file.Name()
}
func (r *Reader) open() error {
path := r.findFile()
if path == "" {
r.log.Debugf("couldn't find log file, used path: '%s', exclude_path: '%s'", r.path, r.excludePath)
return ErrNoMatchedFile
}
r.log.Debug("open log file: ", path)
file, err := os.Open(path)
if err != nil {
return err
}
stat, err := file.Stat()
if err != nil {
return err
}
if _, err = file.Seek(stat.Size(), io.SeekStart); err != nil {
return err
}
r.file = file
return nil
}
func (r *Reader) Read(p []byte) (n int, err error) {
n, err = r.file.Read(p)
if err != nil {
switch err {
case io.EOF:
err = r.handleEOFErr()
case os.ErrInvalid: // r.file is nil after Close
err = r.handleInvalidArgErr()
}
return
}
r.continuousEOF = 0
return
}
func (r *Reader) handleEOFErr() (err error) {
err = io.EOF
r.eofCounter++
r.continuousEOF++
if r.eofCounter < maxEOF || r.continuousEOF < 2 {
return err
}
if err2 := r.reopen(); err2 != nil {
err = err2
}
return err
}
func (r *Reader) handleInvalidArgErr() (err error) {
err = io.EOF
if err2 := r.reopen(); err2 != nil {
err = err2
}
return err
}
func (r *Reader) Close() (err error) {
if r == nil || r.file == nil {
return
}
r.log.Debug("close log file: ", r.file.Name())
err = r.file.Close()
r.file = nil
r.eofCounter = 0
return
}
func (r *Reader) reopen() error {
r.log.Debugf("reopen, look for: %s", r.path)
_ = r.Close()
return r.open()
}
func (r *Reader) findFile() string {
return find(r.path, r.excludePath)
}
func find(path, exclude string) string {
return finder{}.find(path, exclude)
}
// TODO: tests
type finder struct{}
func (f finder) find(path, exclude string) string {
files, _ := filepath.Glob(path)
if len(files) == 0 {
return ""
}
files = f.filter(files, exclude)
if len(files) == 0 {
return ""
}
return f.findLastFile(files)
}
func (f finder) filter(files []string, exclude string) []string {
if exclude == "" {
return files
}
fs := make([]string, 0, len(files))
for _, file := range files {
if ok, _ := filepath.Match(exclude, file); ok {
continue
}
fs = append(fs, file)
}
return fs
}
// TODO: the logic is probably wrong
func (f finder) findLastFile(files []string) string {
sort.Strings(files)
for i := len(files) - 1; i >= 0; i-- {
stat, err := os.Stat(files[i])
if err != nil || !stat.Mode().IsRegular() {
continue
}
return files[i]
}
return ""
}
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