Explain how to read a single inotify event.

From 2c2e9150661fc12142725f97e3cebf8ff64e1264 Mon Sep 17 00:00:00 2001

man7/inotify.7:

- Explain how to read a single inotify event.
- Add missing "struct" in explanation of event size.

man7/inotify.7 +15 -0

 The behavior when the buffer given to
 .BR read (2)

@@ -417,6 +417,28 @@ be aware that by the time you create a watch for the new subdirectory,
 new files may already have been created in the subdirectory.
 Therefore, you may want to scan the contents of the subdirectory
 immediately after adding the watch.
+
+To read a
+.B single
+event requires the buffer provided to
+.BR read (2)
+be large enough to hold the event. However, since inotify employs
+variable-length events for files in a watched directory (via the
+.I name
+field), it is not possible to know exactly how big such a
+buffer should be since the event itself has not yet been read. One
+method to overcome this limitation is to start with a buffer of size
+.I sizeof(struct inotify_event)
+and attempt to read the event. If this fails with
+.BR EINVAL ","
+continue to increase the buffer size by one byte up to

My question is, why do you want to propose this technique for reading a *single* event.?

Quoted 2 lines · Michael Kerrisk (man-pages)

My question is, why do you want to propose this technique for reading a *single* event.?

It could be useful in multithreaded/multiprocess apps that rely on an inotify descriptor to distribute work to a thread pool.  accept() and mq_receive() users do it all the time.