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/* Copyright (C) 1991, 1992, 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. */
/* This file provides glue between Unix stdio and GNU stdio.
It supports use of Unix stdio `getc' and `putc' (and, by extension,
`getchar' and `putchar') macros on GNU stdio streams (they are slow, but
they work). It also supports all stdio operations (including Unix
`getc' and `putc') on Unix's stdin, stdout, and stderr (the elements of
`_iob').
The reasoning behind this is to allow programs (and especially
libraries) compiled with Unix header files to work with the GNU C
library. */
#include <stdio.h>
#include <errno.h>
typedef union
{
struct
{
int magic;
FILE **streamp; /* Overlaps GNU stdio `bufp' member. */
/* These two overlap the GNU stdio `get_limit' and `put_limit'
members. They must be <= `streamp'/`bufp' for GNU getc and putc
to do the right thing. */
FILE **streamp2, **streamp3;
} glue;
struct _iobuf
{
int _cnt;
unsigned char *_ptr;
unsigned char *_base;
int _bufsiz;
short int _flag;
char _file;
} unix_iobuf;
FILE gnu_stream;
} unix_FILE;
/* These are the Unix stdio's stdin, stdout, and stderr.
In Unix stdin is (&_iob[0]), stdout is (&_iob[1]), and stderr is
(&_iob[2]). The magic number marks these as glued streams. The
__validfp macro in stdio.h is used by every stdio function. It checks
for glued streams, and replaces them with the GNU stdio stream. */
unix_FILE _iob[] =
{
#define S(name) { { _GLUEMAGIC, &name, &name, &name } }
S (stdin),
S (stdout),
S (stderr),
#undef S
};
/* Called by the Unix stdio `getc' macro.
The macro is assumed to look something like:
(--file->_cnt < 0 ? _filbuf (file) ...)
In a Unix stdio FILE `_cnt' is the first element.
In a GNU stdio or glued FILE, the first element is the magic number. */
int
_filbuf (unix_FILE *file)
{
switch (++file->glue.magic) /* Compensate for Unix getc's decrement. */
{
case _GLUEMAGIC:
/* This is a glued stream. */
return getc (*file->glue.streamp);
case _IOMAGIC:
/* This is a normal GNU stdio stream. */
return getc ((FILE *) file);
default:
/* Bogus stream. */
__set_errno (EINVAL);
return EOF;
}
}
/* Called by the Unix stdio `putc' macro. Much like getc, above. */
int
_flsbuf (int c, unix_FILE *file)
{
/* Compensate for putc's decrement. */
switch (++file->glue.magic)
{
case _GLUEMAGIC:
return putc (c, *file->glue.streamp);
case _IOMAGIC:
return putc (c, (FILE *) file);
default:
__set_errno (EINVAL);
return EOF;
}
}
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