1 // Copyright (c) 2006, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 // 30 // ProtectedMemoryAllocator 31 // 32 // A very simple allocator class which allows allocation, but not deallocation. 33 // The allocations can be made read-only with the Protect() method. 34 // This class is NOT useful as a general-purpose memory allocation system, 35 // since it does not allow deallocation. It is useful to use for a group 36 // of allocations which are created in the same time-frame and destroyed 37 // in the same time-frame. It is useful for making allocations of memory 38 // which will not need to change often once initialized. This memory can then 39 // be protected from memory smashers by calling the Protect() method. 40 41 #ifndef PROTECTED_MEMORY_ALLOCATOR_H__ 42 #define PROTECTED_MEMORY_ALLOCATOR_H__ 43 44 #include <mach/mach.h> 45 46 // 47 class ProtectedMemoryAllocator { 48 public: 49 ProtectedMemoryAllocator(vm_size_t pool_size); 50 ~ProtectedMemoryAllocator(); 51 52 // Returns a pointer to an allocation of size n within the pool. 53 // Fails by returning NULL is no more space is available. 54 // Please note that the pointers returned from this method should not 55 // be freed in any way (for example by calling free() on them ). 56 char * Allocate(vm_size_t n); 57 58 // Returns the base address of the allocation pool. 59 char * GetBaseAddress() { return (char*)base_address_; } 60 61 // Returns the size of the allocation pool, including allocated 62 // plus free space. 63 vm_size_t GetTotalSize() { return pool_size_; } 64 65 // Returns the number of bytes already allocated in the pool. 66 vm_size_t GetAllocatedSize() { return next_alloc_offset_; } 67 68 // Returns the number of bytes available for allocation. 69 vm_size_t GetFreeSize() { return pool_size_ - next_alloc_offset_; } 70 71 // Makes the entire allocation pool read-only including, of course, 72 // all allocations made from the pool. 73 kern_return_t Protect(); 74 75 // Makes the entire allocation pool read/write. 76 kern_return_t Unprotect(); 77 78 private: 79 vm_size_t pool_size_; 80 vm_address_t base_address_; 81 vm_size_t next_alloc_offset_; 82 bool valid_; 83 }; 84 85 #endif // PROTECTED_MEMORY_ALLOCATOR_H__ 86
