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From: brandon@tdi2.UUCP (Brandon Allbery)
Newsgroups: comp.unix.wizards
Subject: casting args to functions...
Message-ID: <115@tdi2.UUCP>
Date: Mon, 10-Nov-86 17:59:33 EST
Article-I.D.: tdi2.115
Posted: Mon Nov 10 17:59:33 1986
Date-Received: Tue, 11-Nov-86 21:59:22 EST
References: <1376@batcomputer.TN.CORNELL.EDU> <840@ur-valhalla.UUCP> <5068@ukme.ukma.uky.csnet>
Reply-To: brandon@tdi2.UUCP (Brandon Allbery)
Followup-To: net.unix-wizards
Organization: Tridelta Industries, Inc., Mentor, OH
Lines: 32

Expires:


Quoted from <5068@ukme.ukma.uky.csnet> ["Re: Microport Unix -- Large Model Problems"], by david@ukma.uky.csnet (David Herron, NPR Lover)...
+---------------
| In article <840@ur-valhalla.UUCP> dave@valhalla.UUCP (Dave Carlson) writes:
| >A potential problem I smacked into yesterday when porting BSD to SV/AT
| >is ioctl(2) expects as the third argument:
| >union   { int iarg;
| >        char *cparg;}
| >Problem is that the union will pull 4 bytes off the stack (in large model)
| >but the program calling with an integer will only push 2 bytes.  Oh S*$&!
| >I cast my integer args long and everything seems ok but what a pain...
| 
| Argh!  And you're doing a port of an operating system???
| 
| UNIONS are the SAME size regardless of WHICH part of them you use!
| 
| A user which passes an int to a routine expecting a union is ASKING
| for trouble!
+---------------

The problem is not this:  it is that ioctl() is documented as taking a pointer
in some places and as taking an int in others.  Please note that it is not
documented as taking a union, or is the "int" changed to a "long" on machines
with 2-byte integers and 4-byte pointers.  Berkeley int==long-ism strikes
again!

++Brandon
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