Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: Shaun Jackman <sjackman AT rogers DOT wave DOT ca>, djgpp AT delorie DOT com
From: Nate Eldredge <nate AT cartsys DOT com>
Subject: Re: strtod() crashes on the call strtod("$.", &endp);
Date: Sun, 3 May 1998 09:57:03 -0700
Message-ID: <19980503165659.AAA13333@ppp122.cartsys.com>
Precedence: bulk

At 02:42  5/3/1998 -0700, Shaun Jackman wrote:
>I have a program that is crashing within strtod(). I found it unusual
>that it would crash during a library function call. Maybe you somebody
>out there can shed some light on this.
>
>I'm writing a Forth compiler, and was testing it on this script:
>1 if
>  '1 == 1' $.
>  'Cool'   $.
>then
>
>0 if
>  'Uh oh' $.
>then
>
>
>Unfortunately, it crashes.
>I ran gdb on it, and after the crash got a stack frame back-trace.
>The result was:
>
>Program received signal SIGFPE, Arithmetic exception.
>0x25df7 in strtod ()
>(gdb) bt
>#0  0x25df7 in strtod ()
>#1  0x18f9 in is_literal (lexema=0x7f111 "$.") at forth.c:62
>#2  0x2285 in forth (
>    tp=0x7f114 "   'Cool'   $.  then    0 if    'Uh oh' $.  then     ") 
>    at forth.c:433
>#3  0x1738 in main ()
>#4  0x253e6 in __crt1_startup ()
>(gdb)
>
>Which means it crashed on the call strtod("$.", &endp);
>I have no idea why.
>
>I am using gcc version 2.7.2.1

I can't reproduce this. This program:

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
  char *endp;
  printf("%f\n", strtod("$.", &endp));
  return 0;
}

just prints out "0.00000" and doesn't crash.

Here are some thoughts:

* Are you sure you #include <stdlib.h>?
* Are you using DJGPP libc 2.01?
* Does the crash happen consistently?
* Can *you* reproduce the problem with a simple call to `strtod("$.",...)'?
* Is it possible that the calling function is getting garbage in the FPU
registers somehow? I doubt it, but try calling `_fpreset()' (#include
<float.h>) right before the call to `strtod' and see if anything changes.
* Have you changed the exception state with `_control87', perhaps to cause
an exception under some previously benign condition?

Hmm. Hope this gets figured out.

Nate Eldredge
nate AT cartsys DOT com