[libc-commits] [libc] [libc] Implement sleep and usleep for Linux (PR #213912)

[Jeff Bailey via libc-commits]

================
@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Linux implementation of sleep.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/unistd/sleep.h"
+#include "hdr/types/struct_timespec.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/OSUtil/linux/syscall_wrappers/nanosleep.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(unsigned int, sleep, (unsigned int seconds)) {
+  static_assert(sizeof(unsigned int) <= sizeof(time_t), "Avoids overflow");
+  struct timespec req = {seconds, 0};
+  struct timespec rem = {};
+  ErrorOr<int> result = linux_syscalls::nanosleep(&req, &rem);
+  if (!result) {
+    // Cast does not lose information as `remaining` cannot be greater than
+    // `seconds`.
+    return static_cast<unsigned int>(rem.tv_sec);
----------------
kaladron wrote:

Ah, I haven't looked at other implementations.  It just seems weird to me that a sleep 1 could potentially return that it completed when it didn't. =/

I don't feel strongly enough to insist, though.

https://github.com/llvm/llvm-project/pull/213912