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#include "pipe/p_compiler.h"
40
41
42
43/**
44 * Add two size_t values with integer overflow check.
45 * TODO: leverage __builtin_add_overflow where available
46 */
47static inline bool
48add_overflow_size_t(size_t a, size_t b, size_t *res)
49{
50   *res = a + b;
51   return *res < a || *res < b;
52}
53
54
55/**
56 * Return memory on given byte alignment
57 */
58static inline void *
59os_malloc_aligned(size_t size, size_t alignment)
60{
61   char *ptr, *buf;
62   size_t alloc_size;
63
64   /*
65    * Calculate
66    *
67    *   alloc_size = size + alignment + sizeof(void *)
68    *
69    * while checking for overflow.
70    */
71   if (add_overflow_size_t(size, alignment, &alloc_size) ||
72       add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
73      return NULL;
74   }
75
76   ptr = (char *) os_malloc(alloc_size);
77   if (!ptr)
78      return NULL;
79
80   buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
81   *(char **)(buf - sizeof(void *)) = ptr;
82
83   return buf;
84}
85
86
87/**
88 * Free memory returned by os_malloc_aligned().
89 */
90static inline void
91os_free_aligned(void *ptr)
92{
93   if (ptr) {
94      void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
95      void *realAddr = *cubbyHole;
96      os_free(realAddr);
97   }
98}
99