Undocumented "no events" Op on Linux when a watched directory is unmounted #655
Description
When a watched directory is unmounted/deleted? on Linux, fsnotify emits an event with the Op value 0 ("no events") up to ~1 minute later.
This happens when I plug in my camera via USB, let dolphin mount it, watching a mounted subdirectory with fsnotify, and then shutting off my camera.
I could only find this "no events" event mentioned under the "Windows notes" section of the documentation
This happens in fsnotify v1.7.0 and v1.8.0
$ uname -a
Linux kivah 5.15.0-119-generic #129-Ubuntu SMP Fri Aug 2 19:25:20 UTC 2024 x86_64 x86_64 x86_64 GNU/LinuxDistro: Linux Mint 21.3 x86_64
Code to reproduce (click to expand)
package main
import (
"fmt"
"github.com/fsnotify/fsnotify"
)
func main() {
watcher, _ := fsnotify.NewWatcher()
defer watcher.Close()
watcher.Add("/mounted-directory/subdirectory")
go func() {
for {
select {
case event, ok := <-watcher.Events:
if !ok {
return
}
fmt.Println(event)
case _, ok := <-watcher.Errors:
if !ok {
return
}
}
}
}()
select {}
}It would be nice to document that the received event.Op can be 0 in the Watcher struct documentation comments, especially since it can happen on both Windows & Linux.
Thanks!