1 | /*- |
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2 | * Copyright (c) 2002-2004 Tim J. Robbins. |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * |
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14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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24 | * SUCH DAMAGE. |
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25 | */ |
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26 | |
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27 | /* |
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28 | FUNCTION |
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29 | <<ungetwc>>---push wide character data back into a stream |
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30 | |
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31 | INDEX |
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32 | ungetwc |
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33 | INDEX |
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34 | _ungetwc_r |
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35 | |
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36 | SYNOPSIS |
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37 | #include <stdio.h> |
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38 | #include <wchar.h> |
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39 | wint_t ungetwc(wint_t <[wc]>, FILE *<[stream]>); |
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40 | |
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41 | wint_t _ungetwc_r(struct _reent *<[reent]>, wint_t <[wc]>, FILE *<[stream]>); |
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42 | |
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43 | DESCRIPTION |
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44 | <<ungetwc>> is used to return wide characters back to <[stream]> to be |
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45 | read again. If <[wc]> is WEOF, the stream is unchanged. Otherwise, the |
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46 | wide character <[wc]> is put back on the stream, and subsequent reads will see |
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47 | the wide chars pushed back in reverse order. Pushed wide chars are lost if the |
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48 | stream is repositioned, such as by <<fseek>>, <<fsetpos>>, or |
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49 | <<rewind>>. |
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50 | |
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51 | The underlying file is not changed, but it is possible to push back |
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52 | something different than what was originally read. Ungetting a |
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53 | character will clear the end-of-stream marker, and decrement the file |
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54 | position indicator. Pushing back beyond the beginning of a file gives |
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55 | unspecified behavior. |
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56 | |
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57 | The alternate function <<_ungetwc_r>> is a reentrant version. The |
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58 | extra argument <[reent]> is a pointer to a reentrancy structure. |
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59 | |
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60 | RETURNS |
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61 | The wide character pushed back, or <<WEOF>> on error. |
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62 | |
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63 | PORTABILITY |
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64 | C99 |
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65 | */ |
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66 | |
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67 | #include <_ansi.h> |
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68 | #include <reent.h> |
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69 | #include <errno.h> |
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70 | #include <limits.h> |
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71 | #include <stdio.h> |
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72 | #include <stdlib.h> |
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73 | #include <wchar.h> |
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74 | #include "local.h" |
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75 | |
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76 | wint_t |
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77 | _ungetwc_r (struct _reent *ptr, |
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78 | wint_t wc, |
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79 | register FILE *fp) |
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80 | { |
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81 | char buf[MB_LEN_MAX]; |
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82 | size_t len; |
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83 | |
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84 | _newlib_flockfile_start (fp); |
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85 | ORIENT (fp, 1); |
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86 | if (wc == WEOF) |
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87 | wc = WEOF; |
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88 | else if ((len = _wcrtomb_r(ptr, buf, wc, &fp->_mbstate)) == (size_t)-1) |
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89 | { |
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90 | fp->_flags |= __SERR; |
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91 | wc = WEOF; |
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92 | } |
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93 | else |
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94 | while (len-- != 0) |
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95 | if (_ungetc_r(ptr, (unsigned char)buf[len], fp) == EOF) |
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96 | { |
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97 | wc = WEOF; |
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98 | break; |
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99 | } |
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100 | _newlib_flockfile_end (fp); |
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101 | return wc; |
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102 | } |
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103 | |
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104 | /* |
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105 | * MT-safe version. |
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106 | */ |
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107 | wint_t |
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108 | ungetwc (wint_t wc, |
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109 | FILE *fp) |
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110 | { |
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111 | struct _reent *reent = _REENT; |
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112 | |
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113 | CHECK_INIT (reent, fp); |
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114 | return _ungetwc_r (reent, wc, fp); |
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115 | } |
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