[hackers] [ubase] Add vtallow(1) to enable or disable VT switch || sin

[git]

commit 4269d523e2c5cc65c89e5340a55febe72c3d3f49
Author: sin <s...@2f30.org>
Date:   Fri Dec 5 15:04:37 2014 +0000

    Add vtallow(1) to enable or disable VT switch

diff --git a/Makefile b/Makefile
index 9f070bf..a640f50 100644
--- a/Makefile
+++ b/Makefile
@@ -82,6 +82,7 @@ BIN = \
        umount            \
        unshare           \
        uptime            \
+       vtallow           \
        watch             \
        who
 
diff --git a/vtallow.c b/vtallow.c
new file mode 100644
index 0000000..03d67a5
--- /dev/null
+++ b/vtallow.c
@@ -0,0 +1,52 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "util.h"
+
+#define CONSOLE "/dev/console"
+
+#define VT_LOCKSWITCH   0x560B  /* disallow vt switching */
+#define VT_UNLOCKSWITCH 0x560C  /* allow vt switching */
+
+static void
+usage(void)
+{
+       eprintf("usage: vtallow n|y\n");
+}
+
+int
+main(int argc, char *argv[])
+{
+       int fd;
+       int allow;
+
+       ARGBEGIN {
+       default:
+               usage();
+       } ARGEND;
+
+       if (argc != 1)
+               usage();
+
+       if (!strcmp(argv[0], "y"))
+               allow = 1;
+       else if (!strcmp(argv[0], "n"))
+               allow = 0;
+       else
+               usage();
+
+       if ((fd = open(CONSOLE, O_WRONLY)) < 0)
+               eprintf("open %s:", CONSOLE);
+       if (ioctl(fd, allow ? VT_UNLOCKSWITCH : VT_LOCKSWITCH) < 0)
+               eprintf("cannot %s VT switch:",
+                       allow ? "enable" : "disable");
+       close(fd);
+       return 0;
+}