Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!amdahl!ames!sdcsvax!ucsdhub!jack!man!nusdhub!rwhite
From: rwhite@nusdhub.UUCP (Robert C. White Jr.)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: Determining the names of devices installed in DOS
Message-ID: <122@nusdhub.UUCP>
Date: Tue, 13-Oct-87 16:41:56 EDT
Article-I.D.: nusdhub.122
Posted: Tue Oct 13 16:41:56 1987
Date-Received: Thu, 15-Oct-87 19:55:54 EDT
References: <1801@killer.UUCP>
Organization: National University, San Diego
Lines: 32
Keywords: devices, stat(2)
Summary: It's Easy [if I remember correctly]
Xref: mnetor comp.sys.ibm.pc:9032 comp.lang.c:4888

In article <1801@killer.UUCP>, wnp@killer.UUCP (Wolf Paul) writes:
   [Stuff Deleted]
> I find it interesting that apparently the MSC stat(2) function does not
> know how to distinguish between devices and regular files, whereas the
> fstat(2) function does make that distinction. I assume they use ioctl
> on the file handle passed to fstat.

	This is SOOOO.... Simple, that the methodologies described
above look quite convoluted....

1)	Get the "device status word" using ioctl against the open
	file descriptor.  [I don't remember the subcommand, so you'll
	have to look it up]

2)	Mask out the "Block Device" flag.

3)	If the block device flag is set, then you MUST be dealing
	with a file on a disk someware.  If it is not set you have
	an open character device on your hands.


	Only character and block devices are defined in MS-DOS.
Also, the "get device status word" subcommand of the ioctl/int-24
command MUST! return the status word of the device of ANY file
discriptor.  Since MS-DOS does not have pipes, streams, swap-devices,
or "system facilities" defined in the file system.  Because of this
you simply have "Disk Files" and "Character Devices"


Disclaimer:  Neat huh?

Robert.