From a08530e838218b3c5859550058e78b8f1abee434 Mon Sep 17 00:00:00 2001
From: William Jon McCann <mccannwj@acsnb12.pha.jhu.edu>
Date: Wed, 25 Oct 2006 14:38:19 -0400
Subject: Initial import

---
 src/getfd.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 src/getfd.c

(limited to 'src/getfd.c')

diff --git a/src/getfd.c b/src/getfd.c
new file mode 100644
index 0000000..9dbe15c
--- /dev/null
+++ b/src/getfd.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <linux/kd.h>
+#include <sys/ioctl.h>
+
+/*
+ * getfd.c
+ *
+ * Get an fd for use with kbd/console ioctls.
+ * We try several things because opening /dev/console will fail
+ * if someone else used X (which does a chown on /dev/console).
+ */
+
+static int
+is_a_console(int fd) {
+    char arg;
+
+    arg = 0;
+    return (ioctl(fd, KDGKBTYPE, &arg) == 0
+	    && ((arg == KB_101) || (arg == KB_84)));
+}
+
+static int
+open_a_console(char *fnam) {
+    int fd;
+
+    fd = open(fnam, O_RDONLY);
+    if (fd < 0 && errno == EACCES)
+      fd = open(fnam, O_WRONLY);
+    if (fd < 0 || ! is_a_console(fd))
+      return -1;
+    return fd;
+}
+
+int getfd() {
+    int fd;
+
+    fd = open_a_console("/dev/tty");
+    if (fd >= 0)
+      return fd;
+
+    fd = open_a_console("/dev/console");
+    if (fd >= 0)
+      return fd;
+
+    for (fd = 0; fd < 3; fd++)
+      if (is_a_console(fd))
+	return fd;
+
+    return -1;
+}
-- 
cgit