The parameter `refs_check_dir` determines which directory we want to
check references for. But as we always want to check the complete
refs hierarchy, this parameter is always set to "refs".
Drop the parameter and hardcode it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When performing consistency checks we pass the functions that perform
the verification down the calling stack. This is somewhat unnecessary
though, as the set of functions doesn't ever change.
Simplify the code by moving the array into global scope and remove the
parameter.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When iterating through root refs we first need to determine the
directory in which the refs live. This is done by retrieving the root of
the loose refs via `refs->loose->root->name`, and putting it through
`files_ref_path()` to derive the final path.
This is somewhat redundant though: the root name of the loose files
cache is always going to be the empty string. As such, we always end up
passing that empty string to `files_ref_path()` as the ref hierarchy we
want to start. And this actually makes sense: `files_ref_path()` already
computes the location of the root directory, so of course we need to
pass the empty string for the ref hierarchy itself. So going via the
loose ref cache to figure out that the root of a ref hierarchy is empty
is only causing confusion.
But next to the added confusion, it can also lead to a segfault. The
loose ref cache is populated lazily, so it may not always be set. It
seems to be sheer luck that this is a condition we do not currently hit.
The right thing to do would be to call `get_loose_ref_cache()`, which
knows to populate the cache if required.
Simplify the code and fix the potential segfault by simply removing the
indirection via the loose ref cache completely.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Brown-paper-bag fix to a recently graduated
'kn/maintenance-is-needed' topic.
* gf/maintenance-is-needed-fix:
refs: dereference the value of the required pointer
Currently, this always prints yes because required is non-null.
This is the wrong behavior. The boolean must be
dereferenced.
Signed-off-by: Greg Funni <gfunni234@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git maintenance" command learned "is-needed" subcommand to tell if
it is necessary to perform various maintenance tasks.
* kn/maintenance-is-needed:
maintenance: add 'is-needed' subcommand
maintenance: add checking logic in `pack_refs_condition()`
refs: add a `optimize_required` field to `struct ref_storage_be`
reftable/stack: add function to check if optimization is required
reftable/stack: return stack segments directly
Code clean-up.
* kn/refs-optim-cleanup:
t/pack-refs-tests: move the 'test_done' to callees
refs: rename 'pack_refs_opts' to 'refs_optimize_opts'
refs: move to using the '.optimize' functions
Some ref backend storage can hold not just the object name of an
annotated tag, but the object name of the object the tag points at.
The code to handle this information has been streamlined.
* ps/ref-peeled-tags:
t7004: do not chdir around in the main process
ref-filter: fix stale parsed objects
ref-filter: parse objects on demand
ref-filter: detect broken tags when dereferencing them
refs: don't store peeled object IDs for invalid tags
object: add flag to `peel_object()` to verify object type
refs: drop infrastructure to peel via iterators
refs: drop `current_ref_iter` hack
builtin/show-ref: convert to use `reference_get_peeled_oid()`
ref-filter: propagate peeled object ID
upload-pack: convert to use `reference_get_peeled_oid()`
refs: expose peeled object ID via the iterator
refs: refactor reference status flags
refs: fully reset `struct ref_iterator::ref` on iteration
refs: introduce `.ref` field for the base iterator
refs: introduce wrapper struct for `each_ref_fn`
To allow users of the refs namespace to check if the reference backend
requires optimization, add a new field `optimize_required` field to
`struct ref_storage_be`. This field is of type `optimize_required_fn`
which is also introduced in this commit.
Modify the debug, files, packed and reftable backend to implement this
field. A following commit will expose this via 'git pack-refs' and 'git
refs optimize'.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our Bencher dashboards [1] have recently alerted us about a bunch of
performance regressions when writing references, specifically with the
reftable backend. There is a 3x regression when writing many refs with
preexisting refs in the reftable format, and a 10x regression when
migrating refs between backends in either of the formats.
Bisecting the issue lands us at 6ec4c0b45b (refs: don't store peeled
object IDs for invalid tags, 2025-10-23). The gist of the commit is that
we may end up storing peeled objects in both reftables and packed-refs
for corrupted tags, where the claimed tagged object type is different
than the actual tagged object type. This will then cause us to create
the `struct object *` with a wrong type, as well, and obviously nothing
good comes out of that.
The fix for this issue was to introduce a new flag to `peel_object()`
that causes us to verify the tagged object's type before writing it into
the refdb -- if the tag is corrupt, we skip writing the peeled value.
To verify whether the peeled value is correct we have to look up the
object type via the ODB and compare the actual type with the claimed
type, and that additional object lookup is costly.
This also explains why we see the regression only when writing refs with
the reftable backend, but we see the regression with both backends when
migrating refs:
- The reftable backend knows to store peeled values in the new table
immediately, so it has to try and peel each ref it's about to write
to the transaction. So the performance regression is visible for all
writes.
- The files backend only stores peeled values when writing the
packed-refs file, so it wouldn't hit the performance regression for
normal writes. But on ref migrations we know to write all new values
into the packed-refs file immediately, and that's why we see the
regression for both backends there.
Taking a step back though reveals an oddity in the new verification
logic: we not only verify the _tagged_ object's type, but we also verify
the type of the tag itself. But this isn't really needed, as we wouldn't
hit the bug in such a case anyway, as we only hit the issue with corrupt
tags claiming an invalid type for the tagged object.
The consequence of this is that we now started to look up the target
object of every single reference we're about to write, regardless of
whether it even is a tag or not. And that is of course quite costly.
Fix the issue by only verifying the type of the tagged objects. This
means that we of course still have a performance hit for actual tags.
But this only happens for writes anyway, and I'd claim it's preferable
to not store corrupted data in the refdb than to be fast here. Rename
the flag accordingly to clarify that we only verify the tagged object's
type.
This fix brings performance back to previous levels:
Benchmark 1: baseline
Time (mean ± σ): 46.0 ms ± 0.4 ms [User: 40.0 ms, System: 5.7 ms]
Range (min … max): 45.0 ms … 47.1 ms 54 runs
Benchmark 2: regression
Time (mean ± σ): 140.2 ms ± 1.3 ms [User: 77.5 ms, System: 60.5 ms]
Range (min … max): 138.0 ms … 142.7 ms 20 runs
Benchmark 3: fix
Time (mean ± σ): 46.2 ms ± 0.4 ms [User: 40.2 ms, System: 5.7 ms]
Range (min … max): 45.0 ms … 47.3 ms 55 runs
Summary
update-ref: baseline
1.00 ± 0.01 times faster than fix
3.05 ± 0.04 times faster than regression
[1]: https://bencher.dev/perf/git/plots
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* ps/ref-peeled-tags:
t7004: do not chdir around in the main process
ref-filter: fix stale parsed objects
ref-filter: parse objects on demand
ref-filter: detect broken tags when dereferencing them
refs: don't store peeled object IDs for invalid tags
object: add flag to `peel_object()` to verify object type
refs: drop infrastructure to peel via iterators
refs: drop `current_ref_iter` hack
builtin/show-ref: convert to use `reference_get_peeled_oid()`
ref-filter: propagate peeled object ID
upload-pack: convert to use `reference_get_peeled_oid()`
refs: expose peeled object ID via the iterator
refs: refactor reference status flags
refs: fully reset `struct ref_iterator::ref` on iteration
refs: introduce `.ref` field for the base iterator
refs: introduce wrapper struct for `each_ref_fn`
The "debug" ref-backend was missing a method implementation, which
has been corrected.
* xr/ref-debug-remove-on-disk:
refs: add missing remove_on_disk implementation for debug backend
* kn/refs-optim-cleanup:
t/pack-refs-tests: move the 'test_done' to callees
refs: rename 'pack_refs_opts' to 'refs_optimize_opts'
refs: move to using the '.optimize' functions
* ps/ref-peeled-tags: (23 commits)
t7004: do not chdir around in the main process
ref-filter: fix stale parsed objects
ref-filter: parse objects on demand
ref-filter: detect broken tags when dereferencing them
refs: don't store peeled object IDs for invalid tags
object: add flag to `peel_object()` to verify object type
refs: drop infrastructure to peel via iterators
refs: drop `current_ref_iter` hack
builtin/show-ref: convert to use `reference_get_peeled_oid()`
ref-filter: propagate peeled object ID
upload-pack: convert to use `reference_get_peeled_oid()`
refs: expose peeled object ID via the iterator
refs: refactor reference status flags
refs: fully reset `struct ref_iterator::ref` on iteration
refs: introduce `.ref` field for the base iterator
refs: introduce wrapper struct for `each_ref_fn`
builtin/repo: add progress meter for structure stats
builtin/repo: add keyvalue and nul format for structure stats
builtin/repo: add object counts in structure output
builtin/repo: introduce structure subcommand
...
The previous commit removed all references to 'pack_refs()' within
the refs subsystem. Continue this cleanup by also renaming
'pack_refs_opts' to 'refs_optimize_opts' and the respective flags
accordingly. Keeping the naming consistent will make the code easier to
maintain.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `struct ref_store` variable exposes two ways to optimize a reftable
backend:
1. pack_refs
2. optimize
The former was specific to the 'files' + 'packed' refs backend. The
latter is more generic and covers all backends. While the naming is
different, both of these functions perform the same functionality.
Consolidate this code to only maintain the 'optimize' functions. Do this
by modifying the backends so that they exclusively implement the
`optimize` callback, only. All users of the refs subsystem already use
the 'optimize' function so there is no changes needed on the callee
side. Finally, cleanup all references to the 'pack_refs' field of the
structure and code around it.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Both the "files" and "reftable" backend store peeled object IDs for
references that point to tags:
- The "files" backend stores the value when packing refs, where each
peeled object ID is prefixed with "^".
- The "reftable" backend stores the value whenever writing a new
reference that points to a tag via a special ref record type.
Both of these backends use `peel_object()` to find the peeled object ID.
But as explained in the preceding commit, that function does not detect
the case where the tag's tagged object and its claimed type mismatch.
The consequence of storing these bogus peeled object IDs is that we're
less likely to detect such corruption in other parts of Git.
git-for-each-ref(1) for example does not notice anymore that the tag is
broken when using "--format=%(*objectname)" to dereference tags.
One could claim that this is good, because it still allows us to mostly
use the tag as intended. But the biggest problem here is that we now
have different behaviour for such a broken tag depending on whether or
not we have its peeled value in the refdb.
Fix the issue by verifying the object type when peeling the object. If
that verification fails we simply skip storing the peeled value in
either of the reference formats.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When peeling a tag to a non-tag object we repeatedly call
`parse_object()` on the tagged object until we find the first object
that isn't a tag. While this feels sensible at first, there is a big
catch here: `parse_object()` doesn't actually verify the type of the
tagged object.
The relevant code path here eventually ends up in `parse_tag_buffer()`.
Here, we parse the various fields of the tag, including the "type". Once
we've figured out the type and the tagged object ID, we call one of the
`lookup_${type}()` functions for whatever type we have found. There is
two possible outcomes in the successful case:
1. The object is already part of our cached objects. In that case we
double-check whether the type we're trying to look up matches the
type that was cached.
2. The object is _not_ part of our cached objects. In that case, we
simply create a new object with the expected type, but we don't
parse that object.
In the first case we might notice type mismatches, but only in the case
where our cache has the object with the correct type. In the second
case, we'll blindly assume that the type is correct and then go with it.
We'll only notice that the type might be wrong when we try to parse the
object at a later point.
Now arguably, we could change `parse_tag_buffer()` to verify the tagged
object's type for us. But that would have the effect that such a tag
cannot be parsed at all anymore, and we have a small bunch of tests for
exactly this case that assert we still can open such tags. So this
change does not feel like something we can retroactively tighten, even
though one shouldn't ever hit such corrupted tags.
Instead, add a new `flags` field to `peel_object()` that allows the
caller to opt in to strict object verification. This will be wired up at
a subset of callsites over the next few commits.
Note that this change also inlines `deref_tag_noverify()`. There's only
been two callsites of that function, the one we're changing and one in
our test helpers. The latter callsite can trivially use `deref_tag()`
instead, so by inlining the function we avoid having to pass down the
flag.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that the peeled object ID gets propagated via the `struct reference`
there is no need anymore to call into the reference iterator itself to
dereference an object. Remove this infrastructure.
Most of the changes are straight-forward deletions of code. There is one
exception though in `refs/packed-backend.c::write_with_updates()`. Here
we stop peeling the iterator and instead just pass the peeled object ID
of that iterator directly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In preceding commits we have refactored all callers of
`peel_iterated_oid()` to instead use `reference_get_peeled_oid()`. This
allows us to thus get rid of the former function.
Getting rid of that function is nice, but even nicer is that this also
allows us to get rid of the `current_ref_iter` hack. This global
variable tracked the currently-active ref iterator so that we can use it
to peel an object ID. Now that the peeled object ID is propagated via
`struct reference` though we don't have to depend on this hack anymore,
which makes for a more robust and easier-to-understand infrastructure.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Both the "files" and "reftable" backend are able to store peeled values
for tags in the respective formats. This allows for a more efficient
lookup of the target object of such a tag without having to manually
peel via the object database.
The infrastructure to access these peeled object IDs is somewhat funky
though. When iterating through objects, we store a pointer reference to
the current iterator in a global variable. The callbacks invoked by that
iterator are then expected to call `peel_iterated_oid()`, which checks
whether the globally-stored iterator's current reference refers to the
one handed into that function. If so, we ask the iterator to peel the
object, otherwise we manually peel the object via the object database.
Depending on global state like this is somewhat weird and also quite
fragile.
Introduce a new `struct reference::peeled_oid` field that can be
populated by the reference backends. This field can be accessed via a
new function `reference_get_peeled_oid()` that either uses that value,
if set, or alternatively peels via the ODB. With this change we don't
have to rely on global state anymore, but make the peeled object ID
available to the callback functions directly.
Adjust trivial callers that already have a `struct reference` available.
Remaining callers will be adjusted in subsequent commits.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
With the introduction of the `struct ref_iterator::ref` field it now is
a whole lot easier to introduce new fields that become accessible to the
caller without having to adapt every single callsite. But there's a
downside: when a new field is introduced we always have to adapt all
backends to set that field.
This isn't something we can avoid in the general case: when the new
field is expected to be populated by all backends we of course cannot
avoid doing so. But new fields may be entirely optional, in which case
we'd still have such churn. And furthermore, it is very easy right now
to leak state from a previous iteration into the next iteration.
Address this issue by ensuring that the reference backends all fully
reset the field on every single iteration. This ensures that no state
from previous iterations can leak into the next one. And it ensures that
any newly introduced fields will be zeroed out by default.
Note that we don't have to explicitly adapt the "files" backend, as it
uses the `cache_ref_iterator` internally. Furthermore, other "wrapping"
iterators like for example the `prefix_ref_iterator` copy around the
whole reference, so these don't need to be adapted either.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The base iterator has a couple of fields that tracks the name, target,
object ID and flags for the current reference. Due to this design we
have to create a new `struct reference` whenever we want to hand over
that reference to the callback function, which is tedious and not very
efficient.
Convert the structure to instead contain a `struct reference` as member.
This member is expected to be populated by the implementations of the
iterator and is handed over to the callback directly.
While at it, simplify `should_pack_ref()` to take a `struct reference`
directly instead of passing its respective fields.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `each_ref_fn` callback function type is used across our code base
for several different functions that iterate through reference. There's
a bunch of callbacks implementing this type, which makes any changes to
the callback signature extremely noisy. An example of the required churn
is e8207717f1 (refs: add referent to each_ref_fn, 2024-08-09): adding a
single argument required us to change 48 files.
It was already proposed back then [1] that we might want to introduce a
wrapper structure to alleviate the pain going forward. While this of
course requires the same kind of global refactoring as just introducing
a new parameter, it at least allows us to more change the callback type
afterwards by just extending the wrapper structure.
One counterargument to this refactoring is that it makes the structure
more opaque. While it is obvious which callsites need to be fixed up
when we change the function type, it's not obvious anymore once we use
a structure. That being said, we only have a handful of sites that
actually need to populate this wrapper structure: our ref backends,
"refs/iterator.c" as well as very few sites that invoke the iterator
callback functions directly.
Introduce this wrapper structure so that we can adapt the iterator
interfaces more readily.
[1]: <ZmarVcF5JjsZx0dl@tanuki>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"Symlink symref" has been added to the list of things that will
disappear at Git 3.0 boundary.
* ps/symlink-symref-deprecation:
refs/files: deprecate writing symrefs as symbolic links
The debug ref backend (refs_be_debug) was missing the remove_on_disk
function pointer, which caused a segmentation fault when running
'GIT_TRACE_REFS=1 git refs migrate --ref-format=reftable' commands.
Signed-off-by: Xinyu Ruan <r200981113@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Deal more gracefully with directory / file conflicts when the files
backend is used for ref storage, by failing only the ones that are
involved in the conflict while allowing others.
* kn/refs-files-case-insensitive:
refs/files: handle D/F conflicts during locking
refs/files: handle F/D conflicts in case-insensitive FS
refs/files: use correct error type when lock exists
refs/files: catch conflicts on case-insensitive file-systems
"git refs migrate" to migrate the reflog entries from a refs
backend to another had a handful of bugs squashed.
* ps/reflog-migrate-fixes:
refs: fix invalid old object IDs when migrating reflogs
refs: stop unsetting REF_HAVE_OLD for log-only updates
refs/files: detect race when generating reflog entry for HEAD
refs: fix identity for migrated reflogs
ident: fix type of string length parameter
builtin/reflog: implement subcommand to write new entries
refs: export `ref_transaction_update_reflog()`
builtin/reflog: improve grouping of subcommands
Documentation/git-reflog: convert to use synopsis type
The "files" backend has the ability to store symbolic refs as symbolic
links, which can be configured via "core.preferSymlinkRefs". This
feature stems back from the early days: the initial implementation of
symbolic refs used symlinks exclusively. The symref format was only
introduced in 9b143c6e15 (Teach update-ref about a symbolic ref stored
in a textfile., 2005-09-25) and made the default in 9f0bb90d16
(core.prefersymlinkrefs: use symlinks for .git/HEAD, 2006-05-02).
This is all about 20 years ago, and there are no known reasons nowadays
why one would want to use symlinks instead of symrefs. Mark the feature
for deprecation in Git 3.0.
Note that this only deprecates _writing_ symrefs as symbolic links.
Reading such symrefs is still supported for now.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable backend learned to sanity check its on-disk data more
carefully.
* kn/reftable-consistency-checks:
refs/reftable: add fsck check for checking the table name
reftable: add code to facilitate consistency checks
fsck: order 'fsck_msg_type' alphabetically
Documentation/fsck-msgids: remove duplicate msg id
reftable: check for trailing newline in 'tables.list'
refs: move consistency check msg to generic layer
refs: remove unused headers
When `NO_SYMLINK_HEAD` is defined, `create_ref_symlink()` is hard-coded
as `(-1)`, and as a consequence the condition `!create_ref_symlink()`
always evaluates to false, rendering any code guarded by that condition
unreachable.
Therefore, clang is _technically_ correct when it complains about
unreachable code. It does completely miss the fact that this is okay
because on _other_ platforms, where `NO_SYMLINK_HEAD` is not defined,
the code isn't unreachable at all.
Let's use the same trick as in 82e79c6364 (git-compat-util: add
NOT_CONSTANT macro and use it in atfork_prepare(), 2025-03-17) to
appease clang while at the same time keeping the `-Wunreachable` flag
to potentially find _actually_ unreachable code.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Handling of an empty subdirectory of .git/refs/ in the ref-files
backend has been corrected.
* kn/ref-cache-seek-fix:
refs/ref-cache: fix SEGFAULT when seeking in empty directories
Add glue code in 'refs/reftable-backend.c' which calls the reftable
library to perform the fsck checks. Here we also map the reftable errors
to Git' fsck errors.
Introduce a check to validate table names for a given reftable stack.
Also add 'badReftableTableName' as a corresponding error within Git. The
reftable specification mentions:
It suggested to use
${min_update_index}-${max_update_index}-${random}.ref as a naming
convention.
So treat non-conformant file names as warnings.
While adding the fsck header to 'refs/reftable-backend.c', modify the
list to maintain lexicographical ordering.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The files-backend prints a message before the consistency checks run.
Move this to the generic layer so both the files and reftable backend
can benefit from this message.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the 'refs/' namespace, some of the included header files are not
needed, let's remove them.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git refs optimize" is added for not very well explained reason
despite it does the same thing as "git pack-refs"...
* ms/refs-optimize:
t: add test for git refs optimize subcommand
t0601: refactor tests to be shareable
builtin/refs: add optimize subcommand
doc: pack-refs: factor out common options
builtin/pack-refs: factor out core logic into a shared library
builtin/pack-refs: convert to use the generic refs_optimize() API
reftable-backend: implement 'optimize' action
files-backend: implement 'optimize' action
refs: add a generic 'optimize' API
The 'cache_ref_iterator_seek()' function is used to seek the
`ref_iterator` to the desired reference in the ref-cache mechanism. We
use the seeking functionality to implement the '--start-after' flag in
'git-for-each-ref(1)'.
When using the files-backend with packed-refs, it is possible that some
of the refs directories are empty. For e.g. just after repacking, the
'refs/heads' directory would be empty. The ref-cache seek mechanism,
doesn't take this into consideration when descending into a
subdirectory, and makes an out of bounds access, causing SEGFAULT as we
try to access entries within the directory. Fix this by breaking out of
the loop when we enter an empty directory.
Since we start with the base directory of 'refs/' which is never empty,
it is okay to perform this check after the first iteration in the
`do..while` clause.
Add tests which simulate this behavior and also provide coverage over
using the feature over packed-refs.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Deal more gracefully with directory / file conflicts when the files
backend is used for ref storage, by failing only the ones that are
involved in the conflict while allowing others.
* kn/refs-files-case-insensitive:
refs/files: handle D/F conflicts during locking
refs/files: handle F/D conflicts in case-insensitive FS
refs/files: use correct error type when lock exists
refs/files: catch conflicts on case-insensitive file-systems
To make the new generic `optimize` API fully functional, provide an
implementation for the 'reftable' reference backend.
For the reftable backend, the 'optimize' action is to compact its
tables. The existing `reftable_be_pack_refs()` function already provides
this logic, so the new `reftable_be_optimize()` function simply calls
it.
Wire up the new function to the `optimize` slot in the reftable
backend's virtual table.
Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
With the generic `refs_optimize()` API now in place, provide the first
implementation for the 'files' reference backend. This makes the new API
functional for existing repositories and serves as the foundation for
migrating user-facing commands to the new architecture.
The implementation simply calls the existing `files_pack_refs()`
function, as 'packing' is the method used to optimize the files-based
reference store.
Wire up the new `files_optimize()` function to the `optimize` slot in
the files backend's virtual table.
Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The existing `pack-refs` API is conceptually tied to the 'files'
backend, but its behavior is generic (e.g., it triggers compaction for
reftable). This naming is confusing.
Introduce a new generic refs_optimize() API that dispatches to a
backend-specific implementation via a new 'optimize' vtable method.
This lays the architectural groundwork for different reference backends
(like 'files' and 'reftable') to provide their own storage optimization
logic, which will be called from a single, generic entry point.
Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The previous commit added the necessary validation and checks for F/D
conflicts in the files backend when working on case insensitive systems.
There is still a possibility for D/F conflicts. This is a different from
the F/D since for F/D conflicts, there would not be a conflict during
the lock creation phase:
refs/heads/foo.lock
refs/heads/foo/bar.lock
However there would be a conflict when the locks are committed, since we
cannot have 'refs/heads/foo/bar' and 'refs/heads/foo'. These kinds of
conflicts are checked and resolved in
`refs_verify_refnames_available()`, so the previous commit ensured that
for case-insensitive filesystems, we would lowercase the inputs to that
function.
For D/F conflicts, there is a conflict during the lock creation phase
itself:
refs/heads/foo/bar.lock
refs/heads/foo.lock
As in `lock_raw_ref()` after creating the lock, we also check for D/F
conflicts. This can occur in case-insensitive filesystems when trying to
fetch case-conflicted references like:
refs/heads/Foo/new
refs/heads/foo
D/F conflicts can also occur in case-sensitive filesystems, when the
repository already contains a directory with a lock file
'refs/heads/foo/bar.lock' and trying to fetch 'refs/heads/foo'. This
doesn't concern directories containing garbage files as those are
handled on a higher level.
To fix this, simply categorize the error as a name conflict. Also remove
this reference from the list of valid refnames for availability checks.
By categorizing the error and removing it from the list of valid
references, batched updates now knows to reject such reference updates
and apply the other reference updates.
Fix a small typo in `ref_transaction_maybe_set_rejected()` while here.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using the files-backend on case-insensitive filesystems, there is
possibility of hitting F/D conflicts when creating references within a
single transaction, such as:
- 'refs/heads/foo'
- 'refs/heads/Foo/bar'
Ideally such conflicts are caught in `refs_verify_refnames_available()`
which is responsible for checking F/D conflicts within a given
transaction. This utility function is shared across the reference
backends. As such, it doesn't consider the issues of using a
case-insensitive file system, which only affects the files-backend.
While one solution would be to make the function aware of such issues,
this feels like leaking implementation details of file-backend specific
issues into the utility function. So opt for the more simpler option, of
lowercasing all references sent to this function when on a
case-insensitive filesystem and operating on the files-backend.
To do this, simply use a `struct strbuf` to convert the refname to
lowercase and append it to the list of refnames to be checked. Since we
use a `struct strbuf` and the memory is cleared right after, make sure
that the string list duplicates all provided string.
Without this change, the user would simply be left with a repository
with '.lock' files which were created in the 'prepare' phase of the
transaction, as the 'commit' phase would simply abort and not do the
necessary cleanup.
Reported-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When fetching references into a repository, if a lock for a particular
reference exists, then `lock_raw_ref()` throws:
- REF_TRANSACTION_ERROR_CASE_CONFLICT: when there is a conflict
because the transaction contains conflicting references while being
on a case-insensitive filesystem.
- REF_TRANSACTION_ERROR_GENERIC: for all other errors.
The latter causes the entire set of batched updates to fail, even in
case sensitive filessystems.
Instead, return a 'REF_TRANSACTION_ERROR_CREATE_EXISTS' error. This
allows batched updates to reject the individual update which conflicts
with the existing file, while updating the rest of the references.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
During the 'prepare' phase of a reference transaction in the files
backend, we create the lock files for references to be created. When
using batched updates on case-insensitive filesystems, the entire
batched updates would be aborted if there are conflicting names such as:
refs/heads/Foo
refs/heads/foo
This affects all commands which were migrated to use batched updates in
Git 2.51, including 'git-fetch(1)' and 'git-receive-pack(1)'. Before
that, reference updates would be applied serially with one transaction
used per update. When users fetched multiple references on
case-insensitive systems, subsequent references would simply overwrite
any earlier references. So when fetching:
refs/heads/foo: 5f34ec0bfeac225b1c854340257a65b106f70ea6
refs/heads/Foo: ec3053b0977e83d9b67fc32c4527a117953994f3
refs/heads/sample: 2eefd1150e06d8fca1ddfa684dec016f36bf4e56
The user would simply end up with:
refs/heads/foo: ec3053b0977e83d9b67fc32c4527a117953994f3
refs/heads/sample: 2eefd1150e06d8fca1ddfa684dec016f36bf4e56
This is buggy behavior since the user is never informed about the
overrides performed and missing references. Nevertheless, the user is
left with a working repository with a subset of the references. Since
Git 2.51, in such situations fetches would simply fail without updating
any references. Which is also buggy behavior and worse off since the
user is left without any references.
The error is triggered in `lock_raw_ref()` where the files backend
attempts to create a lock file. When a lock file already exists the
function returns a 'REF_TRANSACTION_ERROR_GENERIC'. When this happens,
the entire batched updates, not individual operation, is aborted as if
it were in a transaction.
Change this to return 'REF_TRANSACTION_ERROR_CASE_CONFLICT' instead to
aid the batched update mechanism to simply reject such errors. The
change only affects batched updates since batched updates will reject
individual updates with non-generic errors. So specifically this would
only affect:
1. git fetch
2. git receive-pack
3. git update-ref --batch-updates
This bubbles the error type up to `files_transaction_prepare()` which
tries to lock each reference update. So if the locking fails, we check
if the rejection type can be ignored, which is done by calling
`ref_transaction_maybe_set_rejected()`.
As the error type is now 'REF_TRANSACTION_ERROR_CASE_CONFLICT',
the specific reference update would simply be rejected, while other
updates in the transaction would continue to be applied. This allows
partial application of references in case-insensitive filesystems when
fetching colliding references.
While the earlier implementation allowed the last reference to be
applied overriding the initial references, this change would allow the
first reference to be applied while rejecting consequent collisions.
This should be an okay compromise since with the files backend, there is
no scenario possible where we would retain all colliding references.
Let's also be more proactive and notify users on case-insensitive
filesystems about such problems by providing a brief about the issue
while also recommending using the reftable backend, which doesn't have
the same issue.
Reported-by: Joe Drew <joe.drew@indexexchange.com>
Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git fetch" can clobber a symref that is dangling when the
remote-tracking HEAD is set to auto update, which has been
corrected.
* jk/no-clobber-dangling-symref-with-fetch:
refs: do not clobber dangling symrefs
t5510: prefer "git -C" to subshell for followRemoteHEAD tests
t5510: stop changing top-level working directory
t5510: make confusing config cleanup more explicit
Code clean-ups.
* ps/reftable-libgit2-cleanup:
refs/reftable: always reload stacks when creating lock
reftable: don't second-guess errors from flock interface
reftable/stack: handle outdated stacks when compacting
reftable/stack: allow passing flags to `reftable_stack_add()`
reftable/stack: fix compiler warning due to missing braces
reftable/stack: reorder code to avoid forward declarations
reftable/writer: drop Git-specific `QSORT()` macro
reftable/writer: fix type used for number of records
"git remote rename origin upstream" failed to move origin/HEAD to
upstream/HEAD when origin/HEAD is unborn and performed other
renames extremely inefficiently, which has been corrected.
* ps/remote-rename-fix:
builtin/remote: only iterate through refs that are to be renamed
builtin/remote: rework how remote refs get renamed
builtin/remote: determine whether refs need renaming early on
builtin/remote: fix sign comparison warnings
refs: simplify logic when migrating reflog entries
refs: pass refname when invoking reflog entry callback
"git refs migrate" to migrate the reflog entries from a refs
backend to another had a handful of bugs squashed.
* ps/reflog-migrate-fixes:
refs: fix invalid old object IDs when migrating reflogs
refs: stop unsetting REF_HAVE_OLD for log-only updates
refs/files: detect race when generating reflog entry for HEAD
refs: fix identity for migrated reflogs
ident: fix type of string length parameter
builtin/reflog: implement subcommand to write new entries
refs: export `ref_transaction_update_reflog()`
builtin/reflog: improve grouping of subcommands
Documentation/git-reflog: convert to use synopsis type
When given an expected "before" state, the ref-writing code will avoid
overwriting any ref that does not match that expected state. We use the
null oid as a sentinel value for "nothing should exist", and likewise
that is the sentinel value we get when trying to read a ref that does
not exist.
But there's one corner case where this is ambiguous: dangling symrefs.
Trying to read them will yield the null oid, but there is potentially
something of value there: the dangling symref itself.
For a normal recursive write, this is OK. Imagine we have a symref
"FOO_HEAD" that points to a ref "refs/heads/bar" that does not exist,
and we try to write to it with a create operation like:
oid=$(git rev-parse HEAD) ;# or whatever
git symbolic-ref FOO_HEAD refs/heads/bar
echo "create FOO_HEAD $oid" | git update-ref --stdin
The attempt to resolve FOO_HEAD will actually resolve "bar", yielding
the null oid. That matches our expectation, and the write proceeds. This
is correct, because we are not writing FOO_HEAD at all, but writing its
destination "bar", which in fact does not exist.
But what if the operation asked not to dereference symrefs? Like this:
echo "create FOO_HEAD $oid" | git update-ref --no-deref --stdin
Resolving FOO_HEAD would still result in a null oid, and the write will
proceed. But it will overwrite FOO_HEAD itself, removing the fact that
it ever pointed to "bar".
This case is a little esoteric; we are clobbering a symref with a
no-deref write of a regular ref value. But the same problem occurs when
writing symrefs. For example:
echo "symref-create FOO_HEAD refs/heads/other" |
git update-ref --no-deref --stdin
The "create" operation asked us to create FOO_HEAD only if it did not
exist. But we silently overwrite the existing value.
You can trigger this without using update-ref via the fetch
followRemoteHEAD code. In "create" mode, it should not overwrite an
existing value. But if you manually create a symref pointing to a value
that does not yet exist (either via symbolic-ref or with "remote add
-m"), create mode will happily overwrite it.
Instead, we should detect this case and refuse to write. The correct
specification to overwrite FOO_HEAD in this case is to provide an
expected target ref value, like:
echo "symref-update FOO_HEAD refs/heads/other ref refs/heads/bar" |
git update-ref --no-deref --stdin
Note that the non-symref "update" directive does not allow you to do
this (you can only specify an oid). This is a weakness in the update-ref
interface, and you'd have to overwrite unconditionally, like:
echo "update FOO_HEAD $oid" | git update-ref --no-deref --stdin
Likewise other symref operations like symref-delete do not accept the
"ref" keyword. You should be able to do:
echo "symref-delete FOO_HEAD ref refs/heads/bar"
but cannot (and can only delete unconditionally). This patch doesn't
address those gaps. We may want to do so in a future patch for
completeness, but it's not clear if anybody actually wants to perform
those operations. The symref update case (specifically, via
followRemoteHEAD) is what I ran into in the wild.
The code for the fix is relatively straight-forward given the discussion
above. But note that we have to implement it independently for the files
and reftable backends. The "old oid" checks happen as part of the
locking process, which is implemented separately for each system. We may
want to factor this out somehow, but it's beyond the scope of this
patch. (Another curiosity is that the messages in the reftable code are
marked for translation, but the ones in the files backend are not. I
followed local convention in each case, but we may want to harmonize
this at some point).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When creating a new addition via either `reftable_stack_new_addition()`
or its convenince wrapper `reftable_stack_add()` we:
1. Create the "tables.list.lock" file.
2. Verify that the current version of the "tables.list" file is
up-to-date.
3. Write the new table records if so.
By default, the second step would cause us to bail out if we see that
there has been a concurrent write to the stack that made our in-memory
copy of the stack out-of-date. This is a safety mechanism to not write
records to the stack based on outdated information.
The downside though is that concurrent writes may now cause us to bail
out, which is not a good user experience. In addition, this isn't even
necessary for us, as Git knows to perform all checks for the old state
of references under the lock. (Well, in all except one case: when we
expire the reflog we first create the log iterator before we create the
lock, but this ordering is fixed as part of this commit.)
Consequently, most writers pass the `REFTABLE_STACK_NEW_ADDITION_RELOAD`
flag. The effect of this flag is that we reload the stack after having
acquired the lock in case the stack is out-of-date. This plugs the race
with concurrent writers, but we continue performing the verifications of
the expected old state to catch actual conflicts in the references we
are about to write.
Adapt the remaining callsites that don't yet pass this flag to do so.
While at it, drop a needless manual reload.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `reftable_stack_add()` function is a simple wrapper to lock the
stack, add records to it via a callback and then commit the
result. One problem with it though is that it doesn't accept any flags
for creating the addition. This makes it impossible to automatically
reload the stack in case it was modified before we managed to lock the
stack.
Add a `flags` field to plug this gap and pass it through accordingly.
For now this new flag won't be used by us, but it will be used by
libgit2.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
With `refs_for_each_reflog_ent()` callers can iterate through all the
reflog entries for a given reference. The callback that is being invoked
for each such entry does not receive the name of the reference that we
are currently iterating through. This isn't really a limiting factor, as
callers can simply pass the name via the callback data.
But this layout sometimes does make for a bit of an awkward calling
pattern. One example: when iterating through all reflogs, and for each
reflog we iterate through all refnames, we have to do some extra book
keeping to track which reference name we are currently yielding reflog
entries for.
Change the signature of the callback function so that the reference name
of the reflog gets passed through to it. Adapt callers accordingly and
start using the new parameter in trivial cases. The next commit will
refactor the reference migration logic to make use of this parameter so
that we can simplify its logic a bit.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* ps/reflog-migrate-fixes:
refs: fix invalid old object IDs when migrating reflogs
refs: stop unsetting REF_HAVE_OLD for log-only updates
refs/files: detect race when generating reflog entry for HEAD
refs: fix identity for migrated reflogs
ident: fix type of string length parameter
builtin/reflog: implement subcommand to write new entries
refs: export `ref_transaction_update_reflog()`
builtin/reflog: improve grouping of subcommands
Documentation/git-reflog: convert to use synopsis type
When migrating reflog entries between different storage formats we end
up with invalid old object IDs for the migrated entries: instead of
writing the old object ID of the to-be-migrated entry, we end up with
the all-zeroes object ID.
The root cause of this issue is that we don't know to use the old object
ID provided by the caller. Instead, we manually resolve the old object
ID by resolving the current value of its matching reference. But as that
reference does not yet exist in the target ref storage we always end up
resolving it to all-zeroes.
This issue got unnoticed as there is no user-facing command that would
even show the old object ID. While `git log -g` knows to show the new
object ID, we don't have any formatting directive to show the old object
ID.
Fix the bug by introducing a new flag `REF_LOG_USE_PROVIDED_OIDS`. If
set, backends are instructed to use the old and new object IDs provided
by the caller, without doing any manual resolving. Set this flag in
`ref_transaction_update_reflog()`.
Amend our tests in t1460-refs-migrate to use our test tool to read
reflog entries. This test tool prints out both old and new object ID of
each reflog entry, which fixes the test gap. Furthermore it also prints
the full identity used to write the reflog, which provides test coverage
for the previous commit in this patch series that fixed the identity for
migrated reflogs.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `REF_HAVE_OLD` flag indicates whether a given ref update has its old
object ID set. If so, the value of that field is used to verify whether
the current state of the reference matches this expected state. It is
thus an important part of mitigating races with a concurrent process
that updates the same set of references.
When writing reflogs though we explicitly unset that flag. This is a
sensible thing to do: the old state of reflog entry updates may not
necessarily match the current on-disk state of its accompanying ref, but
it's only intended to signal what old object ID we want to write into
the new reflog entry. For example when migrating refs we end up writing
many reflog entries for a single reference, and most likely those reflog
entries will have many different old object IDs.
But unsetting this flag also removes a useful signal, namely that the
caller _did_ provide an old object ID for a given reflog entry. This
signal will become useful in a subsequent commit, where we add a new
flag that tells the transaction to use the provided old and new object
IDs to write a reflog entry. The `REF_HAVE_OLD` flag is then used as a
signal to verify that the caller really did provide an old object ID.
Stop unsetting the flag so that we can use it as this described signal
in a subsequent commit. Skip checking the old object ID for log-only
updates so that we don't expect it to match the current on-disk state.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When updating a reference that is being pointed to HEAD we don't only
write a reflog message for that particular reference, but also generate
one for HEAD. This logic is handled by `split_head_update()`, where we:
1. Verify that the condition actually triggered. This is done by
reading HEAD at the start of the transaction so that we can then
check whether a given reference update refers to its target.
2. Queue a new log-only update for HEAD in case it did.
But the logic is unfortunately not free of races, as we do not lock the
HEAD reference after we have read its target. This can lead to the
following two scenarios:
- HEAD gets concurrently updated to point to one of the references we
have already processed. This causes us not writing a reflog message
even though we should have done so.
- HEAD gets concurrently updated to no longer point to a reference
anymore that we have already processed. This causes us to write a
reflog message even though we should _not_ have done so.
Improve the situation by introducing a new `REF_LOG_VIA_SPLIT` flag that
is specific to the "files" backend. If set, we will double check that
the HEAD reference still points to the reference that we are creating
the reflog entry for after we have locked HEAD. Furthermore, instead of
manually resolving the old object ID of that entry, we now use the same
old state as for the parent update.
If we detect such a racy update we abort the transaction. This is a bit
heavy-handed: the user didn't even ask us to write a reflog update for
"HEAD", so it might be surprising if we abort the transaction. That
being said:
- Normal users wouldn't typically hit this case as we only hit the
relevant code when committing to a branch that is being pointed to
by "HEAD" directly. Commands like git-commit(1) typically commit to
"HEAD" itself though.
- Scripted users that use git-update-ref(1) and related plumbing
commands are unlikely to hit this case either, as they would have to
update the pointed-to-branch at the same as "HEAD" is being updated,
which is an exceedingly rare event.
The alternative would be to instead drop the log-only update completely,
but that would require more logic that is hard to verify without adding
infrastructure specific for such a test. So we rather do the pragmatic
thing and don't worry too much about an edge case that is very unlikely
to happen.
Unfortunately, this change only helps with the second race. We cannot
reliably plug the first race without locking the HEAD reference at the
start of the transaction. Locking HEAD unconditionally would effectively
serialize all writes though, and that doesn't seem like an option. Also,
double checking its value at the end of the transaction is not an option
either, as its target may have flip-flopped during the transaction.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The config API had a set of convenience wrapper functions that
implicitly use the_repository instance; they have been removed and
inlined at the calling sites.
* ps/config-wo-the-repository: (21 commits)
config: fix sign comparison warnings
config: move Git config parsing into "environment.c"
config: remove unused `the_repository` wrappers
config: drop `git_config_set_multivar()` wrapper
config: drop `git_config_get_multivar_gently()` wrapper
config: drop `git_config_set_multivar_in_file_gently()` wrapper
config: drop `git_config_set_in_file_gently()` wrapper
config: drop `git_config_set()` wrapper
config: drop `git_config_set_gently()` wrapper
config: drop `git_config_set_in_file()` wrapper
config: drop `git_config_get_bool()` wrapper
config: drop `git_config_get_ulong()` wrapper
config: drop `git_config_get_int()` wrapper
config: drop `git_config_get_string()` wrapper
config: drop `git_config_get_string()` wrapper
config: drop `git_config_get_string_multi()` wrapper
config: drop `git_config_get_value()` wrapper
config: drop `git_config_get_value()` wrapper
config: drop `git_config_get()` wrapper
config: drop `git_config_clear()` wrapper
...
Code clean-up.
* kn/for-each-ref-skip-updates:
ref-filter: use REF_ITERATOR_SEEK_SET_PREFIX instead of '1'
t6302: add test combining '--start-after' with '--exclude'
for-each-ref: reword the documentation for '--start-after'
for-each-ref: fix documentation argument ordering
ref-cache: use 'size_t' instead of int for length
"git for-each-ref" learns "--start-after" option to help
applications that want to page its output.
* kn/for-each-ref-skip:
ref-cache: set prefix_state when seeking
for-each-ref: introduce a '--start-after' option
ref-filter: remove unnecessary else clause
refs: selectively set prefix in the seek functions
ref-cache: remove unused function 'find_ref_entry()'
refs: expose `ref_iterator` via 'refs.h'
The commit 090eb5336c (refs: selectively set prefix in the seek
functions, 2025-07-15) modified the ref-cache iterator to support
seeking to a specified marker without setting the prefix.
The commit adds and uses an integer 'len' to capture the length of the
seek marker to compare with the entries of a given directory. Since the
type of the variable is 'int', this is met with a typecast of converting
a `strlen` to 'int' so it can be assigned to the 'len' variable.
This is whole operation is a bit wrong:
1. Since the 'len' variable is eventually used in a 'strncmp', it should
have been of type 'size_t'.
2. This also truncates the value provided from 'strlen' to an int, which
could cause a large refname to produce a negative number.
Let's do the correct thing here and simply use 'size_t' for `len`.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 090eb5336c (refs: selectively set prefix in the seek functions,
2025-07-15) we separated the seeking functionality of reference
iterators from the functionality to set prefix to an iterator. This
allows users of ref iterators to seek to a particular reference to
provide pagination support.
The files-backend, uses the ref-cache iterator to iterate over loose
refs. The iterator tracks directories and entries already processed via
a stack of levels. Each level corresponds to a directory under the files
backend. New levels are added to the stack, and when all entries from a
level is yielded, the corresponding level is popped from the stack.
To accommodate seeking, we need to populate and traverse the levels to
stop the requested seek marker at the appropriate level and its entry
index. Each level also contains a 'prefix_state' which is used for
prefix matching, this allows the iterator to skip levels/entries which
don't match a prefix. The default value of 'prefix_state' is
PREFIX_CONTAINS_DIR, which yields all entries within a level. When
purely seeking without prefix matching, we want to yield all entries.
The commit however, skips setting the value explicitly. This causes the
MemorySanitizer to issue a 'use-of-uninitialized-value' error when
running 't/t6302-for-each-ref-filter'.
Set the value explicitly to avoid to fix the issue.
Reported-by: Kyle Lippincott <spectral@google.com>
Helped-by: Kyle Lippincott <spectral@google.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 036876a106 (config: hide functions using `the_repository` by
default, 2024-08-13) we have moved around a bunch of functions in the
config subsystem that depend on `the_repository`. Those function have
been converted into mere wrappers around their equivalent function that
takes in a repository as parameter, and the intent was that we'll
eventually remove those wrappers to make the dependency on the global
repository variable explicit at the callsite.
Follow through with that intent and remove `git_config_get_int()`. All
callsites are adjusted so that they use
`repo_config_get_int(the_repository, ...)` instead. While some callsites
might already have a repository available, this mechanical conversion is
the exact same as the current situation and thus cannot cause any
regression. Those sites should eventually be cleaned up in a later patch
series.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 036876a106 (config: hide functions using `the_repository` by
default, 2024-08-13) we have moved around a bunch of functions in the
config subsystem that depend on `the_repository`. Those function have
been converted into mere wrappers around their equivalent function that
takes in a repository as parameter, and the intent was that we'll
eventually remove those wrappers to make the dependency on the global
repository variable explicit at the callsite.
Follow through with that intent and remove `git_config()`. All callsites
are adjusted so that they use `repo_config(the_repository, ...)`
instead. While some callsites might already have a repository available,
this mechanical conversion is the exact same as the current situation
and thus cannot cause any regression. Those sites should eventually be
cleaned up in a later patch series.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a ref creation at refs/heads/foo/bar fails, the files backend
now removes refs/heads/foo/ if the directory is otherwise not used.
* ps/refs-files-remove-empty-parent:
refs/files: remove empty parent dirs when ref creation fails
The ref iterator exposes a `ref_iterator_seek()` function. The name
suggests that this would seek the iterator to a specific reference in
some ways similar to how `fseek()` works for the filesystem.
However, the function actually sets the prefix for refs iteration. So
further iteration would only yield references which match the particular
prefix. This is a bit confusing.
Let's add a 'flags' field to the function, which when set with the
'REF_ITERATOR_SEEK_SET_PREFIX' flag, will set the prefix for the
iteration in-line with the existing behavior. Otherwise, the reference
backends will simply seek to the specified reference and clears any
previously set prefix. This allows users to start iteration from a
specific reference.
In the packed and reftable backend, since references are available in a
sorted list, the changes are simply setting the prefix if needed. The
changes on the files-backend are a little more involved, since the files
backend uses the 'ref-cache' mechanism. We move out the existing logic
within `cache_ref_iterator_seek()` to `cache_ref_iterator_set_prefix()`
which is called when the 'REF_ITERATOR_SEEK_SET_PREFIX' flag is set. We
then parse the provided seek string and set the required levels and
their indexes to ensure that seeking is possible.
Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'find_ref_entry' function is no longer used, so remove it.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `ref_iterator` is an internal structure to the 'refs/'
sub-directory, which allows iteration over refs. All reference iteration
is built on top of these iterators.
External clients of the 'refs' subsystem use the various
'refs_for_each...()' functions to iterate over refs. However since these
are wrapper functions, each combination of functionality requires a new
wrapper function. This is not feasible as the functions pile up with the
increase in requirements. Expose the internal reference iterator, so
advanced users can mix and match options as needed.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git push" and "git fetch" are taught to update refs in batches to
gain performance.
* kn/fetch-push-bulk-ref-update:
receive-pack: handle reference deletions separately
refs/files: skip updates with errors in batched updates
receive-pack: use batched reference updates
send-pack: fix memory leak around duplicate refs
fetch: use batched reference updates
refs: add function to translate errors to strings
When creating a new reference in the "files" backend we first create the
directory hierarchy for that reference, then create the lockfile for
that reference, and finally rename the lockfile into place. When the
transaction gets aborted we prune the lockfile, but we don't clean up
the directory hierarchy that we may have created for the lockfile.
In some egde cases this can lead to lots of empty directories being
cluttered in the ".git/refs" directory that really serve no purpose at
all. We know to prune such empty directories when packing refs, but that
only patches over the issue.
Improve this by removing empty parents when cleaning up still-locked
references in `files_transaction_cleanup()`. This function is also
called when preparing or committing the transaction, so this change also
helps when not explicitly aborting the transaction.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The commit 23fc8e4f61 (refs: implement batch reference update support,
2025-04-08) introduced support for batched reference updates. This
allows users to batch updates together, while allowing some of the
updates to fail.
Under the hood, batched updates use the reference transaction mechanism.
Each update which fails is marked as such. Any failed updates must be
skipped over in the rest of the code, as they wouldn't apply any more.
In two of the loops within 'files_transaction_finish()' of the files
backend, the failed updates aren't skipped over. This can cause a
SEGFAULT otherwise. Add the missing skips and a test to validate the
same.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git verify-refs" (and hence "git fsck --reference") started
erroring out in a repository in which secondary worktrees were
prepared with Git 2.43 or lower.
* sj/ref-contents-check-fix:
fsck: ignore missing "refs" directory for linked worktrees
"git refs verify" doesn't work if there are worktrees created on Git
v2.43.0 or older versions. These versions don't automatically create the
"refs" directory, causing the error:
error: cannot open directory .git/worktrees/<worktree name>/refs:
No such file or directory
Since 8f4c00de95 (builtin/worktree: create refdb via ref backend,
2024-01-08), we automatically create the "refs" directory for new
worktrees. And in 7c78d819e6 (ref: support multiple worktrees check for
refs, 2024-11-20), we assume that all linked worktrees have this
directory and would wrongly report an error to the user, thus
introducing compatibility issue.
Check for ENOENT errno before reporting directory access errors for
linked worktrees to maintain backward compatibility.
Reported-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
During fsck, we use "strbuf_read" to read the content of "packed-refs"
without using mmap mechanism. This is a bad practice which would consume
more memory than using mmap mechanism. Besides, as all code paths in
"packed-backend.c" use this way, we should make "fsck" align with the
current codebase.
As we have introduced the helper function "allocate_snapshot_buffer", we
can simply use this function to use mmap mechanism.
Suggested-by: Jeff King <peff@peff.net>
Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"load_contents" would choose which way to load the content of the
"packed-refs". However, we cannot directly use this function when
checking the consistency due to we don't want to open the file. And we
also need to reuse the logic to avoid causing repetition.
Let's create a new helper function "allocate_snapshot_buffer" to extract
the snapshot allocation logic in "load_contents" and update the
"load_contents" to align with the behavior.
Suggested-by: Jeff King <peff@peff.net>
Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We assume the "packed-refs" won't be empty and instead has at least one
line in it (even when there are no refs packed, there is the file header
line). Because there is no terminating LF in the empty file, we will
report "packedRefEntryNotTerminated(ERROR)" to the user.
However, the runtime code paths would accept an empty "packed-refs"
file, for example, "create_snapshot" would simply return the "snapshot"
without checking the content of "packed-refs". So, we should skip
checking the content of "packed-refs" when it is empty during fsck.
After 694b7a1999 (repack_without_ref(): write peeled refs in the
rewritten file, 2013-04-22), we would always write a header into the
"packed-refs" file. So, versions of Git that are not too ancient never
write such an empty "packed-refs" file.
As an empty file often indicates a sign of a filesystem-level issue, the
way we want to resolve this inconsistency is not make everybody totally
silent but notice and report the anomaly.
Let's create a "FSCK_INFO" message id "EMPTY_PACKED_REFS_FILE" to report
to the users that "packed-refs" is empty.
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code clean-up.
* ps/object-file-cleanup:
object-store: merge "object-store-ll.h" and "object-store.h"
object-store: remove global array of cached objects
object: split out functions relating to object store subsystem
object-file: drop `index_blob_stream()`
object-file: split up concerns of `HASH_*` flags
object-file: split out functions relating to object store subsystem
object-file: move `xmmap()` into "wrapper.c"
object-file: move `git_open_cloexec()` to "compat/open.c"
object-file: move `safe_create_leading_directories()` into "path.c"
object-file: move `mkdir_in_gitdir()` into "path.c"
Incorrect sorting of refs with bytes with high-bit set on platforms
with signed char led to a BUG, which has been corrected.
* ps/refname-avail-check-optim:
refs/packed: fix BUG when seeking refs with UTF-8 characters
Updating multiple references have only been possible in all-or-none
fashion with transactions, but it can be more efficient to batch
multiple updates even when some of them are allowed to fail in a
best-effort manner. A new "best effort batches of updates" mode
has been introduced.
* kn/non-transactional-batch-updates:
update-ref: add --batch-updates flag for stdin mode
refs: support rejection in batch updates during F/D checks
refs: implement batch reference update support
refs: introduce enum-based transaction error types
refs/reftable: extract code from the transaction preparation
refs/files: remove duplicate duplicates check
refs: move duplicate refname update check to generic layer
refs/files: remove redundant check in split_symref_update()
The object layer has been updated to take an explicit repository
instance as a parameter in more code paths.
* ps/object-wo-the-repository:
hash: stop depending on `the_repository` in `null_oid()`
hash: fix "-Wsign-compare" warnings
object-file: split out logic regarding hash algorithms
delta-islands: stop depending on `the_repository`
object-file-convert: stop depending on `the_repository`
pack-bitmap-write: stop depending on `the_repository`
pack-revindex: stop depending on `the_repository`
pack-check: stop depending on `the_repository`
environment: move access to "core.bigFileThreshold" into repo settings
pack-write: stop depending on `the_repository` and `the_hash_algo`
object: stop depending on `the_repository`
csum-file: stop depending on `the_repository`
The `safe_create_leading_directories()` function and its relatives are
located in "object-file.c", which is not a good fit as they provide
generic functionality not related to objects at all. Move them into
"path.c", which already hosts `safe_create_dir()` and its relative
`safe_create_dir_in_gitdir()`.
"path.c" is free of `the_repository`, but the moved functions depend on
`the_repository` to read the "core.sharedRepository" config. Adapt the
function signature to accept a repository as argument to fix the issue
and adjust callers accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It was reported that using git-pull(1) in a repository whose remote
contains branches with emojis leads to the following bug:
$ git pull
remote: Enumerating objects: 161255, done.
remote: Counting objects: 100% (55884/55884), done.
remote: Compressing objects: 100% (5518/5518), done.
remote: Total 161255 (delta 54253), reused 50509 (delta 50364),
pack-reused 105371 (from 4)
Receiving objects: 100% (161255/161255), 309.90 MiB | 16.87 MiB/s, done.
Resolving deltas: 100% (118048/118048), completed with 13416 local objects.
From github.com:github/github
97ab7ae3f3745..8fb2f9fa180ed master -> origin/master
[...snip many screenfuls of updates to origin remotes...]
BUG: refs/packed-backend.c:984: packed-refs backend yielded reference
preceding its prefix
error: fetch died of signal 6
This issue bisects to 22600c0452 (refs/iterator: implement seeking for
packed-ref iterators, 2025-03-12) where we have implemented seeking for
the packed-ref iterator. As part of that change we introduced a check
that verifies that the iterator only returns refnames bigger than the
prefix. In theory, this check should always hold: when a prefix is set
we know that we would've seeked that prefix first, so we should never
see a reference sorting before that prefix.
But in practice the check itself is misbehaving when handling unicode
characters. The particular issue triggered with a branch that got the
"shaved ice" unicode character in its name, which is composed of the
bytes "0xEE 0x90 0xBF". The bug triggers when we compare the refname
"refs/heads/<shaved-ice>" to something like "refs/heads/z", and it
specifically hits when comparing the first byte, "0xEE".
The root cause is that the most-significant bit of 0xEE is set. The
`refname` and `prefix` pointers that we use to compare bytes with one
another are both pointers to signed characters. As such, when we
dereference the 0xEE byte the result is a _negative_ value, and this
value will of course compare smaller than "z".
We can see that this issue is avoided in `cmp_packed_refname()`, where
we explicitly cast each byte to its unsigned form. Fix the bug by doing
the same in `packed_ref_iterator_advance()`.
Reported-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* ps/object-wo-the-repository:
hash: stop depending on `the_repository` in `null_oid()`
hash: fix "-Wsign-compare" warnings
object-file: split out logic regarding hash algorithms
delta-islands: stop depending on `the_repository`
object-file-convert: stop depending on `the_repository`
pack-bitmap-write: stop depending on `the_repository`
pack-revindex: stop depending on `the_repository`
pack-check: stop depending on `the_repository`
environment: move access to "core.bigFileThreshold" into repo settings
pack-write: stop depending on `the_repository` and `the_hash_algo`
object: stop depending on `the_repository`
csum-file: stop depending on `the_repository`
The `refs_verify_refnames_available()` is used to batch check refnames
for F/D conflicts. While this is the more performant alternative than
its individual version, it does not provide rejection capabilities on a
single update level. For batched updates, this would mean a rejection of
the entire transaction whenever one reference has a F/D conflict.
Modify the function to call `ref_transaction_maybe_set_rejected()` to
check if a single update can be rejected. Since this function is only
internally used within 'refs/' and we want to pass in a `struct
ref_transaction *` as a variable. We also move and mark
`refs_verify_refnames_available()` to 'refs-internal.h' to be an
internal function.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git supports making reference updates with or without transactions.
Updates with transactions are generally better optimized. But
transactions are all or nothing. This means, if a user wants to batch
updates to take advantage of the optimizations without the hard
requirement that all updates must succeed, there is no way currently to
do so. Particularly with the reftable backend where batching multiple
reference updates is more efficient than performing them sequentially.
Introduce batched update support with a new flag,
'REF_TRANSACTION_ALLOW_FAILURE'. Batched updates while different from
transactions, use the transaction infrastructure under the hood. When
enabled, this flag allows individual reference updates that would
typically cause the entire transaction to fail due to non-system-related
errors to be marked as rejected while permitting other updates to
proceed. System errors referred by 'REF_TRANSACTION_ERROR_GENERIC'
continue to result in the entire transaction failing. This approach
enhances flexibility while preserving transactional integrity where
necessary.
The implementation introduces several key components:
- Add 'rejection_err' field to struct `ref_update` to track failed
updates with failure reason.
- Add a new struct `ref_transaction_rejections` and a field within
`ref_transaction` to this struct to allow quick iteration over
rejected updates.
- Modify reference backends (files, packed, reftable) to handle
partial transactions by using `ref_transaction_set_rejected()`
instead of failing the entire transaction when
`REF_TRANSACTION_ALLOW_FAILURE` is set.
- Add `ref_transaction_for_each_rejected_update()` to let callers
examine which updates were rejected and why.
This foundational change enables batched update support throughout the
reference subsystem. A following commit will expose this capability to
users by adding a `--batch-updates` flag to 'git-update-ref(1)',
providing both a user-facing feature and a testable implementation.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Replace preprocessor-defined transaction errors with a strongly-typed
enum `ref_transaction_error`. This change:
- Improves type safety and function signature clarity.
- Makes error handling more explicit and discoverable.
- Maintains existing error cases, while adding new error cases for
common scenarios.
This refactoring paves the way for more comprehensive error handling
which we will utilize in the upcoming commits to add batch reference
update support.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extract the core logic for preparing individual reference updates from
`reftable_be_transaction_prepare()` into `prepare_single_update()`. This
dedicated function now handles all validation and preparation steps for
each reference update in the transaction, including object ID
verification, HEAD reference handling, and symref processing.
The refactoring consolidates all reference update validation into a
single logical block, which improves code maintainability and
readability. More importantly, this restructuring lays the groundwork
for implementing batched reference update support in the reftable
backend, which will be introduced in a followup commit.
No functional changes are included in this commit - it is purely a code
reorganization to support future enhancements.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Within the files reference backend's transaction's 'finish' phase, a
verification step is currently performed wherein the refnames list is
sorted and examined for multiple updates targeting the same refname.
It has been observed that this verification is redundant, as an
identical check is already executed during the transaction's 'prepare'
stage. Since the refnames list remains unmodified following the
'prepare' stage, this secondary verification can be safely eliminated.
The duplicate check has been removed accordingly, and the
`ref_update_reject_duplicates()` function has been marked as static, as
its usage is now confined to 'refs.c'.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the tracking of refnames in `affected_refnames` from individual
backends into the generic layer in 'refs.c'. This centralizes the
duplicate refname detection that was previously handled separately by
each backend.
Make some changes to accommodate this move:
- Add a `string_list` field `refnames` to `ref_transaction` to contain
all the references in a transaction. This field is updated whenever
a new update is added via `ref_transaction_add_update`, so manual
additions in reference backends are dropped.
- Modify the backends to use this field internally as needed. The
backends need to check if an update for refname already exists when
splitting symrefs or adding an update for 'HEAD'.
- In the reftable backend, within `reftable_be_transaction_prepare()`,
move the `string_list_has_string()` check above
`ref_transaction_add_update()`. Since `ref_transaction_add_update()`
automatically adds the refname to `transaction->refnames`,
performing the check after will always return true, so we perform
the check before adding the update.
This helps reduce duplication of functionality between the backends and
makes it easier to make changes in a more centralized manner.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In `split_symref_update()`, there were two checks for duplicate
refnames:
- At the start, `string_list_has_string()` ensures the refname is not
already in `affected_refnames`, preventing duplicates from being
added.
- After adding the refname, another check verifies whether the newly
inserted item has a `util` value.
The second check is unnecessary because the first one guarantees that
`string_list_insert()` will never encounter a preexisting entry.
The `item->util` field is assigned to validate that a rename doesn't
already exist in the list. The validation is done after the first check.
As this check is removed, clean up the validation and the assignment of
this field in `split_head_update()` and `files_transaction_prepare()`.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code paths to check whether a refname X is available (by seeing
if another ref X/Y exists, etc.) have been optimized.
* ps/refname-avail-check-optim:
refs: reuse iterators when determining refname availability
refs/iterator: implement seeking for files iterators
refs/iterator: implement seeking for packed-ref iterators
refs/iterator: implement seeking for ref-cache iterators
refs/iterator: implement seeking for reftable iterators
refs/iterator: implement seeking for merged iterators
refs/iterator: provide infrastructure to re-seek iterators
refs/iterator: separate lifecycle from iteration
refs: stop re-verifying common prefixes for availability
refs/files: batch refname availability checks for initial transactions
refs/files: batch refname availability checks for normal transactions
refs/reftable: batch refname availability checks
refs: introduce function to batch refname availability checks
builtin/update-ref: skip ambiguity checks when parsing object IDs
object-name: allow skipping ambiguity checks in `get_oid()` family
object-name: introduce `repo_get_oid_with_flags()`
"git fsck" becomes more careful when checking the refs.
* sj/ref-consistency-checks-more:
builtin/fsck: add `git refs verify` child process
packed-backend: check whether the "packed-refs" is sorted
packed-backend: add "packed-refs" entry consistency check
packed-backend: check whether the refname contains NUL characters
packed-backend: add "packed-refs" header consistency check
packed-backend: check if header starts with "# pack-refs with: "
packed-backend: check whether the "packed-refs" is regular file
builtin/refs: get worktrees without reading head information
t0602: use subshell to ensure working directory unchanged
Implement seeking for "files" iterators. As we simply use a ref-cache
iterator under the hood the implementation is straight-forward. Note
that we do not implement seeking on reflog iterators, same as with the
"reftable" backend.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Implement seeking of `packed-ref` iterators. The implementation is again
straight forward, except that we cannot continue to use the prefix
iterator as we would otherwise not be able to reseek the iterator
anymore in case one first asks for an empty and then for a non-empty
prefix. Instead, we open-code the logic to in `advance()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Implement seeking of ref-cache iterators. This is done by splitting most
of the logic to seek iterators out of `cache_ref_iterator_begin()` and
putting it into `cache_ref_iterator_seek()` so that we can reuse the
logic.
Note that we cannot use the optimization anymore where we return an
empty ref iterator when there aren't any references, as otherwise it
wouldn't be possible to reseek the iterator to a different prefix that
may exist. This shouldn't be much of a performance concern though as we
now start to bail out early in case `advance()` sees that there are no
more directories to be searched.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Patrick Steinhardt