Re: Null deref in recursive merge in df73af5f667a479764d2b2195cb0cb60b0b89e3d

[Josh ben Jore <jbenjore@whitepages.com>]

On 7/29/09 9:10 AM, "Clemens Buchacher" <drizzd@aon.at> wrote:
> Hi,
> 
> On Tue, Jul 28, 2009 at 03:23:00PM -0700, Josh ben Jore wrote:
> [...]
>>   CONFLICT (rename/add): Rename
>> config/conf/target/dev-ubuntu/wpn_rails/appserver.yml->config/conf/target/dev
>> /wpn_rails/appserver.yml
>> in Temporary merge branch 1. config/conf/target/dev/wpn_rails/appse2
>>   Adding as config/conf/target/dev/wpn_rails/appserver.yml~Temporary merge
>> branch 2 instead
>>   Skipped config/conf/target/dev/wpn_rails/appserver.yml (merged same as
>> existing)
> [...]
>>   There are unmerged index entries:
>>   2 config/conf/target/dev/wpn_rails/appserver.yml
>>   3 config/conf/target/dev/wpn_rails/appserver.yml
>>   Merging:
>>   virtual merged tree
>>   e4a886b Adding legacy click log processing scripts
>>   found 1 common ancestor(s):
>>   09fb055 Merge commit 'rel_090630_prod_02'
>> Segmentation fault
> 
> Yeah, if process_entry leaves unmerged entries, write_tree_from_memory will
> return NULL. I can reproduce with the following script (same principle as
> t7405).
> 
> Clemens
> ---
> 
> diff --git a/t/t6035-merge-recursive-ra.sh b/t/t6035-merge-recursive-ra.sh
> new file mode 100755

Thank you for the unit test. It fails as expected but I didn't verify that
it failed with the segfault as I'm experiencing. Your explanation of "There
are unmerged index entries:" is interesting. I've taken that as the focal
point for working around the bug in my repo with the unfixed software.

I've also started getting acquainted with the code in merge_tree to see if I
can identify the problem. I do not understand the se_stage values of 0 vs 2
or 3. These are not defined as constants or documented in the code. I'm
viewing them as magic for now. :-/

Josh