src/malloc/lite_malloc.c

   1 #include <stdlib.h>
   2 #include <stdint.h>
   3 #include <limits.h>
   4 #include <errno.h>
   5 #include "lock.h"
   6 #include "malloc_impl.h"
   7
   8 #define ALIGN 16
   9
  10 static void *__simple_malloc(size_t n)
  11 {
  12         static char *cur, *end;
  13         static volatile int lock[1];
  14         size_t align=1, pad;
  15         void *p;
  16
  17         if (!n) n++;
  18         while (align<n && align<ALIGN)
  19                 align += align;
  20
  21         LOCK(lock);
  22
  23         pad = -(uintptr_t)cur & align-1;
  24
  25         if (n <= SIZE_MAX/2 + ALIGN) n += pad;
  26
  27         if (n > end-cur) {
  28                 size_t m = n;
  29                 char *new = __expand_heap(&m);
  30                 if (!new) {
  31                         UNLOCK(lock);
  32                         return 0;
  33                 }
  34                 if (new != end) {
  35                         cur = new;
  36                         n -= pad;
  37                         pad = 0;
  38                 }
  39                 end = new + m;
  40         }
  41
  42         p = cur + pad;
  43         cur += n;
  44         UNLOCK(lock);
  45         return p;
  46 }
  47
  48 weak_alias(__simple_malloc, malloc);
  49
  50 static void *__simple_calloc(size_t m, size_t n)
  51 {
  52         if (n && m > (size_t)-1/n) {
  53                 errno = ENOMEM;
  54                 return 0;
  55         }
  56         return __simple_malloc(n * m);
  57 }
  58
  59 weak_alias(__simple_calloc, calloc);