cp/mv/dd to handle SIGXFSZ?

[Micah Cowan]

In the Ubuntu bugtracker, Malone, we've been getting several submissions 
of an issue, usually phrased along the lines of "cp dumps core on copy 
of > 4GB file to vfat (or usb)", etc. See 
https://bugs.launchpad.net/ubuntu/+source/coreutils/+bug/75574

I'd like to see a handler installed for SIGXFSZ in cp, mv and dd, so 
that a user-friendly warning can be issued instead of a core-dump, and 
processing of any remaining source files may continue unabated.

As you will see in the comments of the bug whose link I gave above, I'm 
aware that this will break POSIX (which specifies default handling for 
signals in the various utils), but I feel the utility of handling this 
signal would outweigh the benefits of strict adherence to the standard 
(which of course, could be re-enabled via POSIXLY_CORRECT).


As a secondary note, some users are disgruntled that cp will go ahead 
and copy 4GB of data before it realizes there is a problem, and would 
prefer a preemptive check to see what the maximum file size is. I 
absolutely understand that such a thing would not be preferable as 
default behavior, as it would break portability too much. And, I don't 
even know whether determining such a thing is possible (if so, it's 
probably not portable). But I'd like to know (a) if it is in fact 
possible, and (b) if possible, what is the feasibility of adding a 
suitable option to enable such a check?

--
Thanks,
Micah J. Cowan
Programmer, musician, typesetting enthusiast, gamer...
http://micah.cowan.name/