Comment 37 for bug 727064

(In reply to comment #18)
> The problem we're facing just made this fact plain: there is no reason why
> memcpy should not be memmove.

If these two functions should behave in the same way, then why not all programmers use memmove (which has fewer requirements)?

If memcpy is called while the objects overlap, the bug is not necessarily that memmove should have been used instead. The cause may be an incorrect size. So, with this point of view, it should be safer to abort than letting the program behave in an uncontrolled way.

(In reply to comment #25)
> So, again, I think we need at least a transition period so that people can
> detect and fix the issues.

But it may be difficult to detect the issues. For instance, zsh was affected by a similar problem (now fixed in CVS only) with the optimized strcpy, but to detect the problem, it involves keyboard input:

  http://www.zsh.org/mla/workers/2011/msg00533.html
  http://www.zsh.org/mla/workers/2011/msg00544.html

For strcpy, this is even worse, as there is no strmove function, so that either programmers have to write non-portable code or they have to reimplement a naive version of strcpy or find some other workaround, such as memmove + strlen:

  http://www.zsh.org/mla/workers/2011/msg00542.html

I suppose that if this has been done for memcpy, then strcpy should also be patched in some way...