[lldb-dev] Assert in DYLDRendezvous::UpdateSOEntries

[Kopec, Matt]

Unfortunately, the original author of the majority of the original POSIX/Linux code isn't around anymore.

However, looking into the issue, I think the code here is expecting an eConsistent state after an eAdd/eDelete since the library entries don't get updated until you actually get the eConsistent state. This is probably why there is an m_previous and m_current.

Maybe the behaviour you see is ok. I'm not sure. I think better understanding of the system dynamic linker/loader behaviour here may be needed.

Curiously, do you get the same assert without a step? i.e. just running?

Thanks,
Matt

On 2013-06-13, at 9:50 PM, Michael Sartain <mikesart at gmail.com> wrote:

> I just hit the below assert on line 138 stepping over a dlclose().
> 
> 120| bool
> 121| DYLDRendezvous::UpdateSOEntries()
> 122| {
> 123|     SOEntry entry;
> 124|
> 125|     if (m_current.map_addr == 0)
> 126|         return false;
> 127|
> 128|     // When the previous and current states are consistent this is the first
> 129|     // time we have been asked to update.  Just take a snapshot of the currently
> 130|     // loaded modules.
> 131|     if (m_previous.state == eConsistent && m_current.state == eConsistent)
> 132|         return TakeSnapshot(m_soentries);
> 133|
> 134|     // If we are about to add or remove a shared object clear out the current
> 135|     // state and take a snapshot of the currently loaded images.
> 136|     if (m_current.state == eAdd || m_current.state == eDelete)
> 137|     {
> 138+>        assert(m_previous.state == eConsistent);
> 139|         m_soentries.clear();
> 140|         m_added_soentries.clear();
> 141|         m_removed_soentries.clear();
> 142|         return TakeSnapshot(m_soentries);
> 143|     }
> 
> It's called by this code in DYLDRendezvous::Resolve():
> 
> 106|     // The rendezvous was successfully read.  Update our internal state.
> 107|     m_rendezvous_addr = info_addr;
> 108|     m_previous = m_current;
> 109|     m_current = info;
> 110|
> 111+>    return UpdateSOEntries();
> 
> m_previous is being set to m_current and both are eDelete now, but that assert above is claiming it should be eConsistent.
> 
> Is this a bogus assert, or is the Resolve() function messing with m_previous when it shouldn't be?
>  -Mike
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