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115 lines
3.4 KiB
C
115 lines
3.4 KiB
C
/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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/* This file provides glue between Unix stdio and GNU stdio.
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It supports use of Unix stdio `getc' and `putc' (and, by extension,
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`getchar' and `putchar') macros on GNU stdio streams (they are slow, but
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they work). It also supports all stdio operations (including Unix
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`getc' and `putc') on Unix's stdin, stdout, and stderr (the elements of
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`_iob').
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The reasoning behind this is to allow programs (and especially
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libraries) compiled with Unix header files to work with the GNU C
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library. */
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#include <ansidecl.h>
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#include <stdio.h>
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#include <errno.h>
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typedef union
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{
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struct
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{
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int magic;
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FILE **streamp; /* Overlaps GNU stdio `bufp' member. */
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/* These two overlap the GNU stdio `get_limit' and `put_limit'
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members. They must be <= `streamp'/`bufp' for GNU getc and putc
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to do the right thing. */
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FILE **streamp2, **streamp3;
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} glue;
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struct _iobuf
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{
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int _cnt;
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unsigned char *_ptr;
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unsigned char *_base;
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int _bufsiz;
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short int _flag;
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char _file;
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} unix_iobuf;
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FILE gnu_stream;
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} unix_FILE;
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/* These are the Unix stdio's stdin, stdout, and stderr.
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In Unix stdin is (&_iob[0]), stdout is (&_iob[1]), and stderr is
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(&_iob[2]). The magic number marks these as glued streams. The
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__validfp macro in stdio.h is used by every stdio function. It checks
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for glued streams, and replaces them with the GNU stdio stream. */
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unix_FILE _iob[] =
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{
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#define S(name) { { _GLUEMAGIC, &name, &name, &name } }
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S (stdin),
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S (stdout),
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S (stderr),
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#undef S
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};
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/* Called by the Unix stdio `getc' macro.
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The macro is assumed to look something like:
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(--file->_cnt < 0 ? _filbuf (file) ...)
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In a Unix stdio FILE `_cnt' is the first element.
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In a GNU stdio or glued FILE, the first element is the magic number. */
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int
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DEFUN(_filbuf, (file), unix_FILE *file)
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{
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switch (++file->glue.magic) /* Compensate for Unix getc's decrement. */
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{
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case _GLUEMAGIC:
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/* This is a glued stream. */
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return getc (*file->glue.streamp);
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case _IOMAGIC:
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/* This is a normal GNU stdio stream. */
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return getc ((FILE *) file);
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default:
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/* Bogus stream. */
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errno = EINVAL;
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return EOF;
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}
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}
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/* Called by the Unix stdio `putc' macro. Much like getc, above. */
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int
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DEFUN(_flsbuf, (c, file),
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int c AND unix_FILE *file)
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{
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/* Compensate for putc's decrement. */
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switch (++file->glue.magic)
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{
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case _GLUEMAGIC:
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return putc (c, *file->glue.streamp);
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case _IOMAGIC:
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return putc (c, (FILE *) file);
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default:
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errno = EINVAL;
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return EOF;
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}
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}
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