From 2cf0f64722a92dffa12d43a4c0383a9d76becbcc Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sat, 19 Sep 2020 18:03:10 +0200
Subject: Move linux-specific futex code into `sys` module.

---
 library/std/src/sys/unix/futex.rs | 38 ++++++++++++++++++++++++++++++++++++++
 library/std/src/sys/unix/mod.rs   |  1 +
 2 files changed, 39 insertions(+)
 create mode 100644 library/std/src/sys/unix/futex.rs

(limited to 'library/std/src/sys')

diff --git a/library/std/src/sys/unix/futex.rs b/library/std/src/sys/unix/futex.rs
new file mode 100644
index 00000000000..6af06aa5f7e
--- /dev/null
+++ b/library/std/src/sys/unix/futex.rs
@@ -0,0 +1,38 @@
+#![cfg(any(target_os = "linux", target_os = "android"))]
+
+use crate::sync::atomic::AtomicI32;
+use crate::time::Duration;
+
+pub fn futex_wait(futex: &AtomicI32, expected: i32, timeout: Option<Duration>) {
+    let timespec;
+    let timespec_ptr = match timeout {
+        Some(timeout) => {
+            timespec = libc::timespec {
+                tv_sec: timeout.as_secs() as _,
+                tv_nsec: timeout.subsec_nanos() as _,
+            };
+            &timespec as *const libc::timespec
+        }
+        None => crate::ptr::null(),
+    };
+    unsafe {
+        libc::syscall(
+            libc::SYS_futex,
+            futex as *const AtomicI32,
+            libc::FUTEX_WAIT | libc::FUTEX_PRIVATE_FLAG,
+            expected,
+            timespec_ptr,
+        );
+    }
+}
+
+pub fn futex_wake(futex: &AtomicI32) {
+    unsafe {
+        libc::syscall(
+            libc::SYS_futex,
+            futex as *const AtomicI32,
+            libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG,
+            1,
+        );
+    }
+}
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index eddf00d3979..6c623e21099 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -49,6 +49,7 @@ pub mod env;
 pub mod ext;
 pub mod fd;
 pub mod fs;
+pub mod futex;
 pub mod io;
 #[cfg(target_os = "l4re")]
 mod l4re;
-- 
cgit 1.4.1-3-g733a5


From 485f882d7713b0e0b864fc8b21368910e5b8b0a7 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sun, 20 Sep 2020 00:17:05 +0200
Subject: Check conversion from Duration to timespec in futex_wait.

---
 library/std/src/sys/unix/futex.rs | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

(limited to 'library/std/src/sys')

diff --git a/library/std/src/sys/unix/futex.rs b/library/std/src/sys/unix/futex.rs
index 6af06aa5f7e..e6f0c48c59b 100644
--- a/library/std/src/sys/unix/futex.rs
+++ b/library/std/src/sys/unix/futex.rs
@@ -1,27 +1,26 @@
 #![cfg(any(target_os = "linux", target_os = "android"))]
 
+use crate::convert::TryInto;
+use crate::ptr::null;
 use crate::sync::atomic::AtomicI32;
 use crate::time::Duration;
 
 pub fn futex_wait(futex: &AtomicI32, expected: i32, timeout: Option<Duration>) {
-    let timespec;
-    let timespec_ptr = match timeout {
-        Some(timeout) => {
-            timespec = libc::timespec {
-                tv_sec: timeout.as_secs() as _,
-                tv_nsec: timeout.subsec_nanos() as _,
-            };
-            &timespec as *const libc::timespec
-        }
-        None => crate::ptr::null(),
-    };
+    let timespec = timeout.and_then(|d| {
+        Some(libc::timespec {
+            // Sleep forever if the timeout is longer than fits in a timespec.
+            tv_sec: d.as_secs().try_into().ok()?,
+            // This conversion never truncates, as subsec_nanos is always <1e9.
+            tv_nsec: d.subsec_nanos() as _,
+        })
+    });
     unsafe {
         libc::syscall(
             libc::SYS_futex,
             futex as *const AtomicI32,
             libc::FUTEX_WAIT | libc::FUTEX_PRIVATE_FLAG,
             expected,
-            timespec_ptr,
+            timespec.as_ref().map_or(null(), |d| d as *const libc::timespec),
         );
     }
 }
-- 
cgit 1.4.1-3-g733a5