230 lines
7.3 KiB
C
230 lines
7.3 KiB
C
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/***
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*ungetwc.c - unget a wide character from a stream
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*
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* Copyright (c) 1993-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines ungetwc() - pushes a wide character back onto an input stream
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*
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*Revision History:
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* 04-26-93 CFW Module created.
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* 04-30-93 CFW Bring wide char support from ungetc.c.
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* 05-10-93 CFW Optimize, fix error handling.
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* 06-02-93 CFW Wide get/put use wint_t.
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* 07-16-93 SRW ALPHA Merge
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* 09-15-93 CFW Use ANSI conformant "__" names.
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* 10-01-93 CFW Test only for TEXT, update comments.
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* 10-28-93 CFW Test for both IOSTRG and TEXT.
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* 11-10-93 GJF Merged in NT SDK version (picked up fix to a cast
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* expression). Also replaced MTHREAD with _MT.
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* 02-07-94 CFW POSIXify.
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* 08-31-94 CFW Fix for "C" locale, call wctomb().
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* 02-06-94 CFW assert -> _ASSERTE.
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* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
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* 06-12-95 GJF Replaced _osfile[] with _osfile() (macro referencing
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* field in ioinfo struct).
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* 07-28-95 GJF Replaced _osfile() with _osfile_safe().
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* 03-02-98 GJF Exception-safe locking.
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* 11-05-08 GJF Don't push back characters onto strings (i.e., when
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* called by swscanf).
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* 12-16-99 GB Modified for the case when return value from wctomb is
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* greater then 2.
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*
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*******************************************************************************/
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#ifndef _POSIX_
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#include <cruntime.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <file2.h>
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#include <dbgint.h>
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#include <internal.h>
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#include <mtdll.h>
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#include <msdos.h>
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#include <errno.h>
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#include <wchar.h>
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#include <setlocal.h>
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#ifdef _MT /* multi-thread; define both ungetwc and _lk_ungetwc */
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/***
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*wint_t ungetwc(ch, stream) - put a wide character back onto a stream
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*
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*Purpose:
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* Guaranteed one char pushback on a stream as long as open for reading.
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* More than one char pushback in a row is not guaranteed, and will fail
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* if it follows an ungetc which pushed the first char in buffer. Failure
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* causes return of WEOF.
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*
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*Entry:
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* wint_t ch - wide character to push back
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* FILE *stream - stream to push character onto
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*
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*Exit:
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* returns ch
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* returns WEOF if tried to push WEOF, stream not opened for reading or
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* or if we have already ungetc'd back to beginning of buffer.
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*
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*Exceptions:
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*
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*******************************************************************************/
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wint_t __cdecl ungetwc (
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REG2 wint_t ch,
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REG1 FILE *stream
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)
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{
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wint_t retval;
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_ASSERTE(stream != NULL);
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_lock_str(stream);
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__try {
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retval = _ungetwc_lk (ch, stream);
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}
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__finally {
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_unlock_str(stream);
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}
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return(retval);
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}
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/***
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*_ungetwc_lk() - Ungetwc() core routine (locked version)
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*
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*Purpose:
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* Core ungetwc() routine; assumes stream is already locked.
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*
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* [See ungetwc() above for more info.]
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*
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*Entry: [See ungetwc()]
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*
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*Exit: [See ungetwc()]
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*
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*Exceptions:
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*
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*******************************************************************************/
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wint_t __cdecl _ungetwc_lk (
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wint_t ch,
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FILE *str
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)
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{
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#else /* non multi-thread; just define ungetc */
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wint_t __cdecl ungetwc (
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wint_t ch,
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FILE *str
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)
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{
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#endif /* rejoin common code */
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_ASSERTE(str != NULL);
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/*
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* Requirements for success:
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*
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* 1. Character to be pushed back on the stream must not be WEOF.
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*
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* 2. The stream must currently be in read mode, or must be open for
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* update (i.e., read/write) and must NOT currently be in write
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* mode.
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*/
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if ( (ch != WEOF) &&
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( (str->_flag & _IOREAD) || ((str->_flag & _IORW) &&
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!(str->_flag & _IOWRT))
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)
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)
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{
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/* If stream is unbuffered, get one. */
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if (str->_base == NULL)
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_getbuf(str);
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#ifndef _NTSUBSET_
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if (!(str->_flag & _IOSTRG) && (_osfile_safe(_fileno(str)) &
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FTEXT))
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{
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/*
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* Text mode, sigh... Convert the wc to a mbc.
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*/
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int size, i;
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char mbc[MB_LEN_MAX];
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if ((size = wctomb(mbc, ch)) == -1)
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{
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/*
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* Conversion failed! Set errno and return
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* failure.
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*/
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errno = EILSEQ;
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return WEOF;
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}
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/* we know _base != NULL; since file is buffered */
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if (str->_ptr < str->_base + size)
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{
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if (str->_cnt)
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/* my back is against the wall; i've already done
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* ungetwc, and there's no room for this one
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*/
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return WEOF;
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if (size > str->_bufsiz)
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return WEOF;
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str->_ptr = size + str->_base;
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}
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for ( i = size -1; i >= 0; i--)
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{
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*--str->_ptr = mbc[i];
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}
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str->_cnt += size;
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str->_flag &= ~_IOEOF;
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str->_flag |= _IOREAD; /* may already be set */
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return (wint_t) (0x0ffff & ch);
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}
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#endif
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/*
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* Binary mode or a string (from swscanf) - push back the wide
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* character
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*/
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/* we know _base != NULL; since file is buffered */
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if (str->_ptr < str->_base + sizeof(wchar_t))
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{
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if (str->_cnt)
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/* my back is against the wall; i've already done
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* ungetc, and there's no room for this one
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*/
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return WEOF;
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if (sizeof(wchar_t) > str->_bufsiz)
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return WEOF;
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str->_ptr = sizeof(wchar_t) + str->_base;
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}
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if (str->_flag & _IOSTRG) {
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/* If stream opened by swscanf do not modify buffer */
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if (*--((wchar_t *)(str->_ptr)) != (wchar_t)ch) {
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++((wchar_t *)(str->_ptr));
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return WEOF;
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}
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} else
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*--((wchar_t *)(str->_ptr)) = (wchar_t)(ch & 0xffff);
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str->_cnt += sizeof(wchar_t);
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str->_flag &= ~_IOEOF;
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str->_flag |= _IOREAD; /* may already be set */
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return (wint_t)(ch & 0xffff);
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}
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return WEOF;
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}
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#endif /* _POSIX_ */
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