platform_bionic/libc/bionic/mremap.cpp

/*
 * Copyright (C) 2015 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <errno.h>
#include <sys/mman.h>
#include <stdarg.h>
#include <stdint.h>
#include <unistd.h>

#include "private/bionic_macros.h"

extern "C" void* ___mremap(void*, size_t, size_t, int, void*);

void* mremap(void* old_address, size_t old_size, size_t new_size, int flags, ...) {
  // prevent allocations large enough for `end - start` to overflow
  size_t rounded = BIONIC_ALIGN(new_size, PAGE_SIZE);
  if (rounded < new_size || rounded > PTRDIFF_MAX) {
    errno = ENOMEM;
    return MAP_FAILED;
  }

  void* new_address = nullptr;
  // The optional argument is only valid if the MREMAP_FIXED flag is set,
  // so we assume it's not present otherwise.
  if ((flags & MREMAP_FIXED) != 0) {
    va_list ap;
    va_start(ap, flags);
    new_address = va_arg(ap, void*);
    va_end(ap);
  }
  return ___mremap(old_address, old_size, new_size, flags, new_address);
}