evalcmd.cpp

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/*
 * PROJECT:     ReactOS Shell
 * LICENSE:     LGPL-2.1+ (https://spdx.org/licenses/LGPL-2.1+)
 * PURPOSE:     SHEvaluateSystemCommandTemplate
 * COPYRIGHT:   Copyright 2026 Katayama Hirofumi MZ <katayama.hirofumi.mz@gmail.com>
 */
 
#include <windef.h>
#include <shlobj.h>
#include <shlwapi.h>
#include <shlguid_undoc.h>
#include <shlobj_undoc.h>
#include <shlwapi_undoc.h>
#include <strsafe.h>
#include <pathcch.h>
#include <assert.h>
 
#define PATH_VALID_CHARS \
    (PATH_CHAR_CLASS_DOT | PATH_CHAR_CLASS_SEMICOLON | PATH_CHAR_CLASS_COMMA | \
     PATH_CHAR_CLASS_SPACE | PATH_CHAR_CLASS_OTHER_VALID)
 
static PCWSTR _PathGetArgsLikeCreateProcess(PCWSTR lpString)
{
    PCWSTR pch;
    if (*lpString == L'"')
    {
        pch = StrChrW(lpString + 1, L'"');
        if (pch)
        {
            ++pch;
            if (*pch == L' ')
                ++pch;
            return pch;
        }
    }
    else
    {
        pch = StrChrW(lpString, L' ');
        if (pch)
            return pch + 1;
    }
    return &lpString[lstrlenW(lpString)];
}
 
static HRESULT
_PathCopyExeAndTrimWhiteSpaces(PWSTR pszBuff, size_t cchBuff, PCWSTR pszSrc, size_t cchSrc)
{
    HRESULT hr = StringCchCopyNW(pszBuff, cchBuff, pszSrc, cchSrc);
    if (SUCCEEDED(hr))
        StrTrimW(pszBuff, L" \t");
    return hr;
}
 
static BOOL _PathMatchesSuspicious(PCWSTR lpString)
{
    WCHAR pszPath[MAX_PATH];
    SHGetFolderPathW(NULL, CSIDL_PROGRAM_FILES, NULL, 0, pszPath);
    INT cch = lstrlenW(pszPath);
    return StrCmpNIW(lpString, pszPath, cch) == 0;
}
 
// This function attempts to find where the "arguments" portion of a command-line path string
static PCWSTR _PathGuessNextBestArgs(PCWSTR pszPath)
{
    PCWSTR pSpaceStart = NULL;
    BOOL bValid = TRUE;
 
    for (; *pszPath && bValid; ++pszPath)
    {
        switch (*pszPath)
        {
            case L' ':
                if (!pSpaceStart)
                    pSpaceStart = pszPath;
                break;
 
            case L'"':
            case L'%':
                bValid = FALSE;
                break;
 
            case L'\\':
                bValid = !PathIsUNCW(pszPath);
                if (bValid)
                    pSpaceStart = NULL;
                break;
 
            default:
                bValid = PathIsValidCharW(*pszPath, PATH_VALID_CHARS);
                break;
        }
    }
 
    if (pSpaceStart)
    {
        while (*pSpaceStart == L' ')
            ++pSpaceStart;
        return pSpaceStart;
    }
 
    return bValid ? pszPath : NULL;
}
 
static VOID _MakeAppPathKey(PCWSTR pszPath, PWSTR pszDest, UINT cchDest)
{
    HRESULT hr = PathCchCombineEx(pszDest, cchDest,
                                  L"Software\\Microsoft\\Windows\\CurrentVersion\\App Paths",
                                  pszPath, PATHCCH_NONE);
    if (SUCCEEDED(hr))
        PathCchAddExtension(pszDest, cchDest, L".exe");
}
 
static BOOL _GetAppPath(PCWSTR pszPath, PWSTR pszValue, DWORD cchValue)
{
    WCHAR szSubKey[MAX_PATH];
    _MakeAppPathKey(pszPath, szSubKey, _countof(szSubKey));
    DWORD cbData = cchValue * sizeof(WCHAR);
    LSTATUS error = SHGetValueW(HKEY_LOCAL_MACHINE, szSubKey, NULL, NULL, pszValue, &cbData);
    return error == ERROR_SUCCESS;
}
 
static HRESULT _PathExeExists(_In_ PCWSTR pszPath)
{
    WCHAR szPath[MAX_PATH];
    StringCchCopyW(szPath, _countof(szPath), pszPath);
 
    DWORD dwWhich = WHICH_PIF | WHICH_COM | WHICH_EXE | WHICH_BAT | WHICH_CMD | WHICH_OPTIONAL;
    DWORD attrs;
    if (!PathFileExistsDefExtAndAttributesW(szPath, dwWhich, &attrs) ||
        (attrs & FILE_ATTRIBUTE_DIRECTORY))
    {
        return CO_E_APPNOTFOUND;
    }
    return S_OK;
}
 
static HRESULT
_PathFindInFolder(_In_ INT csidl, _In_ PCWSTR pszSrc, _Out_ PWSTR pszPath, _In_ UINT cchPath)
{
    WCHAR szDir[MAX_PATH];
    HRESULT hr = SHGetFolderPathW(0, csidl, 0, 0, szDir);
    if (FAILED(hr))
        return hr;
 
    hr = PathCchCombineEx(pszPath, cchPath, szDir, pszSrc, PATHCCH_NONE);
    if (FAILED(hr))
        return hr;
 
    return _PathExeExists(pszPath);
}
 
static HRESULT _PathFindInSystem(_Inout_ PWSTR pszPath, _In_ UINT cchPath)
{
    WCHAR szPath[MAX_PATH];
    HRESULT hr = _PathFindInFolder(CSIDL_SYSTEM, pszPath, szPath, _countof(szPath));
    if (FAILED(hr))
        hr = _PathFindInFolder(CSIDL_WINDOWS, pszPath, szPath, _countof(szPath));
    if (FAILED(hr))
        return hr;
    return StringCchCopyW(pszPath, cchPath, szPath);
}
 
/*************************************************************************
 * SHEvaluateSystemCommandTemplate [SHELL32.@] (Vista+)
 * SHEvaluateSystemCommandTemplate [SHLWAPI.552] (XP SP1 and SP2)
 *
 * https://learn.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-shevaluatesystemcommandtemplate
 * https://github.com/tpn/winsdk-10/blob/9b69fd26ac0c7d0b83d378dba01080e93349c2ed/Include/10.0.16299.0/um/shellapi.h#L525
 */
EXTERN_C
HRESULT WINAPI
SHEvaluateSystemCommandTemplate(
    _In_ PCWSTR pszCmdTemplate,
    _Outptr_ PWSTR *ppszApplication,
    _Outptr_opt_ PWSTR *ppszCommandLine,
    _Outptr_opt_ PWSTR *ppszParameters)
{
    HRESULT hr;
    BOOL bQuoted;
    WCHAR szExe[MAX_PATH], szProgram[MAX_PATH];
 
    PCWSTR pszArgs = _PathGetArgsLikeCreateProcess(pszCmdTemplate);
    UINT cchArgs = (UINT)(pszArgs - pszCmdTemplate);
    hr = _PathCopyExeAndTrimWhiteSpaces(szExe, _countof(szExe), pszCmdTemplate, cchArgs);
    if (FAILED(hr))
        goto Exit;
 
    // Unquote if necessary
    bQuoted = (szExe[0] == L'"');
    if (bQuoted)
        PathUnquoteSpacesW(szExe);
 
    hr = StringCchCopyW(szProgram, _countof(szProgram), szExe);
    assert(SUCCEEDED(hr));
 
    if (PathIsAbsolute(szExe))
    {
        if (bQuoted)
        {
            hr = _PathExeExists(szExe);
        }
        else // Not quoted
        {
            if (_PathMatchesSuspicious(szExe)) // ProgramFiles-likely?
                hr = HRESULT_FROM_WIN32(ERROR_PATH_NOT_FOUND);
            else
                hr = _PathExeExists(szExe);
        }
 
        // Detect where the full executable path ends and the arguments start
        while (FAILED(hr))
        {
            if (bQuoted || !*pszArgs)
                break;
 
            pszArgs = _PathGuessNextBestArgs(pszArgs);
            if (!pszArgs)
                break;
 
            cchArgs = (UINT)(pszArgs - pszCmdTemplate);
            hr = _PathCopyExeAndTrimWhiteSpaces(szExe, _countof(szExe), pszCmdTemplate, cchArgs);
            if (FAILED(hr))
                break;
 
            hr = _PathExeExists(szExe);
        }
    }
    else
    {
        if (!PathIsFileSpecW(szExe))
        {
            hr = E_ACCESSDENIED;
            goto Exit;
        }
 
        if (_GetAppPath(szExe, szExe, _countof(szExe)))
        {
            hr = StringCchCopyW(szProgram, _countof(szProgram), PathFindFileNameW(szExe));
        }
        else if (SHWindowsPolicyEx(POLID_UsePathEnvVarForCommandTemplates, FALSE))
        {
            hr = PathFindOnPathExW(szExe, NULL, PATH_VALID_CHARS) ? S_OK : CO_E_APPNOTFOUND;
        }
        else
        {
            hr = _PathFindInSystem(szExe, _countof(szExe));
        }
    }
 
Exit:
    *ppszApplication = NULL;
    if (ppszCommandLine)
        *ppszCommandLine = NULL;
    if (ppszParameters)
        *ppszParameters = NULL;
 
    if (!pszArgs)
        pszArgs = L"";
 
    // Create output strings
    if (SUCCEEDED(hr))
        hr = SHStrDupW(szExe, ppszApplication);
 
    if (SUCCEEDED(hr) && ppszCommandLine)
    {
        size_t cch = lstrlenW(szProgram) + lstrlenW(pszArgs) + 4; // 4 for '"', '"', ' ', NUL
        hr = SHCoAlloc(cch * sizeof(WCHAR), (PVOID*)ppszCommandLine);
        if (SUCCEEDED(hr))
            hr = StringCchPrintfW(*ppszCommandLine, cch, L"\"%s\" %s", szProgram, pszArgs);
    }
 
    if (SUCCEEDED(hr) && ppszParameters)
        hr = SHStrDupW(pszArgs, ppszParameters);
 
    if (FAILED(hr))
    {
        // Clean up
        if (*ppszApplication)
        {
            CoTaskMemFree(*ppszApplication);
            *ppszApplication = NULL;
        }
        if (ppszCommandLine && *ppszCommandLine)
        {
            CoTaskMemFree(*ppszCommandLine);
            *ppszCommandLine = NULL;
        }
        if (ppszParameters && *ppszParameters)
        {
            CoTaskMemFree(*ppszParameters);
            *ppszParameters = NULL;
        }
    }
 
    return hr;
}