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/*
* Copyright (C) 2014 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.
*/
#pragma once
#include <stdlib.h>
#include <limits.h>
#include <android-base/macros.h>
struct LinkerBlockAllocatorPage;
/*
* This class is a non-template version of the LinkerTypeAllocator
* It keeps code inside .cpp file by keeping the interface
* template-free.
*
* Please use LinkerTypeAllocator<type> where possible (everywhere).
*/
class LinkerBlockAllocator {
public:
explicit LinkerBlockAllocator(size_t block_size);
void* alloc();
void free(void* block);
void protect_all(int prot);
// Purge all pages if all previously allocated blocks have been freed.
void purge();
private:
void create_new_page();
LinkerBlockAllocatorPage* find_page(void* block);
size_t block_size_;
LinkerBlockAllocatorPage* page_list_;
void* free_block_list_;
size_t allocated_;
DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator);
};
/*
* A simple allocator for the dynamic linker. An allocator allocates instances
* of a single fixed-size type. Allocations are backed by page-sized private
* anonymous mmaps.
*
* The differences between this allocator and BionicAllocator are:
* 1. This allocator manages space more efficiently. BionicAllocator operates in
* power-of-two sized blocks up to 1k, when this implementation splits the
* page to aligned size of structure; For example for structures with size
* 513 this allocator will use 516 (520 for lp64) bytes of data where
* generalized implementation is going to use 1024 sized blocks.
*
* 2. This allocator does not munmap allocated memory, where BionicAllocator does.
*
* 3. This allocator provides mprotect services to the user, where BionicAllocator
* always treats its memory as READ|WRITE.
*/
template<typename T>
class LinkerTypeAllocator {
public:
LinkerTypeAllocator() : block_allocator_(sizeof(T)) {}
T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); }
void free(T* t) { block_allocator_.free(t); }
void protect_all(int prot) { block_allocator_.protect_all(prot); }
private:
LinkerBlockAllocator block_allocator_;
DISALLOW_COPY_AND_ASSIGN(LinkerTypeAllocator);
};
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