[Bug translator/11853] New: staprun errors do not appear on xterm

[Bug translator/11853] New: staprun errors do not appear on xterm

[andi-bz at firstfloor dot org]

With stap 1.3

By mistake I tried to do a probe without being root.

This just gives a useless error message:
Pass 5: run failed.  Try again with another '--vp 00001' option.

Even with -vvvvvvvvvv and the suggest --vp option it doesn't get
better, it doesn't say anywhere that I'm not root.

It looks like this gets printed internally according to strace by
one of the children:
13352 execve("/bin/sh", ["sh", "-c", "/pkg/systemtap-1.3/bin/staprun -"...], [/*
82 vars */]) = 0
...
13352 write(2, "ERROR: The effective user ID of "..., 141) = 141
13352 exit_group(1)                     = ?

but that never appeared on my xterm. It should.

-- 
           Summary: staprun errors do not appear on xterm
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: andi-bz at firstfloor dot org
  GCC host triplet: x86_64-linux


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[Bug translator/11853] staprun errors do not appear on xterm

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-07-29 12:18 -------
Andi, could you check whether something closes stderr in
your strace log?  I can't reproduce this by hand.  Are
you in stapdev/stapusr?

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING


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[Bug translator/11853] staprun errors do not appear on xterm

[andi-bz at firstfloor dot org]

------- Additional Comments From andi-bz at firstfloor dot org  2010-07-29 14:46 -------
Created an attachment (id=4886)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4886&action=view)
strace log

I don't see any close(2) before the euid error output, there's only one 
afterwards, but it's in a different process.

Attaching the full log.


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[Bug translator/11853] staprun errors do not appear on xterm

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-07-29 15:05 -------
OK, that log includes lots of messages printed to stderr, both
from the stap process, and the fork/exec'd staprun.  What subset
of those messages did you see on your xterm?  (There appears to
be no misuse of O_CLOEXEC.)

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[Bug translator/11853] staprun errors do not appear on xterm

[andi-bz at firstfloor dot org]

------- Additional Comments From andi-bz at firstfloor dot org  2010-07-29 15:21 -------
% stap chdir.stp 
Pass 5: run failed.  Try again with another '--vp 00001' option.
% 


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[Bug translator/11853] staprun errors do not appear on xterm

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-07-29 15:36 -------
(In reply to comment #4)
> % stap chdir.stp 
> Pass 5: run failed.  Try again with another '--vp 00001' option.
> % 

That's not from the run that generated the strace logs though.

Also, try running staprun by hand (stap -p4 -mfoo foo.stp; staprun foo.ko).


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[Bug translator/11853] staprun errors do not appear on xterm

[andi-bz at firstfloor dot org]

------- Additional Comments From andi-bz at firstfloor dot org  2010-07-29 15:52 -------
Created an attachment (id=4887)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4887&action=view)
script

Here's a full typescript with no error.

But the error should appear without any special options anyways.


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[Bug translator/11853] staprun errors do not appear on xterm

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-07-29 17:37 -------
I can't figure this one out yet.  It certainly seems like the
various processes are sending the messages out.

One thing that's clear though is that the strace is not quite pure,
possibly complicated by staprun's setuid nature.  The typescript
traffic includes attempts to load the module (the "inserting module"
parts) that don't show up in the strace.  Maybe another syscall
tracing widget is needed.  Does older systemtap work on this
kernel?

I get the sense that some security widget is killing staprun and
perhaps its stderr channel.  Does dmesg help?


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[Bug translator/11853] staprun errors do not appear on xterm

[andi-bz at firstfloor dot org]

------- Additional Comments From andi-bz at firstfloor dot org  2010-07-29 18:27 -------
There's nothing in dmesg and I don't run any security modules like selinux or
similar.

It might be that strace affects the output. I can try again with the other
syscall tracer.


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