Hi James, On Tue, Dec 6, 2011 at 10:40 PM, James Hunt <james.hunt@xxxxxxxxxx> wrote: > man7/inotify.7: > > - Explain how to read a single inotify event. > - Add missing "struct" in explanation of event size. Re your patch: > --- a/man7/inotify.7 > +++ b/man7/inotify.7 > @@ -144,7 +144,7 @@ including the null bytes; > the length of each > .I inotify_event > structure is thus > -.IR "sizeof(inotify_event)+len" . > +.IR "sizeof(struct inotify_event)+len" . Applied. > 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 > +.I "sizeof(struct inotify_event)+NAME_MAX" > +until > +.BR read (2) > +does not returnvi > +.BR EINVAL "." > +Note that this technique is not particularly efficient. > + > .SH "BUGS" > In kernels before 2.6.16, the > .B IN_ONESHOT I've just now added a note to the page that specifying a buffer size of at least "sizeof(struct inotify_event) + NAME_MAX + 1" is sufficient to read *at least* one event. My question is, why do you want to propose this technique for reading a *single* event.? Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
