Date: Sun, 22 Jan 2006 14:27:41 +0100 From: Peter <bagoap@xs4all.nl> To: freebsd-questions@freebsd.org Subject: wait(2) does not return after SIGCONT Message-ID: <7.0.1.0.2.20060122134143.02183648@thuiswater.nl>
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Hello,
I call waitpid() with the WUNTRACED|WCONTINUED options set in order
to know when the child process receives SIGSTOP's and SIGCONT's. The
SIGSTOP is not the problem, but I can't get the SIGCONTs to work. The
appended code illustrates the problem: SIGCONTs to the child do
continue the child process but waitpid() remains blocked and the
SIGCONT is just not noticed by the parent.
The code is however fully functional under Sparc Solaris 2 (can't
remember the exact version). Under FreeBSD it only works when the
SIGCONT is sent directly from the parent (see the line in the example
code that is commented-out). But this is not what I want.
What am I missing? Thanks!
(problem seen with FreeBSD 5.3, 5.4 and 6.0, i386 and adm64)
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>
main() {
pid_t pid;
if ( (pid = fork()) == -1 )
printf("could not fork");
else if ( pid == 0 ) { /* child */
sleep(1); /* wait for the parent to prepair */
kill(getpid(),SIGSTOP); /* send SIGSTOP to myself */
while(1); /* loop */
}
else { /* parent */
int stat;
waitpid(pid,&stat,WUNTRACED|WCONTINUED);
while ( WIFSTOPPED(stat) || WIFCONTINUED(stat) ) {
if ( WIFSTOPPED(stat) ) {
printf("child was stopped\n");
/* if the next line is uncommented, SIGCONT is caught property */
/* kill(pid,SIGCONT); */
}
if ( WIFCONTINUED(stat) ) {
/* this part is never reached */
printf("child was continued\n");
kill(pid,SIGTERM); /* terminate child */
}
waitpid(pid,&stat,WUNTRACED|WCONTINUED);
}
}
}
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