src/util/os_memory_aligned.h

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  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  */
  43 static inline bool
  44 add_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
  53 static inline void *
  54 os_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  */
  70 static inline void *
  71 os_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  */
 102 static inline void
 103 os_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  */
 117 static inline void *
 118 os_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 }