From 111272567f63e4e5faf5a8e5b518c4e68d9d96bf Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Mon, 2 Nov 2026 03:17:09 +0000
Subject: use poll(2)

---
 module-test/self_pipe.c | 51 +++++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 12 deletions(-)

(limited to 'module-test/self_pipe.c')

diff --git a/module-test/self_pipe.c b/module-test/self_pipe.c
index ae271c3..38c8fb9 100644
--- a/module-test/self_pipe.c
+++ b/module-test/self_pipe.c
@@ -8,10 +8,14 @@
    -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
 
@@ -19,7 +23,10 @@
 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};
 
@@ -31,25 +38,45 @@ void sigusr1_handler(int signum)
     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];
-    fd_set rset;
-    FD_ZERO(&rset);
-    FD_SET(STDIN_FILENO, &rset);
-    FD_SET(self_pipe_fd[0], &rset);
-    select(max_fd+1, &rset, nullptr, nullptr, nullptr);
-    if (FD_ISSET(self_pipe_fd[0], &rset))
+
+    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(self_pipe_fd[0], s, len);
+        return read(STDIN_FILENO, s, len);
     }
-    else if (FD_ISSET(STDIN_FILENO, &rset))
+    else if ((fds[1].revents) & POLLIN) // pipe
     {
-        return read(STDIN_FILENO, s, len);
+        return read(self_pipe_fd[0], s, len);
     }
-    return -1;
+    
+    return -2;
 }
 
 
@@ -65,10 +92,10 @@ handler_t *Signal(int signum, handler_t *handler)
     return (old_action.sa_handler);
 }
 
-int main()
+int main(int argc, char **argv)
 {
-    printf("Do not enter anything\n");
     Signal(SIGUSR1, sigusr1_handler);
+    Signal(SIGUSR2, sigusr2_handler);
     pipe(self_pipe_fd);
     int pid = getpid();
     printf("Running PID: %d\n", pid);
-- 
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