Add CreateWellKnownSid()

Signed-off-by: Simon Rozman <simon@rozman.si>

UnitTests/Win.cpp

@@ -31,6 +31,12 @@ namespace UnitTests
 			}
 		}
 
+		TEST_METHOD(CreateWellKnownSid)
+		{
+			std::unique_ptr<SID> sid;
+			Assert::IsTrue(::CreateWellKnownSid(WinBuiltinAdministratorsSid, NULL, sid));
+		}
+
 		TEST_METHOD(library)
 		{
 			winstd::library lib_shell32(LoadLibraryEx(_T("shell32.dll"), NULL, LOAD_LIBRARY_AS_DATAFILE | LOAD_LIBRARY_AS_IMAGE_RESOURCE));

include/WinStd/Win.h

@@ -1240,6 +1240,33 @@ static _Success_(return != 0) BOOL LookupAccountSidW(_In_opt_z_ LPCWSTR lpSystem
     return FALSE;
 }
 
+///
+/// Creates a SID for predefined aliases.
+///
+/// \sa [CreateWellKnownSid function](https://learn.microsoft.com/en-us/windows/win32/api/securitybaseapi/nf-securitybaseapi-createwellknownsid)
+///
+static _Success_(return != FALSE) BOOL CreateWellKnownSid(_In_ WELL_KNOWN_SID_TYPE WellKnownSidType, _In_opt_ PSID DomainSid, _Inout_ std::unique_ptr<SID> &Sid)
+{
+    BYTE szStackBuffer[WINSTD_STACK_BUFFER_BYTES/sizeof(BYTE)];
+    DWORD dwSize = sizeof(szStackBuffer);
+
+    // Try with stack buffer first.
+    if (CreateWellKnownSid(WellKnownSidType, DomainSid, szStackBuffer, &dwSize)) {
+        // Copy from stack.
+        Sid.reset((SID*)new BYTE[dwSize]);
+        memcpy(Sid.get(), szStackBuffer, dwSize);
+        return TRUE;
+    }
+    for (;;) {
+        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+            return FALSE;
+        // Allocate on heap and retry.
+        Sid.reset((SID*)new BYTE[dwSize]);
+        if (CreateWellKnownSid(WellKnownSidType, DomainSid, Sid.get(), &dwSize))
+            return TRUE;
+    }
+}
+
 ///
 /// Retrieves a specified type of information about an access token. The calling process must have appropriate access rights to obtain the information.
 ///