137 lines
2.8 KiB
Go
137 lines
2.8 KiB
Go
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// Copyright (c) 2019 FOSS contributors of https://github.com/nxadm/tail
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// Copyright (c) 2015 HPE Software Inc. All rights reserved.
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// Copyright (c) 2013 ActiveState Software Inc. All rights reserved.
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package watch
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import (
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"fmt"
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"os"
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"path/filepath"
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"github.com/nxadm/tail/util"
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"github.com/fsnotify/fsnotify"
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"gopkg.in/tomb.v1"
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)
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// InotifyFileWatcher uses inotify to monitor file changes.
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type InotifyFileWatcher struct {
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Filename string
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Size int64
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}
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func NewInotifyFileWatcher(filename string) *InotifyFileWatcher {
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fw := &InotifyFileWatcher{filepath.Clean(filename), 0}
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return fw
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}
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func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
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err := WatchCreate(fw.Filename)
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if err != nil {
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return err
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}
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defer RemoveWatchCreate(fw.Filename)
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// Do a real check now as the file might have been created before
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// calling `WatchFlags` above.
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if _, err = os.Stat(fw.Filename); !os.IsNotExist(err) {
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// file exists, or stat returned an error.
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return err
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}
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events := Events(fw.Filename)
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for {
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select {
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case evt, ok := <-events:
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if !ok {
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return fmt.Errorf("inotify watcher has been closed")
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}
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evtName, err := filepath.Abs(evt.Name)
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if err != nil {
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return err
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}
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fwFilename, err := filepath.Abs(fw.Filename)
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if err != nil {
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return err
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}
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if evtName == fwFilename {
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return nil
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}
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case <-t.Dying():
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return tomb.ErrDying
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}
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}
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panic("unreachable")
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}
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func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, pos int64) (*FileChanges, error) {
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err := Watch(fw.Filename)
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if err != nil {
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return nil, err
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}
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changes := NewFileChanges()
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fw.Size = pos
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go func() {
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events := Events(fw.Filename)
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for {
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prevSize := fw.Size
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var evt fsnotify.Event
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var ok bool
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select {
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case evt, ok = <-events:
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if !ok {
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RemoveWatch(fw.Filename)
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return
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}
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case <-t.Dying():
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RemoveWatch(fw.Filename)
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return
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}
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switch {
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case evt.Op&fsnotify.Remove == fsnotify.Remove:
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fallthrough
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case evt.Op&fsnotify.Rename == fsnotify.Rename:
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RemoveWatch(fw.Filename)
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changes.NotifyDeleted()
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return
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//With an open fd, unlink(fd) - inotify returns IN_ATTRIB (==fsnotify.Chmod)
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case evt.Op&fsnotify.Chmod == fsnotify.Chmod:
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fallthrough
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case evt.Op&fsnotify.Write == fsnotify.Write:
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fi, err := os.Stat(fw.Filename)
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if err != nil {
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if os.IsNotExist(err) {
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RemoveWatch(fw.Filename)
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changes.NotifyDeleted()
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return
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}
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// XXX: report this error back to the user
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util.Fatal("Failed to stat file %v: %v", fw.Filename, err)
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}
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fw.Size = fi.Size()
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if prevSize > 0 && prevSize > fw.Size {
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changes.NotifyTruncated()
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} else {
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changes.NotifyModified()
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}
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prevSize = fw.Size
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}
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}
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}()
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return changes, nil
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}
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