mirror of https://github.com/containers/podman.git
104 lines
2.9 KiB
Go
104 lines
2.9 KiB
Go
package hooks
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import (
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"context"
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"os"
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"path/filepath"
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"github.com/fsnotify/fsnotify"
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"github.com/sirupsen/logrus"
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)
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// Monitor dynamically monitors hook directories for additions,
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// updates, and removals.
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//
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// This function writes two empty structs to the sync channel: the
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// first is written after the watchers are established and the second
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// when this function exits. The expected usage is:
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//
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// ctx, cancel := context.WithCancel(context.Background())
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// sync := make(chan error, 2)
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// go m.Monitor(ctx, sync)
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// err := <-sync // block until writers are established
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// if err != nil {
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// return err // failed to establish watchers
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// }
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// // do stuff
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// cancel()
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// err = <-sync // block until monitor finishes
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func (m *Manager) Monitor(ctx context.Context, sync chan<- error) {
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watcher, err := fsnotify.NewWatcher()
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if err != nil {
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sync <- err
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return
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}
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defer watcher.Close()
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for _, dir := range m.directories {
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err = watcher.Add(dir)
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if err != nil {
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logrus.Errorf("failed to watch %q for hooks", dir)
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sync <- err
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return
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}
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logrus.Debugf("monitoring %q for hooks", dir)
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}
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sync <- nil
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for {
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select {
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case event := <-watcher.Events:
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filename := filepath.Base(event.Name)
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if len(m.directories) <= 1 {
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if event.Op&fsnotify.Remove == fsnotify.Remove {
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ok := m.remove(filename)
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if ok {
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logrus.Debugf("removed hook %s", event.Name)
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}
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} else if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write {
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err = m.add(event.Name)
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if err == nil {
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logrus.Debugf("added hook %s", event.Name)
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} else if err != ErrNoJSONSuffix {
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logrus.Errorf("failed to add hook %s: %v", event.Name, err)
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}
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}
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} else if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write || event.Op&fsnotify.Remove == fsnotify.Remove {
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err = nil
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found := false
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for i := len(m.directories) - 1; i >= 0; i-- {
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path := filepath.Join(m.directories[i], filename)
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err = m.add(path)
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if err == nil {
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found = true
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logrus.Debugf("(re)added hook %s (triggered activity on %s)", path, event.Name)
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break
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} else if err == ErrNoJSONSuffix {
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found = true
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break // this is not going to change for fallback directories
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} else if os.IsNotExist(err) {
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continue // move on to the next fallback directory
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} else {
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found = true
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logrus.Errorf("failed to (re)add hook %s (triggered by activity on %s): %v", path, event.Name, err)
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break
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}
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}
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if (found || event.Op&fsnotify.Remove == fsnotify.Remove) && err != nil {
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ok := m.remove(filename)
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if ok {
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logrus.Debugf("removed hook %s (triggered by activity on %s)", filename, event.Name)
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}
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}
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}
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case <-ctx.Done():
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err = ctx.Err()
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logrus.Debugf("hook monitoring canceled: %v", err)
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sync <- err
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close(sync)
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return
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}
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}
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}
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