rework threadname test for more consistency

This commit is contained in:
Ralf Jung 2024-10-13 09:13:33 +02:00
parent a495a79db9
commit b2b0d240a2
2 changed files with 125 additions and 65 deletions

View File

@ -1,9 +1,23 @@
//@ignore-target: windows # No pthreads on Windows //@ignore-target: windows # No pthreads on Windows
use std::ffi::CStr; use std::ffi::{CStr, CString};
#[cfg(not(target_os = "freebsd"))]
use std::ffi::CString;
use std::thread; use std::thread;
const MAX_THREAD_NAME_LEN: usize = {
cfg_if::cfg_if! {
if #[cfg(any(target_os = "linux"))] {
16
} else if #[cfg(any(target_os = "illumos", target_os = "solaris"))] {
32
} else if #[cfg(target_os = "macos")] {
libc::MAXTHREADNAMESIZE // 64, at the time of writing
} else if #[cfg(target_os = "freebsd")] {
usize::MAX // as far as I can tell
} else {
panic!()
}
}
};
fn main() { fn main() {
// The short name should be shorter than 16 bytes which POSIX promises // The short name should be shorter than 16 bytes which POSIX promises
// for thread names. The length includes a null terminator. // for thread names. The length includes a null terminator.
@ -52,46 +66,64 @@ fn main() {
} }
thread::Builder::new() thread::Builder::new()
.name(short_name.clone())
.spawn(move || { .spawn(move || {
// Rust remembers the full thread name itself. // Set short thread name.
assert_eq!(thread::current().name(), Some(short_name.as_str())); let cstr = CString::new(short_name.clone()).unwrap();
assert!(cstr.to_bytes_with_nul().len() <= MAX_THREAD_NAME_LEN); // this should fit
// Note that glibc requires 15 bytes long buffer exculding a null terminator.
// Otherwise, `pthread_getname_np` returns an error.
let mut buf = vec![0u8; short_name.len().max(15) + 1];
assert_eq!(get_thread_name(&mut buf), 0);
let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
// POSIX seems to promise at least 15 chars excluding a null terminator.
assert_eq!(short_name.as_bytes(), cstr.to_bytes());
// Also test directly calling pthread_setname to check its return value.
assert_eq!(set_thread_name(&cstr), 0); assert_eq!(set_thread_name(&cstr), 0);
// For glibc used by linux-gnu there should be a failue, // Now get it again, in various ways.
// if a shorter than 16 bytes buffer is provided, even if that would be
// large enough for the thread name.
#[cfg(target_os = "linux")]
assert_eq!(get_thread_name(&mut buf[..15]), libc::ERANGE);
// Solaris compatible implementations return an error, // POSIX seems to promise at least 15 chars excluding a null terminator.
// if the buffer is shorter than the thread name. let mut buf = vec![0u8; short_name.len().max(15) + 1];
#[cfg(any(target_os = "illumos", target_os = "solaris"))] assert_eq!(get_thread_name(&mut buf), 0);
assert_eq!(get_thread_name(&mut buf[..4]), libc::ERANGE); let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
// On macOS and FreeBSD it's not an error for the buffer to be assert_eq!(cstr.to_bytes(), short_name.as_bytes());
// too short for the thread name -- they truncate instead.
#[cfg(any(target_os = "freebsd", target_os = "macos"))]
{
// Ensure that a zero sized buffer returns no error.
assert_eq!(get_thread_name(&mut buf[..0]), 0);
// Ensure that a shorter tnan required buffer still returns no error, // Test what happens when the buffer is shorter than 16, but still long enough.
// and gives a prefix of the thread name. let res = get_thread_name(&mut buf[..15]);
assert_eq!(get_thread_name(&mut buf[..4]), 0); cfg_if::cfg_if! {
let cstr = CStr::from_bytes_until_nul(&buf).unwrap(); if #[cfg(target_os = "linux")] {
assert_eq!(cstr.to_bytes_with_nul().len(), 4); // For glibc used by linux-gnu there should be a failue,
assert!(short_name.as_bytes().starts_with(cstr.to_bytes())); // if a shorter than 16 bytes buffer is provided, even if that would be
// large enough for the thread name.
assert_eq!(res, libc::ERANGE);
} else {
// Everywhere else, this should work.
assert_eq!(res, 0);
// POSIX seems to promise at least 15 chars excluding a null terminator.
let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
assert_eq!(short_name.as_bytes(), cstr.to_bytes());
}
}
// Test what happens when the buffer is too short even for the short name.
let res = get_thread_name(&mut buf[..4]);
cfg_if::cfg_if! {
if #[cfg(any(target_os = "freebsd", target_os = "macos"))] {
// On macOS and FreeBSD it's not an error for the buffer to be
// too short for the thread name -- they truncate instead.
assert_eq!(res, 0);
let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
assert_eq!(cstr.to_bytes_with_nul().len(), 4);
assert!(short_name.as_bytes().starts_with(cstr.to_bytes()));
} else {
// The rest should give an error.
assert_eq!(res, libc::ERANGE);
}
}
// Test zero-sized buffer.
let res = get_thread_name(&mut []);
cfg_if::cfg_if! {
if #[cfg(any(target_os = "freebsd", target_os = "macos"))] {
// On macOS and FreeBSD it's not an error for the buffer to be
// too short for the thread name -- even with size 0.
assert_eq!(res, 0);
} else {
// The rest should give an error.
assert_eq!(res, libc::ERANGE);
}
} }
}) })
.unwrap() .unwrap()
@ -99,37 +131,52 @@ fn main() {
.unwrap(); .unwrap();
thread::Builder::new() thread::Builder::new()
.name(long_name.clone())
.spawn(move || { .spawn(move || {
// Rust remembers the full thread name itself. // Set full thread name.
assert_eq!(thread::current().name(), Some(long_name.as_str())); let cstr = CString::new(long_name.clone()).unwrap();
let res = set_thread_name(&cstr);
// But the system is limited -- make sure we successfully set a truncation. cfg_if::cfg_if! {
// Note that there's no specific to glibc buffer requirement, since the value if #[cfg(target_os = "freebsd")] {
// `long_name` is longer than 16 bytes including a null terminator. // Names of all size are supported.
let mut buf = vec![0u8; long_name.len() + 1]; assert!(cstr.to_bytes_with_nul().len() <= MAX_THREAD_NAME_LEN);
assert_eq!(get_thread_name(&mut buf), 0); assert_eq!(res, 0);
} else if #[cfg(target_os = "macos")] {
let cstr = CStr::from_bytes_until_nul(&buf).unwrap(); // Name is too long.
// POSIX seems to promise at least 15 chars excluding a null terminator. assert!(cstr.to_bytes_with_nul().len() > MAX_THREAD_NAME_LEN);
assert!( assert_eq!(res, libc::ENAMETOOLONG);
cstr.to_bytes().len() >= 15, } else {
"name is too short: len={}", // Name is too long.
cstr.to_bytes().len() assert!(cstr.to_bytes_with_nul().len() > MAX_THREAD_NAME_LEN);
); assert_eq!(res, libc::ERANGE);
assert!(long_name.as_bytes().starts_with(cstr.to_bytes())); }
}
// Also test directly calling pthread_setname to check its return value. // Set the longest name we can.
let truncated_name = &long_name[..long_name.len().min(MAX_THREAD_NAME_LEN - 1)];
let cstr = CString::new(truncated_name).unwrap();
assert_eq!(set_thread_name(&cstr), 0); assert_eq!(set_thread_name(&cstr), 0);
// But with a too long name it should fail (except on FreeBSD where // Now get it again, in various ways.
// names of arbitrary size seem to be supported).
// On macOS, the error code is different.
#[cfg(not(any(target_os = "freebsd", target_os = "macos")))]
assert_eq!(set_thread_name(&CString::new(long_name).unwrap()), libc::ERANGE);
#[cfg(target_os = "macos")] // This name should round-trip properly.
assert_eq!(set_thread_name(&CString::new(long_name).unwrap()), libc::ENAMETOOLONG); let mut buf = vec![0u8; long_name.len() + 1];
assert_eq!(get_thread_name(&mut buf), 0);
let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
assert_eq!(cstr.to_bytes(), truncated_name.as_bytes());
// Test what happens when our buffer is just one byte too small.
let res = get_thread_name(&mut buf[..truncated_name.len()]);
cfg_if::cfg_if! {
if #[cfg(any(target_os = "freebsd", target_os = "macos"))] {
// On macOS and FreeBSD it's not an error for the buffer to be
// too short for the thread name -- they truncate instead.
assert_eq!(res, 0);
let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
assert_eq!(cstr.to_bytes(), &truncated_name.as_bytes()[..(truncated_name.len() - 1)]);
} else {
// The rest should give an error.
assert_eq!(res, libc::ERANGE);
}
}
}) })
.unwrap() .unwrap()
.join() .join()

View File

@ -16,6 +16,19 @@ fn main() {
.join() .join()
.unwrap(); .unwrap();
// Long thread name.
let long_name = std::iter::once("test_named_thread_truncation")
.chain(std::iter::repeat(" long").take(100))
.collect::<String>();
thread::Builder::new()
.name(long_name.clone())
.spawn(move || {
assert_eq!(thread::current().name().unwrap(), long_name);
})
.unwrap()
.join()
.unwrap();
// Also check main thread name. // Also check main thread name.
assert_eq!(thread::current().name().unwrap(), "main"); assert_eq!(thread::current().name().unwrap(), "main");
} }