1 files changed, 114 insertions, 0 deletions
diff --git a/stdio/glue.c b/stdio/glue.c
new file mode 100644
index 0000000000..6ef52a7ada
--- /dev/null
+++ b/stdio/glue.c
@@ -0,0 +1,114 @@
+/* Copyright (C) 1991, 1992 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., 675 Mass Ave,
+Cambridge, MA 02139, 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 <ansidecl.h>
+#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
+DEFUN(_filbuf, (file), 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.  */
+      errno = EINVAL;
+      return EOF;
+    }
+}
+
+/* Called by the Unix stdio `putc' macro.  Much like getc, above.  */
+int
+DEFUN(_flsbuf, (c, file),
+      int c AND 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:
+      errno = EINVAL;
+      return EOF;
+    }
+}