claenups for previous commit

[oweals/busybox.git] / console-tools / setlogcons.c

diff --git a/console-tools/setlogcons.c b/console-tools/setlogcons.c
index 1b5814eee1815299b5b70632eb3349c124ca2cc2..0fad6600aa4d348c7bfd6d971d08c855b132d42c 100644 (file)
--- a/console-tools/setlogcons.c
+++ b/console-tools/setlogcons.c
@@ -15,32 +15,52 @@
 //config:      help
 //config:      This program redirects the output console of kernel messages.
 
-//applet:IF_SETLOGCONS(APPLET(setlogcons, BB_DIR_USR_SBIN, BB_SUID_DROP))
+//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:       "Redirect the kernel output to console N. Default:0 (current console)"
+//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) */
+               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;
 }