Verified Commit 35b30e6f authored by jD91mZM2's avatar jD91mZM2

Fix sigaction Undefind Behavior

Rust does not allow a `fn`-pointer to be null. This fixes that, while
luckily doing it in a way that leaves system calls
backwards-compatible :)
parent dcacbaed
......@@ -107,22 +107,21 @@ impl DerefMut for Packet {
}
}
#[derive(Copy, Clone, Debug)]
#[derive(Copy, Clone, Debug, Default, PartialEq)]
#[repr(C)]
pub struct SigAction {
pub sa_handler: extern "C" fn(usize),
pub sa_handler: Option<extern "C" fn(usize)>,
pub sa_mask: [u64; 2],
pub sa_flags: usize,
}
impl Default for SigAction {
fn default() -> Self {
Self {
sa_handler: unsafe { mem::transmute(0usize) },
sa_mask: [0; 2],
sa_flags: 0,
}
}
#[allow(dead_code)]
unsafe fn _assert_size_of_function_is_sane() {
// Transmuting will complain *at compile time* if sizes differ.
// Rust forbids a fn-pointer from being 0 so to allow SIG_DFL to
// exist, we use Option<extern "C" fn(usize)> which will mean 0
// becomes None
let _ = mem::transmute::<Option<extern "C" fn(usize)>, usize>(None);
}
#[derive(Copy, Clone, Debug, Default, PartialEq)]
......
......@@ -409,3 +409,62 @@ fn unlink() {
fn sched_yield() {
assert_eq!(dbg!(crate::sched_yield()), Ok(0));
}
#[test]
fn sigaction() {
use std::{
mem,
sync::atomic::{AtomicBool, Ordering}
};
let child = unsafe { dbg!(crate::clone(0)).unwrap() };
if child == 0 {
static SA_HANDLER_WAS_RAN: AtomicBool = AtomicBool::new(false);
let pid = dbg!(crate::getpid()).unwrap();
extern "C" fn hello_im_a_signal_handler(signal: usize) {
assert_eq!(dbg!(signal), crate::SIGUSR1);
SA_HANDLER_WAS_RAN.store(true, Ordering::SeqCst);
}
let my_signal_handler = crate::SigAction {
sa_handler: Some(hello_im_a_signal_handler),
..Default::default()
};
dbg!(crate::sigaction(crate::SIGUSR1, Some(&my_signal_handler), None)).unwrap();
dbg!(crate::kill(pid, crate::SIGUSR1)).unwrap(); // calls handler
let mut old_signal_handler = crate::SigAction::default();
dbg!(crate::sigaction(
crate::SIGUSR1,
Some(&crate::SigAction {
sa_handler: unsafe { mem::transmute::<usize, Option<extern "C" fn(usize)>>(crate::SIG_IGN) },
..Default::default()
}),
Some(&mut old_signal_handler)
)).unwrap();
assert_eq!(my_signal_handler, old_signal_handler);
dbg!(crate::kill(pid, crate::SIGUSR1)).unwrap(); // does nothing
dbg!(crate::sigaction(
crate::SIGUSR1,
Some(&crate::SigAction {
sa_handler: unsafe { mem::transmute::<usize, Option<extern "C" fn(usize)>>(crate::SIG_DFL) },
..Default::default()
}),
Some(&mut old_signal_handler)
)).unwrap();
dbg!(crate::kill(pid, crate::SIGUSR1)).unwrap(); // actually exits
} else {
let mut status = 0;
dbg!(crate::waitpid(child, &mut status, 0)).unwrap();
assert!(crate::wifsignaled(status));
assert_eq!(crate::wtermsig(status), crate::SIGUSR1);
}
}
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