linker/linker_memory.cpp

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "linker_allocator.h"

#include <stdlib.h>
#include <sys/cdefs.h>
#include <unistd.h>

#include "private/libc_logging.h"

static LinkerMemoryAllocator g_linker_allocator;
static pid_t fallback_tid = 0;

// Used by libdebuggerd_handler to switch allocators during a crash dump, in
// case the linker heap is corrupted. Do not use this function.
extern "C" void __linker_use_fallback_allocator() {
  if (fallback_tid != 0) {
    __libc_format_log(ANDROID_LOG_ERROR, "libc",
                      "attempted to set fallback allocator multiple times");
    return;
  }

  fallback_tid = gettid();
}

static LinkerMemoryAllocator& get_fallback_allocator() {
  static LinkerMemoryAllocator fallback_allocator;
  return fallback_allocator;
}

static LinkerMemoryAllocator& get_allocator() {
  if (__predict_false(fallback_tid) && __predict_false(gettid() == fallback_tid)) {
    return get_fallback_allocator();
  }
  return g_linker_allocator;
}

void* malloc(size_t byte_count) {
  return get_allocator().alloc(byte_count);
}

void* calloc(size_t item_count, size_t item_size) {
  return get_allocator().alloc(item_count*item_size);
}

void* realloc(void* p, size_t byte_count) {
  return get_allocator().realloc(p, byte_count);
}

void free(void* ptr) {
  get_allocator().free(ptr);
}