wait4() WNOHANG ignored when tracing under 2.0.28

Matthias Urlichs (smurf@work.smurf.noris.de)
3 Feb 1997 09:32:12 +0100

The following code

/* foo.c */
#include <sys/wait.h>
main() {
int pid = fork();
int val;

if(pid == 0) {
sleep(5);
exit(0);
}

wait4(-1,&val,WNOHANG,NULL);
}

does NOT work when traced:

# strace -f foo
[...]
personality(PER_LINUX) = 0
fork() = 21389
[pid 21388] wait4(-1, <unfinished ...>
[pid 21389] nanosleep(0xbffff8f8, 0xbffff8f8, 0x40091770, 0x1, 0x80485ac) = 0
[pid 21389] _exit(0) = ?
<... wait4 resumed> 0xbffff90c, WNOHANG, NULL) = 0
_exit(0) = ?

The main program returns immediately when I'm not tracing.

Ideas, anybody? 

-- 
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