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Merged
stephenegriffin merged 3 commits into from
Sep 24, 2025
Merged

Better fallbacks for finding olmapi32 #122

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428a998
Better fallbacks for finding olmapi32
stephenegriffin Sep 23, 2025
a143189
Add a couple fallback qualifiers
stephenegriffin Sep 24, 2025
c9e47d6
remove unused var
stephenegriffin Sep 24, 2025
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142 changes: 90 additions & 52 deletions library/stubutils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,20 @@ namespace mapistub
L"{BC174BAD-2F53-4855-A1D5-1D575C19B1EA}", // O11_CATEGORY_GUID_CORE_OFFICE (debug) // STRING_OK
};

std::vector<std::wstring> g_OutlookQualifiers = {
// Possible qualifiers for MsiProvideQualifiedComponent
L"outlook.x64.exe",
L"outlook.exe",
L"excel.exe",
L"winword.exe",
L"wwlib.dll",
L"powerpnt.exe",
L"msaccess.exe",
L"onenote.exe",
L"mspub.exe",
L"visio.exe",
L"mspub.exe"};

std::wstring GetInstalledOutlookMAPI(int iOutlook);
std::wstring GetInstalledOutlookMAPI(const std::wstring component);

Expand Down Expand Up @@ -262,6 +276,9 @@ namespace mapistub
// Whether or not we should ignore the registry and load MAPI from the system directory
static bool s_fForceSystemMAPI = false;

// Preference flag for olmapi32.dll, true by default
static bool s_fPreferOlmapi32 = true;

static volatile HMODULE g_hinstMAPI = nullptr;
HMODULE g_hModPstPrx32 = nullptr;

Expand Down Expand Up @@ -468,70 +485,63 @@ namespace mapistub
return hkeyMapiClient;
}

// Looks up Outlook's path given its qualified component guid
std::wstring GetOutlookPath(_In_ const std::wstring& szCategory, _Out_opt_ bool* lpb64)
// Looks up olmapi32.dll path given a qualified component guid
std::wstring GetOLMAPI32Path(_In_ const std::wstring& szCategory)
{
logLoadMapi(L"Enter GetOutlookPath: szCategory = %ws\n", szCategory.c_str());
logLoadMapi(L"Enter GetOLMAPI32Path: szCategory = %ws\n", szCategory.c_str());
DWORD dwValueBuf = 0;
std::wstring path;

if (lpb64) *lpb64 = false;

auto hRes = MyMsiProvideQualifiedComponent(
szCategory.c_str(),
L"outlook.x64.exe", // STRING_OK
static_cast<DWORD>(INSTALLMODE_DEFAULT),
nullptr,
&dwValueBuf);
LogError(L"GetOutlookPath: MsiProvideQualifiedComponent(x64)", hRes);
if (hRes == S_OK)
{
if (lpb64) *lpb64 = true;
}
else
auto hRes = E_FAIL;
int usedIndex = -1;
for (int i = 0; i < static_cast<int>(g_OutlookQualifiers.size()); ++i)
{
logLoadMapi(L"GetOLMAPI32Path: qualifier = %ws\n", g_OutlookQualifiers[i].c_str());
dwValueBuf = 0;
hRes = MyMsiProvideQualifiedComponent(
szCategory.c_str(),
L"outlook.exe", // STRING_OK
g_OutlookQualifiers[i].c_str(),
static_cast<DWORD>(INSTALLMODE_DEFAULT),
nullptr,
&dwValueBuf);
LogError(L"GetOutlookPath: MsiProvideQualifiedComponent(x86)", hRes);
LogError(L"GetOLMAPI32Path: MsiProvideQualifiedComponent", hRes);
if (hRes == S_OK)
{
usedIndex = i;
break;
}
}

if (hRes == S_OK)
if (hRes == S_OK && usedIndex != -1)
{
dwValueBuf += 1;
const auto lpszTempPath = std::wstring(dwValueBuf, '\0');

hRes = MyMsiProvideQualifiedComponent(
szCategory.c_str(),
L"outlook.x64.exe", // STRING_OK
g_OutlookQualifiers[usedIndex].c_str(),
static_cast<DWORD>(INSTALLMODE_DEFAULT),
const_cast<wchar_t*>(lpszTempPath.c_str()),
&dwValueBuf);
LogError(L"GetOutlookPath: MsiProvideQualifiedComponent(x64)", hRes);
if (hRes != S_OK)
LogError(L"GetOLMAPI32Path: MsiProvideQualifiedComponent (path)", hRes);
if (hRes == S_OK && !lpszTempPath.empty())
{
hRes = MyMsiProvideQualifiedComponent(
szCategory.c_str(),
L"outlook.exe", // STRING_OK
static_cast<DWORD>(INSTALLMODE_DEFAULT),
const_cast<wchar_t*>(lpszTempPath.c_str()),
&dwValueBuf);
LogError(L"GetOutlookPath: MsiProvideQualifiedComponent(x86)", hRes);
}
WCHAR szDrive[_MAX_DRIVE] = {0};
WCHAR szOutlookPath[MAX_PATH] = {0};
const auto errNo = _wsplitpath_s(
lpszTempPath.c_str(), szDrive, _MAX_DRIVE, szOutlookPath, MAX_PATH, nullptr, NULL, nullptr, NULL);
LogError(L"GetOLMAPI32Path: _wsplitpath_s", errNo);

if (hRes == S_OK)
{
path = lpszTempPath;
logLoadMapi(L"Exit GetOutlookPath: Path = %ws\n", path.c_str());
if (errNo == ERROR_SUCCESS)
{
path = std::wstring(szDrive) + std::wstring(szOutlookPath) + WszOlMAPI32DLL;
logLoadMapi(L"GetOLMAPI32Path: found %ws\n", path.c_str());
}
}
}

if (path.empty())
{
logLoadMapi(L"Exit GetOutlookPath: nothing found\n");
logLoadMapi(L"Exit GetOLMAPI32Path: nothing found\n");
}

return path;
Expand All @@ -557,23 +567,12 @@ namespace mapistub
{
logLoadMapi(L"Enter GetInstalledOutlookMAPI(%s)\n", component.c_str());

auto lpszTempPath = GetOutlookPath(component, nullptr);
auto szPath = GetOLMAPI32Path(component);

if (!lpszTempPath.empty())
if (!szPath.empty())
{
WCHAR szDrive[_MAX_DRIVE] = {0};
WCHAR szOutlookPath[MAX_PATH] = {0};
const auto errNo = _wsplitpath_s(
lpszTempPath.c_str(), szDrive, _MAX_DRIVE, szOutlookPath, MAX_PATH, nullptr, NULL, nullptr, NULL);
LogError(L"GetOutlookPath: _wsplitpath_s", errNo);

if (errNo == ERROR_SUCCESS)
{
const auto szPath = std::wstring(szDrive) + std::wstring(szOutlookPath) + WszOlMAPI32DLL;

logLoadMapi(L"GetInstalledOutlookMAPI: found %ws\n", szPath.c_str());
return szPath;
}
logLoadMapi(L"GetInstalledOutlookMAPI: found %ws\n", szPath.c_str());
return szPath;
}

logLoadMapi(L"Exit GetInstalledOutlookMAPI: found nothing\n");
Expand All @@ -595,42 +594,75 @@ namespace mapistub
return paths;
}

/*
* GetMAPIPaths - Returns a list of possible MAPI DLL paths in order of preference.
*
* Order of preference:
* 1. If ForceSystemMAPI is set, prefer the system directory MAPI32.dll only.
* 2. If ForceOutlookMAPI is set, prefer the Outlook MAPI client registry key.
* 3. DllPathEx registry value from the selected MAPI client.
* 4. All installed Outlook MAPI implementations (from known component GUIDs).
* 5. DllPath registry value from the selected MAPI client.
* 6. MSI-based MAPI path from the selected MAPI client.
* 7. If not forcing Outlook, fallback to system directory MAPI32.dll.
*/
std::vector<std::wstring> GetMAPIPaths()
{
// Holds the ordered list of possible MAPI DLL paths
auto paths = std::vector<std::wstring>();
std::wstring szPath;

// 1. If ForceSystemMAPI is set, only use the system directory MAPI32.dll
if (s_fForceSystemMAPI)
{
szPath = GetMAPISystemDir();
if (!szPath.empty()) paths.push_back(szPath);
return paths;
}

// 2. Select the MAPI client registry key: Outlook if forced, otherwise default
auto hkeyMapiClient = HKEY{};
if (s_fForceOutlookMAPI)
hkeyMapiClient = GetHKeyMapiClient(WszOutlookMapiClientName);
else
hkeyMapiClient = GetHKeyMapiClient(L"");

// 3. Prefer DllPathEx registry value from the selected MAPI client
szPath = RegQueryWszExpand(hkeyMapiClient, WszValueNameDllPathEx);
if (!szPath.empty()) paths.push_back(szPath);

// 4. Add all installed Outlook MAPI implementations (from known component GUIDs)
auto outlookPaths = GetInstalledOutlookMAPI();
paths.insert(end(paths), std::begin(outlookPaths), std::end(outlookPaths));

// 5. Prefer DllPath registry value from the selected MAPI client
szPath = RegQueryWszExpand(hkeyMapiClient, WszValueNameDllPath);
if (!szPath.empty()) paths.push_back(szPath);

// 6. Prefer MSI-based MAPI path from the selected MAPI client
szPath = GetMailClientFromMSIData(hkeyMapiClient);
if (!szPath.empty()) paths.push_back(szPath);

// 7. If not forcing Outlook, fallback to system directory MAPI32.dll
if (!s_fForceOutlookMAPI)
{
szPath = GetMAPISystemDir();
if (!szPath.empty()) paths.push_back(szPath);
}

if (hkeyMapiClient) RegCloseKey(hkeyMapiClient);

// If olmapi32 preference is set, bubble all olmapi32.dll paths to the top (case-insensitive)
if (s_fPreferOlmapi32)
{
auto is_olmapi32 = [](const std::wstring& path) {
std::wstring lower = path;
std::transform(lower.begin(), lower.end(), lower.begin(), ::towlower);
return lower.find(L"olmapi32.dll") != std::wstring::npos;
};
static_cast<void>(std::stable_partition(paths.begin(), paths.end(), is_olmapi32));
}

return paths;
}

Expand Down Expand Up @@ -777,4 +809,10 @@ namespace mapistub
logLoadMapi(L"ForceSystemMAPI: fForce = 0x%08X\n", fForce);
s_fForceSystemMAPI = fForce;
}

void PreferOlmapi32(bool fPrefer)
{
logLoadMapi(L"PreferOlmapi32: fPrefer = 0x%08X\n", fPrefer);
s_fPreferOlmapi32 = fPrefer;
}
} // namespace mapistub
5 changes: 3 additions & 2 deletions library/stubutils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,8 @@ namespace mapistub
std::wstring GetComponentPath(const std::wstring& szComponent, const std::wstring& szQualifier, bool fInstall);
extern std::vector<std::wstring> g_pszOutlookQualifiedComponents;
std::vector<std::wstring> GetMAPIPaths();
// Looks up Outlook's path given its qualified component guid
std::wstring GetOutlookPath(_In_ const std::wstring& szCategory, _Out_opt_ bool* lpb64);
// Looks up olmapi32.dll path using a qualified component guid
std::wstring GetOLMAPI32Path(_In_ const std::wstring& szCategory);
std::wstring GetInstalledOutlookMAPI(int iOutlook);
std::wstring GetMAPISystemDir();

Expand All @@ -49,4 +49,5 @@ namespace mapistub
void UnloadPrivateMAPI();
void ForceOutlookMAPI(bool fForce);
void ForceSystemMAPI(bool fForce);
void PreferOlmapi32(bool fPrefer);
} // namespace mapistub
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