path: root/libio/libioP.h

/* Copyright (C) 1993-2017 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.

   As a special exception, if you link the code in this file with
   files compiled with a GNU compiler to produce an executable,
   that does not cause the resulting executable to be covered by
   the GNU Lesser General Public License.  This exception does not
   however invalidate any other reasons why the executable file
   might be covered by the GNU Lesser General Public License.
   This exception applies to code released by its copyright holders
   in files containing the exception.  */

/* NOTE: libio is now exclusively used only by glibc since libstdc++ has its
   own implementation.  As a result, functions that were implemented for C++
   (like *sputn) may no longer have C++ semantics.  This is of course only
   relevant for internal callers of these functions since these functions are
   not intended for external use otherwise.

   FIXME: All of the C++ cruft eventually needs to go away.  */

#include <stddef.h>

#include <errno.h>
#ifndef __set_errno
# define __set_errno(Val) errno = (Val)
#endif
#if defined __GLIBC__ && __GLIBC__ >= 2
# include <libc-lock.h>
#else
/*# include <comthread.h>*/
#endif

#include <math_ldbl_opt.h>

#include "iolibio.h"

/* Control of exported symbols.  Used in glibc.  By default we don't
   do anything.  */
#ifndef libc_hidden_proto
# define libc_hidden_proto(name)
#endif
#ifndef libc_hidden_def
# define libc_hidden_def(name)
#endif
#ifndef libc_hidden_weak
# define libc_hidden_weak(name)
#endif

#ifdef __cplusplus
extern "C" {
#endif

#define _IO_seek_set 0
#define _IO_seek_cur 1
#define _IO_seek_end 2

/* THE JUMPTABLE FUNCTIONS.

 * The _IO_FILE type is used to implement the FILE type in GNU libc,
 * as well as the streambuf class in GNU iostreams for C++.
 * These are all the same, just used differently.
 * An _IO_FILE (or FILE) object is allows followed by a pointer to
 * a jump table (of pointers to functions).  The pointer is accessed
 * with the _IO_JUMPS macro.  The jump table has an eccentric format,
 * so as to be compatible with the layout of a C++ virtual function table.
 * (as implemented by g++).  When a pointer to a streambuf object is
 * coerced to an (_IO_FILE*), then _IO_JUMPS on the result just
 * happens to point to the virtual function table of the streambuf.
 * Thus the _IO_JUMPS function table used for C stdio/libio does
 * double duty as the virtual function table for C++ streambuf.
 *
 * The entries in the _IO_JUMPS function table (and hence also the
 * virtual functions of a streambuf) are described below.
 * The first parameter of each function entry is the _IO_FI