[libc-commits] [libc] [libc] Implement ppoll in poll (PR #225767)

[Aman Maurya via libc-commits]

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@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 ppoll.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/poll/ppoll.h"
+
+#include "hdr/signal_macros.h"
+#include "hdr/types/nfds_t.h"
+#include "hdr/types/sigset_t.h"
+#include "hdr/types/struct_pollfd.h"
+#include "hdr/types/struct_timespec.h"
+#include "src/__support/OSUtil/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // SYS_ppoll, SYS_ppoll_time64
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, ppoll,
+                   (struct pollfd * fds, nfds_t nfds,
+                    const struct timespec *tmo_p, const sigset_t *sigmask)) {
+  timespec ts;
+  timespec *tsp = nullptr;
+  if (tmo_p != nullptr) {
+    ts = *tmo_p;
+    tsp = &ts;
+  }
+
+#if defined(SYS_ppoll_time64)
+  // The kernel expects the signal mask size in bytes, not the number of
+  // signals. NSIG is the signal count, so NSIG / 8 gives the byte size.
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ppoll_time64, fds, nfds, tsp,
+                                              sigmask, NSIG / 8);
+#elif defined(SYS_ppoll)
+  static_assert(
+      sizeof(timespec::tv_nsec) == sizeof(long),
+      "This legacy syscall fallback is only safe on platforms where tv_nsec "
+      "matches the register size (long). It is unsafe on 32-bit platforms "
+      "with 64-bit tv_nsec.");
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ppoll, fds, nfds, tsp,
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amanmaurya92 wrote:

ohh, I am now using syscall_wrappers. thanks for the review.

https://github.com/llvm/llvm-project/pull/225767