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signals related question
Post 302106912 by matrixmadhan on Tuesday 13th of February 2007 07:13:47 AM
02-13-2007
Quote:
I know that if an application is in the sleep state, When a signal is catched, it will be processed by the handler. But what happens if it's processing something?
take this example program
Code:
#include <stdio.h>
#include <signal.h>
void process(void);
void sigFunc(int);
void sigFunc(int sigNo) {
printf("Received Signal: %d\n", sigNo);
exit (1);
}
void process() {
//Run it with printf uncommented and sleep commented
//For the second time do the vice-versa
//printf("What am I doing\n");
sleep(1);
}
int main()
{
signal(SIGUSR1, sigFunc);
while (1) {
process();
}
return 0;
}If you do run the program in two different ways, where printf is active, therefore its processing
and in the second form where it is in sleep mode, thereby after executing the sleep call
in either of the case, whatever be the state of the program that is in memory when kernel delivers a signal to the process,
if the signal handler is registered with a function 'f' it would be executed else default action of the delivered signal would be executed.
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LEARN ABOUT HPUX
sigpending
sigpending(2) System Calls Manual sigpending(2) NAME
sigpending - examine pending signals SYNOPSIS
DESCRIPTION
stores the set of signals that are blocked from delivery and are pending to the calling thread, at the location pointed to by set. RETURN VALUE
Upon successful completion, returns 0. Otherwise -1 is returned and is set to indicate the error. ERRORS
fails if the following condition is encountered: set points to an invalid address. The reliable detection of this error is implementation-dependent. APPLICATION USAGE
Threads Considerations The set of signals returned by is the union of the signals pending on the process and calling thread. A signal may be pending on the process if all threads block the signal. The set of signals returned by is only advisory. Since other threads may be executing at the time of the call, a signal pending on the process may be delivered to a thread after this system call returns. For more information regarding signals and threads, refer to signal(5). LWP (Lightweight Processes) Considerations The set of signals returned by is the union of the signals pending on the process and calling LWP. AUTHOR
was derived from the IEEE POSIX 1003.1-1988 Standard. SEE ALSO
sigaction(2), sigsuspend(2), sigprocmask(2), sigsetops(3C), signal(5). CHANGE HISTORY
First release in Issue 3. STANDARDS CONFORMANCE
: AES, SVID3, XPG3, XPG4, FIPS 151-2, POSIX.1 sigpending(2)