WinApi2

Microsoft Windows user-mode API access with clean Rust types.

Execution mode

Some Windows APIs execute in several layers:

• The stable user-mode component
• The unstable native component
• The system call to the kernel

For example, to terminate a process, one typically calls the stable user-mode function kernel32.TerminateProcess, which itself calls the unstable native function ntdll.NtTerminateProcess, which then performs a system call to ntoskrnl.NtTerminateProcess.

This crate allows to call every single variant in this chain, but also provides a default option. What the default option uses can be defined with the winapi attribute:

Attribute	Usage
Unspecified	Stable user-mode
native	Unstable native
syscall	Direct system call

The attribute can be specified as an argument to rustc via --cfg winapi="syscall", or used by cargo build by specifying the following in the .cargo/config file at the crate-root:

[target.YOUR_TARGET]
rustflags = ['--cfg', 'winapi="syscall"']

Using the syscall mode/functions

System calls are done by triggering a transition from user- to kernel-mode - the executing thread will end up at a specific function in the Windows kernel. To know which function the user wanted to call, a 0 (ntoskrnl.exe) or 0x1000 (win32k.sys) based index must be specified in the eax register.

The crate loads these indices from the crate::SYSCALL_IDS variable, which must be set by the crate user prior to any winapi2 usage. Either set them explicitly, or call a function like winapi2::SyscallIds::initialize_statically to outsource the task to the library itself:

fn main() {
    // Either outsourced:
    winapi2::SyscallIds::initialize_statically();

    // Or explicit:
    #[cfg(target_arch = "x86")]
    unsafe {
        winapi2::SYSCALL_IDS = Some(winapi2::SyscallIds {
            terminate_process: 0x0001,
            // .. set all the system specific system call ids.
        });
    }

    #[cfg(target_arch = "x86_64")]
    unsafe {
        winapi2::SYSCALL_IDS = Some(winapi2::SyscallIds {
            terminate_process: 0x0001,
            // .. set all the system specific system call ids.
        });
    }

    // Now the `syscall` mode and specific `*_syscall` functions can be used.
    winapi2::Process::current().terminate_syscall(0);
}

Warning: This is architecture specific! It supports 32 bit applications on a 32 bit Windows system, and 64 bit applications on a 64 bit Windows system. Executing a system call in a 32 bit application on a 64 bit Windows system ("WOW64") will not work and potentially crash the application if no exception handlers are set up!

This project assumes target_pointer_width >= 32.

Compiler builtins

This crate optionally provides implementations for the symbols: __chkstk, __fltused, __alldiv, __allrem, __aulldiv and __aullrem (and others of the same kind), if the feature builtins is used:

[dependencies]
winapi2 = { ..., features = ["builtins"] }