Replace VirtualQueryEx() call by GetModuleHandleExA() call

Usage of VirtualQueryEx() call is needed for retrieving HMODULE of passed
function address and it is just an undocumented hack. Based on @rhabacker's
tests it is unstable and does not work correctly.

https://github.com/dlfcn-win32/dlfcn-win32/pull/72#issuecomment-656581418

So replace VirtualQueryEx() call by standard GetModuleHandleExA() function
with special GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS flag which should do
the same thing but it is documented and it is working correctly.

1 files changed, 2 insertions, 16 deletions

diff --git a/dlfcn.c b/dlfcn.c
index 01e878b..a45a619 100644
--- a/dlfcn.c
+++ b/dlfcn.c
@@ -369,24 +369,10 @@ void *dlsym( void *handle, const char *name )
          * The next object is the one found upon the application of a load

          * order symbol resolution algorithm. To get caller function of dlsym()

          * use _ReturnAddress() intrinsic. To get HMODULE of caller function

-         * use undocumented hack from https://stackoverflow.com/a/2396380

-         * The HMODULE of a DLL is the same value as the module's base address.

+         * use standard GetModuleHandleExA() function.

          */

-        MEMORY_BASIC_INFORMATION info;

-        size_t sLen;

-        sLen = VirtualQueryEx( hCurrentProc, _ReturnAddress(), &info, sizeof( info ) );

-        if( sLen != sizeof( info ) )

-        {

-            if( sLen != 0 )

-                SetLastError( ERROR_INVALID_PARAMETER );

+        if( !GetModuleHandleExA( GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, (LPCSTR) _ReturnAddress( ), &hCaller ) )

             goto end;

-        }

-        hCaller = (HMODULE) info.AllocationBase;

-        if( !hCaller )

-        {

-            SetLastError( ERROR_INVALID_PARAMETER );

-            goto end;

-        }

     }

 

     if( handle != RTLD_NEXT )