1: /* Copyright (C) 1993, 1996, 1997, 1998, 2002, 2003, 2004
    2:    Free Software Foundation, Inc.
    3:    This file is part of the GNU C Library.
    4: 
    5:    The GNU C Library is free software; you can redistribute it and/or
    6:    modify it under the terms of the GNU Lesser General Public
    7:    License as published by the Free Software Foundation; either
    8:    version 2.1 of the License, or (at your option) any later version.
    9: 
   10:    The GNU C Library is distributed in the hope that it will be useful,
   11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13:    Lesser General Public License for more details.
   14: 
   15:    You should have received a copy of the GNU Lesser General Public
   16:    License along with the GNU C Library; if not, write to the Free
   17:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   18:    02111-1307 USA.
   19: 
   20:    As a special exception, if you link the code in this file with
   21:    files compiled with a GNU compiler to produce an executable,
   22:    that does not cause the resulting executable to be covered by
   23:    the GNU Lesser General Public License.  This exception does not
   24:    however invalidate any other reasons why the executable file
   25:    might be covered by the GNU Lesser General Public License.
   26:    This exception applies to code released by its copyright holders
   27:    in files containing the exception.  */
   28: 
   29: #include "../libio/libioP.h"
   30: #include <limits.h>
   31: 
   32: char *
   33: __gets_chk (char *buf, size_t size)
   34: {
   35:   _IO_size_t count;
   36:   int ch;
   37:   char *retval;
   38: 
   39:   if (size == 0)
   40:     __chk_fail ();
   41: 
   42:   _IO_acquire_lock (_IO_stdin);
   43:   ch = _IO_getc_unlocked (_IO_stdin);
   44:   if (ch == EOF)
   45:     {
   46:       retval = NULL;
   47:       goto unlock_return;
   48:     }
   49:   if (ch == '\n')
   50:     count = 0;
   51:   else
   52:     {
   53:       /* This is very tricky since a file descriptor may be in the
   54:          non-blocking mode. The error flag doesn't mean much in this
   55:          case. We return an error only when there is a new error. */
   56:       int old_error = _IO_stdin->_IO_file_flags & _IO_ERR_SEEN;
   57:       _IO_stdin->_IO_file_flags &= ~_IO_ERR_SEEN;
   58:       buf[0] = (char) ch;
   59:       count = INTUSE(_IO_getline) (_IO_stdin, buf + 1, size - 1, '\n', 0) + 1;
   60:       if (_IO_stdin->_IO_file_flags & _IO_ERR_SEEN)
   61:         {
   62:           retval = NULL;
   63:           goto unlock_return;
   64:         }
   65:       else
   66:         _IO_stdin->_IO_file_flags |= old_error;
   67:     }
   68:   if (count >= size)
   69:     __chk_fail ();
   70:   buf[count] = 0;
   71:   retval = buf;
   72: unlock_return:
   73:   _IO_release_lock (_IO_stdin);
   74:   return retval;
   75: }
   76: 
   77: link_warning (__gets_chk, "the `gets' function is dangerous and should not be used.")