Re: A89: fwrite function

To: assembly-89@lists.ticalc.org
Subject: Re: A89: fwrite function
From: Scott Dial <wrath@calc.org>
Date: Thu, 20 Jul 2000 23:50:22 -0500
Organization: ByMe Inc. Technologies \ TCPA
References: <20000720083805.1197.qmail@hotmail.com>
Reply-To: assembly-89@lists.ticalc.org


This is my third time writing this email (don't ask), so this is the
abrigded version of this email. fwrite is "buggy" or rather implemented
badly. fwrite does no memory checking, thus does not allocate the space
nessecary for the data being wrote. I suggest that the fwrite
implementation be changed to something similar to this: (btw, fputs has
a similar problem... which I don't have time to rewrite)

unsigned __fwrite(int(*fnc)(int,FILE*),void *ptr,unsigned size,unsigned
n,FILE *f)
{
  unsigned i,j,free,needed;
  int saveflags=f->flags;
  f->flags|=_F_BIN;
  free = f->alloc - f->pos - f->base; //I believe this is correct?
  needed = size*n;
  if(needed>free)
  {
    HeapUnlock(f->handle);
    if(!HeapRealloc(f->handle,f->alloc+=needed-free)) __FERROR(f);
    base=f->base=HLock(f->handle);
    f->fpos+=base-oldbase;
    oldbase=base;
  }
  for(i=0;i<n;i++)
    for(j=0;j<size;j++)
      if(fnc(*(char*)ptr++,f)<0) goto exit;
exit:
  f->flags=saveflags;
  return i;
}

Michael Cowart wrote:
> 
> Ok, what is wrong here?
> 
> FILE *fp = fopen("example","wb");
> fwrite (vplane0,3840,1,fp); /*vplane is a pointer to a 3840
> byte screen buffer*/
> fputc(0,fp);
> fputs("PNT",fp);
> fputc(0,fp);
> fputc(OTH_TAG,fp);
> fclose(fp);
> 
> When I create this file, it's only 371 bytes long... Is fwrite buggy, or am
> I just insane : ) ?
> 
> Thanx,
> Michael Cowart

-- 
Scott "Wrath" Dial
wrath@calc.org
ICQ#3608935
Member of TCPA - tcpa.calc.org
PGP key available

_____NetZero Free Internet Access and Email______
   http://www.netzero.net/download/index.html

Follow-Ups:

Re: A89: fwrite function

From: Scott Dial <wrath@calc.org>

References:

A89: fwrite function

From: "Michael Cowart" <freakonaleash881@hotmail.com>