Date: Mon, 20 Mar 2006 13:45:33 -0800
From: "Randy.Dunlap" <rdunlap@xenotime.net>
To: dreiners@iastate.edu
Cc: linux-kernel@vger.kernel.org
Subject: Re: VFAT: Can't create file named 'aux.h'?
Message-Id: <20060320134533.febb0155.rdunlap@xenotime.net>
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On Mon, 20 Mar 2006 15:40:22 -0600 Dirk Reiners wrote:

> 
> 	Hi everybody,
> 
> while trying to back up a couple Linux directories to a FAT disk I ran
> into a weird situation: I can't create a file called aux.h on the FAT
> system! 
> 
> Here's how to reproduce it:
> 
> cd /tmp
> dd if=/dev/zero of=vfat_img bs=1M count=1
> /sbin/losetup /dev/loop7 vfat_img
> /sbin/mkfs.vfat /dev/loop7
> mkdir vfat_mnt
> mount -t vfat /dev/loop7 vfat_mnt
> touch vfat_mnt/auy.h
> touch vfat_mnt/aux.h
> 
> auy.h is happily created, aux.h gives "touch: setting times of
> `vfat_mnt/aux.h': No such file or directory", and no file is created.
> This happened to me on the system described below, but I could reproduce
> the same behavior on a system booted from RHEL4 CDs, an old Knoppix
> (3.4), and friends could reproduce it on other systems, too, so it
> doesn't seem to be very related to a specific version.
> 
> As a workaround I tar/bzipped my dirs, but that behavior seems very
> unusual and doesn't inspire a lot of confidence in vfat... What am I
> missing here?

"AUX" is (was) a reserved "filename" in DOS.  The Linux MS-DOS
filesystem preserves (protects) that.  The extension part does not
matter; it only checks the first 8 characters of the filename.
You'll need to use a different filesystem or filename...


fs/msdos/namei.c:

		for (reserved = reserved_names; *reserved; reserved++)
			if (!strncmp(res, *reserved, 8))
				return -EINVAL;

/* MS-DOS "device special files" */
static const unsigned char *reserved_names[] = {
	"CON     ", "PRN     ", "NUL     ", "AUX     ",
	"LPT1    ", "LPT2    ", "LPT3    ", "LPT4    ",
	"COM1    ", "COM2    ", "COM3    ", "COM4    ",
	NULL
};


---
~Randy
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