Message-Id: <m0ymH42-000C5CC@sloep111.cs.vu.nl>
Date:     Wed, 17 Jun 98 14:11:42 MET DST
From: Michel de Ruiter  <mdruiter AT cs DOT vu DOT nl>
To: dj AT delorie DOT com
cc: djgpp-workers AT delorie DOT com
Subject:  rewind and 2.02 alpha
Precedence: bulk

Hi, workers,

I don't know if this has been up here before (I'm only reading this
list since a month or so), but I've encountered a problem with the
latest 2.02-alpha (980101, can I get a newer one somewhere?). This
problem was *not* in v2.01.

When a file is opened "wt+" (or "wb+"), it is written to, rewinded
(whether with rewind() or fseek()) and read from, the latter doesn't
work. Take the following little program:

#include <stdio.h>

int main(void)
{
  FILE *f;
  char buf[100];
  char *p;

  f = fopen("__tmp__.$$$", "wt+");
  fputs("abcdefghijklmnopqrstuvwxyz0123456789\n\n", f);
  rewind(f);

  p = fgets(buf, 10, f);
  printf("p = 0x%08p\n", p);
  if (p != NULL)
    printf("buf = `%s'\n", buf);

  fclose(f);
  return 0;
}

It returns p = 0x0, where 2.01 would give "abcdefghi". An interesting
point: it doesn't seem to work on Solaris 5.5.1 either (also returns
NULL), and Linux.

Is this, uh, like, documented somewhere? The libc.inf specificially
says a file opened with "+" should set it's position (with rewind,
fseek or fsetpos) before reading/writing.


As I'm at it, why does `gcc -Wall' give this warning, as it is usual
practice:
testit.c: In function `main':
testit.c:14: warning: flag `0' used with type `p'

--
Groeten, Michel.        http://www.cs.vu.nl/~mdruiter
  ____________
  \  /====\  /          "You know, Beavis, you need things that suck,
   \/      \/           to have things that are cool", Butt-Head.