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     MALLOC(3)                                               MALLOC(3)

          malloc, free, realloc, calloc - main memory allocator

          char *malloc(size)
          unsigned size;

          char *ptr;

          char *realloc(ptr, size)
          char *ptr;
          unsigned size;

          char *calloc(nelem, elsize)
          unsigned nelem, elsize;

          Malloc and free provide a simple general-purpose memory
          allocation package.  Malloc returns a pointer to a block of
          at least size bytes beginning on a word boundary.

          The argument to free is a pointer to a block previously
          allocated by malloc; this space is made available for fur-
          ther allocation, but its contents are left undisturbed.

          Needless to say, grave disorder will result if the space
          assigned by malloc is overrun or if some random number is
          handed to free.

          Malloc allocates the first big enough contiguous reach of
          free space found in a circular search from the last block
          allocated or freed, coalescing adjacent free blocks as it
          searches.  It calls sbrk (see break(2)) to get more memory
          from the system when there is no suitable space already

          Realloc changes the size of the block pointed to by ptr to
          size bytes and returns a pointer to the (possibly moved)
          block.  The contents will be unchanged up to the lesser of
          the new and old sizes.

          Realloc also works if ptr points to a block freed since the
          last call of malloc, realloc or calloc; thus sequences of
          free, malloc and realloc can exploit the search strategy of
          malloc to do storage compaction.

          Calloc allocates space for an array of nelem elements of
          size elsize. The space is initialized to zeros.

     MALLOC(3)                                               MALLOC(3)

          Each of the allocation routines returns a pointer to space
          suitably aligned (after possible pointer coercion) for stor-
          age of any type of object.

          Malloc, realloc and calloc return a null pointer (0) if
          there is no available memory or if the arena has been
          detectably corrupted by storing outside the bounds of a
          block.  Malloc may be recompiled to check the arena very
          stringently on every transaction; see the source code.

          When realloc returns 0, the block pointed to by ptr may be