Date: Wed, 18 Apr 2001 19:04:28 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: djgpp AT delorie DOT com
Subject: Re: MINGW vs DJGPP
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On Wed, 18 Apr 2001, Waldemar Schultz wrote:

> more problems with MINGW port of gcc-2.95.2:
> 
> strw.c:
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <string.h>
> 
>  int main(void)
>  {
>  char *bbb="ABCDefgh";
> 
>   strlwr(bbb);
>   printf("%s\n",bbb);
>   return EXIT_SUCCESS;
>  }
> 
> #66:W98>gcc -c strw.c -g -W -Wall
> #66:W98>gcc strw.o -o strw.exe -mwindows -mconsole
> #66:W98>strw.exe
> STRW verursachte einen Fehler durch eine ungültige Seite [error: invalid
> page]

This is a classic gotcha with GCC.  The bug is in your program: you are 
trying to change a read-only string.

GCC by default puts constant strings into read-only storage, so trying to 
modify it triggers a protection violation.  This will happen on any 
platform; DJGPP avoids this problem because our .data and .text segments 
overlap (due to subtleties of exception handling in DPMI environment), 
and that prevents us from making the code segment write-protected.  MinGW 
doesn't have this problem, so your bug is exposed.