[libc-commits] [libc] [libc] Implement waitid in sys/wait (PR #227815)

[Pavel Labath via libc-commits]

================
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+/// Syscall wrapper for waitid.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_SYSCALL_WRAPPERS_WAITID_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_SYSCALL_WRAPPERS_WAITID_H
+
+#include "hdr/types/id_t.h"
+#include "hdr/types/idtype_t.h"
+#include "hdr/types/siginfo_t.h"
+#include "hdr/types/struct_rusage.h"
+#include "src/__support/OSUtil/linux/syscall.h" // For syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> waitid(idtype_t idtype, id_t id, siginfo_t *infop,
+                                int options, struct rusage *rusage = nullptr) {
+#ifdef SYS_waitid
+  return syscall_checked<int>(SYS_waitid, idtype, id, infop, options, rusage);
+#else
+#error "waitid syscall not available."
+#endif
----------------
labath wrote:

We generally use ifdefs only when there's more than one way to implement a given wrapper. If there's just one, the compiler error is pretty clear even without it.

```suggestion
  return syscall_checked<int>(SYS_waitid, idtype, id, infop, options, rusage);
```

https://github.com/llvm/llvm-project/pull/227815