1 // Copyright 2018 The Android Open Source Project 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 #pragma once 15 16 #include <inttypes.h> 17 #include <stddef.h> 18 #include <string.h> 19 20 namespace android { 21 namespace base { 22 23 // Class to create sub-allocations in an existing buffer. Similar interface to 24 // Pool, but underlying mechanism is different as it's difficult to combine 25 // same-size heaps in Pool with a preallocated buffer. 26 class SubAllocator { 27 public: 28 // |pageSize| determines both the alignment of pointers returned 29 // and the multiples of space occupied. 30 SubAllocator( 31 void* buffer, 32 uint64_t totalSize, 33 uint64_t pageSize); 34 35 // Memory is freed from the perspective of the user of 36 // SubAllocator, but the prealloced buffer is not freed. 37 ~SubAllocator(); 38 39 // returns null if the allocation cannot be satisfied. 40 void* alloc(size_t wantedSize); 41 void free(void* ptr); 42 void freeAll(); 43 uint64_t getOffset(void* ptr); 44 45 // Convenience function to allocate an array 46 // of objects of type T. 47 template <class T> allocArray(size_t count)48 T* allocArray(size_t count) { 49 size_t bytes = sizeof(T) * count; 50 void* res = alloc(bytes); 51 return (T*) res; 52 } 53 strDup(const char * toCopy)54 char* strDup(const char* toCopy) { 55 size_t bytes = strlen(toCopy) + 1; 56 void* res = alloc(bytes); 57 memset(res, 0x0, bytes); 58 memcpy(res, toCopy, bytes); 59 return (char*)res; 60 } 61 strDupArray(const char * const * arrayToCopy,size_t count)62 char** strDupArray(const char* const* arrayToCopy, size_t count) { 63 char** res = allocArray<char*>(count); 64 65 for (size_t i = 0; i < count; i++) { 66 res[i] = strDup(arrayToCopy[i]); 67 } 68 69 return res; 70 } 71 dupArray(const void * buf,size_t bytes)72 void* dupArray(const void* buf, size_t bytes) { 73 void* res = alloc(bytes); 74 memcpy(res, buf, bytes); 75 return res; 76 } 77 78 private: 79 class Impl; 80 Impl* mImpl = nullptr; 81 }; 82 83 } // namespace base 84 } // namespace android 85