#include <errno.h>
#include <stdio.h>
#include <poll.h>
int main() {
* Start a process with popen and watch the pipe using poll().
* We should get these events (preferrably in this exact order):
* - 3 reads of the values 1, 2 and 3 from the bash script
* - 1 end of file event (that should make the pipe readable)
* - 1 EINTR return from poll because of the SIGCHLD signal when the child process terminates
*
* Currently, the EINTR return happens before the end of file event notification.
*/
FILE* f = popen("/bin/bash -c 'for i in 1 2 3; do { echo $i; sleep 1; }; done'", "r");
printf("f=%p\n", f);
int fd = fileno(f);
printf("fd=%d\n", fd);
struct pollfd pfd;
pfd.fd = fd;
pfd.events = POLLIN | POLLRDBAND;
char buffer[80];
while (1) {
int rv = poll(&pfd, 1, 500);
printf("rv=%d\n", rv);
if (rv == 0)
continue;
if (rv < 0) {
if (errno == EINTR) {
puts("warning: received SIGCHLD before stream close event");
continue;
} else {
printf("poll returns with error %s\n", strerror(errno));
break;
}
}
printf("events=%08x revents=%08x\n", pfd.events, pfd.revents);
if ((pfd.events & pfd.revents) == 0)
break;
fgets(buffer, 79, f);
printf("output: %s", buffer);
}
return 0;
}
