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c9fbe018f1
Before when handling panics and hard-fail was activated, Servo would just exit with an error return code. This isn't interpreted as a crash by the WPT test runner. This change raises a SEGV signal instead, which means that panics should more reliably be treated as crashes. This doesn't seem to change any test results, at least any non-flaky test results. It is necessary for the test in #32782 to work though. Signed-off-by: Martin Robinson <mrobinson@igalia.com>
70 lines
3.2 KiB
Rust
70 lines
3.2 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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#[cfg(not(any(target_os = "macos", target_os = "linux")))]
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pub fn install() {}
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#[cfg(any(target_os = "macos", target_os = "linux"))]
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pub fn install() {
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use std::io::Write;
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use std::sync::atomic;
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use std::thread;
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use crate::backtrace;
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extern "C" fn handler(sig: i32) {
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// Only print crash message and backtrace the first time, to avoid
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// infinite recursion if the printing causes another signal.
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static BEEN_HERE_BEFORE: atomic::AtomicBool = atomic::AtomicBool::new(false);
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if !BEEN_HERE_BEFORE.swap(true, atomic::Ordering::SeqCst) {
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// stderr is unbuffered, so we won’t lose output if we crash later
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// in this handler, and the std::io::stderr() call never allocates.
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// std::io::stdout() allocates the first time it’s called, which in
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// practice will often segfault (see below).
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let stderr = std::io::stderr();
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let mut stderr = stderr.lock();
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let _ = write!(&mut stderr, "Caught signal {sig}");
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if let Some(name) = thread::current().name() {
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let _ = write!(&mut stderr, " in thread \"{}\"", name);
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}
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let _ = writeln!(&mut stderr);
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// This call always allocates, which in practice will segfault if
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// we’re handling a non-main-thread (e.g. layout) segfault. Strictly
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// speaking in POSIX terms, this is also undefined behaviour.
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let _ = backtrace::print(&mut stderr);
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}
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// Outside the BEEN_HERE_BEFORE check, we must only call functions we
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// know to be “async-signal-safe”, which includes sigaction(), raise(),
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// and _exit(), but generally doesn’t include anything that allocates.
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// https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03_03
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raise_signal_or_exit_with_error(sig);
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}
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signal!(libc::SIGSEGV, handler); // handle segfaults
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signal!(libc::SIGILL, handler); // handle stack overflow and unsupported CPUs
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signal!(libc::SIGIOT, handler); // handle double panics
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signal!(libc::SIGBUS, handler); // handle invalid memory access
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}
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#[cfg(not(any(target_os = "macos", target_os = "linux")))]
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pub(crate) fn raise_signal_or_exit_with_error(_signal: i32) {
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std::process::exit(1);
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}
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#[cfg(any(target_os = "macos", target_os = "linux"))]
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pub(crate) fn raise_signal_or_exit_with_error(signal: i32) {
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unsafe {
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// Reset the signal to the default action, and reraise the signal.
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// Unlike libc::_exit(sig), which terminates the process normally,
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// this terminates abnormally just like an uncaught signal, allowing
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// mach (or your shell) to distinguish it from an ordinary exit, and
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// allows your kernel to make a core dump if configured to do so.
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let mut action: libc::sigaction = std::mem::zeroed();
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action.sa_sigaction = libc::SIG_DFL;
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libc::sigaction(signal, &action, std::ptr::null_mut());
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libc::raise(signal);
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}
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}
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