rust/library/std/tests/switch-stdout.rs
Nicholas Nethercote 84ac80f192 Reformat use declarations.
The previous commit updated `rustfmt.toml` appropriately. This commit is
the outcome of running `x fmt --all` with the new formatting options.
2024-07-29 08:26:52 +10:00

72 lines
1.9 KiB
Rust

#![cfg(any(target_family = "unix", target_family = "windows"))]
use std::fs::File;
use std::io::{Read, Write};
mod common;
#[cfg(unix)]
use std::os::fd::OwnedFd;
#[cfg(windows)]
use std::os::windows::io::OwnedHandle;
#[cfg(unix)]
fn switch_stdout_to(file: OwnedFd) -> OwnedFd {
use std::os::unix::prelude::*;
extern "C" {
fn dup(old: i32) -> i32;
fn dup2(old: i32, new: i32) -> i32;
}
unsafe {
let orig_fd = dup(1);
assert_ne!(orig_fd, -1);
let res = OwnedFd::from_raw_fd(orig_fd);
assert_eq!(dup2(file.as_raw_fd(), 1), 1);
res
}
}
#[cfg(windows)]
fn switch_stdout_to(file: OwnedHandle) -> OwnedHandle {
use std::os::windows::prelude::*;
extern "system" {
fn GetStdHandle(nStdHandle: u32) -> *mut u8;
fn SetStdHandle(nStdHandle: u32, handle: *mut u8) -> i32;
}
const STD_OUTPUT_HANDLE: u32 = (-11i32) as u32;
const INVALID_HANDLE_VALUE: *mut u8 = !0 as *mut u8;
unsafe {
let orig_hdl = GetStdHandle(STD_OUTPUT_HANDLE);
assert!(!orig_hdl.is_null() && orig_hdl != INVALID_HANDLE_VALUE);
let rc = SetStdHandle(STD_OUTPUT_HANDLE, file.into_raw_handle() as *mut _);
assert!(rc != 0);
OwnedHandle::from_raw_handle(orig_hdl as _)
}
}
#[test]
#[cfg_attr(miri, ignore)] // dup/SetStdHandle not supported by Miri
fn switch_stdout() {
let temp = common::tmpdir();
let path = temp.join("switch-stdout-output");
let f = File::create(&path).unwrap();
let mut stdout = std::io::stdout();
stdout.write(b"foo\n").unwrap();
stdout.flush().unwrap();
let orig_hdl = switch_stdout_to(f.into());
stdout.write(b"bar\n").unwrap();
stdout.flush().unwrap();
switch_stdout_to(orig_hdl);
let mut contents = String::new();
File::open(&path).unwrap().read_to_string(&mut contents).unwrap();
assert_eq!(contents, "bar\n");
}