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Simplify dwrite.dll loading process #6538

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Merged
merged 2 commits into from
Apr 27, 2023
Merged

Simplify dwrite.dll loading process #6538

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4ee95e8
Simplify dwrite loading process
kant2002 May 5, 2022
e92a05c
Remove noop
kant2002 May 5, 2022
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30 changes: 1 addition & 29 deletions src/Microsoft.DotNet.Wpf/src/Shared/cpp/dwriteloader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7,37 +7,9 @@
namespace WPFUtils
{

#if defined(__cplusplus_cli)
#endif
HMODULE LoadDWriteLibraryAndGetProcAddress(void **pfncptrDWriteCreateFactory)
{
HMODULE hDWriteLibrary = nullptr;

// KB2533623 introduced the LOAD_LIBRARY_SEARCH_SYSTEM32 flag. It also introduced
// the AddDllDirectory function. We test for presence of AddDllDirectory as an
// indirect evidence for the support of LOAD_LIBRARY_SEARCH_SYSTEM32 flag.
HMODULE hKernel32 = GetModuleHandle(L"kernel32.dll");
if (hKernel32 != nullptr)
{
if (GetProcAddress(hKernel32, "AddDllDirectory") != nullptr)
{
// All supported platforms newer than Vista SP2 shipped with dwrite.dll.
// On Vista SP2, the .NET servicing process will ensure that a MSU containing
// dwrite.dll will be delivered as a prerequisite - effectively guaranteeing that
// this following call to LoadLibraryEx(dwrite.dll) will succeed, and that it will
// not be susceptible to typical DLL planting vulnerability vectors.
hDWriteLibrary = LoadLibraryEx(L"dwrite.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
}
else
{
// LOAD_LIBRARY_SEARCH_SYSTEM32 is not supported on this OS.
// Fall back to using plain ol' LoadLibrary
// There is risk that this call might fail, or that it might be
// susceptible to DLL hijacking.
hDWriteLibrary = LoadLibrary(L"dwrite.dll");
}
}

HMODULE hDWriteLibrary = LoadLibraryEx(L"dwrite.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
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@lindexi lindexi May 5, 2022 •
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Windows 7, Windows Server 2008 R2, Windows Vista and Windows Server 2008: This value requires KB2533623 to be installed. See https://docs.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibraryexa

Thank you.

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Argh! I miss that. But only Windows 7 SP1 is possible applicable since other OS does not supported by .NET 7
And even that seems to be KB2533623 required for .NET see dotnet/docs#20459

But I hardly can understand is ESU has this patch or not.

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@Symbai Symbai May 5, 2022 •
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Vista and 2008 Server are not in the list of supported OS (at least for .NET 6) (research took too long, at time of answering kant2002 answer was not there)

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That should be slated for .NET 8 then. That way Win 7 would be out of support at release date (Nov 2023) and not important anymore.

if (hDWriteLibrary)
{
*pfncptrDWriteCreateFactory = GetProcAddress(hDWriteLibrary, "DWriteCreateFactory");
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