From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinrich Schuchardt Subject: Re: [patch] fanotify.7: Fix description of FAN_EVENT_NEXT() Date: Wed, 21 May 2014 08:19:25 +0200 Message-ID: <537C456D.5090005@gmx.de> References: <53799494.2080609@gmail.com> <537A5454.2040707@gmx.de> <537B05F5.7010800@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <537B05F5.7010800-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Michael Kerrisk (man-pages)" Cc: "linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-man@vger.kernel.org On 20.05.2014 09:36, Michael Kerrisk (man-pages) wrote: > Hi Heinrich, > > On 05/19/2014 08:58 PM, Heinrich Schuchardt wrote: >> Hello Michael, >> >> the proposed new description of FAN_EVENT_NEXT is correct. > > Thanks for checking. I've added a Reviewed-by for you. > >> >> Should FAN_EVENT_METADATA_LEN also be put into the section with macros? >> >> .B FAN_EVENT_METADATA_LEN >> This macro returns the size of structure >> .I fanotify_event_metadata >> in bytes. >> This is the minimum size (and currently the only size) of any event >> metadata. > > I'm inclined not to, but I might be wrong. Is there a reason that > user-space might use it? FAN_EVENT_METADATA_LEN is the minimum size of a buffer used to read fanotify events. Of cause the user may use sizeof to calculate it himself. Anyway there is already some mentioning of FAN_EVENT_METADATA_LEN in fanotify.7. You remarked inotify read buffers should be 4 byte aligned on some CPUs. Shouldn't the same hold true for fanotify? Best regards Heinrich > > Cheers, > > Michael > > >> On 19.05.2014 07:20, Michael Kerrisk (man-pages) wrote: >>> Hi Heinrich, >>> >>> I realized that the description of FAN_EVENT_NEXT() is not quite correct. >>> It does not update 'meta', but instead returns a pointer to the next >>> structure. I tried also to add a bit more detail to the description. >>> Does the following patch look okay to you? >>> >>> Cheers, >>> >>> Michael >>> >>> >>> --- a/man7/fanotify.7 >>> +++ b/man7/fanotify.7 >>> @@ -309,13 +309,24 @@ against the length of the metadata structure and the >>> field of the first metadata structure in the buffer. >>> .TP >>> .B FAN_EVENT_NEXT(meta, len) >>> -This macro sets the pointer >>> -.I meta >>> -to the next metadata structure using the length indicated in the >>> +This macro uses the length indicated in the >>> .I event_len >>> -field of the metadata structure and reduces the remaining length of the >>> -buffer >>> -.IR len . >>> +field of the metadata structure pointed to by >>> +.IR meta >>> +to calculate the address of the next metadata structure that follows >>> +.IR meta . >>> +.I len >>> +is the number of bytes of metadata that currently remain in the buffer. >>> +The macro returns a pointer to the next metadata structure that follows >>> +.IR meta , >>> +and reduces >>> +.I len >>> +by the number of bytes in the the metadata structure that >>> +has been skipped over (i.e., it subtracts >>> +.IR meta\->event_len >>> +from >>> +.IR len ). >>> +.\" >>> .SS Monitoring an fanotify file descriptor for events >>> When an fanotify event occurs, the fanotify file descriptor indicates as >>> readable when passed to >>> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html