Passing user input to signal handlers.

[vasanth2K8]

Hi all,
Iam using uclibc on uclinux and writing a timer application (where on expiry of timer, a user specified signal is generated). The possible signal handlers are

void func(int signal) and
void func(int signo ,siginfo_t* pInfo,void* context) depending whether or not SA_SIGINFO is reset ot not.

But the problem is that there is no way of passing a user input to the signal handler.

Any way of achieving this ?


Vasanth

[wje_lf]

Do this at the command line:

man sigqueue

If that man page is not installed on your system, google for this:

linux man sigqueue

If you choose the linux.die.net site, note that they have written this up under both section 2 and section 3 of the manual. I have no idea why they did that; the documentation under section 2 seems slightly more useful.

Hope this helps.

[vasanth2K8]

Hi,
Thanks for the reply.

But the issue is that the signal generation is done automatically on expiration of timer and is not under my control. I can atmost specify the signal to be sent and the signal handler.

glibc does have a provision for specifying a notification function and a notification attribute on expiration of timer.But this facility is unavailable in uclibc.

[wje_lf]

Oops. My bad. I saw that you were using uclibc, but I didn't know what uclibc was: a replacement, effectively, for glibc.

I imagine you've already eliminated the following possibility, but in case you haven't:

If you only have one timer counting down at a time, why not put the parameter in question into a global, and upon expiration of the timer, let the signal handler pick it up from there?

Maybe a stupid question, but stupid questions are my specialty. :)

[vasanth2K8]

Hi,
Having the input parameter as global is not possible in the present scenario because iam encapsulating the POSIX timer as a C++ class and each object of that class will have a separate input argument. and its not practical for having many global variables as there will be lots of timer objects.