Matty wrote:
> On 4/5/07, James Carlson <james.d.carlson at sun.com> wrote:
>> Darren J Moffat writes:
>> > Matty wrote:
>> > > Howdy,
>> > >
>> > > Most Linux and BSD distributions ship with a version of dd that
>> > > displays the status of a copy operation when a SIGUSR1 signal is
>> > > received. For some reason /usr/bin/dd on Solaris hosts doesn't
>> contain
>> > > this capability, and I would like to add it. After reading through
>> the
>> > > source code for dd.c, it looks like adding this support would be as
>> > > simple as installing a signal handler for SIGUSR1, and having it call
>> > > the function stats. I am attaching code (which I copied from the dd
>> > > that ships with Fedora Core Linux)
>> >
>> > What license is that dd code you copied under ?
>> >
>> > You can't just copy code like that without considering the licenses.
>>
>> Indeed. That's GPLv2 code, which would require OpenSolaris dd to
>> become GPLv2 as well.
>>
>> That can't be done. Either start provably from scratch or use
>> software under a compatible license.
>
> Your absolutely right, and Stephen Hahn was nice enough to point this
> out in an email last night. Since the existing code uses signal to
> register the SIGINT signal handler (I reckon the issues Bart mentioned
> are minimized since it exit()'s after printing the statistics):
>
> if (signal(SIGINT, SIG_IGN) != SIG_IGN)
> {
> (void) signal(SIGINT, term);
> }
>
> Do folks see any issue with using similar code to add a SIGUSR1 signal
> handler?:
>
> if (signal(SIGUSR1, SIG_IGN) != SIG_IGN)
> {
> (void) signal(SIGUSR1, stats);
> }
>
> This would minmize the amount of code that would need to be added to
> get stats functionality, and would address the license issues. If this
> solution isn't acceptable, could I get a sponsor assigned to help me
> work through a community approved solution?
>
> Thanks,
> - Ryan
Note that SA_RESTART must be set; otherwise dd from a pipe or other slow
device will return an error condition. I also like Casper's suggestion
to use sprintf and write to stderr, since sprintf is now
async-signal-safe.
I can help you get this into shape.
- Bart
--
Bart Smaalders Solaris Kernel Performance
barts at cyber.eng.sun.com http://blogs.sun.com/barts
