glibc/stdio/gets.c

/* Copyright (C) 1991, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <stdio.h>
#include <errno.h>
#include <string.h>

link_warning (gets, "the `gets' function is dangerous and should not be used.")

/* Read a newline-terminated string from stdin into S,
   removing the trailing newline.  Return S or NULL.  */
char *
gets (s)
     char *s;
{
  register char *p = s;
  register int c;
  FILE *stream = stdin;

  if (!__validfp (stream) || p == NULL)
    {
      __set_errno (EINVAL);
      return NULL;
    }

  if (feof (stream) || ferror (stream))
    return NULL;

  while ((c = getchar ()) != EOF)
    if (c == '\n')
      break;
    else
      *p++ = c;

  *p = '\0';

  /* Return null if we had an error, or if we got EOF
     before writing any characters.  */

  if (ferror (stream) || (feof (stream) && p == s))
    return NULL;

  return s;
}