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// run-pass
// no-prefer-dynamic
// ignore-wasm32-bare no libc
// ignore-windows
// ignore-sgx no libc
// ignore-emscripten no processes
// ignore-sgx no processes
// ignore-fuchsia no fork
#![feature(rustc_private)]
#![feature(never_type)]
#![feature(panic_always_abort)]
extern crate libc;
use std::alloc::{GlobalAlloc, Layout};
use std::fmt;
use std::panic::{self, panic_any};
use std::os::unix::process::{CommandExt, ExitStatusExt};
use std::process::{self, Command, ExitStatus};
use std::sync::atomic::{AtomicU32, Ordering};
use libc::c_int;
/// This stunt allocator allows us to spot heap allocations in the child.
struct PidChecking<A> {
parent: A,
require_pid: AtomicU32,
}
#[global_allocator]
static ALLOCATOR: PidChecking<std::alloc::System> = PidChecking {
parent: std::alloc::System,
require_pid: AtomicU32::new(0),
};
impl<A> PidChecking<A> {
fn engage(&self) {
let parent_pid = process::id();
eprintln!("engaging allocator trap, parent pid={}", parent_pid);
self.require_pid.store(parent_pid, Ordering::Release);
}
fn check(&self) {
let require_pid = self.require_pid.load(Ordering::Acquire);
if require_pid != 0 {
let actual_pid = process::id();
if require_pid != actual_pid {
unsafe {
libc::raise(libc::SIGUSR1);
}
}
}
}
}
unsafe impl<A:GlobalAlloc> GlobalAlloc for PidChecking<A> {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
self.check();
self.parent.alloc(layout)
}
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
self.check();
self.parent.dealloc(ptr, layout)
}
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
self.check();
self.parent.alloc_zeroed(layout)
}
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
self.check();
self.parent.realloc(ptr, layout, new_size)
}
}
fn expect_aborted(status: ExitStatus) {
dbg!(status);
let signal = status.signal().expect("expected child process to die of signal");
#[cfg(not(target_os = "android"))]
assert!(signal == libc::SIGABRT || signal == libc::SIGILL || signal == libc::SIGTRAP);
#[cfg(target_os = "android")]
{
// Android signals an abort() call with SIGSEGV at address 0xdeadbaad
// See e.g. https://groups.google.com/g/android-ndk/c/laW1CJc7Icc
assert!(signal == libc::SIGSEGV);
// Additional checks performed:
// 1. Find last tombstone (similar to coredump but in text format) from the
// same executable (path) as we are (must be because of usage of fork):
// This ensures that we look into the correct tombstone.
// 2. Cause of crash is a SIGSEGV with address 0xdeadbaad.
// 3. libc::abort call is in one of top two functions on callstack.
// The last two steps distinguish between a normal SIGSEGV and one caused
// by libc::abort.
let this_exe = std::env::current_exe().unwrap().into_os_string().into_string().unwrap();
let exe_string = format!(">>> {this_exe} <<<");
let tombstone = (0..100)
.map(|n| format!("/data/tombstones/tombstone_{n:02}"))
.filter(|f| std::path::Path::new(&f).exists())
.map(|f| std::fs::read_to_string(&f).expect("Cannot read tombstone file"))
.filter(|f| f.contains(&exe_string))
.last()
.expect("no tombstone found");
println!("Content of tombstone:\n{tombstone}");
assert!(
tombstone.contains("signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr deadbaad")
);
let abort_on_top = tombstone
.lines()
.skip_while(|l| !l.contains("backtrace:"))
.skip(1)
.take_while(|l| l.starts_with(" #"))
.take(2)
.any(|f| f.contains("/system/lib/libc.so (abort"));
assert!(abort_on_top);
}
}
fn main() {
ALLOCATOR.engage();
fn run(do_panic: &dyn Fn()) -> ExitStatus {
let child = unsafe { libc::fork() };
assert!(child >= 0);
if child == 0 {
panic::always_abort();
do_panic();
process::exit(0);
}
let mut status: c_int = 0;
let got = unsafe { libc::waitpid(child, &mut status, 0) };
assert_eq!(got, child);
let status = ExitStatus::from_raw(status.into());
status
}
fn one(do_panic: &dyn Fn()) {
let status = run(do_panic);
expect_aborted(status);
}
one(&|| panic!());
one(&|| panic!("some message"));
one(&|| panic!("message with argument: {}", 42));
#[derive(Debug)]
struct Wotsit { }
one(&|| panic_any(Wotsit { }));
let mut c = Command::new("echo");
unsafe {
c.pre_exec(|| panic!("{}", "crash now!"));
}
let st = c.status().expect("failed to get command status");
expect_aborted(st);
struct DisplayWithHeap;
impl fmt::Display for DisplayWithHeap {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
let s = vec![0; 100];
let s = std::hint::black_box(s);
write!(f, "{:?}", s)
}
}
// Some panics in the stdlib that we want not to allocate, as
// otherwise these facilities become impossible to use in the
// child after fork, which is really quite awkward.
one(&|| { None::<DisplayWithHeap>.unwrap(); });
one(&|| { None::<DisplayWithHeap>.expect("unwrapped a none"); });
one(&|| { std::str::from_utf8(b"\xff").unwrap(); });
one(&|| {
let x = [0, 1, 2, 3];
let y = x[std::hint::black_box(4)];
let _z = std::hint::black_box(y);
});
// Finally, check that our stunt allocator can actually catch an allocation after fork.
// ie, that our test is effective.
let status = run(&|| panic!("allocating to display... {}", DisplayWithHeap));
dbg!(status);
assert_eq!(status.signal(), Some(libc::SIGUSR1));
}
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