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

   1 //===---------- Linux implementation of the POSIX mremap 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/mremap.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13
  14 #include "src/__support/macros/config.h"
  15 #include "src/errno/libc_errno.h"
  16 #include <linux/param.h> // For EXEC_PAGESIZE.
  17 #include <stdarg.h>
  18 #include <sys/syscall.h> // For syscall numbers.
  19
  20 namespace LIBC_NAMESPACE_DECL {
  21
  22 LLVM_LIBC_FUNCTION(void *, mremap,
  23                    (void *old_address, size_t old_size, size_t new_size,
  24                     int flags, ... /* void *new_address */)) {
  25
  26   long ret = 0;
  27   void *new_address = nullptr;
  28   if (flags & MREMAP_FIXED) {
  29     va_list varargs;
  30     va_start(varargs, flags);
  31     new_address = va_arg(varargs, void *);
  32     va_end(varargs);
  33   }
  34   ret = LIBC_NAMESPACE::syscall_impl<long>(SYS_mremap, old_address, old_size,
  35                                            new_size, flags, new_address);
  36
  37   if (ret < 0 && ret > -EXEC_PAGESIZE) {
  38     libc_errno = static_cast<int>(-ret);
  39     return MAP_FAILED;
  40   }
  41
  42   return reinterpret_cast<void *>(ret);
  43 }
  44
  45 } // namespace LIBC_NAMESPACE_DECL