stack overflow bug in ofstream::operator<<

Christopher Faylor me@cgf.cx
Tue Jun 28 17:59:00 GMT 2005


On Tue, Jun 28, 2005 at 06:41:09PM +0100, Dave Korn wrote:
>Well, I was proposing testing how much space was available on the
>stack, so that we never alloca past the bottom of it, and hence don't
>*need* any kind of signal handler.

If we are going to check how much stack space is available, it might be
nice to make a __alloca_which_returns_NULL which returns NULL when there
isn't enough space available.  That could be used for other things.

OTOH, the functionality I'm adding would allow you to do this:

.
.
.
  {
  char *p;
  bool malloced;
  myfault efault;
  if (efault.faulted ())
    {
      p = malloc (n);
      malloced = true;
    }
  else
    {
      p = alloca (n);
      malloced = false;
    }
  }

If alloca actually SEGVs when it tries to allocate too much space then
this would just allocate space with malloc whenever alloca fails.

This is still a more heavy weight solution than just checking the stack
to see what's available, though.

cgf



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