poll sketch

kernel_module/test/poll.c

@@ -0,0 +1,37 @@
+#define _XOPEN_SOURCE 700
+#include <fcntl.h> /* creat, O_CREAT */
+#include <poll.h> /* poll */
+#include <stdio.h> /* printf, puts, snprintf */
+#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
+#include <unistd.h> /* read */
+
+int main(int argc, char **argv) {
+    char buf[1024];
+    int fd, n;
+    short revents;
+    struct pollfd pfd;
+
+    fd = open(argv[1], O_RDONLY | O_NONBLOCK);
+    pfd.fd = fd;
+    pfd.events = POLLIN;
+    while (1) {
+        puts("loop");
+        poll(&pfd, 1, -1);
+        revents = pfd.revents;
+        if (revents & POLLIN) {
+            n = read(pfd.fd, buf, sizeof(buf));
+            printf("POLLIN n=%d buf=%.*s\n", n, n, buf);
+        }
+        if (revents & POLLHUP) {
+            printf("POLLHUP\n");
+            close(pfd.fd);
+            break;
+        }
+        if (revents & POLLNVAL) {
+            printf("POLLNVAL\n");
+        }
+        if (revents & POLLERR) {
+            printf("POLLERR\n");
+        }
+    }
+}