Date: Mon, 13 Jul 2009 16:39:09 -0400 From: John Baldwin <jhb@freebsd.org> To: Tijl Coosemans <tijl@ulyssis.org> Cc: Nate Eldredge <neldredge@math.ucsd.edu>, freebsd-hackers@freebsd.org, Alexander Best <alexbestms@math.uni-muenster.de>, Alan Cox <alc@freebsd.org> Subject: Re: mmap/munmap with zero length Message-ID: <200907131639.10346.jhb@freebsd.org> In-Reply-To: <200907132133.52217.tijl@ulyssis.org> References: <permail-200907050732251e86ffa8000022a8-a_best01@message-id.uni-muenster.de> <200907131428.08923.jhb@freebsd.org> <200907132133.52217.tijl@ulyssis.org>
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On Monday 13 July 2009 3:33:51 pm Tijl Coosemans wrote: > On Monday 13 July 2009 20:28:08 John Baldwin wrote: > > On Sunday 05 July 2009 3:32:25 am Alexander Best wrote: > >> so mmap differs from the POSIX recommendation right. the malloc.conf > >> option seems more like a workaround/hack. imo it's confusing to have > >> mmap und munmap deal differently with len=0. being able to > >> succesfully alocate memory which cannot be removed doesn't seem > >> logical to me. > > > > This should fix it: > > > > --- //depot/user/jhb/acpipci/vm/vm_mmap.c > > +++ /home/jhb/work/p4/acpipci/vm/vm_mmap.c > > @@ -229,7 +229,7 @@ > > > > fp = NULL; > > /* make sure mapping fits into numeric range etc */ > > - if ((ssize_t) uap->len < 0 || > > + if ((ssize_t) uap->len <= 0 || > > ((flags & MAP_ANON) && uap->fd != -1)) > > return (EINVAL); > > Why not "uap->len == 0"? Sizes of 2GiB and more (32bit) shouldn't cause > an error. I don't actually disagree and know of locally modified versions of FreeBSD that remove this check for precisely that reason. -- John Baldwin
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