1 files changed, 206 insertions, 0 deletions

diff --git a/private/crt32/stdio/ungetwc.c b/private/crt32/stdio/ungetwc.c
new file mode 100644
index 000000000..5d3c82994
--- /dev/null
+++ b/private/crt32/stdio/ungetwc.c
@@ -0,0 +1,206 @@
+/***
+*ungetc.c - unget a character from a stream
+*
+*	Copyright (c) 1993, Microsoft Corporation. All rights reserved.
+*
+*Purpose:
+*	defines ungetc() - pushes a character back onto an input stream
+*
+*Revision History:
+*	04-26-93  CFW	Module created.
+*	04-30-93  CFW	Bring wide char support from ungetc.c.
+*	05-10-93  CFW	Optimize, fix error handling.
+*	06-02-93  CFW	Wide get/put use wint_t.
+*       07-16-93  SRW   ALPHA Merge
+*
+*******************************************************************************/
+
+#include <cruntime.h>
+#include <stdio.h>
+#include <file2.h>
+#include <assert.h>
+#include <internal.h>
+#include <os2dll.h>
+#include <msdos.h>
+#include <errno.h>
+#include <wchar.h>
+#include <setlocal.h>
+
+#ifdef MTHREAD	/* multi-thread; define both ungetwc and _lk_ungetwc */
+
+/***
+*wint_t ungetwc(ch, stream) - put a wide character back onto a stream
+*
+*Purpose:
+*	Guaranteed one char pushback on a stream as long as open for reading.
+*	More than one char pushback in a row is not guaranteed, and will fail
+*	if it follows an ungetc which pushed the first char in buffer. Failure
+*	causes return of WEOF.
+*
+*Entry:
+*	wint_t ch - wide character to push back
+*	FILE *stream - stream to push character onto
+*
+*Exit:
+*	returns ch
+*	returns WEOF if tried to push WEOF, stream not opened for reading or
+*	or if we have already ungetc'd back to beginning of buffer.
+*
+*Exceptions:
+*
+*******************************************************************************/
+
+wint_t _CRTAPI1 ungetwc (
+	REG2 wint_t ch,
+	REG1 FILE *stream
+	)
+{
+	wint_t retval;
+	int index;
+
+	assert(stream != NULL);
+
+	index = _iob_index(stream);
+
+	_lock_str(index);
+
+	retval = _ungetwc_lk (ch, stream);
+
+	_unlock_str(index);
+
+	return(retval);
+}
+
+/***
+*_ungetwc_lk() -  Ungetwc() core routine (locked version)
+*
+*Purpose:
+*	Core ungetwc() routine; assumes stream is already locked.
+*
+*	[See ungetwc() above for more info.]
+*
+*Entry: [See ungetwc()]
+*
+*Exit:	[See ungetwc()]
+*
+*Exceptions:
+*
+*******************************************************************************/
+
+wint_t _CRTAPI1 _ungetwc_lk (
+	wint_t ch,
+	FILE *str
+	)
+{
+
+#else	/* non multi-thread; just define ungetc */
+
+wint_t _CRTAPI1 ungetwc (
+	wint_t ch,
+	FILE *str
+	)
+{
+
+#endif	/* rejoin common code */
+
+	assert(str != NULL);
+
+	/*
+	 * Requirements for success:
+	 *
+	 * 1. Character to be pushed back on the stream must not be WEOF.
+	 *
+	 * 2. The stream must currently be in read mode, or must be open for
+	 *    update (i.e., read/write) and must NOT currently be in write
+	 *    mode.
+	 */
+	if ( (ch != WEOF) &&
+	     ( (str->_flag & _IOREAD) || ((str->_flag & _IORW) &&
+		!(str->_flag & _IOWRT))
+	     )
+	   )
+	{
+		/* If stream is unbuffered, get one. */
+		if (str->_base == NULL)
+			_getbuf(str);
+
+#ifndef _NTSUBSET_
+		if (!(str->_flag & _IOSTRG) && _osfile[_fileno(str)] & FTEXT)
+		{
+			/*
+			 * Text mode, sigh... Convert the wc to a mbc.
+			 */
+			int size, defused;
+			char mbc[4];
+
+			size = WideCharToMultiByte(_lc_codepage,
+						   WC_COMPOSITECHECK | WC_SEPCHARS,
+						   (wchar_t *)&ch,
+						   1,
+						   mbc,
+						   MB_CUR_MAX,
+						   NULL,
+						   &defused);
+
+			if ( (size == 0) || defused )
+			{
+				/*
+				 * Conversion failed! Set errno and return
+				 * failure.
+				 */
+				errno = EILSEQ;
+				return WEOF;
+			}
+
+			/* we know _base != NULL; since file is buffered */
+			if (str->_ptr == str->_base)
+			{
+				if (str->_cnt)
+				/* my back is against the wall; i've already done
+				 * ungetwc, and there's no room for this one
+				 */
+					return WEOF;
+				str->_ptr += size;
+			}
+
+			if ( size == 1 )
+			{
+		                *--str->_ptr = mbc[0];
+			}
+			else /* size == 2 */
+			{
+		                *--str->_ptr = mbc[1];
+		                *--str->_ptr = mbc[0];
+			}
+
+			str->_cnt += size;
+
+			str->_flag &= ~_IOEOF;
+			str->_flag |= _IOREAD;	/* may already be set */
+			return (wint_t) (0x0ffff & ch);
+		}
+#endif
+	      	/*
+		 * Binary mode - push back the wide char.
+		 */
+		/* we know _base != NULL; since file is buffered */
+		if (str->_ptr == str->_base)
+		{
+			if (str->_cnt)
+				/* my back is against the wall; i've already done
+				 * ungetc, and there's no room for this one
+				 */
+				return WEOF;
+			str->_ptr += sizeof(wchar_t);
+		}
+
+		str->_cnt += sizeof(wchar_t);
+
+		str->_flag &= ~_IOEOF;
+		str->_flag |= _IOREAD;	/* may already be set */
+
+		return (wint_t) (*--((wchar_t *)(str->_ptr)) = (wchar_t)(ch & 0xffff));
+
+	}
+	return WEOF;
+}