std: Be resilient to failure in pthread_getattr_np

This can fail on linux for various reasons, such as the /proc filesystem not
being mounted. There are already many cases where we can't set up stack guards,
so just don't worry about this case and communicate that no guard was enabled.

I've confirmed that this allows the compiler to run in a chroot without /proc
mounted.

Closes #22642

1 files changed, 4 insertions, 4 deletions

diff --git a/src/libstd/sys/common/thread_info.rs b/src/libstd/sys/common/thread_info.rs
index ae55bae37aa..bb47c946e49 100644
--- a/src/libstd/sys/common/thread_info.rs
+++ b/src/libstd/sys/common/thread_info.rs
@@ -18,7 +18,7 @@ use thread::Thread;
 use thread::LocalKeyState;
 
 struct ThreadInfo {
-    stack_guard: usize,
+    stack_guard: Option<usize>,
     thread: Thread,
 }
 
@@ -33,7 +33,7 @@ impl ThreadInfo {
         THREAD_INFO.with(move |c| {
             if c.borrow().is_none() {
                 *c.borrow_mut() = Some(ThreadInfo {
-                    stack_guard: 0,
+                    stack_guard: None,
                     thread: NewThread::new(None),
                 })
             }
@@ -47,10 +47,10 @@ pub fn current_thread() -> Option<Thread> {
 }
 
 pub fn stack_guard() -> Option<usize> {
-    ThreadInfo::with(|info| info.stack_guard)
+    ThreadInfo::with(|info| info.stack_guard).and_then(|o| o)
 }
 
-pub fn set(stack_guard: usize, thread: Thread) {
+pub fn set(stack_guard: Option<usize>, thread: Thread) {
     THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
     THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo{
         stack_guard: stack_guard,