Linux Device Drivers 3 examples

1 files changed, 57 insertions, 0 deletions

diff --git a/misc-progs/asynctest.c b/misc-progs/asynctest.c
new file mode 100644
index 0000000..8dcb458
--- /dev/null
+++ b/misc-progs/asynctest.c
@@ -0,0 +1,57 @@
+/*
+ * asynctest.c: use async notification to read stdin
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files.  The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates.   No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <fcntl.h>
+
+int gotdata=0;
+void sighandler(int signo)
+{
+    if (signo==SIGIO)
+        gotdata++;
+    return;
+}
+
+char buffer[4096];
+
+int main(int argc, char **argv)
+{
+    int count;
+    struct sigaction action;
+
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = sighandler;
+    action.sa_flags = 0;
+
+    sigaction(SIGIO, &action, NULL);
+
+    fcntl(STDIN_FILENO, F_SETOWN, getpid());
+    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL) | FASYNC);
+
+    while(1) {
+        /* this only returns if a signal arrives */
+        sleep(86400); /* one day */
+        if (!gotdata)
+            continue;
+        count=read(0, buffer, 4096);
+        /* buggy: if avail data is more than 4kbytes... */
+        write(1,buffer,count);
+        gotdata=0;
+    }
+}