libc/src/sys/mman/linux/posix_madvise.cpp

   1 //===---------- Linux implementation of the POSIX posix_madvise 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/mman/posix_madvise.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13
  14 #include <sys/syscall.h> // For syscall numbers.
  15
  16 namespace LIBC_NAMESPACE {
  17
  18 // This function is currently linux only. It has to be refactored suitably if
  19 // posix_madvise is to be supported on non-linux operating systems also.
  20 LLVM_LIBC_FUNCTION(int, posix_madvise, (void *addr, size_t size, int advice)) {
  21   // POSIX_MADV_DONTNEED does nothing because the default MADV_DONTNEED may
  22   // cause data loss, which the posix madvise does not allow.
  23   if (advice == POSIX_MADV_DONTNEED) {
  24     return 0;
  25   }
  26   int ret = LIBC_NAMESPACE::syscall_impl<int>(
  27       SYS_madvise, reinterpret_cast<long>(addr), size, advice);
  28   return ret < 0 ? -ret : 0;
  29 }
  30
  31 } // namespace LIBC_NAMESPACE