1//===---------- Linux implementation of the epoll_wait function -----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/sys/epoll/epoll_wait.h"
10
11#include "hdr/signal_macros.h" // for NSIG
12#include "hdr/types/sigset_t.h"
13#include "hdr/types/struct_epoll_event.h"
14#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
15#include "src/__support/common.h"
16#include "src/__support/libc_errno.h"
17#include "src/__support/macros/config.h"
18#include "src/__support/macros/sanitizer.h"
19
20#include <sys/syscall.h> // For syscall numbers.
21
22namespace LIBC_NAMESPACE_DECL {
23
24LLVM_LIBC_FUNCTION(int, epoll_wait,
25 (int epfd, struct epoll_event *events, int maxevents,
26 int timeout)) {
27#ifdef SYS_epoll_wait
28 int ret = LIBC_NAMESPACE::syscall_impl<int>(
29 SYS_epoll_wait, epfd, reinterpret_cast<long>(events), maxevents, timeout);
30#elif defined(SYS_epoll_pwait)
31 int ret = LIBC_NAMESPACE::syscall_impl<int>(
32 SYS_epoll_pwait, epfd, reinterpret_cast<long>(events), maxevents, timeout,
33 reinterpret_cast<long>(nullptr), NSIG / 8);
34#else
35#error "epoll_wait and epoll_pwait are unavailable. Unable to build epoll_wait."
36#endif
37 // A negative return value indicates an error with the magnitude of the
38 // value being the error code.
39 if (ret < 0) {
40 libc_errno = -ret;
41 return -1;
42 }
43
44 MSAN_UNPOISON(events, ret * sizeof(struct epoll_event));
45
46 return ret;
47}
48
49} // namespace LIBC_NAMESPACE_DECL
50

source code of libc/src/sys/epoll/linux/epoll_wait.cpp