Re: Problem setting up systemtap 1.6 client/server on Ubutu 11.10

[Alex Wolfson <alex dot wolfson at canonical dot com>]

Hi Josh,

I had "compose in HTML" set in thunderbird, but never had message 
screwed up so badly before. I disabled HTML, hope it will prevent 
messages from screwing again.

I applied the pacth you mentioned and was able to build and setup 
client/server. I used my laptop as a server. The only minor discrepancy 
- server was not discovered automatically, so I need  add "--use-server 
IP" to stap command. I like client/server a lot - much nicer then 
manually copying modules around or install all debug symbols on system 
under test.

I need to test more the scripts and the build and will put client/server 
setups scripts to that list, hopefully next week. I will also put 
prebuilt .deb packages into PPA, so ubuntu users would be able to use 
version 1.6 of the systemtap now, while it makes its way to official 
pool. It is currently 1.4

Thank you very match for your help,

Alex

On 10/21/2011 02:18 AM, Josh Stone wrote:
> For some reason, your mailer or the list server mangled your reply, but
> picking out pieces...
>
> Alex Wolfson wrote:
> > Hi Josh,
> >
> > Thank you for the feedback.
> >
> > I found the place when stap-serverd is failing
> > it is in stap-serverd.cxx
> >
> > static void
> > initialize (int argc, char **argv) {
> > .....
> >     string login = getlogin ();
> > getlogin returns NULL
>
> > |getlogin| is an unsafe and deprecated way of determining the logged-in
> > user. It's probably trying to open a record of logged-in users, perhaps
> > |utmp| or something. The correct way to determine the user you're
> > running as (which might not be the same as the logged-in user, but is
> > almost always better to use anyway) is |getpwuid(getuid())|
> >
> > So after I replaced
> >
> > string login = getlogin ();
> >
> > with
> >
> > struct passwd *pwd;
> > pwd = getpwuid(getuid());
> > string login = pwd->pw_name;
> >
> > I can now manualy run
> >
> > ./stap-serverd
> >
> >    without std::logic_error
> >
> > Looks like this bug is specific ether to Ubuntu or my setup.
> >
> > I hope to find time to finish my script next week and provide a patch
> > for getlogin and whatever else will show up.
> > Probably replacing getlogin() call is a good idea anyway.
> >
> > Thanks,
> >
> > Alex
>
> It looks like we did run into this bug, and Dave already fixed it:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=737095
>
> commit 3845290458cd498e490078318ae5306911cb47a9
> Author: Dave Brolley<brolley@redhat.com>
> Date:   Tue Sep 13 11:07:11 2011 -0400
>
>      RHBZ 737095: Unable to start a systemtap server
>
>      - Don't use getlogin to obtain user name because it can fail.
>      - Establish server log before issuing any messages.
>      - Failure of avahi to advertise is now only a warning. Avahi is not
>        always available and the server can still be used directly.
>
> There are two other commits mentioned in the bug too, but this is the
> one make a similar getlogin change as you propose.
>
> HTH,
> Josh