*
* Based on setlogcons (kbd-1.12) by Andries E. Brouwer
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+//config:config SETLOGCONS
+//config: bool "setlogcons (1.8 kb)"
+//config: default y
+//config: select PLATFORM_LINUX
+//config: help
+//config: This program redirects the output console of kernel messages.
+
+//applet:IF_SETLOGCONS(APPLET_NOEXEC(setlogcons, setlogcons, BB_DIR_USR_SBIN, BB_SUID_DROP, setlogcons))
+
+//kbuild:lib-$(CONFIG_SETLOGCONS) += setlogcons.o
+
+//usage:#define setlogcons_trivial_usage
+//usage: "[N]"
+//usage:#define setlogcons_full_usage "\n\n"
+//usage: "Pin kernel output to VT console N. Default:0 (do not pin)"
+
+// Comment from kernel source:
+/* ...
+ * By default, the kernel messages are always printed on the current virtual
+ * console. However, the user may modify that default with the
+ * TIOCL_SETKMSGREDIRECT ioctl call.
+ *
+ * This function sets the kernel message console to be @new. It returns the old
+ * virtual console number. The virtual terminal number 0 (both as parameter and
+ * return value) means no redirection (i.e. always printed on the currently
+ * active console).
*/
#include "libbb.h"
-int setlogcons_main(int argc, char **argv);
-int setlogcons_main(int argc, char **argv)
+int setlogcons_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int setlogcons_main(int argc UNUSED_PARAM, char **argv)
{
+ char *devname;
struct {
char fn;
char subarg;
- } arg;
-
- arg.fn = 11; /* redirect kernel messages */
- arg.subarg = 0; /* to specified console (current as default) */
+ } arg = {
+ 11, /* redirect kernel messages (TIOCL_SETKMSGREDIRECT) */
+ 0
+ };
- if (argc == 2)
- arg.subarg = xatoul_range(argv[1], 0, 63);
+ if (argv[1])
+ arg.subarg = xatou_range(argv[1], 0, 63);
- if (ioctl(xopen(VC_1, O_RDONLY), TIOCLINUX, &arg))
- bb_perror_msg_and_die("TIOCLINUX");
+ /* Can just call it on "/dev/tty1" always, but...
+ * in my testing, inactive (never opened) VTs are not
+ * redirected to, despite ioctl not failing.
+ *
+ * By using "/dev/ttyN", ensure it is activated.
+ */
+ devname = xasprintf("/dev/tty%u", arg.subarg);
+ xioctl(xopen(devname, O_RDONLY), TIOCLINUX, &arg);
- return 0;
+ return EXIT_SUCCESS;
}