Date: Fri, 22 Dec 2000 09:35:13 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: "G. Adam Stanislav" <adam@whizkidtech.net> Cc: hackers@FreeBSD.ORG Subject: Re: A bug in mmap? Message-ID: <20001222093512.L19572@fw.wintelcom.net> In-Reply-To: <20001222112836.A239@whizkidtech.net>; from adam@whizkidtech.net on Fri, Dec 22, 2000 at 11:28:36AM -0600 References: <20001222112836.A239@whizkidtech.net>
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* G. Adam Stanislav <adam@whizkidtech.net> [001222 09:30] wrote: > I think I have just discovered a bug... (FreeBSD 3.1). > > Here is the scenario: The program (I have written) opens a file as O_RDWR, > then uses mmap with PROT_READ | PROT_WRITE and MAP_SHARED. It works on > the data, optionally reduces the file size, then unmaps and closes it. > > Everything works fine as long as the file is on a native FreeBSD disk. > But if it is on a Windows formatted hard drive mounted under FreeBSD, > *sometimes* the file ends up filled with NULs. > > Could it be mmap may get confused by a Windows formated drive? It does NOT > return an error, but it fills the mapped area with zeros. It overwrites > the contents of the file with zeros, but does not change the directory > information (i.e., the time of the last access, and such). > > It never happens on a FreeBSD drive, only on a Windows formated drive, > which makes it rather spooky. Most likely a result of a bug in the msdosfs code, perhaps you can help track it down? I don't use msdosfs. :( -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] "I have the heart of a child; I keep it in a jar on my desk." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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