Rust for Windows

https://kennykerr.ca/rust-getting-started
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Rust for Windows provides comprehensive Rust bindings for the Windows API, enabling safe and...
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### Get Computer Name (Two-Step Call with Vec)

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Demonstrates the two-step process for getting the computer name using `GetComputerNameW`. The first call determines the required buffer size, and the second call populates a `Vec` buffer. This method involves a heap allocation.

```rust
#![allow(unused)]
fn main() {
let mut buff_len = 0u32;

unsafe {
    // this function will return an error code because it
    // did not actually write the string. This is normal.
    let e = GetComputerNameW(None, &mut buff_len).unwrap_err();
    debug_assert_eq!(e.code(), HRESULT::from(ERROR_BUFFER_OVERFLOW));
}

// buff len now has the length of the string (in UTF-16 characters)
// the function would like to write. This *includes* the
// null terminator. Let's create a vector buffer and feed that to the function.
let mut buffer = Vec::<u16>::with_capacity(buff_len as usize);

unsafe {
    WindowsProgramming::GetComputerNameW(
        Some(PWSTR(buffer.as_mut_ptr())),
        &mut buff_len).unwrap();

    // set the vector length
    // buff_len now includes the size, which *does not include* the null terminator.
    // let's set the length to just before the terminator so we don't have to worry
    // about it in later conversions.
    buffer.set_len(buff_len);
}

// we can now convert this to a valid Rust string
// omitting the null terminator
String::from_utf16_lossy(&buffer)
}

```

--------------------------------

### Example Output

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

The expected output when running the complete sample code, showing the final count of the incremented counter.

```text
counter: 10
```

--------------------------------

### Get Computer Name (widestring crate)

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Demonstrates using the `widestring` crate to work directly with UTF-16 strings. This example retrieves the computer name into a buffer and then creates a `Utf16Str` slice, allowing for direct display or further UTF-16 manipulation without immediate conversion to UTF-8.

```rust
#![allow(unused)]
fn main() {
// for this example, we'll just use an array again

let mut name = [0u16; MAX_COMPUTERNAME_LENGTH as usize + 1];
let mut len = name.len() as u32;

unsafe {
    GetComputerNameW(
        Some(PWSTR(name.as_mut_ptr())),
        &mut len)
        .unwrap();
}

// we can make a UTF16Str slice directly from the buffer,
// without needing to do any copy. This will error if the buffer
// isn't valid UTF-16. 
let wstr = Utf16Str::from_slice(&name[..len as usize])
    .unwrap();

// this can be displayed as is.
println!("Computer name is {}", wstr);

// we can also transfer it into owned string, which can
}

```

--------------------------------

### Add windows-targets and windows-bindgen to Cargo.toml

Source: https://kennykerr.ca/rust-getting-started/standalone-code-generation.html

Add the windows-targets crate as a regular dependency and windows-bindgen as a dev dependency to your Cargo.toml file. This setup ensures you have the necessary import libraries and the tool for generating bindings.

```toml
[dependencies.windows-targets]
version = "0.52"

[dev-dependencies.windows-bindgen]
version = "0.52"

```

--------------------------------

### Get Computer Name (Array, Single Call)

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Optimizes getting the computer name by using a fixed-size array, avoiding heap allocation. This is possible because the maximum computer name length is known at compile time. It also skips the two-step call by ensuring the buffer is sufficiently large.

```rust
#![allow(unused)]
fn main() {
// avoid the heap allocation since we already know how big this 
// buffer needs to be at compile time. 

let mut name = [0u16; MAX_COMPUTERNAME_LENGTH as usize + 1];
let mut len = name.len() as u32;

// we can also skip the two-step call, since we know our buffer
// is already larger than any possible computer name

unsafe {
    GetComputerNameW(
        Some(PWSTR(name.as_mut_ptr())),
        &mut len)
        .unwrap();
}

// the function writes to len with the number of 
// UTF-16 characters in the string. We can use this
// to slice the buffer. 
String::from_utf16_lossy(&name[..len as usize])
}

```

--------------------------------

### Import Windows API Functions in Rust

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Use a 'use' declaration to make Windows API functions and types more accessible in your Rust code. This example imports Result and threading-related types.

```rust
#![allow(unused)]
fn main() {
use windows::{core::Result, Win32::System::Threading::*};
}
```

--------------------------------

### Get Computer Name (HStringBuilder)

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Uses `HStringBuilder` from the `windows-strings` crate for a more ergonomic approach to generating strings. This method handles heap allocation and null termination automatically, simplifying the conversion to an `HSTRING` and then a Rust `String`.

```rust
#![allow(unused)]
fn main() {
// pre-allocate a HSTRING buffer on the heap
// (you do not need to add one to len for the null terminator,
// the hstring builder will handle that automatically)

let mut buffer = HStringBuilder::new(
    MAX_COMPUTERNAME_LENGTH as usize);

let mut len = buffer.len() as u32 + 1;

unsafe {
    GetComputerNameW(
        Some(PWSTR(buffer.as_mut_ptr())),
        &mut len).unwrap();
}

// we can now generate a valid HSTRING from the HStringBuilder
let buffer = HSTRING::from(buffer);

// and we can now return a rust string from the HSTRING:
buffer.to_string_lossy()
}

```

--------------------------------

### Generate Windows Bindings with windows-bindgen

Source: https://kennykerr.ca/rust-getting-started/standalone-code-generation.html

Write a test function that uses the `windows_bindgen::bindgen` function to generate Rust bindings. Specify the output file, configuration, and filters for the APIs you want to include. This example generates bindings for `GetTickCount`.

```rust
#![allow(unused)]
fn main() {
#[test]
fn bindgen() {
    let args = [
        "--out",
        "src/bindings.rs",
        "--config",
        "flatten",
        "--filter",
        "Windows.Win32.System.SystemInformation.GetTickCount",
    ];

    windows_bindgen::bindgen(args).unwrap();
}
}

```

--------------------------------

### Use Generated Windows API Bindings

Source: https://kennykerr.ca/rust-getting-started/standalone-code-generation.html

Import the generated bindings module and call Windows API functions within an unsafe block. This example demonstrates calling the `GetTickCount` function from the generated `bindings.rs` file.

```rust
mod bindings;

fn main() {
    unsafe {
        println!("{}", bindings::GetTickCount());
    }
}

```

--------------------------------

### Import necessary modules

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-com-api.html

Import core types and COM-related modules from the windows crate to facilitate API calls.

```rust
use windows::{core::*, Win32::System::Com::*};

```

--------------------------------

### Configure windows Crate Dependency

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Add the windows crate to your Cargo.toml file and enable the necessary feature for Data::Xml::Dom.

```toml
[dependencies.windows]
version = "0.52"
features = [
    "Data_Xml_Dom",
]

```

--------------------------------

### Basic Rust Main Function with Result

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Set up a main function that returns a Result<()> for automatic error propagation, simplifying WinRT API calls.

```rust
fn main() -> Result<()> {

    Ok(())
}

```

--------------------------------

### Basic Main Function Structure for Unsafe Operations

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Set up a main function that returns a Result and includes an unsafe block. Many Windows API calls are inherently unsafe and require this explicit block.

```rust
__
fn main() -> Result<()> {
    unsafe {
        
    }

    Ok(())
}

```

--------------------------------

### Call Windows APIs

Source: https://kennykerr.ca/rust-getting-started/understanding-windows-targets.html

Make calls to Windows APIs after defining them using the `link` macro. Ensure these calls are within an `unsafe` block as they interact with external system functions.

```rust
fn main() {
    unsafe {
        SetLastError(1234);
        assert_eq!(GetLastError(), 1234);
    }
}
```

--------------------------------

### Add windows-targets to Cargo.toml

Source: https://kennykerr.ca/rust-getting-started/understanding-windows-targets.html

Add this to your Cargo.toml file to include the windows-targets crate for linker support.

```toml
[dependencies.windows-targets]
version = "0.52"
```

--------------------------------

### Add windows crate dependency

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-com-api.html

Configure your Cargo.toml to include the windows crate with the necessary features for COM interop.

```toml
[dependencies.windows]
version = "0.52"
features = [
    "Win32_System_Com",
]

```

--------------------------------

### Import WinRT APIs in Rust

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Use a 'use' declaration to make WinRT APIs like XmlDocument and core helpers more accessible in your Rust code.

```rust
use windows::{core::*, Data::Xml::Dom::XmlDocument};

```

--------------------------------

### Add Windows Crate Dependency

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Specify the 'windows' crate and required features in your Cargo.toml file. Features like Win32_Foundation and Win32_System_Threading are common for Windows API interactions.

```toml
[dependencies.windows]
version = "0.52"
features = [
    "Win32_Foundation",
    "Win32_System_Threading",
]
```

--------------------------------

### Create a new XmlDocument Instance

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Instantiate an XmlDocument object using its 'new' method. WinRT calls are generally safe and do not require an 'unsafe' block.

```rust
let doc = XmlDocument::new()?;

```

--------------------------------

### Define a C-Style Callback Function

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Implement a callback function with the 'extern "system"' ABI. This function will be executed by the thread pool and should handle shared state safely, like incrementing a RwLock-protected counter.

```rust
#![allow(unused)]
fn main() {
extern "system" fn callback(_: PTP_CALLBACK_INSTANCE, _: *mut std::ffi::c_void, _: PTP_WORK) {
    let mut counter = COUNTER.write().unwrap();
    *counter += 1;
}
}
```

--------------------------------

### Call MessageBoxW with HSTRING literals

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Use the h! macro from 'windows-strings' to create HSTRINGs from string literals for calling Windows APIs. This handles null termination and UTF-16 conversion.

```rust
#![allow(unused)]
fn main() {
// use string literals when calling a message box. 
let text = h!("Hello from rust!");
let caption = h!("From Rust");

unsafe {
    // call the MessageBox function and return MESSAGEBOX_RESULT
    UI::WindowsAndMessaging::MessageBoxW(None, 
        text, 
        caption,
        UI::WindowsAndMessaging::MESSAGEBOX_STYLE(0) // message box OK
    )
}
}
```

--------------------------------

### Call MessageBoxW with manually converted Rust strings

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Manually convert Rust strings to UTF-16 byte vectors with null terminators to call Windows APIs. This method is more verbose than using macros.

```rust
#![allow(unused)]
fn main() {
// this works for any &str, not just literals
let text = "I am a message to display!";
let caption = "Message from Rust!";

// convert our text and caption to UTF-16 bytes,
// add null terminators using chain, and then collect
// the result into a vec
let text = text.encode_utf16()
    .chain(iter::once(0u16))
    .collect::<Vec<u16>>();
let caption = caption.encode_utf16()
    .chain(iter::once(0u16))
    .collect::<Vec<u16>>();

// call the API, wrapping our vec pointer in a PCWSTR struct.
unsafe {
    UI::WindowsAndMessaging::MessageBoxW(None, 
        PCWSTR(text.as_ptr()), 
        PCWSTR(caption.as_ptr()),
        UI::WindowsAndMessaging::MESSAGEBOX_STYLE(0) // message box OK
    )
}
}
```

--------------------------------

### Call MessageBoxW with HSTRING from Rust strings

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Use HSTRING::from() to convert Rust strings to HSTRINGs, which can be used directly with Windows APIs expecting PCWSTR. This simplifies UTF-16 conversion and null termination.

```rust
#![allow(unused)]
fn main() {
let text = "I am a message to display!";
let caption = "Message from Rust!";

// convert our strings into UTF-16 
// this incurrs a performance cost because there is a copy + conversion
// from the standard rust utf-8 string.

// we are using HSTRING, which is an immutable UTF-16 string
// in the windows-strings crate. It can be generated from a standard
// rust string, and it can be used in place of a PCWSTR anywhere in the
// windows API. 

unsafe {
    UI::WindowsAndMessaging::MessageBoxW(None, 
        &HSTRING::from(text), 
        &HSTRING::from(caption),
        UI::WindowsAndMessaging::MESSAGEBOX_STYLE(0) // message box OK
    )
    }
}
```

--------------------------------

### Inspect IUri interface methods

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-com-api.html

Call methods like GetDomain and GetPort on the IUri interface to retrieve URI components. These methods invoke virtual functions through the COM interface.

```rust
let domain = uri.GetDomain()?;
let port = uri.GetPort()?;

println!("{domain} ({port})");

```

--------------------------------

### Rust Implementation of CreateJsonValidator API

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

This function serves as the entry point for the CreateJsonValidator API, translating the HRESULT return type to a standard Rust Result for internal error handling.

```rust
#![allow(unused)]
fn main() {
#[no_mangle]
unsafe extern "system" fn CreateJsonValidator(
    schema: *const u8,
    schema_len: usize,
    handle: *mut usize,
) -> HRESULT {
    create_validator(schema, schema_len, handle).into()
}
}
```

--------------------------------

### Call CreateUri function

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-com-api.html

Use the CreateUri function to parse a URI string into an IUri interface. The w! macro is used for null-terminated wide strings.

```rust
let uri = CreateUri(w!("http://kennykerr.ca"), Uri_CREATE_CANONICALIZE, 0)?;

```

--------------------------------

### Cargo.toml for JSON Validator Project

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

This Cargo.toml file configures the Rust project for building a dynamic library (cdylib) and specifies dependencies for JSON parsing and Windows API support.

```toml
[package]
name = "json_validator"
edition = "2021"

[lib]
crate-type = ["cdylib"]

[dependencies]
jsonschema = "0.17"
serde_json = "1.0"

[dependencies.windows]
version = "0.52"
features = [
    "Win32_Foundation",
    "Win32_System_Com",
]
```

--------------------------------

### Helper Function for Parsing Raw JSON Data

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Safely parses raw byte slices into `serde_json::Value`, handling null pointers and UTF-8 conversion errors. It maps underlying errors to Windows HRESULTs.

```rust
#![allow(unused)]
fn main() {
unsafe fn json_from_raw_parts(value: *const u8, value_len: usize) -> Result<serde_json::Value> {
    if value.is_null() {
        return Err(E_POINTER.into());
    }

    let value = std::slice::from_raw_parts(value, value_len);

    let value =
        std::str::from_utf8(value).map_err(|_| Error::from(ERROR_NO_UNICODE_TRANSLATION))?;

    serde_json::from_str(value).map_err(|error| Error::new(E_INVALIDARG, format!("{error}").into()))
}
}
```

--------------------------------

### Define External Functions with link Macro

Source: https://kennykerr.ca/rust-getting-started/understanding-windows-targets.html

Use the `link` macro to declare external functions from DLLs that your Rust code will call. This macro handles the necessary linker configurations.

```rust
#![allow(unused)]
fn main() {
windows_targets::link!("kernel32.dll" "system" fn SetLastError(code: u32));
windows_targets::link!("kernel32.dll" "system" fn GetLastError() -> u32);
}
```

--------------------------------

### Validate JSON Function Entry Point

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Public entry point for validating a JSON value against a compiled schema. Forwards the call to the internal `validate` function and converts the result to HRESULT.

```rust
#![allow(unused)]
fn main() {
#[no_mangle]
unsafe extern "system" fn ValidateJson(
    handle: usize,
    value: *const u8,
    value_len: usize,
    sanitized_value: *mut *mut u8,
    sanitized_value_len: *mut usize,
) -> HRESULT {
    validate(
        handle,
        value,
        value_len,
        sanitized_value,
        sanitized_value_len,
    )
    .into()
}
}
```

--------------------------------

### Rust Use Declarations for JSON Validator

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Imports necessary types and traits from the `jsonschema`, `windows`, and standard library for implementing the JSON validator API.

```rust
#![allow(unused)]
fn main() {
use jsonschema::JSONSchema;
use windows::{core::*, Win32::Foundation::*, Win32::System::Com::*};
}
```

--------------------------------

### Basic unsafe block for COM calls

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-com-api.html

Wrap COM API calls within an unsafe block, as they involve foreign function interfaces.

```rust
fn main() -> Result<()> {
    unsafe {
        
        Ok(())
    }
}

```

--------------------------------

### Load XML String into XmlDocument

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Use the LoadXml method to parse an XML string. The 'h!' macro is provided by the windows crate for creating HSTRINGs.

```rust
doc.LoadXml(h!("<html>hello world</html>"))?;

```

--------------------------------

### Return First Error in Rust

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

This snippet demonstrates how to return the first error from a collection of errors, commonly used in validation scenarios.

```rust
Err(Error::new(E_INVALIDARG, message.into()))
}
```

--------------------------------

### Append to Utf16String in Rust

Source: https://kennykerr.ca/rust-getting-started/string-tutorial.html

Demonstrates appending a string literal to a Utf16String using the '+' operator and a macro for efficient conversion.

```rust
let mut wstring = Utf16String::from(wstr);

// let's append another string. We'll use a macro to avoid
// any UTF conversion at runtime. 
wstring = wstring + utf16str!("!!!");
```

--------------------------------

### Initialize a Shared Counter with RwLock

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Declare a static counter protected by a RwLock for safe concurrent access from multiple threads. This is essential when using thread pools for shared mutable state.

```rust
#![allow(unused)]
fn main() {
static COUNTER: std::sync::RwLock<i32> = std::sync::RwLock::new(0);
}
```

--------------------------------

### Create JSON Validator Function

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Compiles a JSON schema from raw parts into a usable validator handle. Handles null pointers and invalid schema formats, returning a boxed compiled schema on success.

```rust
#![allow(unused)]
fn main() {
unsafe fn create_validator(schema: *const u8, schema_len: usize, handle: *mut usize) -> Result<()> {
    let schema = json_from_raw_parts(schema, schema_len)?;

    let compiled = JSONSchema::compile(&schema)
        .map_err(|error| Error::new(E_INVALIDARG, error.to_string().into()))?;

    if handle.is_null() {
        return Err(E_POINTER.into());
    }

    *handle = Box::into_raw(Box::new(compiled)) as usize;

    Ok(())
}
}
```

--------------------------------

### Inspect XmlDocument Element

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-winrt-api.html

Retrieve the document element, assert its node name, and print its inner text. These methods invoke virtual functions through COM interfaces.

```rust
let root = doc.DocumentElement()?;
assert!(root.NodeName()? == "html");
println!("{}", root.InnerText()?);

```

--------------------------------

### Create a Thread Pool Work Object

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Use the CreateThreadpoolWork function to create a work object. This object represents a unit of work to be submitted to the thread pool. It requires a callback function.

```rust
#![allow(unused)]
fn main() {
let work = CreateThreadpoolWork(Some(callback), None, None)?;
}
```

--------------------------------

### Wait for Thread Pool Callbacks to Complete

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Employ WaitForThreadpoolWorkCallbacks to block execution until all submitted work items have finished. Setting the second parameter to 'false' ensures the wait is blocking.

```rust
#![allow(unused)]
fn main() {
WaitForThreadpoolWorkCallbacks(work, false);
}
```

--------------------------------

### Submit Work to the Thread Pool

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Use SubmitThreadpoolWork to add the created work object to the thread pool's queue. This function can be called multiple times to submit the same work repeatedly.

```rust
#![allow(unused)]
fn main() {
for _ in 0..10 {
    SubmitThreadpoolWork(work);
}
}
```

--------------------------------

### Internal create_validator Function Signature

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

The internal `create_validator` function mirrors the public API but uses Rust's `Result` type for more idiomatic error propagation.

```rust
#![allow(unused)]
fn main() {
unsafe fn create_validator(schema: *const u8, schema_len: usize, handle: *mut usize) -> Result<()> {
    // ...

    Ok(())
}
}
```

--------------------------------

### Internal JSON Validation Logic

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Performs the core JSON validation logic. It dereferences the schema handle, parses the input value, and validates it against the schema, optionally producing a sanitized output.

```rust
unsafe fn validate(
    handle: usize,
    value: *const u8,
    value_len: usize,
    sanitized_value: *mut *mut u8,
    sanitized_value_len: *mut usize,
) -> Result<()> {
    // ...
}
```

```rust
if handle == 0 {
    return Err(E_HANDLE.into());
}

let schema = &*(handle as *const JSONSchema);
```

```rust
let value = json_from_raw_parts(value, value_len)?;
```

```rust
if schema.is_valid(&value) {
    if !sanitized_value.is_null() && !sanitized_value_len.is_null() {
        let value = value.to_string();

        *sanitized_value = CoTaskMemAlloc(value.len()) as _;

        if (*sanitized_value).is_null() {
            return Err(E_OUTOFMEMORY.into());
        }

        (*sanitized_value).copy_from(value.as_ptr(), value.len());
        *sanitized_value_len = value.len();
    }

    Ok(())
} else {
    // ...
}
```

```rust
let mut message = String::new();

if let Some(error) = schema.validate(&value).unwrap_err().next() {
    message = error.to_string();
}

```

--------------------------------

### Win32-style JSON Validator API Declarations

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

These are the C++ style declarations for the JSON validator API functions: CreateJsonValidator, ValidateJson, and CloseJsonValidator.

```c++
HRESULT __stdcall CreateJsonValidator(char const* schema, size_t schema_len, uintptr_t* handle);

HRESULT __stdcall ValidateJson(uintptr_t handle, char const* value, size_t value_len, char** sanitized_value, size_t* sanitized_value_len);

void __stdcall CloseJsonValidator(uintptr_t handle);
```

--------------------------------

### Print Final Counter Value

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Read and print the final value of the shared counter after all thread pool operations have completed. This demonstrates the result of the concurrent increments.

```rust
#![allow(unused)]
fn main() {
let counter = COUNTER.read().unwrap();
println!("counter: {}", *counter);
}
```

--------------------------------

### Close JSON Validator Function

Source: https://kennykerr.ca/rust-getting-started/implement-win32-api.html

Frees the memory allocated for a compiled JSON schema validator. Accepts a handle (usize) and safely drops the boxed schema if the handle is non-zero.

```rust
#![allow(unused)]
fn main() {
#[no_mangle]
unsafe extern "system" fn CloseJsonValidator(handle: usize) {
    if handle != 0 {
        _ = Box::from_raw(handle as *mut JSONSchema);
    }
}
}
```

--------------------------------

### Close the Thread Pool Work Object

Source: https://kennykerr.ca/rust-getting-started/calling-your-first-windows-api.html

Call CloseThreadpoolWork to release the resources associated with the work object after it's no longer needed. This prevents memory leaks.

```rust
#![allow(unused)]
fn main() {
CloseThreadpoolWork(work);
}
```
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