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From: lad@eplrx7.UUCP (Lawrence Dziegielewski)
Newsgroups: comp.lang.c
Subject: bug (?) in 4.(2,3)?
Message-ID: <462@eplrx7.UUCP>
Date: Thu, 27-Aug-87 16:04:29 EDT
Article-I.D.: eplrx7.462
Posted: Thu Aug 27 16:04:29 1987
Date-Received: Sat, 29-Aug-87 11:52:01 EDT
Organization: E.I. DuPont Co. Engineering Physics Lab
Lines: 43
Keywords: external declaration of a system call


Consider the following program:

------------------------------------
#include <stdio.h>

char fstat;

main()
{
	FILE *fp;
	fp = fopen("testfile", "w");
	fprintf(fp, "xxxxx");
	fclose(fp);
}
------------------------------------


On our Sun Unix 3.4 and DEC Ultrix 2.0,
it results in either a "bus error" or "segmentation fault",
which occurs deep within the fprintf().

On Unix System V and MS-DOS Lattice C,
it executes without problem, as it should.


The problem is that the character variable 'fstat',
declared externally, conflicts with the fstat() system call.

If this is indeed a problem for Berkley, then the compiler
ought flag the external declaration as a redeclaration, but
this is not the case, it compiles without incident. Also note
that fstat is declared char, fstat() is int.

This feature is not limited to fstat() - it fails just as well
for other system calls. (But not on System V or Lattice C).


-- 
	Lawrence A. Dziegielewski	|	E.I. Dupont Co.
	{uunet!dgis!psuvax1}!eplrx7!lad	|	Engineering Physics Lab
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