winapi - 使用Rust语言使用winapi SetClipboardData

Question

我试图使用Rust中的winapi crate 将数据设置到Windows cipboard中(Rust和win32 api都是新的)。

SetClipboardData调用的输入需要文件类型，C通用指针或Rust中的*mut libc::c_void。
(以下链接的文档)

在最终版本中，我计划复制图像文件，但是使用文本字符串进行测试失败，这是它的代码:

extern crate winapi;
extern crate libc;

fn main() {
    let mut test = "test\r\n";
    let test_ptr: *mut libc::c_void = &mut test as *mut _ as *mut libc::c_void;
    loop {
        if (condition)  
        {
            // let mut test = "test\r\n";  // these commented lets are refered to issue 2
            // let test_ptr: *mut libc::c_void = &mut test as *mut _ as *mut libc::c_void; 
            unsafe {winapi::um::winuser::SetClipboardData(winapi::um::winuser::CF_TEXT, test_ptr);}
        }
    }
}

笔记:

指针转换是通过以下方式实现的:Working with c_void in an FFI

此调用的WinAPI文档:nf-winuser-setclipboarddata

rust 中的

winapi文档:fn.SetClipboardData

问题1:

照原样编写代码，它不会出错，但是也无法正常工作，剪贴板中什么也没有。

问题2:

当指针声明在循环内时，我的程序出现错误，出现错误:process didn't exit successfully: exit code: 0xc0000374, STATUS_HEAP_CORRUPTION)。
这让我感到困惑，因为我期望我的值在堆栈中，而不是堆中。而且，如果我不正确，则winapi希望数据位于堆栈中。

任何帮助，将不胜感激。

Answer 1

所提供的代码存在多个问题。最突出的是，SetClipboardData希望将HANDLE分配给使用GlocalAlloc分配的内存。严格要求在执行操作之前调用OpenClipboard。

一个更微妙的问题是与CF_TEXT一起使用的字符编码要求。此剪贴板格式需要使用ANSI(代码页)编码的文本。由于Rust整个内部都使用Unicode，因此最好改用CF_UNICODETEXT并将其转换为UTF-16。

以下是一个粗略的实现:

[dependencies]
winapi = { version = "0.3.8", features = ["winuser", "winbase"] }

use std::ptr;
use winapi::um::winbase::{GlobalAlloc, GlobalFree, GlobalLock, GlobalUnlock, GMEM_MOVEABLE};
use winapi::um::winuser::{CloseClipboard, OpenClipboard, SetClipboardData, CF_UNICODETEXT};

fn copy_to_clipboard(text: &str) {
    // Needs to be UTF-16 encoded
    let mut text_utf16: Vec<u16> = text.encode_utf16().collect();
    // And zero-terminated before passing it into `SetClipboardData`
    text_utf16.push(0);
    // Allocate memory
    let hglob =
        unsafe { GlobalAlloc(GMEM_MOVEABLE, text_utf16.len() * std::mem::size_of::<u16>()) };
    // Retrieve writeable pointer to memory
    let dst = unsafe { GlobalLock(hglob) };
    // Copy data
    unsafe { ptr::copy_nonoverlapping(text_utf16.as_ptr(), dst as _, text_utf16.len()) };
    // Release writeable pointer
    unsafe { GlobalUnlock(hglob) };

    // Everything is set up now, let's open the clipboard
    unsafe { OpenClipboard(ptr::null_mut()) };
    // And apply data
    unsafe { SetClipboardData(CF_UNICODETEXT, hglob) };

    // Clean up
    unsafe { GlobalFree(hglob) };
    unsafe { CloseClipboard() };
}

fn main() {
    copy_to_clipboard("Hello, world!");
}

为简便起见，已省略了错误处理。该示例旨在说明如何使用winapi crate访问剪贴板。这不是生产就绪的代码质量。

包括错误处理在内的安全实现可能如下所示。它使用scopeguard条板箱进行资源清理:

[dependencies]
winapi = { version = "0.3.8", features = ["winuser", "winbase"] }
scopeguard = "1.1.0"

use scopeguard::defer;
use std::io::Error;
use std::ptr;
use winapi::shared::minwindef::FALSE;
use winapi::um::winbase::{GlobalAlloc, GlobalFree, GlobalLock, GlobalUnlock, GMEM_MOVEABLE};
use winapi::um::winuser::{CloseClipboard, OpenClipboard, SetClipboardData, CF_UNICODETEXT};

fn copy_to_clipboard(text: &str) -> Result<(), Error> {
    // Needs to be UTF-16 encoded
    let mut text_utf16: Vec<u16> = text.encode_utf16().collect();
    // And zero-terminated before passing it into `SetClipboardData`
    text_utf16.push(0);
    // Allocate memory
    let hglob =
        unsafe { GlobalAlloc(GMEM_MOVEABLE, text_utf16.len() * std::mem::size_of::<u16>()) };
    if hglob == ptr::null_mut() {
        return Err(Error::last_os_error());
    }
    // Ensure cleanup on scope exit
    defer!(unsafe { GlobalFree(hglob) };);

    // Retrieve writeable pointer to memory
    let dst = unsafe { GlobalLock(hglob) };
    if dst == ptr::null_mut() {
        return Err(Error::last_os_error());
    }
    // Copy data
    unsafe { ptr::copy_nonoverlapping(text_utf16.as_ptr(), dst as _, text_utf16.len()) };
    // Release writeable pointer
    unsafe { GlobalUnlock(hglob) };

    // Everything is set up now, let's open the clipboard
    let success = unsafe { OpenClipboard(ptr::null_mut()) } != FALSE;
    if !success {
        return Err(Error::last_os_error());
    }
    // Ensure cleanup on scope exit
    defer!(unsafe { CloseClipboard() };);
    // And apply data
    let success = unsafe { SetClipboardData(CF_UNICODETEXT, hglob) } != ptr::null_mut();
    if !success {
        return Err(Error::last_os_error());
    }

    Ok(())
}

fn main() {
    copy_to_clipboard("Hello, world!").expect("Failed to copy text to clipboard.");
}