On 13/12/2015 18:53, walter harms wrote:
I am not sure that i understood what you want ... i would answer the question: * what is the actual size of struct inotify_event ? inotify(7) says: the length of each inotify_event structure is thus sizeof(struct inotify_event)+len
Please fix the manual page: the actual size is sizeof (struct inotify_event) where struct inotify_event is as described below with a size parameter for the name field of NAME_MAX+1 and the actual string contained in that field has a length of /len/ (and is probably NULL terminated at len+1).
With your answer the actual size would be the length of the fixed prefix fields (w/o) plus the size of a pointer (sizeof(void*) for the name field w/o parameter plus len): thus you might be off by the size of a pointer. Each inotify message has the same width. This only refers to the structure described in the manual page! An actual sizeof (struct inotify_event) might yield the correct result as the system headers probably contain the correct structure. But that diversion is what makes the manual page a little bit confusing and presenting a pointer instead of a fixed size array is just plainly wrong.
Please review my original message as well as reference documentation regarding the C programming language.
HTH, Michael
hope that helps .. re, wh Am 13.12.2015 13:09, schrieb Michael Titke:Hello! The current version of the manual page describing /inotify/ (as well as the version installed with Ubuntu 15.04 frozen to Violet Indigo) contains a descriptive C structure describing the /inotify//messages/: struct inotify_event { int wd; /* Watch descriptor */ uint32_t mask; /* Mask describing event */ uint32_t cookie; /* Unique cookie associating related events (for rename(2)) */ uint32_t len; /* Size of name field */ char name[]; /* Optional null-terminated name */ }; As part of the development of VSI I translated the above structure without much thinking into a corresponding byte structure description: (define inotify-event-header (byte-structure-description (wd int) (mask 4) ; [sic! that was an uint32] (cookie 4) (len 4) ;(name pointer) ; That's not a pointer but an array: NAME_MAX + 1 )) Now while the prefix (or header) of the message is described adequately the specification of the tail array as a char name[] would in C be interpreted as a pointer onto a char. One might insert a length parameter like char name[NAME_MAX + 1] or exclude that tail array from the structure and describe the message in terms of /prefix/ or /header/ and /tail array/. struct inotify_event { int wd; /* Watch descriptor */ uint32_t mask; /* Mask describing event */ uint32_t cookie; /* Unique cookie associating related events (for rename(2)) */ uint32_t len; /* Size of name field */ char name[NAME_MAX + 1]; /* Optional null-terminated name */ }; With that length parameter in the structure the size of the messages is described adequately but the actual length of the name might be confused with the maximum size which usually includes some (tail) padding. I'm sorry but I don't know enough about /iNotify/ to craft a patch for this. Is this a datagram channel where half-read messages will vanish? Perhaps I should continue reading the manual page. :-) Regards, Michael -- VSI: https://code.launchpad.net/viper-system-interface (reason: 550 5.7.1 Content-Policy reject msg: The message contains HTML subpart, therefore we consider it SPAM or Outlook Virus. TEXT/PLAIN is accepted.! BF:<U PS That's not really up to the standard but "... since hosts aren't required to relay mail at all ..." someone presumes something. -- 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
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