libc/src/sched/linux/sched_getaffinity.cpp

   1 //===-- Implementation of sched_getaffinity -------------------------------===//
   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/sched/sched_getaffinity.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/errno/libc_errno.h"
  14
  15 #include <sched.h>
  16 #include <stdint.h>
  17 #include <sys/syscall.h> // For syscall numbers.
  18
  19 namespace LIBC_NAMESPACE {
  20
  21 LLVM_LIBC_FUNCTION(int, sched_getaffinity,
  22                    (pid_t tid, size_t cpuset_size, cpu_set_t *mask)) {
  23   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_sched_getaffinity, tid,
  24                                               cpuset_size, mask);
  25   if (ret < 0) {
  26     libc_errno = -ret;
  27     return -1;
  28   }
  29   if (size_t(ret) < cpuset_size) {
  30     // This means that only |ret| bytes in |mask| have been set. We will have to
  31     // zero out the remaining bytes.
  32     auto *mask_bytes = reinterpret_cast<uint8_t *>(mask);
  33     for (size_t i = size_t(ret); i < cpuset_size; ++i)
  34       mask_bytes[i] = 0;
  35   }
  36   return 0;
  37 }
  38
  39 } // namespace LIBC_NAMESPACE