*
* 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: "[N]"
//usage:#define setlogcons_full_usage "\n\n"
-//usage: "Redirect the kernel output to console N (0 for current)"
+//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) MAIN_EXTERNALLY_VISIBLE;
int setlogcons_main(int argc UNUSED_PARAM, char **argv)
{
+ char *devname;
struct {
char fn;
char subarg;
- } arg = { 11, /* redirect kernel messages */
- 0 /* to specified console (current as default) */
- };
+ } arg = {
+ 11, /* redirect kernel messages (TIOCL_SETKMSGREDIRECT) */
+ 0
+ };
if (argv[1])
arg.subarg = xatou_range(argv[1], 0, 63);
- xioctl(xopen(VC_1, O_RDONLY), TIOCLINUX, &arg);
+ /* 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 EXIT_SUCCESS;
}