[UCRT] Import Microsoft.Windows.SDK.CRTSource version 10.0.22621.3

Imported from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3
License: MIT

sdk/lib/ucrt/conio/putch.cpp

@@ -0,0 +1,82 @@
+//
+// putch.cpp
+//
+//      Copyright (c) Microsoft Corporation. All rights reserved.
+//
+// Defines _putch(), which writes a character to the console.
+//
+#include <conio.h>
+#include <corecrt_internal_lowio.h>
+#include <corecrt_internal_mbstring.h>
+#include <corecrt_internal_stdio.h>
+#include <corecrt_internal_ptd_propagation.h>
+#include <stdlib.h>
+
+// Writes a wide character to the console.  Returns the character on success,
+// EOF on failure.
+extern "C" int __cdecl _putch(int const c)
+{
+    return __acrt_lock_and_call(__acrt_conio_lock, [&]
+    {
+        return _putch_nolock(c);
+    });
+}
+
+extern "C" int __cdecl _putch_nolock_internal(int const c, __crt_cached_ptd_host& ptd)
+{
+    __acrt_ptd*     const raw_ptd      = ptd.get_raw_ptd();
+    unsigned char*  const ch_buf       = raw_ptd->_putch_buffer;
+    unsigned short* const pch_buf_used = &raw_ptd->_putch_buffer_used;
+
+    // We can only use the character directly if we are sure that the machine
+    // is big-endian.
+    int result = c;
+
+    // Why are we using putwch to write to Console when we could have
+    // written straight away to Console? The problem we have in writing to
+    // Console is that CRT codepage is different from Console codepage and
+    // thus to write to console, we will need to convert the codepage. Here
+    // we can use unicode version of these routines and this way we will
+    // only have to do one conversion and rest will be handled by putwch.
+
+    // The usual way people call putch is character by character. Also
+    // there is no way we can convert partial MBCS to unicode character. To
+    // address this issue, we buffer all the lead bytes and combine them
+    // with trail bytes and then do the conversion.
+    if (*pch_buf_used == 1)
+    {
+        _ASSERTE(isleadbyte(ch_buf[0]) != 0);
+
+        ch_buf[1] = static_cast<unsigned char>(c);
+    }
+    else
+    {
+        ch_buf[0] = static_cast<unsigned char>(c);
+    }
+
+    if (*pch_buf_used == 0 && isleadbyte(ch_buf[0]))
+    {
+        // We still need trail byte, wait for it.
+        *pch_buf_used = 1;
+    }
+    else
+    {
+        wchar_t wchar;
+        if (_mbtowc_internal(&wchar, reinterpret_cast<char const*>(ch_buf), *pch_buf_used + 1, ptd) == -1 ||
+            _putwch_nolock(wchar) == WEOF)
+        {
+            result = EOF;
+        }
+
+        // Since we have processed full MBCS character, we should reset ch_buf_used.
+        *pch_buf_used = 0;
+    }
+
+    return result;
+}
+
+extern "C" int __cdecl _putch_nolock(int const c)
+{
+     __crt_cached_ptd_host ptd;
+     return _putch_nolock_internal(c, ptd);
+}