PVOID WINAPI DetourFindFunction()

in src/modules.cpp [142:244]
83 lines of code
12 McCabe index (conditional complexity)

PVOID WINAPI DetourFindFunction(_In_ LPCSTR pszModule,
                                _In_ LPCSTR pszFunction)
{
    if (pszFunction == NULL) {
        SetLastError(ERROR_INVALID_PARAMETER);
        return NULL;
    }

    /////////////////////////////////////////////// First, try GetProcAddress.
    //
#pragma prefast(suppress:28752, "We don't do the unicode conversion for LoadLibraryExA.")
    HMODULE hModule = LoadLibraryExA(pszModule, NULL, 0);
    if (hModule == NULL) {
        return NULL;
    }

    PBYTE pbCode = (PBYTE)GetProcAddress(hModule, pszFunction);
    if (pbCode) {
        return pbCode;
    }

    ////////////////////////////////////////////////////// Then try ImageHelp.
    //
    DETOUR_TRACE(("DetourFindFunction(%hs, %hs)\n", pszModule, pszFunction));
    PDETOUR_SYM_INFO pSymInfo = DetourLoadImageHlp();
    if (pSymInfo == NULL) {
        DETOUR_TRACE(("DetourLoadImageHlp failed: %lu\n",
                      GetLastError()));
        return NULL;
    }

    if (pSymInfo->pfSymLoadModule64(pSymInfo->hProcess, NULL,
                                    (PCHAR)pszModule, NULL,
                                    (DWORD64)hModule, 0) == 0) {
        if (ERROR_SUCCESS != GetLastError()) {
            DETOUR_TRACE(("SymLoadModule64(%p) failed: %lu\n",
                          pSymInfo->hProcess, GetLastError()));
            return NULL;
        }
    }

    HRESULT hrRet;
    CHAR szFullName[512];
    IMAGEHLP_MODULE64 modinfo;
    ZeroMemory(&modinfo, sizeof(modinfo));
    modinfo.SizeOfStruct = sizeof(modinfo);
    if (!pSymInfo->pfSymGetModuleInfo64(pSymInfo->hProcess, (DWORD64)hModule, &modinfo)) {
        DETOUR_TRACE(("SymGetModuleInfo64(%p, %p) failed: %lu\n",
                      pSymInfo->hProcess, hModule, GetLastError()));
        return NULL;
    }

    hrRet = StringCchCopyA(szFullName, sizeof(szFullName)/sizeof(CHAR), modinfo.ModuleName);
    if (FAILED(hrRet)) {
        DETOUR_TRACE(("StringCchCopyA failed: %08lx\n", hrRet));
        return NULL;
    }
    hrRet = StringCchCatA(szFullName, sizeof(szFullName)/sizeof(CHAR), "!");
    if (FAILED(hrRet)) {
        DETOUR_TRACE(("StringCchCatA failed: %08lx\n", hrRet));
        return NULL;
    }
    hrRet = StringCchCatA(szFullName, sizeof(szFullName)/sizeof(CHAR), pszFunction);
    if (FAILED(hrRet)) {
        DETOUR_TRACE(("StringCchCatA failed: %08lx\n", hrRet));
        return NULL;
    }

    struct CFullSymbol : SYMBOL_INFO {
        CHAR szRestOfName[512];
    } symbol;
    ZeroMemory(&symbol, sizeof(symbol));
    //symbol.ModBase = (ULONG64)hModule;
    symbol.SizeOfStruct = sizeof(SYMBOL_INFO);
#ifdef DBHLPAPI
    symbol.MaxNameLen = sizeof(symbol.szRestOfName)/sizeof(symbol.szRestOfName[0]);
#else
    symbol.MaxNameLength = sizeof(symbol.szRestOfName)/sizeof(symbol.szRestOfName[0]);
#endif

    if (!pSymInfo->pfSymFromName(pSymInfo->hProcess, szFullName, &symbol)) {
        DETOUR_TRACE(("SymFromName(%hs) failed: %lu\n", szFullName, GetLastError()));
        return NULL;
    }

#if defined(DETOURS_IA64)
    // On the IA64, we get a raw code pointer from the symbol engine
    // and have to convert it to a wrapped [code pointer, global pointer].
    //
    PPLABEL_DESCRIPTOR pldEntry = (PPLABEL_DESCRIPTOR)DetourGetEntryPoint(hModule);
    PPLABEL_DESCRIPTOR pldSymbol = new PLABEL_DESCRIPTOR;

    pldSymbol->EntryPoint = symbol.Address;
    pldSymbol->GlobalPointer = pldEntry->GlobalPointer;
    return (PBYTE)pldSymbol;
#elif defined(DETOURS_ARM)
    // On the ARM, we get a raw code pointer, which we must convert into a
    // valied Thumb2 function pointer.
    return DETOURS_PBYTE_TO_PFUNC(symbol.Address);
#else
    return (PBYTE)symbol.Address;
#endif
}