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Add set_value_multistring_nothrow for REG_MULTI_SZ writes #631

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Add set_value_multistring_nothrow for REG_MULTI_SZ writes #631

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98ac5fc
Add set_value_multistring_nothrow for REG_MULTI_SZ writes
Apr 20, 2026
76f3cc5
Rewrite set_value_multistring_nothrow without internal exceptions
Apr 22, 2026
aa93024
Address review feedback: use unique_process_heap_ptr, simplify memcpy…
May 1, 2026
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38 changes: 38 additions & 0 deletions include/wil/registry.h
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Original file line number Diff line number Diff line change
Expand Up @@ -884,6 +884,44 @@ namespace reg
return ::wil::reg::set_value_expanded_string_nothrow(key, nullptr, value_name, data);
}

#if WIL_USE_STL || defined(WIL_DOXYGEN)
/**
* @brief Writes a REG_MULTI_SZ value from a std::vector<std::wstring>
* @param key An open or well-known registry key
* @param subkey The name of the subkey to append to `key`.
* If `nullptr`, then `key` is used without modification.
* @param value_name The name of the registry value whose data is to be updated.
* Can be nullptr to write to the unnamed default registry value.
* @param data A std::vector<std::wstring> to write to the specified registry value.
* Each string will be marshaled to a contiguous null-terminator-delimited multi-sz string
* @return HRESULT error code indicating success or failure (does not throw C++ exceptions)
*/
inline HRESULT set_value_multistring_nothrow(
HKEY key, _In_opt_ PCWSTR subkey, _In_opt_ PCWSTR value_name, const ::std::vector<::std::wstring>& data) WI_NOEXCEPT
{
wchar_t* buffer = nullptr;
DWORD bufferSizeBytes = 0;
RETURN_IF_FAILED(reg_view_details::get_multistring_from_wstrings_nothrow(data, &buffer, &bufferSizeBytes));
const auto hr = HRESULT_FROM_WIN32(::RegSetKeyValueW(key, subkey, value_name, REG_MULTI_SZ, buffer, bufferSizeBytes));
::HeapFree(::GetProcessHeap(), 0, buffer);
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return hr;
}

/**
* @brief Writes a REG_MULTI_SZ value from a std::vector<std::wstring>
* @param key An open or well-known registry key
* @param value_name The name of the registry value whose data is to be updated.
* Can be nullptr to write to the unnamed default registry value.
* @param data A std::vector<std::wstring> to write to the specified registry value.
* Each string will be marshaled to a contiguous null-terminator-delimited multi-sz string.
* @return HRESULT error code indicating success or failure (does not throw C++ exceptions)
*/
inline HRESULT set_value_multistring_nothrow(HKEY key, _In_opt_ PCWSTR value_name, const ::std::vector<::std::wstring>& data) WI_NOEXCEPT
{
return ::wil::reg::set_value_multistring_nothrow(key, nullptr, value_name, data);
}
#endif // WIL_USE_STL

#if defined(__WIL_OBJBASE_H_) || defined(WIL_DOXYGEN)
/**
* @brief Writes raw bytes into a registry value under a specified key of the specified type
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51 changes: 51 additions & 0 deletions include/wil/registry_helpers.h
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Expand Up @@ -227,6 +227,57 @@ namespace reg
}
#endif

#if WIL_USE_STL
inline HRESULT get_multistring_from_wstrings_nothrow(
const ::std::vector<::std::wstring>& data, _Out_ wchar_t** buffer, _Out_ DWORD* bufferSizeBytes) WI_NOEXCEPT
{
*buffer = nullptr;
*bufferSizeBytes = 0;

size_t total_size_bytes = sizeof(wchar_t); // final double-null terminator
for (const auto& str : data)
{
const size_t entry_size = (str.size() + 1) * sizeof(wchar_t);
if (total_size_bytes + entry_size < total_size_bytes || total_size_bytes + entry_size > MAXDWORD)
{
return E_INVALIDARG;
}
total_size_bytes += entry_size;
}

if (data.empty())
{
total_size_bytes = 2 * sizeof(wchar_t);
}

auto result = static_cast<wchar_t*>(::HeapAlloc(::GetProcessHeap(), 0, total_size_bytes));
if (!result)
{
return E_OUTOFMEMORY;
}

size_t offset = 0;
if (data.empty())
{
result[offset++] = L'\0';
}
else
{
for (const auto& str : data)
{
memcpy(result + offset, str.c_str(), str.size() * sizeof(wchar_t));
offset += str.size();
result[offset++] = L'\0';
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}
}
result[offset] = L'\0';

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*buffer = result;
*bufferSizeBytes = static_cast<DWORD>(total_size_bytes);
return S_OK;
}
#endif

#if defined(__WIL_OBJBASE_H_)
template <size_t C>
void get_multistring_bytearray_from_strings_nothrow(const PCWSTR data[C], ::wil::unique_cotaskmem_array_ptr<BYTE>& multistring) WI_NOEXCEPT
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105 changes: 105 additions & 0 deletions tests/RegistryTests.cpp
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Expand Up @@ -3028,6 +3028,111 @@ TEST_CASE("BasicRegistryTests::multi-strings", "[registry]")
}
#endif
#endif

#if WIL_USE_STL && defined(WIL_ENABLE_EXCEPTIONS)
SECTION("set_value_multistring_nothrow/get_value_multistring_nothrow: with open key")
{
wil::unique_hkey hkey;
REQUIRE_SUCCEEDED(wil::reg::create_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, hkey, wil::reg::key_access::readwrite));

for (const auto& value : multiStringTestVector)
{
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(hkey.get(), stringValueName, value));
auto result = wil::reg::get_value_multistring(hkey.get(), stringValueName);
// set_value_multistring_nothrow should produce the same result as set_value_multistring
wil::reg::set_value_multistring(hkey.get(), multiStringValueName, value);
auto expected = wil::reg::get_value_multistring(hkey.get(), multiStringValueName);
REQUIRE(result == expected);
}

// and verify default value name
const std::vector<std::wstring> testValue{L"hello", L"world"};
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(hkey.get(), nullptr, testValue));
auto result = wil::reg::get_value_multistring(hkey.get(), nullptr);
REQUIRE(result == testValue);
}

SECTION("set_value_multistring_nothrow/get_value_multistring_nothrow: with string key")
{
for (const auto& value : multiStringTestVector)
{
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(HKEY_CURRENT_USER, testSubkey, stringValueName, value));
auto result = wil::reg::get_value_multistring(HKEY_CURRENT_USER, testSubkey, stringValueName);
// set_value_multistring_nothrow should produce the same result as set_value_multistring
wil::reg::set_value_multistring(HKEY_CURRENT_USER, testSubkey, multiStringValueName, value);
auto expected = wil::reg::get_value_multistring(HKEY_CURRENT_USER, testSubkey, multiStringValueName);
REQUIRE(result == expected);
}

// and verify default value name
const std::vector<std::wstring> testValue{L"hello", L"world"};
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(HKEY_CURRENT_USER, testSubkey, nullptr, testValue));
auto result = wil::reg::get_value_multistring(HKEY_CURRENT_USER, testSubkey, nullptr);
REQUIRE(result == testValue);
}

SECTION("set_value_multistring_nothrow: empty array with open key")
{
wil::unique_hkey hkey;
REQUIRE_SUCCEEDED(wil::reg::create_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, hkey, wil::reg::key_access::readwrite));

// When passed an empty array, set_value_multistring_nothrow writes 2 null-terminators
// (i.e. a single empty string), matching the behavior of set_value_multistring
const std::vector<std::wstring> arrayOfOne{L""};
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(hkey.get(), stringValueName, test_multistring_empty));
auto result = wil::reg::get_value_multistring(hkey.get(), stringValueName);
REQUIRE(result == arrayOfOne);

// and verify default value name
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(hkey.get(), nullptr, test_multistring_empty));
result = wil::reg::get_value_multistring(hkey.get(), nullptr);
REQUIRE(result == arrayOfOne);
}

SECTION("set_value_multistring_nothrow: empty array with string key")
{
const std::vector<std::wstring> arrayOfOne{L""};
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(HKEY_CURRENT_USER, testSubkey, stringValueName, test_multistring_empty));
auto result = wil::reg::get_value_multistring(HKEY_CURRENT_USER, testSubkey, stringValueName);
REQUIRE(result == arrayOfOne);

// and verify default value name
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(HKEY_CURRENT_USER, testSubkey, nullptr, test_multistring_empty));
result = wil::reg::get_value_multistring(HKEY_CURRENT_USER, testSubkey, nullptr);
REQUIRE(result == arrayOfOne);
}

SECTION("set_value_multistring_nothrow: fails with E_ACCESSDENIED on read-only key")
{
wil::unique_hkey hkey;
REQUIRE_SUCCEEDED(wil::reg::create_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, hkey, wil::reg::key_access::readwrite));

wil::unique_hkey readOnlyKey;
REQUIRE_SUCCEEDED(wil::reg::open_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, readOnlyKey, wil::reg::key_access::read));

const std::vector<std::wstring> testValue{L"test"};
auto hr = wil::reg::set_value_multistring_nothrow(readOnlyKey.get(), stringValueName, testValue);
REQUIRE(hr == E_ACCESSDENIED);
}

SECTION("set_value_multistring_nothrow: round-trip with nothrow get via cotaskmem")
{
wil::unique_hkey hkey;
REQUIRE_SUCCEEDED(wil::reg::create_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, hkey, wil::reg::key_access::readwrite));

const std::vector<std::wstring> testValue{L"alpha", L"bravo", L"charlie"};
REQUIRE_SUCCEEDED(wil::reg::set_value_multistring_nothrow(hkey.get(), stringValueName, testValue));

#if defined(__WIL_OBJBASE_H_)
wil::unique_cotaskmem_array_ptr<wil::unique_cotaskmem_string> result{};
REQUIRE_SUCCEEDED(wil::reg::get_value_multistring_nothrow(hkey.get(), stringValueName, result));
REQUIRE(result.size() == 3);
REQUIRE(std::wstring_view(result[0]) == L"alpha");
REQUIRE(std::wstring_view(result[1]) == L"bravo");
REQUIRE(std::wstring_view(result[2]) == L"charlie");
#endif // defined(__WIL_OBJBASE_H_)
}
#endif // WIL_USE_STL && defined(WIL_ENABLE_EXCEPTIONS)
}

#if defined(__WIL_OBJBASE_H_)
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