Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site cbosgd.UUCP Path: utzoo!linus!decvax!harpo!whuxlm!whuxl!houxm!ihnp4!cbosgd!ka From: ka@cbosgd.UUCP (Kenneth Almquist) Newsgroups: net.news Subject: Re: unable to abort replies Message-ID: <478@cbosgd.UUCP> Date: Wed, 7-Nov-84 03:18:54 EST Article-I.D.: cbosgd.478 Posted: Wed Nov 7 03:18:54 1984 Date-Received: Thu, 8-Nov-84 07:08:25 EST References: <484@astrovax.UUCP> Reply-To: ka@cbosgd.UUCP (Kenneth Almquist) Organization: Bell Labs, Columbus Lines: 36 > I see from the code that the criteria for cancelling the reply is that > the modification time of the file be same after invoking the editor as > before. I can't really visualize right now why this would fail but > maybe it is due to 1 second time quantization (although it would seem > to me to be more likely to fail in the sense of erroneously cancelling > a reply). > > Does anybody have any ideas? In case it makes any difference we are > running 4.2 BSD. In order to save on memory, System V and its predecessors do not include the modified time of a file in the in core copy of the inode. Instead the in core copy of the file simply has a flag which is set when the file is modified. When the inode is next written to disk, the modified flag on the in core copy of the inode is cleared and the modified time on the disk copy of the inode is set to current time, which of course is not necessarily the same as the time that the modified flag was set. I was a little surprised to read that the code also fails under 4.2 BSD since under 4.2 the in core copy of the inode does include the modified time of the file. However, a look at the 4.2 BSD code reveals that 4.2 BSD has a modified flag, and updates the modified time on an inode to the current time before writing the inode to disk when the modified flag is set. Perhaps the Berkeley people are more committed to being compatible with System V than we realized :-). The moral of all of this is, don't expect file modification times to be recorded down to the precise second. Using the file modification time would be a bad practice even if UN*X supported it because people tend to get in the habit of writing before they exit the editor even when they haven't made any changes. 2.11 vnews assumes that the user doesn't want to post a reply if 1) The file size is not changed, and 2) A checksum of the file is the same as when the file was written. Kenneth Almquist