[ I don't have much experience with either readline or signals, so ]
[ please forgive any ignorance (or stupidity) on my part. :) ]
readline 7.0 is causing a bug[*] in Twinkle, where we are normally
blocking SIGALRM in all threads, with one thread dedicated to calling
sigwait(). Upon calling readline(), SIGALRM now apparently becomes
unblocked (or caught and rethrown, I guess), resulting in the program
aborting. This was not the case with 6.3.
This has been reported and confirmed on Debian/Ubuntu (amd64) so far.
I'm attaching a small example that reproduces this behavior:
$ gcc -o readline_sigalrm readline_sigalrm.c -lreadline -lpthread
$ ./readline_sigalrm
> Alarm clock
Note that disabling rl_catch_signals doesn't have any effect on this.
(This probably wouldn't be a good solution for us anyway.)
(I also noticed that this only seemed to occur when readline() was
called from the main thread. I suppose this could very well be
OS-specific, though.)
Please let me know if there's anything I can do to help. Thanks!
[*] https://github.com/LubosD/twinkle/issues/89
/*
* With readline 7.0, this aborts after one second due to SIGALRM.
*/
#include <pthread.h>
#include <readline/readline.h>
#include <signal.h>
#include <sys/time.h>
/* Dedicated thread to catch SIGALRM */
void *sigwait_thread (void *arg) {
sigset_t *sigset = arg;
int sig;
for (;;) sigwait(sigset, &sig);
}
int main() {
/* Block SIGALRM */
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGALRM);
pthread_sigmask(SIG_BLOCK, &sigset, NULL);
/* Create and detach sigwait thread */
pthread_t sigwait_tid;
pthread_create(&sigwait_tid, NULL, sigwait_thread, &sigset);
pthread_detach(sigwait_tid);
/* Set up a 1-second recurring timer */
struct itimerval itv = {{1, 0}, {1, 0}};
setitimer(ITIMER_REAL, &itv, NULL);
//rl_catch_signals = 0; /* This would have no effect anyway */
while (readline("> "));
return 0;
}
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