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ungetwc.c revision 1.3 
      1 /* $NetBSD: ungetwc.c,v 1.3 2005/06/12 05:21:27 lukem Exp $ */
      2 
      3 /*-
      4  * Copyright (c)2001 Citrus Project,
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  *
     28  * $Citrus$
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 #if defined(LIBC_SCCS) && !defined(lint)
     33 __RCSID("$NetBSD: ungetwc.c,v 1.3 2005/06/12 05:21:27 lukem Exp $");
     34 #endif /* LIBC_SCCS and not lint */
     35 
     36 #include <assert.h>
     37 #include <errno.h>
     38 #include <stdio.h>
     39 #include <wchar.h>
     40 #include "reentrant.h"
     41 #include "local.h"
     42 
     43 wint_t
     44 ungetwc(wint_t wc, FILE *fp)
     45 {
     46 	struct wchar_io_data *wcio;
     47 
     48 	_DIAGASSERT(fp);
     49 
     50 	if (wc == WEOF)
     51 		return WEOF;
     52 
     53 	FLOCKFILE(fp);
     54 	_SET_ORIENTATION(fp, 1);
     55 	/*
     56 	 * XXX since we have no way to transform a wchar string to
     57 	 * a char string in reverse order, we can't use ungetc.
     58 	 */
     59 	/* XXX should we flush ungetc buffer? */
     60 
     61 	wcio = WCIO_GET(fp);
     62 	if (wcio == 0) {
     63 		FUNLOCKFILE(fp);
     64 		errno = ENOMEM; /* XXX */
     65 		return WEOF;
     66 	}
     67 
     68 	if (wcio->wcio_ungetwc_inbuf >= WCIO_UNGETWC_BUFSIZE) {
     69 		FUNLOCKFILE(fp);
     70 		return WEOF;
     71 	}
     72 
     73 	wcio->wcio_ungetwc_buf[wcio->wcio_ungetwc_inbuf++] = wc;
     74 	__sclearerr(fp);
     75 	FUNLOCKFILE(fp);
     76 
     77 	return wc;
     78 }
     79