dbcs.cpp

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.

#include"precomp.h"
#include"dbcs.h"
#include"misc.h"

#include"../types/inc/convert.hpp"

#include"../interactivity/inc/ServiceLocator.hpp"

#pragma hdrstop

using Microsoft::Console::Interactivity::ServiceLocator;
// Routine Description:
// - This routine check bisected on Ascii string end.
// Arguments:
// - pchBuf - Pointer to Ascii string buffer.
// - cbBuf - Number of Ascii string.
// Return Value:
// - TRUE - Bisected character.
// - FALSE - Correctly.
boolCheckBisectStringA(_In_reads_bytes_(cbBuf) PCHAR pchBuf, _In_ DWORD cbBuf, const CPINFO* const pCPInfo)
{
while (cbBuf)
 {
if (IsDBCSLeadByteConsole(*pchBuf, pCPInfo))
 {
if (cbBuf <= 1)
 {
returntrue;
 }
else
 {
 pchBuf += 2;
 cbBuf -= 2;
 }
 }
else
 {
 pchBuf++;
 cbBuf--;
 }
 }

returnfalse;
}

// Routine Description:
// - Checks if a char is a lead byte for a given code page.
// Arguments:
// - ch - the char to check.
// - pCPInfo - the code page to check the char in.
// Return Value:
// true if ch is a lead byte, false otherwise.
boolIsDBCSLeadByteConsole(const CHAR ch, const CPINFO* const pCPInfo)
{
FAIL_FAST_IF_NULL(pCPInfo);
// NOTE: This must be unsigned for the comparison. If we compare signed, this will never hit
// because lead bytes are ironically enough always above 0x80 (signed char negative range).
constauto uchComparison = (unsignedchar)ch;

auto i = 0;
// this is ok because the array is guaranteed to have 2
// null bytes at the end.
while (pCPInfo->LeadByte[i])
 {
if (pCPInfo->LeadByte[i] <= uchComparison && uchComparison <= pCPInfo->LeadByte[i + 1])
 {
returntrue;
 }
 i += 2;
 }
returnfalse;
}

BYTE CodePageToCharSet(const UINT uiCodePage)
{
 CHARSETINFO csi{};

if (!TranslateCharsetInfo((DWORD*)IntToPtr(uiCodePage), &csi, TCI_SRCCODEPAGE))
 {
// On OneCore-based editions of Windows, the extension apiset containing
// TranslateCharsetInfo is not hosted. OneCoreUAP hosts it, but the lower
// editions do not. If we find that we failed to delay-load it, fall back
// to our "simple" OneCore-OK implementation.
if (GetLastError() == ERROR_PROC_NOT_FOUND)
 {
switch (uiCodePage)
 {
case CP_JAPANESE:
 csi.ciCharset = SHIFTJIS_CHARSET;
break;
case CP_CHINESE_SIMPLIFIED:
 csi.ciCharset = GB2312_CHARSET;
break;
case CP_KOREAN:
 csi.ciCharset = HANGEUL_CHARSET;
break;
case CP_CHINESE_TRADITIONAL:
 csi.ciCharset = CHINESEBIG5_CHARSET;
break;
 }
 }
else
 {
 csi.ciCharset = OEM_CHARSET;
 }
 }

return (BYTE)csi.ciCharset;
}

BOOL IsAvailableEastAsianCodePage(const UINT uiCodePage)
{
constauto CharSet = CodePageToCharSet(uiCodePage);

switch (CharSet)
 {
case SHIFTJIS_CHARSET:
case HANGEUL_CHARSET:
case CHINESEBIG5_CHARSET:
case GB2312_CHARSET:
returntrue;
default:
returnfalse;
 }
}