Home | History | Annotate | Download | only in linker 
      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:
     62   LinkerAllocator() : block_allocator_(sizeof(T)) {}
     63   T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); }
     64   void free(T* t) { block_allocator_.free(t); }
     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