path: root/libio/libioP.h

/*
Copyright (C) 1993 Free Software Foundation

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

This 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 General Public License for more details.

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

As a special exception, if you link this library with files
compiled with a GNU compiler to produce an executable, this does not cause
the resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why
the executable file might be covered by the GNU General Public License. */

#include <errno.h>
#ifndef errno
extern int errno;
#endif
#include <libc-lock.h>

#include "iolibio.h"

#if defined (__STDC__) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(__cplusplus)
/* All known AIX compilers implement these things (but don't always
   define __STDC__).  The RISC/OS MIPS compiler defines these things
   in SVR4 mode, but does not define __STDC__.  */

#define	AND		,
#define	DEFUN(name, arglist, args)	name(args)
#define	DEFUN_VOID(name)		name(void)

#else	/* Not ANSI C.  */

#define	AND		;
#ifndef const /* some systems define it in header files for non-ansi mode */
#define	const
#endif
#define	DEFUN(name, arglist, args)	name arglist args;
#define	DEFUN_VOID(name)		name()
#endif	/* ANSI C.  */

#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 a 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_FILE/streambuf
 * object being acted on (i.e. the 'this' parameter).
 */

#define _IO_JUMPS(THIS) ((struct _IO_FILE_plus*)(THIS))->vtable
#ifdef _G_USING_THUNKS
#define JUMP_FIELD(TYPE, NAME) TYPE NAME
#define JUMP0(FUNC, THIS) _IO_JUMPS(THIS)->FUNC(THIS)
#define JUMP1(FUNC, THIS, X1) _IO_JUMPS(THIS)->FUNC(THIS, X1)
#define JUMP2(FUNC, THIS, X1, X2) _IO_JUMPS(THIS)->FUNC(THIS, X1, X2)
#define JUMP3(FUNC, THIS, X1,X2,X3) _IO_JUMPS(THIS)->FUNC(THIS, X1,X2, X3)
#define JUMP_INIT(NAME, VALUE) VALUE
#define JUMP_INIT_DUMMY JUMP_INIT(dummy, 0), JUMP_INIT(dummy2, 0)
#else
/* These macros will change when we re-implement vtables to use "thunks"! */
#define JUMP_FIELD(TYPE, NAME) struct { short delta1, delta2; TYPE pfn; } NAME
#define JUMP0(FUNC, THIS) _IO_JUMPS(THIS)->FUNC.pfn(THIS)
#define JUMP1(FUNC, THIS, X1) _IO_JUMPS(THIS)->FUNC.pfn(THIS, X1)
#define JUMP2(FUNC, THIS, X1, X2) _IO_JUMPS(THIS)->FUNC.pfn(THIS, X1, X2)
#define JUMP3(FUNC, THIS, X1,X2,X3) _IO_JUMPS(THIS)->FUNC.pfn(THIS, X1,X2, X3)
#define JUMP_INIT(NAME, VALUE) {0, 0, VALUE}
#define JUMP_INIT_DUMMY JUMP_INIT(dummy, 0)
#endif

/* The 'finish' function does any final cleaning up of an _IO_FILE object.
   It does not delete (free) it, but does everything else to finalize it/
   It matches the streambuf::~streambuf virtual destructor.  */
typedef void (*_IO_finish_t) __P((_IO_FILE*, int)); /* finalize */
#define _IO_FINISH(FP) JUMP1(__finish, FP, 0)

/* The 'overflow' hook flushes the buffer.
   The second argument is a character, or EOF.
   It matches the streambuf::overflow virtual function. */
typedef int (*_IO_overflow_t) __P((_IO_FILE*, int));
#define _IO_OVERFLOW(FP, CH) JUMP1(__overflow, FP, CH)

/* The 'underflow' hook tries to fills the get buffer.
   It returns the next character (as an unsigned char) or EOF.  The next
   character remains in the get buffer, and the get position is not changed.
   It matches the streambuf::underflow virtual function. */
typedef int (*_IO_underflow_t) __P((_IO_FILE*));
#define _IO_UNDERFLOW(FP) JUMP0(__underflow, FP)

/* The 'uflow' hook returns the next character in the input stream
   (cast to unsigned char), and increments the read position;
   EOF is returned on failure.
   It matches the streambuf::uflow virtual function, which is not in the
   cfront implementation, but was added to C++ by the ANSI/ISO committee. */
#define _IO_UFLOW(FP) JUMP0(__uflow, FP)

/* The 'pbackfail' hook handles backing up.
   It matches the streambuf::pbackfail virtual function. */
typedef int (*_IO_pbackfail_t) __P((_IO_FILE*, int));
#define _IO_PBACKFAIL(FP, CH) JUMP1(__pbackfail, FP, CH)

/* The 'xsputn' hook writes upto N characters from buffer DATA.
   Returns the number of character actually written.
   It matches the streambuf::xsputn virtual function. */
typedef _IO_size_t (*_IO_xsputn_t)
  __P((_IO_FILE *FP, const void *DATA, _IO_size_t N));
#define _IO_XSPUTN(FP, DATA, N) JUMP2(__xsputn, FP, DATA, N)

/* The 'xsgetn' hook reads upto N characters into buffer DATA.
   Returns the number of character actually read.
   It matches the streambuf::xsgetn virtual function. */
typedef _IO_size_t (*_IO_xsgetn_t) __P((_IO_FILE*FP, void*DATA, _IO_size_t N));
#define _IO_XSGETN(FP, DATA, N) JUMP2(__xsgetn, FP, DATA, N)

/* The 'seekoff' hook moves the stream position to a new position
   relative to the start of the file (if DIR==0), the current position
   (MODE==1), or the end of the file (MODE==2).
   It matches the streambuf::seekoff virtual function.
   It is also used for the ANSI fseek function. */
typedef _IO_fpos_t (*_IO_seekoff_t)
  __P((_IO_FILE* FP, _IO_off_t OFF, int DIR, int MODE));
#define _IO_SEEKOFF(FP, OFF, DIR, MODE) JUMP3(__seekoff, FP, OFF, DIR, MODE)

/* The 'seekpos' hook also moves the stream position,
   but to an absolute position given by a fpos_t (seekpos).
   It matches the streambuf::seekpos virtual function.
   It is also used for the ANSI fgetpos and fsetpos functions.  */
/* The _IO_seek_cur and _IO_seek_end options are not allowed. */
typedef _IO_fpos_t (*_IO_seekpos_t) __P((_IO_FILE*, _IO_fpos_t, int));
#define _IO_SEEKPOS(FP, POS, FLAGS) JUMP2(__seekpos, FP, POS, FLAGS)

/* The 'setbuf' hook gives a buffer to the file.
   It matches the streambuf::setbuf virtual function. */
typedef _IO_FILE* (*_IO_setbuf_t) __P((_IO_FILE*, char *, _IO_ssize_t));
#define _IO_SETBUF(FP, BUFFER, LENGTH) JUMP2(__setbuf, FP, BUFFER, LENGTH)

/* The 'sync' hook attempts to synchronize the internal data structures
   of the file with the external state.
   It matches the streambuf::sync virtual function. */
typedef int (*_IO_sync_t) __P((_IO_FILE*));
#define _IO_SYNC(FP) JUMP0(__sync, FP)

/* The 'doallocate' hook is used to tell the file to allocate a buffer.
   It matches the streambuf::doallocate virtual function, which is not
   in the ANSI/ISO C++ standard, but is part traditional implementations. */
typedef int (*_IO_doallocate_t) __P((_IO_FILE*));
#define _IO_DOALLOCATE(FP) JUMP0(__doallocate, FP)

/* The following four hooks (sysread, syswrite, sysclose, sysseek, and
   sysstat) are low-level hooks specific to this implementation.
   There is no correspondence in the ANSI/ISO C++ standard library.
   The hooks basically correspond to the Unix system functions
   (read, write, close, lseek, and stat) except that a _IO_FILE*
   parameter is used instead of a integer file descriptor;  the default
   implementation used for normal files just calls those functions.
   The advantage of overriding these functions instead of the higher-level
   ones (underflow, overflow etc) is that you can leave all the buffering
   higher-level functions.  */

/* The 'sysread' hook is used to read data from the external file into
   an existing buffer.  It generalizes the Unix read(2) function.
   It matches the streambuf::sys_read virtual function, which is
   specific to this implementation. */
typedef _IO_ssize_t (*