On Tue, Apr 30, 2013 at 3:43 PM, Thomas Rast <tr...@inf.ethz.ch> wrote:
> Nguyễn Thái Ngọc Duy <pclo...@gmail.com> writes:
>> The idea behind this series is, after add_submodule_odb, odb may have
>> new temporary objects that only appear after the call. These temporary
>> objects may lead to repo corruption (e.g. some new objects are created
>> and point to these temporary objects). This series attempts to catch
>> those cases. It would make it safer to dig deeper into submodule's odb,
>> e.g. to implement unified git-diff.
>> Previous approach  is record the odb source, then check if the
>> source is from submodule's odb. But that means we rely on the
>> lookup order in sha1_file.c. This approach instead allows the caller
>> to select what odb sources it wants to look up from.
>> The checks are also less drastic than before. Checks are now done at
>> higher level, e.g. commit_tree(), instead of at write_sha1_file,
>> because we do allow to write objects that point to nowhere.
>> Another new thing from previous round is I completely forbid the use
>> of add_submodule_odb in security sensitive commands like index-pack or
>> rev-list. We could loosen up later if we need to.
>> For fun, I set object_database_contaminated to 1 by default and ran
>> the test suite. It passed :)
> How does this interact with alternates set up by the user? It's not
> immediately obvious from the commit messages (hint hint) or the comments
> near ODB_LOCAL etc.
Room for improvement in the next reroll. Basically objects are put in
the following sources:
- ODB_CACHED: builtin objects, always exist
- ODB_LOCAL: objects in $GIT_DIR/objects
- ODB_ALT: objects from $GIT_DIR/objects/info/alternates
- and later ODB_EXTALT: objects added by add_submodule_odb()
Many functions now take "origin" as argument. If you pass ODB_ALT, it
will only lookup objects from $GIT_DIR/objects/info/alternates for
example, which might fail if the object does not exist there, or if
it's in a pack and some of the required bases are elsewhere.
By default, everything uses odb_default as the origin, which is
ODB_CACHED|ODB_LOCAL|ODB_ALT (for this patch), so nothing is really
changed regarding alternates setup.
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