Win32 Kernel API Functions

This section provides an overview and reference for fundamental Kernel API functions in the Windows operating system. These functions are crucial for managing system resources, processes, threads, and core operating system operations.

Core Concepts

The Win32 Kernel API is the lowest-level API exposed by the Windows operating system for user-mode applications. It provides access to essential system services, including:

Process and thread creation and management.
Memory allocation and manipulation.
File and I/O operations.
Synchronization primitives.
System information retrieval.

Key Kernel Functions

Process and Thread Management

`CreateProcess`

BOOL CreateProcess( LPCSTR lpApplicationName, LPSTR lpCommandLine, LPSECURITY_ATTRIBUTES lpProcessAttributes, LPSECURITY_ATTRIBUTES lpThreadAttributes, BOOL bInheritHandles, DWORD dwCreationFlags, LPVOID lpEnvironment, LPCSTR lpCurrentDirectory, STARTUPINFO* lpStartupInfo, PROCESS_INFORMATION* lpProcessInformation );

Creates a new process and its primary thread. The new process is represented by a handle to both the process and its primary thread. The function replaces the calling process with the specified application module.

`GetCurrentProcessId`

DWORD GetCurrentProcessId(void);

Retrieves the process identifier of the calling process.

`CreateThread`

HANDLE CreateThread( LPSECURITY_ATTRIBUTES lpThreadAttributes, SIZE_T dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress, LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId );

Creates a thread to execute within the virtual address space of the calling process.

`ExitThread`

VOID ExitThread( DWORD dwExitCode );

Terminates the calling thread and provides the exit code.

Memory Management

`VirtualAlloc`

LPVOID VirtualAlloc( LPVOID lpAddress, SIZE_T dwSize, DWORD flAllocationType, DWORD flProtect );

Reserves, commits, or changes the state of a region of pages in the virtual address space of the calling process.

`VirtualFree`

BOOL VirtualFree( LPVOID lpAddress, SIZE_T dwSize, DWORD dwFreeType );

Releases, decommits, or uncommits a region of pages within the virtual address space of the calling process.

Handle Management

`CloseHandle`

BOOL CloseHandle( HANDLE hObject );

Closes an open object handle.

`DuplicateHandle`

BOOL DuplicateHandle( HANDLE hSourceProcessHandle, HANDLE hSourceHandle, HANDLE hTargetProcessHandle, LPHANDLE lpTargetHandle, DWORD dwDesiredAccess, BOOL bInheritHandle, DWORD dwOptions );

Duplicates an existing handle in the system.

Table of Common Kernel Functions

Function Name	Description
`CreateProcess`	Creates a new process.
`GetCurrentProcess`	Retrieves a pseudo-handle for the current process.
`GetCurrentProcessId`	Retrieves the identifier of the current process.
`CreateThread`	Creates a new thread.
`ExitProcess`	Terminates the current process.
`ExitThread`	Terminates the calling thread.
`VirtualAlloc`	Allocates memory in the virtual address space.
`VirtualFree`	Frees memory allocated by `VirtualAlloc`.
`CloseHandle`	Closes an object handle.
`WaitForSingleObject`	Waits until an object becomes signaled.
`Sleep`	Suspends the current thread for a specified interval.

Note: This is a simplified overview. For detailed parameter descriptions, return values, and error handling, please refer to the official Microsoft documentation.

Exploring the Win32 Kernel API is essential for understanding the low-level operations of Windows and for developing system-level software.