From ce53d67c5ea60a210c4c248722a431756c494140 Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Sun, 1 Nov 2026 09:24:47 +0000
Subject: rewrite in C

---
 module-test/self_pipe.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 module-test/self_pipe.c

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

diff --git a/module-test/self_pipe.c b/module-test/self_pipe.c
new file mode 100644
index 0000000..ae271c3
--- /dev/null
+++ b/module-test/self_pipe.c
@@ -0,0 +1,83 @@
+/*
+ *
+ * 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
+ */
+
+#include <stdio.h>
+#include <sys/select.h>
+#include <unistd.h>
+#include <signal.h>
+
+#define TMP_SIZE 1024
+
+
+typedef void handler_t(int);
+handler_t *Signal(int signum, handler_t *handler);
+void sigusr1_handler(int signum);
+int my_read(char *s, int len);
+
+int self_pipe_fd[2] = {-1, -1};
+
+
+
+void sigusr1_handler(int signum)
+{
+    char tmp = 'A';
+    write(self_pipe_fd[1], &tmp, 1);
+}
+
+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))
+    {
+        return read(self_pipe_fd[0], s, len);
+    }
+    else if (FD_ISSET(STDIN_FILENO, &rset))
+    {
+        return read(STDIN_FILENO, s, len);
+    }
+    return -1;
+}
+
+
+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()
+{
+    printf("Do not enter anything\n");
+    Signal(SIGUSR1, sigusr1_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;
+}
\ No newline at end of file
-- 
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