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/**************************************************************************
*
* Copyright 2008-2010 VMware, Inc.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Memory alignment wrappers.
*/
#ifndef _OS_MEMORY_H_
#error "Must not be included directly. Include os_memory.h instead"
#endif
/**
* Add two size_t values with integer overflow check.
* TODO: leverage __builtin_add_overflow where available
*/
static inline bool
add_overflow_size_t(size_t a, size_t b, size_t *res)
{
*res = a + b;
return *res < a || *res < b;
}
/**
* Return memory on given byte alignment
*/
static inline void *
os_malloc_aligned(size_t size, size_t alignment)
{
char *ptr, *buf;
size_t alloc_size;
/*
* Calculate
*
* alloc_size = size + alignment + sizeof(void *)
*
* while checking for overflow.
*/
if (add_overflow_size_t(size, alignment, &alloc_size) ||
add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
return NULL;
}
ptr = (char *) os_malloc(alloc_size);
if (!ptr)
return NULL;
buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
*(char **)(buf - sizeof(void *)) = ptr;
return buf;
}
/**
* Free memory returned by os_malloc_aligned().
*/
static inline void
os_free_aligned(void *ptr)
{
if (ptr) {
void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
void *realAddr = *cubbyHole;
os_free(realAddr);
}
}
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