1/**************************************************************************
2 *
3 * Copyright 2008-2010 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28
29/*
30 * Memory alignment wrappers.
31 */
32
33
34#ifndef _OS_MEMORY_H_
35#error "Must not be included directly. Include os_memory.h instead"
36#endif
37
38
39/**
40 * Add two size_t values with integer overflow check.
41 * TODO: leverage __builtin_add_overflow where available
42 */
43static inline bool
44add_overflow_size_t(size_t a, size_t b, size_t *res)
45{
46   *res = a + b;
47   return *res < a || *res < b;
48}
49
50
51#if defined(HAVE_POSIX_MEMALIGN)
52
53static inline void *
54os_malloc_aligned(size_t size, size_t alignment)
55{
56   void *ptr;
57   alignment = (alignment + sizeof(void*) - 1) & ~(sizeof(void*) - 1);
58   if(posix_memalign(&ptr, alignment, size) != 0)
59      return NULL;
60   return ptr;
61}
62
63#define os_free_aligned(_ptr) free(_ptr)
64
65#else
66
67/**
68 * Return memory on given byte alignment
69 */
70static inline void *
71os_malloc_aligned(size_t size, size_t alignment)
72{
73   char *ptr, *buf;
74   size_t alloc_size;
75
76   /*
77    * Calculate
78    *
79    *   alloc_size = size + alignment + sizeof(void *)
80    *
81    * while checking for overflow.
82    */
83   if (add_overflow_size_t(size, alignment, &alloc_size) ||
84       add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
85      return NULL;
86   }
87
88   ptr = (char *) os_malloc(alloc_size);
89   if (!ptr)
90      return NULL;
91
92   buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
93   *(char **)(buf - sizeof(void *)) = ptr;
94
95   return buf;
96}
97
98
99/**
100 * Free memory returned by os_malloc_aligned().
101 */
102static inline void
103os_free_aligned(void *ptr)
104{
105   if (ptr) {
106      void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
107      void *realAddr = *cubbyHole;
108      os_free(realAddr);
109   }
110}
111
112#endif
113
114/**
115 * Reallocate memeory, with alignment
116 */
117static inline void *
118os_realloc_aligned(void *ptr, size_t oldsize, size_t newsize, size_t alignment)
119{
120   const size_t copySize = MIN2(oldsize, newsize);
121   void *newBuf = os_malloc_aligned(newsize, alignment);
122   if (newBuf && ptr && copySize > 0) {
123      memcpy(newBuf, ptr, copySize);
124   }
125
126   os_free_aligned(ptr);
127   return newBuf;
128}
129