klibc/klibc/realloc.c

   1 /*
   2  * realloc.c
   3  */
   4
   5 #include <stdlib.h>
   6 #include <string.h>
   7
   8 #include "malloc.h"
   9
  10 /* FIXME: This is cheesy, it should be fixed later */
  11
  12 void *realloc(void *ptr, size_t size)
  13 {
  14   struct free_arena_header *ah;
  15   void *newptr;
  16   size_t oldsize;
  17
  18   if ( !ptr )
  19     return malloc(size);
  20
  21   if ( size == 0 ) {
  22     free(ptr);
  23     return NULL;
  24   }
  25
  26   /* Add the obligatory arena header, and round up */
  27   size = (size+2*sizeof(struct arena_header)-1) & ARENA_SIZE_MASK;
  28
  29   ah = (struct free_arena_header *)
  30     ((struct arena_header *)ptr - 1);
  31
  32   if ( ah->a.size >= size && size >= (ah->a.size >> 2) ) {
  33     /* This field is a good size already. */
  34     return ptr;
  35   } else {
  36     /* Make me a new block.  This is kind of bogus; we should
  37        be checking the adjacent blocks to see if we can do an
  38        in-place adjustment... fix that later. */
  39
  40     oldsize = ah->a.size - sizeof(struct arena_header);
  41
  42     newptr = malloc(size);
  43     memcpy(newptr, ptr, (size < oldsize) ? size : oldsize);
  44     free(ptr);
  45
  46     return newptr;
  47   }
  48 }
  49