Date: Mon, 1 Aug 2005 01:46:01 +0300 From: Giorgos Keramidas <keramida@freebsd.org> To: Garrett Wollman <wollman@csail.mit.edu> Cc: freebsd-current@freebsd.org Subject: Re: mmap bug? Message-ID: <20050731224601.GA2024@gothmog.gr> In-Reply-To: <17133.21281.703540.383144@khavrinen.csail.mit.edu> References: <20050731141801.GA49300@gothmog.gr> <84dead7205073108564f71f1ab@mail.gmail.com> <20050731160853.GC49839@gothmog.gr> <84dead720507311115290f0140@mail.gmail.com> <20050731201858.GC1052@gothmog.gr> <17133.21281.703540.383144@khavrinen.csail.mit.edu>
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On 2005-07-31 18:39, Garrett Wollman <wollman@csail.mit.edu> wrote: ><<On Sun, 31 Jul 2005 23:18:58 +0300, Giorgos Keramidas <keramida@FreeBSD.ORG> said: >> The bug seems to be elsewhere, namely to the fact that the filesystem >> code never realizes the file has changed size after I use mmap() to map >> a region beyond its current size and write past its current end. > > You should not expect it to do that. If you want to extend a file, > use ftruncate() before mapping it. Anything written past the end of a > file should be discarded on last close. I see. Thank you for the explanation :) It seems strange though that when the test program runs and finishes, munmapping the region and closing the file the data is still visible. Perhaps the fact that I used MAP_SHARED plays a role in that? Is the fact that the data written to the mapped region visible after the close (by mapping the same region) expected too? - Giorgos
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