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  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. ANSI_SYNOPSIS
  37.         #include <stdio.h>
  38.         #include <wchar.h>
  39.         wint_t ungetwc(wint_t <[wc]>, FILE *<[stream]>);
  40.  
  41.         wint_t _ungetwc_r(struct _reent *<[reent]>, 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. #include <_ansi.h>
  68. #include <reent.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
  77. _DEFUN(_ungetwc_r, (ptr, wc, fp),
  78.         struct _reent *ptr _AND
  79.         wint_t wc _AND
  80.         register FILE *fp)
  81. {
  82.   char buf[MB_LEN_MAX];
  83.   size_t len;
  84.  
  85.   _newlib_flockfile_start (fp);
  86.   ORIENT (fp, 1);
  87.   if (wc == WEOF)
  88.     wc = WEOF;
  89.   else if ((len = _wcrtomb_r(ptr, buf, wc, &fp->_mbstate)) == (size_t)-1)
  90.     {
  91.       fp->_flags |= __SERR;
  92.       wc = WEOF;
  93.     }
  94.   else
  95.     while (len-- != 0)
  96.       if (_ungetc_r(ptr, (unsigned char)buf[len], fp) == EOF)
  97.         {
  98.           wc = WEOF;
  99.           break;
  100.         }
  101.   _newlib_flockfile_end (fp);
  102.   return wc;
  103. }
  104.  
  105. /*
  106.  * MT-safe version.
  107.  */
  108. wint_t
  109. _DEFUN(ungetwc, (wint_t wc, FILE *fp),
  110.         wint_t wc _AND
  111.         FILE *fp)
  112. {
  113.   struct _reent *reent = _REENT;
  114.  
  115.   CHECK_INIT (reent, fp);
  116.   return _ungetwc_r (reent, wc, fp);
  117. }
  118.