[debian-mysql] Bug#739846: Bug#739846: invoke-rc.d: initscript mysql, action "start" failed.

[Bob Proulx]

Hi James,

James Page wrote:
> On 23/02/14 05:51, Bob Proulx wrote:
> > Diff'ing the newest /etc/init.d/mysql against the previous one
> > shows this important difference:
> > 
> > @@ -186,4 +186,3 @@ ;; esac
> > 
> > -exit 0
> > 
> > The exit 0 at the end of the script was dropped.  This causes the 
> > script to exit with the exit code of the last command run which is 
> > usually non-zero.  In the case that the script exits non-zero then
> > the upgrade fails to configure the new package.
> 
> I can't see this change in the debdiff between -1 and -2 as in AFAICT
> the init script has never had an exit 0 at the end.  Is it possible
> this was a local change?

You are right.  It was a local change I had made previously for this
same problem.  I had previously debugged that the /etc/init.d/mysql
script would exit non-zero by mistake on a normal exit and added that
to the bottom of my copy of the script.

I had also modified /etc/mysql/debian-start (hey it is a conffile
after all) to avoid printing this message:

  echo "Checking for tables which need an upgrade, are corrupt or were "
  echo "not closed cleanly."

I had commented that out.  It is an unfortunate message IMNHO.  It
runs those in the background asynchronously and therefore I don't see
the need to inform the caller.  Plus it is a scary reading message and
scares people.  Therefore I tried silencing it.  Because of that
change the start script exits non-zero.

	        # Now start mysqlcheck or whatever the admin wants.
	        output=$(/etc/mysql/debian-start)
		[ -n "$output" ] && log_action_msg "$output"

If /etc/mysql/debian-start outputs something, anything, then the test
for -n "$output" is true and then log_action_msg logs it and also
returns 0.  But if /etc/mysql/debian-start emits nothing then output
is empty and -n "" is non-zero.  At that point things fall through to
the bottom of the script and exits with the last exit code which means
the script exits non-zero as well.  Because the action exits non-zero
the postinst script fails and dpkg --configure fails.

Would it be possible to put an exit 0 at the bottom of the script?  It
would be good programming.  I think it is definitely unintended to
exit non-zero when /etc/mysql/debian-start doesn't print anything.
Note that the /etc/init.d/skeleton previously included a ":" at the
bottom to essentially do the same thing in a different way.  I think
ending with a ":" to be more obscure than the more explicit exit 0 and
therefore prefer the latter.  But either would be the same.  All of
the error handling in the script explicitly exits with a non-zero
error upon detecting an error.

Thanks,
Bob
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