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// libtest used to panic if it hit the thread limit. This often resulted in spurious test failures
// (thread 'main' panicked at 'called Result::unwrap() on an Err value: Os
// { code: 11, kind: WouldBlock, message: "Resource temporarily unavailable" }' ...
// error: test failed, to rerun pass '--lib').
// Since the fix in #81546, the test should continue to run synchronously
// if it runs out of threads. Therefore, this test's final execution step
// should succeed without an error.
// See https://github.com/rust-lang/rust/pull/81546
//@ only-linux
// Reason: thread limit modification
//@ ignore-cross-compile
// Reason: this test fails armhf-gnu, reasons unknown
//@ needs-unwind
// Reason: this should be ignored in cg_clif (Cranelift) CI and anywhere
// else that uses panic=abort.
use run_make_support::{libc, rustc};
fn main() {
rustc().input("test.rs").arg("--test").run();
// We need to emulate an environment for libtest where threads are exhausted and spawning
// new threads are guaranteed to fail. This was previously achieved by ulimit shell builtin
// that called out to prlimit64 underneath to set resource limits (specifically thread
// number limits). Now that we don't have a shell, we need to implement that ourselves.
// See https://linux.die.net/man/2/setrlimit
// The fork + exec is required because we cannot first try to limit the number of
// processes/threads to 1 and then try to spawn a new process to run the test. We need to
// setrlimit and run the libtest test program in the same process.
let pid = unsafe { libc::fork() };
assert!(pid >= 0);
// If the process ID is 0, this is the child process responsible for running the test
// program.
if pid == 0 {
let test = c"test";
// The argv array should be terminated with a NULL pointer.
let argv = [test.as_ptr(), std::ptr::null()];
// rlim_cur is soft limit, rlim_max is hard limit.
// By setting the limit very low (max 1), we ensure that libtest is unable to create new
// threads.
let rlimit = libc::rlimit { rlim_cur: 1, rlim_max: 1 };
// RLIMIT_NPROC: The maximum number of processes (or, more precisely on Linux,
// threads) that can be created for the real user ID of the calling process. Upon
// encountering this limit, fork(2) fails with the error EAGAIN.
// Therefore, set the resource limit to RLIMIT_NPROC.
let ret = unsafe { libc::setrlimit(libc::RLIMIT_NPROC, &rlimit as *const libc::rlimit) };
assert_eq!(ret, 0);
// Finally, execute the 2 tests in test.rs.
let ret = unsafe { libc::execv(test.as_ptr(), argv.as_ptr()) };
assert_eq!(ret, 0);
} else {
// Otherwise, other process IDs indicate that this is the parent process.
let mut status: libc::c_int = 0;
let ret = unsafe { libc::waitpid(pid, &mut status as *mut libc::c_int, 0) };
assert_eq!(ret, pid);
assert!(libc::WIFEXITED(status));
assert_eq!(libc::WEXITSTATUS(status), 0);
}
}
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