1 /*-
2 * Copyright (c) 2002-2004 Tim J. Robbins.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 /*
28 FUNCTION
29 <<ungetwc>>---push wide character data back into a stream
30
31 INDEX
32 ungetwc
33 INDEX
34 _ungetwc_r
35
36 SYNOPSIS
37 #include <stdio.h>
38 #include <wchar.h>
39 wint_t ungetwc(wint_t <[wc]>, FILE *<[stream]>);
40
41 wint_t ungetwc( wint_t <[wc]>, FILE *<[stream]>);
42
43 DESCRIPTION
44 <<ungetwc>> is used to return wide characters back to <[stream]> to be
45 read again. If <[wc]> is WEOF, the stream is unchanged. Otherwise, the
46 wide character <[wc]> is put back on the stream, and subsequent reads will see
47 the wide chars pushed back in reverse order. Pushed wide chars are lost if the
48 stream is repositioned, such as by <<fseek>>, <<fsetpos>>, or
49 <<rewind>>.
50
51 The underlying file is not changed, but it is possible to push back
52 something different than what was originally read. Ungetting a
53 character will clear the end-of-stream marker, and decrement the file
54 position indicator. Pushing back beyond the beginning of a file gives
55 unspecified behavior.
56
57 The alternate function <<_ungetwc_r>> is a reentrant version. The
58 extra argument <[reent]> is a pointer to a reentrancy structure.
59
60 RETURNS
61 The wide character pushed back, or <<WEOF>> on error.
62
63 PORTABILITY
64 C99
65 */
66
67 #define _DEFAULT_SOURCE
68 #include <_ansi.h>
69 #include <errno.h>
70 #include <limits.h>
71 #include <stdio.h>
72 #include <stdlib.h>
73 #include <wchar.h>
74 #include "local.h"
75
76 wint_t
ungetwc(wint_t wc,register FILE * fp)77 ungetwc (
78 wint_t wc,
79 register FILE *fp)
80 {
81 char buf[MB_LEN_MAX];
82 size_t len;
83
84 _newlib_flockfile_start (fp);
85 ORIENT (fp, 1);
86 if (wc == WEOF)
87 wc = WEOF;
88 else if ((len = wcrtomb(buf, wc, &fp->_mbstate)) == (size_t)-1)
89 {
90 fp->_flags |= __SERR;
91 wc = WEOF;
92 }
93 else
94 while (len-- != 0)
95 if (ungetc( (unsigned char)buf[len], fp) == EOF)
96 {
97 wc = WEOF;
98 break;
99 }
100 _newlib_flockfile_end (fp);
101 return wc;
102 }
103
