| // Copyright (c) 2006, Google Inc. |
| // 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. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // 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. |
| // |
| // ProtectedMemoryAllocator |
| // |
| // A very simple allocator class which allows allocation, but not deallocation. |
| // The allocations can be made read-only with the Protect() method. |
| // This class is NOT useful as a general-purpose memory allocation system, |
| // since it does not allow deallocation. It is useful to use for a group |
| // of allocations which are created in the same time-frame and destroyed |
| // in the same time-frame. It is useful for making allocations of memory |
| // which will not need to change often once initialized. This memory can then |
| // be protected from memory smashers by calling the Protect() method. |
| |
| #ifndef PROTECTED_MEMORY_ALLOCATOR_H__ |
| #define PROTECTED_MEMORY_ALLOCATOR_H__ |
| |
| #include <mach/mach.h> |
| |
| // |
| class ProtectedMemoryAllocator { |
| public: |
| ProtectedMemoryAllocator(vm_size_t pool_size); |
| ~ProtectedMemoryAllocator(); |
| |
| // Returns a pointer to an allocation of size n within the pool. |
| // Fails by returning NULL is no more space is available. |
| // Please note that the pointers returned from this method should not |
| // be freed in any way (for example by calling free() on them ). |
| char * Allocate(vm_size_t n); |
| |
| // Returns the base address of the allocation pool. |
| char * GetBaseAddress() { return (char*)base_address_; } |
| |
| // Returns the size of the allocation pool, including allocated |
| // plus free space. |
| vm_size_t GetTotalSize() { return pool_size_; } |
| |
| // Returns the number of bytes already allocated in the pool. |
| vm_size_t GetAllocatedSize() { return next_alloc_offset_; } |
| |
| // Returns the number of bytes available for allocation. |
| vm_size_t GetFreeSize() { return pool_size_ - next_alloc_offset_; } |
| |
| // Makes the entire allocation pool read-only including, of course, |
| // all allocations made from the pool. |
| kern_return_t Protect(); |
| |
| // Makes the entire allocation pool read/write. |
| kern_return_t Unprotect(); |
| |
| private: |
| vm_size_t pool_size_; |
| vm_address_t base_address_; |
| vm_size_t next_alloc_offset_; |
| bool valid_; |
| }; |
| |
| #endif // PROTECTED_MEMORY_ALLOCATOR_H__ |