Article View: comp.sys.dec
Article #4087Re: strcat(foo,NULL) core dumps on Ultrix
From: Larry Meehan
Date: Wed, 12 Jun 1991 04:00
Date: Wed, 12 Jun 1991 04:00
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1902 bytes
In <966@sdrc.COM> wggabb@sdrc.COM (Rob Gabbard) writes:
>A call to strcat with NULL as the second argument core dumps with a memory
>fault on Ultrix.
...
>Actually, just coding strcat(foo,NULL) will dump. Anyone run into this ?
>Am I doing a no-no here.
You must be on one of the MIPS-based DEC systems. Due to a quirk of the VAX
port of ULTRIX, you can get by with what you are trying to do, but you are,
strictly speaking, doing a no-no. The thing to remember is that NULL is not
the same thing as "", since strcat(foo,"") will work just fine. This program
will fail too for *exactly* the same reason:
main()
{
char *p, c;
p = (char *) 0;
c = *p;
}
If you look in /usr/include/stdio.h, you will see that NULL is really just 0,
so our programs are trying to access location 0 which is legal on a VAX, but
not on the MIPS implementation of Ultrix. A lot of "bug-free" code broke
when it was moved from VAX to non-VAX systems. The little program above dumps
core on a MIPS CPU and runs without errors on a VAX. The program is at fault,
not Ultrix. Hope this helps.
--
Larry Meehan University Computing Services
lwm@ucs.indiana.edu Indiana University
("Industry without art is brutality." -- Ananda Coomaraswamy)
--
Larry Meehan University Computing Services
lwm@ucs.indiana.edu Indiana University
("Industry without art is brutality." -- Ananda Coomaraswamy)
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!news.cs.indiana.edu!bronze!lwm From: lwm@bronze.ucs.indiana.edu (Larry Meehan) Newsgroups: comp.sys.dec Subject: Re: strcat(foo,NULL) core dumps on Ultrix Keywords: null NULL Message-ID: <1991Jun12.040043.24091@bronze.ucs.indiana.edu> Date: 12 Jun 91 04:00:43 GMT Article-I.D.: bronze.1991Jun12.040043.24091 References: <966@sdrc.COM> Organization: Indiana University Lines: 37