LoadLibraryW

LoadLibraryW is a Windows API function that loads a dynamic-link library (DLL) into the address space of the calling process. It is the wide-character version of LoadLibrary and accepts a single parameter: a null-terminated wide string specifying the file name or path of the module to load. The function returns a handle to the loaded module (HMODULE) on success or NULL on failure. When successful, the module’s reference count is incremented.

If the library is loaded for the first time, LoadLibraryW causes the DLL to be initialized by invoking its DllMain function with the DLL_PROCESS_ATTACH reason. If the library is already loaded, the function returns a handle to the existing module and increments its reference count. LoadLibraryW also loads any dependent DLLs required by the module, using the process’s current search order to locate them. The module’s code then becomes available for use via GetProcAddress to obtain function pointers and for calling the library’s exported routines. To unload the module, FreeLibrary must be invoked to decrement the reference count.

Usage commonly involves obtaining a function pointer from the loaded library with GetProcAddress after a successful LoadLibraryW, performing the required operations, and then calling FreeLibrary when the library is no longer needed. For more control over how libraries are searched and loaded, LoadLibraryExW provides flags that modify the search behavior.

Error handling is performed by checking for NULL return and querying GetLastError for the specific failure code. Security considerations include avoiding DLL search-order hijacking by using absolute paths or by configuring the process to use controlled DLL search paths (e.g., via SetDefaultDllDirectories or AddDllDirectory). LoadLibraryW is part of the Windows API and is declared in Kernel32.dll, typically used in C/C++ and other languages that interoperate with native Windows APIs.