if (__brk (0) < 0) return (void *) -1;
{ extern void _end;  if (__brk (0) < 0)		 return (void *) -1;   if (!__libc_multiple_libcs && __curbrk == &_end) { size_t pg = __getpagesize (); ptrdiff_t rest = pg - ((&_end - (void *) 0) & (pg - 1));  if (__brk (__curbrk + rest) < 0) return (void *) -1; } }
__sbrk (ptrdiff_t increment){  void *oldbrk;  /* If this is not part of the dynamic library or the library is used     via dynamic loading in a statically linked program update     __curbrk from the kernel's brk value.  That way two separate     instances of __brk and __sbrk can share the heap, returning     interleaved pieces of it.  */  if (__curbrk == NULL || __libc_multiple_libcs)    if (__brk (0) < 0)      return (void *) -1;  if (increment == 0)    return __curbrk;  oldbrk = __curbrk;  if (__brk (oldbrk + increment) < 0)    return (void *) -1;  return oldbrk;}