GetSystemDirectory

GetSystemDirectory is a Win32 API function in Kernel32.dll that retrieves the path of the system directory for the current process. The system directory typically contains core Windows system files such as DLLs.

The function signature is UINT GetSystemDirectory(LPTSTR lpBuffer, UINT uSize); It writes the path to the buffer pointed to by lpBuffer, which has a size expressed in TCHARs as uSize. On success, the return value is the length of the string copied to the buffer, not including the terminating null character. If the buffer is too small, the return value is the size of the buffer that would have been required, in TCHARs, including the terminating null character.

The returned string is null-terminated. The system directory returned by GetSystemDirectory can be used to construct paths to system components by appending file names, such as dynamic-link libraries, executables, or other system files.

Notes and considerations include platform and architecture behavior. On 64-bit Windows, the value returned can depend on the process architecture due to file system redirection (WOW64). A 64-bit process typically receives C:\Windows\System32, while a 32-bit process running under WOW64 may receive C:\Windows\SysWOW64. For scenarios requiring the true, non-mirrored system directory, developers may combine GetSystemDirectory with additional checks (such as IsWow64Process or GetNativeSystemInfo) to determine the appropriate path.

See also GetSystemDirectoryA and GetSystemDirectoryW for ANSI and Unicode variants, GetWindowsDirectory, and IsWow64Process.

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