Added nstd_os_windows_shared_lib_add_dir.

Author: RustEnthusiast

include/nstd/os/windows/shared_lib.h

@@ -1,5 +1,6 @@
 #ifndef NSTD_OS_WINDOWS_SHARED_LIB_H
 #define NSTD_OS_WINDOWS_SHARED_LIB_H
+#include "../../core/def.h"
 #include "../../core/optional.h"
 #include "../../nstd.h"
 
@@ -12,6 +13,22 @@ typedef struct {
 /// An optional (possibly null) shared Windows library handle.
 NSTDOptional(NSTDWindowsSharedLib) NSTDWindowsOptionalSharedLib;
 
+/// Adds a directory to the system's search path used to load shared libraries.
+///
+/// # Parameters:
+///
+/// - `const NSTDChar *path` - A path to a directory to search when looking for DLLs. Pass null to
+/// restore the default search order.
+///
+/// # Returns
+///
+/// `NSTDErrorCode errc` - Nonzero on error.
+///
+/// # Safety
+///
+/// See <https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setdlldirectorya>.
+NSTDAPI NSTDErrorCode nstd_os_windows_shared_lib_add_dir(const NSTDChar *path);
+
 /// Loads a shared library/module by name.
 ///
 /// # Parameters:

src/os/windows/shared_lib.rs

@@ -1,6 +1,11 @@
 //! Shared library/module access for Windows.
-use crate::{core::optional::NSTDOptional, NSTDAny, NSTDAnyMut, NSTDChar, NSTDInt};
-use windows_sys::Win32::System::LibraryLoader::{FreeLibrary, GetProcAddress, LoadLibraryA};
+use crate::{
+    core::{def::NSTDErrorCode, optional::NSTDOptional},
+    NSTDAny, NSTDAnyMut, NSTDChar, NSTDInt,
+};
+use windows_sys::Win32::System::LibraryLoader::{
+    FreeLibrary, GetProcAddress, LoadLibraryA, SetDllDirectoryA,
+};
 
 /// A handle to a loaded library.
 #[repr(C)]
@@ -20,6 +25,28 @@ impl Drop for NSTDWindowsSharedLib {
 /// An optional (possibly null) shared Windows library handle.
 pub type NSTDWindowsOptionalSharedLib = NSTDOptional<NSTDWindowsSharedLib>;
 
+/// Adds a directory to the system's search path used to load shared libraries.
+///
+/// # Parameters:
+///
+/// - `const NSTDChar *path` - A path to a directory to search when looking for DLLs. Pass null to
+/// restore the default search order.
+///
+/// # Returns
+///
+/// `NSTDErrorCode errc` - Nonzero on error.
+///
+/// # Safety
+///
+/// See <https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setdlldirectorya>.
+#[inline]
+#[cfg_attr(feature = "clib", no_mangle)]
+pub unsafe extern "C" fn nstd_os_windows_shared_lib_add_dir(
+    path: *const NSTDChar,
+) -> NSTDErrorCode {
+    (SetDllDirectoryA(path.cast()) == 0).into()
+}
+
 /// Loads a shared library/module by name.
 ///
 /// # Parameters: