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/*
*
* test self pipe
$ gcc \
module-test/self_pipe.c \
-std=gnu23 \
-O0 -ggdb3 -fno-omit-frame-pointer -fno-inline \
-o module-test/self_pipe.out
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/select.h>
#include <unistd.h>
#include <signal.h>
#include <poll.h>
#include <errno.h>
#define TMP_SIZE 1024
typedef void handler_t(int);
handler_t *Signal(int signum, handler_t *handler);
void sigusr1_handler(int signum);
void sigusr2_handler(int signum);
int my_read(char *s, int len);
int my_poll(struct pollfd fds[], nfds_t nfds);
int self_pipe_fd[2] = {-1, -1};
void sigusr1_handler(int signum)
{
char tmp = 'A';
write(self_pipe_fd[1], &tmp, 1);
}
void sigusr2_handler(int signum) { /* empty */ }
int my_poll(struct pollfd fds[], nfds_t nfds)
{
while (true)
{
int ret = poll(fds, nfds, -1);
// if not signal'd
if (!(ret == -1 && errno == EINTR))
return ret;
}
}
int my_read(char *s, int len)
{
int max_fd;
if (STDIN_FILENO > self_pipe_fd[0]) max_fd = STDIN_FILENO;
else max_fd = self_pipe_fd[0];
struct pollfd fds[2];
fds[0].fd = STDIN_FILENO;
fds[0].events = POLLIN;
fds[1].fd = self_pipe_fd[0];
fds[1].events = POLLIN;
my_poll(fds, 2);
if ((fds[0].revents) & POLLIN) // stdin
{
return read(STDIN_FILENO, s, len);
}
else if ((fds[1].revents) & POLLIN) // pipe
{
return read(self_pipe_fd[0], s, len);
}
return -2;
}
handler_t *Signal(int signum, handler_t *handler)
{
struct sigaction action, old_action;
action.sa_handler = handler;
sigemptyset(&action.sa_mask); /* block sigs of type being handled */
action.sa_flags = SA_RESTART; /* restart syscalls if possible */
sigaction(signum, &action, &old_action);
return (old_action.sa_handler);
}
int main(int argc, char **argv)
{
Signal(SIGUSR1, sigusr1_handler);
Signal(SIGUSR2, sigusr2_handler);
pipe(self_pipe_fd);
int pid = getpid();
printf("Running PID: %d\n", pid);
printf("Do not enter anything\n");
char tmp[TMP_SIZE];
while (my_read(tmp, TMP_SIZE))
printf("Hi\n");
printf("Finished\n");
return 0;
}
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