bak

userland/kernel_modules/poll.c

@@ -0,0 +1,41 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#poll */
+
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#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, i, n;
+    short revents;
+    struct pollfd pfd;
+
+    if (argc < 2) {
+        fprintf(stderr, "usage: %s <poll-device>\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+    fd = open(argv[1], O_RDONLY | O_NONBLOCK);
+    if (fd == -1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+    pfd.fd = fd;
+    pfd.events = POLLIN;
+    while (1) {
+        puts("loop");
+        i = poll(&pfd, 1, -1);
+        if (i == -1) {
+            perror("poll");
+            assert(0);
+        }
+        revents = pfd.revents;
+        if (revents & POLLIN) {
+            n = read(pfd.fd, buf, sizeof(buf));
+            printf("POLLIN n=%d buf=%.*s\n", n, n, buf);
+        }
+    }
+}