src/basic/alloc-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <malloc.h>
   4 #include <stdint.h>
   5 #include <string.h>
   6
   7 #include "alloc-util.h"
   8 #include "macro.h"
   9 #include "memory-util.h"
  10
  11 void* memdup(const void *p, size_t l) {
  12         void *ret;
  13
  14         assert(l == 0 || p);
  15
  16         ret = malloc(l ?: 1);
  17         if (!ret)
  18                 return NULL;
  19
  20         return memcpy_safe(ret, p, l);
  21 }
  22
  23 void* memdup_suffix0(const void *p, size_t l) {
  24         void *ret;
  25
  26         assert(l == 0 || p);
  27
  28         /* The same as memdup() but place a safety NUL byte after the allocated memory */
  29
  30         if (_unlikely_(l == SIZE_MAX)) /* prevent overflow */
  31                 return NULL;
  32
  33         ret = malloc(l + 1);
  34         if (!ret)
  35                 return NULL;
  36
  37         ((uint8_t*) ret)[l] = 0;
  38         return memcpy_safe(ret, p, l);
  39 }
  40
  41 void* greedy_realloc(
  42                 void **p,
  43                 size_t need,
  44                 size_t size) {
  45
  46         size_t a, newalloc;
  47         void *q;
  48
  49         assert(p);
  50
  51         /* We use malloc_usable_size() for determining the current allocated size. On all systems we care
  52          * about this should be safe to rely on. Should there ever arise the need to avoid relying on this we
  53          * can instead locally fall back to realloc() on every call, rounded up to the next exponent of 2 or
  54          * so. */
  55
  56         if (*p && (size == 0 || (MALLOC_SIZEOF_SAFE(*p) / size >= need)))
  57                 return *p;
  58
  59         if (_unlikely_(need > SIZE_MAX/2)) /* Overflow check */
  60                 return NULL;
  61         newalloc = need * 2;
  62
  63         if (size_multiply_overflow(newalloc, size))
  64                 return NULL;
  65         a = newalloc * size;
  66
  67         if (a < 64) /* Allocate at least 64 bytes */
  68                 a = 64;
  69
  70         q = realloc(*p, a);
  71         if (!q)
  72                 return NULL;
  73
  74         return *p = q;
  75 }
  76
  77 void* greedy_realloc0(
  78                 void **p,
  79                 size_t need,
  80                 size_t size) {
  81
  82         size_t before, after;
  83         uint8_t *q;
  84
  85         assert(p);
  86
  87         before = MALLOC_SIZEOF_SAFE(*p); /* malloc_usable_size() will return 0 on NULL input, as per docs */
  88
  89         q = greedy_realloc(p, need, size);
  90         if (!q)
  91                 return NULL;
  92
  93         after = MALLOC_SIZEOF_SAFE(q);
  94
  95         if (size == 0) /* avoid division by zero */
  96                 before = 0;
  97         else
  98                 before = (before / size) * size; /* Round down */
  99
 100         if (after > before)
 101                 memzero(q + before, after - before);
 102
 103         return q;
 104 }
 105
 106 void* greedy_realloc_append(
 107                 void **p,
 108                 size_t *n_p,
 109                 const void *from,
 110                 size_t n_from,
 111                 size_t size) {
 112
 113         uint8_t *q;
 114
 115         assert(p);
 116         assert(n_p);
 117         assert(from || n_from == 0);
 118
 119         if (n_from > SIZE_MAX - *n_p)
 120                 return NULL;
 121
 122         q = greedy_realloc(p, *n_p + n_from, size);
 123         if (!q)
 124                 return NULL;
 125
 126         memcpy_safe(q + *n_p * size, from, n_from * size);
 127
 128         *n_p += n_from;
 129
 130         return q;
 131 }
 132
 133 void *expand_to_usable(void *ptr, size_t newsize _unused_) {
 134         return ptr;
 135 }