1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef __LINKER_ALLOCATOR_H
18 #define __LINKER_ALLOCATOR_H
19 
20 #include <stdlib.h>
21 #include <limits.h>
22 #include "private/bionic_macros.h"
23 
24 struct LinkerAllocatorPage;
25 
26 /*
27  * This class is a non-template version of the LinkerAllocator
28  * It keeps code inside .cpp file by keeping the interface
29  * template-free.
30  *
31  * Please use LinkerAllocator<type> where possible (everywhere).
32  */
33 class LinkerBlockAllocator {
34  public:
35   explicit LinkerBlockAllocator(size_t block_size);
36 
37   void* alloc();
38   void free(void* block);
39   void protect_all(int prot);
40 
41  private:
42   void create_new_page();
43   LinkerAllocatorPage* find_page(void* block);
44 
45   size_t block_size_;
46   LinkerAllocatorPage* page_list_;
47   void* free_block_list_;
48 
49   DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator);
50 };
51 
52 /*
53  * We can't use malloc(3) in the dynamic linker.
54  *
55  * A simple allocator for the dynamic linker. An allocator allocates instances
56  * of a single fixed-size type. Allocations are backed by page-sized private
57  * anonymous mmaps.
58  */
59 template<typename T>
60 class LinkerAllocator {
61  public:
LinkerAllocator()62   LinkerAllocator() : block_allocator_(sizeof(T)) {}
alloc()63   T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); }
free(T * t)64   void free(T* t) { block_allocator_.free(t); }
protect_all(int prot)65   void protect_all(int prot) { block_allocator_.protect_all(prot); }
66  private:
67   LinkerBlockAllocator block_allocator_;
68   DISALLOW_COPY_AND_ASSIGN(LinkerAllocator);
69 };
70 #endif // __LINKER_ALLOCATOR_H
71