#include <bus.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define t(stmt) if (stmt) goto fail
static size_t pauser_count = 0;
static size_t pausers_size = 0;
static char* pausers = NULL;
static int is_moc_playing(void)
{
return !WEXITSTATUS(system("env LANG=C mocp -i 2>/dev/null | grep 'State: PLAY' >/dev/null"));
}
/* In a proper implementation, message whould be copyied, and then
* a new thread would be created that parsed the copy. But that is
* too much for an example, especially since it would also require
* a mutex to make sure two threads do not modify data at the same
* time, causing chaos. */
static int callback(const char *message, void *user_data)
{
char *msg = NULL;
size_t len = 0;
while ((len < 2047) && message[len])
len++;
msg = malloc((len + 1) * sizeof(char));
t(msg == NULL);
memcpy(msg, message, len * sizeof(char));
msg[len] = 0;
/* BEGIN run as in a separate thread */
if (pauser_count || is_moc_playing()) {
char *begin = strchr(msg, ' ');
ssize_t pid;
int requests_pause;
if (begin == NULL)
goto done;
*begin++ = 0;
pid = (ssize_t)atoll(msg);
if (pid < 1) /* We need a real PID, too bad there is
no convient way to detect if it dies. */
goto done;
if ((strstr(begin, "force-pause ") == begin) || !strcmp(begin, "force-pause"))
requests_pause = 1;
else if ((strstr(begin, "unforce-pause ") == begin) || !strcmp(begin, "unforce-pause"))
requests_pause = 0;
else
goto done;
if ((size_t)pid >= pausers_size) {
pausers = realloc(pausers, (size_t)(pid + 1) * sizeof(char));
t(pausers == NULL); /* Let's ignore the memory leak. */
memset(pausers + pausers_size, 0, ((size_t)(pid + 1) - pausers_size) * sizeof(char));
pausers_size = (size_t)(pid + 1);
}
if (pausers[pid] ^ requests_pause) {
pauser_count += requests_pause ? 1 : -1;
pausers[pid] = requests_pause;
if (pauser_count == (size_t)requests_pause)
system(requests_pause ? "mocp -P" : "mocp -U");
}
}
/* END run as in a separate thread */
goto done;
(void) user_data;
fail:
perror("monitor");
return -1;
done:
free(msg);
return 1;
}
int main()
{
bus_t bus;
t(bus_open(&bus, "/tmp/example-bus", BUS_RDONLY));
t(bus_read(&bus, callback, NULL));
bus_close(&bus);
free(pausers);
return 0;
fail:
perror("monitor");
bus_close(&bus);
free(pausers);
return 1;
}
