[Buildroot] [Bug 8911] New: Using sysvinit inittab and "single" user mode the rcS script still runs

[Buildroot] [Bug 8911] New: Using sysvinit inittab and "single" user mode the rcS script still runs

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8911

            Bug ID: 8911
           Summary: Using sysvinit inittab and "single" user mode the rcS
                    script still runs
           Product: buildroot
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Other
          Assignee: unassigned at buildroot.uclibc.org
          Reporter: ckhardin at exablox.com
                CC: buildroot at uclibc.org
  Target Milestone: ---

Expected single user behavior to NOT run the rcS script when runlevel S is
given to sysvinit.


From the busybox code - when going into single user, the logic is conditional
to not even parse the inittab and jump into the single user shell.

busybox/init/init.c

        /* Check if we are supposed to be in single user mode */
        if (argv[1]
         && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 ||
LONE_CHAR(argv[1], '1'))
        ) {
                /* ??? shouldn't we set RUNLEVEL="b" here? */
                /* Start a shell on console */
                new_init_action(RESPAWN, bb_default_login_shell, "");
        } else {
                /* Not in single user mode - see what inittab says */

                /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
                 * then parse_inittab() simply adds in some default
                 * actions (i.e., INIT_SCRIPT and a pair
                 * of "askfirst" shells) */
                parse_inittab();
        }

However, the sysvinit uses the runlevels and the sysinit action runs before a
runlevel has been selected - so, the rcS always runs.

I believe this diff gets what should happen, but their might be a context that
I don't know about for not doing this.

diff --git a/package/sysvinit/inittab b/package/sysvinit/inittab
index 27eb4a6..fad91ea 100644
--- a/package/sysvinit/inittab
+++ b/package/sysvinit/inittab
@@ -10,7 +10,7 @@ si2::sysinit:/bin/mkdir -p /dev/pts
 si3::sysinit:/bin/mkdir -p /dev/shm
 si4::sysinit:/bin/mount -a
 si5::sysinit:/bin/hostname -F /etc/hostname
-si6::sysinit:/etc/init.d/rcS
+rcS:12345:wait:/etc/init.d/rcS

 # S0:1:respawn:/sbin/getty -L ttyS0 115200 vt100 # GENERIC_SERIAL

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[Buildroot] [Bug 8911] Using sysvinit inittab and "single" user mode the rcS script still runs

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8911

Peter Korsgaard <jacmet@uclibc.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from Peter Korsgaard <jacmet@uclibc.org> ---
Fixed on the next branch, thanks:

commit eda809cd052dea73bca02385c7a10a4d7795c912
Author: Charles Hardin <ckhardin@exablox.com>
Date:   Sat May 21 13:11:10 2016 -0700

    sysvinit: update the inittab to support "single" from the kernel

    Closes #8911

    When the kernel passes single in the command line, this translates
    into an init -s option that is suppose to drop into a shell after
    the sysinit and before the runlevel.

    So, in busybox this is hardcoded - but, in sysvinit using the
    sysinit action for the rcS means that it will always be executed
    even when trying to get into single user mode for repair.

    This change should run rcS in all of the expected runlevels
    1-5 and should achieve the desired result compared to the busybox
    and still allow a single user shell to get started as expected
    before running rcS.

    Signed-off-by: Charles Hardin <ckhardin@exablox.com>
    Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

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