aom_mem.c (2771B)
1 /* 2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved. 3 * 4 * This source code is subject to the terms of the BSD 2 Clause License and 5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 6 * was not distributed with this source code in the LICENSE file, you can 7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 8 * Media Patent License 1.0 was not distributed with this source code in the 9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 10 */ 11 12 #include "aom_mem.h" 13 #include <assert.h> 14 #include <stdlib.h> 15 #include <string.h> 16 #include "include/aom_mem_intrnl.h" 17 #include "aom/aom_integer.h" 18 19 static size_t GetAllocationPaddingSize(size_t align) { 20 assert(align > 0); 21 assert(align < SIZE_MAX - ADDRESS_STORAGE_SIZE); 22 return align - 1 + ADDRESS_STORAGE_SIZE; 23 } 24 25 // Returns 0 in case of overflow of nmemb * size. 26 static int check_size_argument_overflow(size_t nmemb, size_t size, 27 size_t align) { 28 if (nmemb == 0) return 1; 29 const size_t alloc_padding = GetAllocationPaddingSize(align); 30 #if defined(AOM_MAX_ALLOCABLE_MEMORY) 31 assert(AOM_MAX_ALLOCABLE_MEMORY >= alloc_padding); 32 assert(AOM_MAX_ALLOCABLE_MEMORY <= SIZE_MAX); 33 if (size > (AOM_MAX_ALLOCABLE_MEMORY - alloc_padding) / nmemb) return 0; 34 #else 35 if (size > (SIZE_MAX - alloc_padding) / nmemb) return 0; 36 #endif 37 return 1; 38 } 39 40 static size_t *GetMallocAddressLocation(void *const mem) { 41 return ((size_t *)mem) - 1; 42 } 43 44 static void SetActualMallocAddress(void *const mem, 45 const void *const malloc_addr) { 46 size_t *const malloc_addr_location = GetMallocAddressLocation(mem); 47 *malloc_addr_location = (size_t)malloc_addr; 48 } 49 50 static void *GetActualMallocAddress(void *const mem) { 51 const size_t *const malloc_addr_location = GetMallocAddressLocation(mem); 52 return (void *)(*malloc_addr_location); 53 } 54 55 void *aom_memalign(size_t align, size_t size) { 56 void *x = NULL; 57 if (!check_size_argument_overflow(1, size, align)) return NULL; 58 const size_t aligned_size = size + GetAllocationPaddingSize(align); 59 void *const addr = malloc(aligned_size); 60 if (addr) { 61 x = aom_align_addr((unsigned char *)addr + ADDRESS_STORAGE_SIZE, align); 62 SetActualMallocAddress(x, addr); 63 } 64 return x; 65 } 66 67 void *aom_malloc(size_t size) { return aom_memalign(DEFAULT_ALIGNMENT, size); } 68 69 void *aom_calloc(size_t num, size_t size) { 70 if (!check_size_argument_overflow(num, size, DEFAULT_ALIGNMENT)) return NULL; 71 const size_t total_size = num * size; 72 void *const x = aom_malloc(total_size); 73 if (x) memset(x, 0, total_size); 74 return x; 75 } 76 77 void aom_free(void *memblk) { 78 if (memblk) { 79 void *addr = GetActualMallocAddress(memblk); 80 free(addr); 81 } 82 }