As reported in [1] the "UNUSED(var)" macro introduced in
2174b8c75d (Merge branch 'jk/unused-annotation' into next,
2022-08-24) breaks coccinelle's parsing of our sources in files where
it occurs.
Let's instead partially go with the approach suggested in [2] of
making this not take an argument. As noted in [1] "coccinelle" will
ignore such tokens in argument lists that it doesn't know about, and
it's less of a surprise to syntax highlighters.
This undoes the "help us notice when a parameter marked as unused is
actually use" part of 9b24034754 (git-compat-util: add UNUSED macro,
2022-08-19), a subsequent commit will further tweak the macro to
implement a replacement for that functionality.
1. https://lore.kernel.org/git/220825.86ilmg4mil.gmgdl@evledraar.gmail.com/
2. https://lore.kernel.org/git/220819.868rnk54ju.gmgdl@evledraar.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The refs code uses various polymorphic types (e.g., loose vs packed
ref_stores, abstracted iterators). Not every virtual function or
callback needs all of its parameters. Let's mark the unused ones to
quiet -Wunused-parameter.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Functions used with for_each_ref(), etc, need to conform to the
each_ref_fn interface. But most of them don't need every parameter;
let's annotate the unused ones to quiet -Wunused-parameter.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce and apply coccinelle rule to discourage an explicit
comparison between a pointer and NULL, and applies the clean-up to
the maintenance track.
* ep/maint-equals-null-cocci:
tree-wide: apply equals-null.cocci
tree-wide: apply equals-null.cocci
contrib/coccinnelle: add equals-null.cocci
Code clean-up.
* ab/refs-various-fixes:
refs debug: add a wrapper for "read_symbolic_ref"
packed-backend: remove stub BUG(...) functions
misc *.c: use designated initializers for struct assignments
refs: use designated initializers for "struct ref_iterator_vtable"
refs: use designated initializers for "struct ref_storage_be"
Updates to refs traditionally weren't fsync'ed, but we can
configure using core.fsync variable to do so.
* ps/fsync-refs:
core.fsync: new option to harden references
In cd475b3b03 (refs: add ability for backends to special-case reading
of symbolic refs, 2022-03-01) when the "read_symbolic_ref" callback
was added we'd fall back on "refs_read_raw_ref" if there wasn't any
backend implementation of "read_symbolic_ref".
As discussed in the preceding commit this would only happen if we were
running the "debug" backend, e.g. in the "setup for ref completion"
test in t9902-completion.sh with:
GIT_TRACE_REFS=1 git fetch --no-tags other
Let's improve the trace output, but and also eliminate the
now-redundant refs_read_raw_ref() fallback case. As noted in the
preceding commit the "packed" backend will never call
refs_read_symbolic_ref() (nor is it ever going to). For any future
backend such as reftable it's OK to ask that they either implement
this (or a wrapper) themselves.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove the stub BUG(...) functions previously used by the "struct
ref_storage_be refs_be_packed" backend.
We never call any functions in the packed backend by using it as a
"normal" primary ref store, instead we'll always initialize a "files"
backend ref-store.
It will then via the "packed_ref_store" member of "struct
files_ref_store" call selected functions in the "packed" backend, and
we'll in addition call others via wrappers in refs.c.
So while these would arguably give us *slightly* more meaningful error
messages we'll NULL the missing members in the initializer anyway, so
we'll reliably get a segfault if we're ever changing the backend and
having it call something it doesn't have.
So there's no need for this verbose boilerplate, and as shown in a
subsequent commit it might even lead to some confusion about the
packed backend being a "real" backend. Let's make it clear that it's
not.
As an aside, this also fixes a warning emitted by SunCC in at least
versions 12.5 and 12.6 of Oracle Developer Studio:
"refs/packed-backend.c", line 1599: warning: Function has no return statement : packed_create_symref
"refs/packed-backend.c", line 1606: warning: Function has no return statement : packed_rename_ref)
"refs/packed-backend.c", line 1613: warning: Function has no return statement : packed_copy_ref
"refs/packed-backend.c", line 1648: warning: Function has no return statement : packed_create_reflog
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the definition of the three refs backends we currently carry to
use designated initializers.
The "= NULL" assignments being retained here are redundant, and could
be removed, but let's keep them for clarity. All of these backends
define almost all fields, so we're not saving much in terms of line
count by omitting these, but e.g. for "refs_be_debug" it's immediately
apparent that we're omitting "init" when comparing its assignment to
the others.
This is a follow-up to similar work merged in bd4232fac3 (Merge
branch 'ab/struct-init', 2021-07-16), a4b9fb6a5c (Merge branch
'ab/designated-initializers-more', 2021-10-18) and a30321b9ea (Merge
branch 'ab/designated-initializers' into
ab/designated-initializers-more, 2021-09-27).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When writing both loose and packed references to disk we first create a
lockfile, write the updated values into that lockfile, and on commit we
rename the file into place. According to filesystem developers, this
behaviour is broken because applications should always sync data to disk
before doing the final rename to ensure data consistency [1][2][3]. If
applications fail to do this correctly, a hard crash of the machine can
easily result in corrupted on-disk data.
This kind of corruption can in fact be easily observed with Git when the
machine hard-resets shortly after writing references to disk. On
machines with ext4, this will likely lead to the "empty files" problem:
the file has been renamed, but its data has not been synced to disk. The
result is that the reference is corrupt, and in the worst case this can
lead to data loss.
Implement a new option to harden references so that users and admins can
avoid this scenario by syncing locked loose and packed references to
disk before we rename them into place.
[1]: https://thunk.org/tytso/blog/2009/03/15/dont-fear-the-fsync/
[2]: https://btrfs.wiki.kernel.org/index.php/FAQ (What are the crash guarantees of overwrite-by-rename)
[3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/admin-guide/ext4.rst (see auto_da_alloc)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When reading references via `files_read_raw_ref()` we always consult
both the loose reference, and if that wasn't found, we also consult the
packed-refs file. While this makes sense to read a generic reference, it
is wasteful in the case where we only care about symbolic references:
the packed-refs backend does not support them, and thus it cannot ever
return one for us.
Special-case reading of symbolic references for the files backend such
that we always skip asking the packed-refs backend.
We use `refs_read_symbolic_ref()` extensively to determine whether we
need to skip updating local symbolic references during a fetch, which is
why the change results in a significant speedup when doing fetches in
repositories with huge numbers of references. The following benchmark
executes a mirror-fetch in a repository with about 2 million references
via `git fetch --prune --no-write-fetch-head +refs/*:refs/*`:
Benchmark 1: HEAD~
Time (mean ± σ): 68.372 s ± 2.344 s [User: 65.629 s, System: 8.786 s]
Range (min … max): 65.745 s … 70.246 s 3 runs
Benchmark 2: HEAD
Time (mean ± σ): 60.259 s ± 0.343 s [User: 61.019 s, System: 7.245 s]
Range (min … max): 60.003 s … 60.649 s 3 runs
Summary
'HEAD' ran
1.13 ± 0.04 times faster than 'HEAD~'
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reading of symbolic and non-symbolic references is currently treated the
same in reference backends: we always call `refs_read_raw_ref()` and
then decide based on the returned flags what type it is. This has one
downside though: symbolic references may be treated different from
normal references in a backend from normal references. The packed-refs
backend for example doesn't even know about symbolic references, and as
a result it is pointless to even ask it for one.
There are cases where we really only care about whether a reference is
symbolic or not, but don't care about whether it exists at all or may be
a non-symbolic reference. But it is not possible to optimize for this
case right now, and as a consequence we will always first check for a
loose reference to exist, and if it doesn't, we'll query the packed-refs
backend for a known-to-not-be-symbolic reference. This is inefficient
and requires us to search all packed references even though we know to
not care for the result at all.
Introduce a new function `refs_read_symbolic_ref()` which allows us to
fix this case. This function will only ever return symbolic references
and can thus optimize for the scenario layed out above. By default, if
the backend doesn't provide an implementation for it, we just use the
old code path and fall back to `read_raw_ref()`. But in case the backend
provides its own, more efficient implementation, we will use that one
instead.
Note that this function is explicitly designed to not distinguish
between missing references and non-symbolic references. If it did, we'd
be forced to always search the packed-refs backend to see whether the
symbolic reference the user asked for really doesn't exist, or if it
exists as a non-symbolic reference.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Because a deletion of ref would need to remove it from both the
loose ref store and the packed ref store, a delete-ref operation
that logically removes one ref may end up invoking ref-transaction
hook twice, which has been corrected.
* ps/avoid-unnecessary-hook-invocation-with-packed-refs:
refs: skip hooks when deleting uncovered packed refs
refs: do not execute reference-transaction hook on packing refs
refs: demonstrate excessive execution of the reference-transaction hook
refs: allow skipping the reference-transaction hook
refs: allow passing flags when beginning transactions
refs: extract packed_refs_delete_refs() to allow control of transaction
Remove the now-unused "failure_errno" parameter from the
refs_resolve_ref_unsafe() signature. In my recent 96f6623ada (Merge
branch 'ab/refs-errno-cleanup', 2021-11-29) series we made all of its
callers explicitly request the errno via an output parameter.
As that series shows all but one caller ended up passing in a
boilerplate "ignore_errno", since they only cared about whether the
return value was NULL or not, i.e. if the ref could be resolved.
There was one small issue with that series fixed with a follow-up in
31e3912369 (Merge branch 'ab/refs-errno-cleanup', 2022-01-14) a small
bug in that series was fixed.
After those two there was one caller left in sequencer.c that used the
"failure_errno', but as of the preceding commit it uses a boilerplate
"ignore_errno" instead.
This leaves the public refs API without any use of "failure_errno" at
all. We could still do with a bit of cleanup and generalization
between refs.c and refs/files-backend.c before the "reftable"
integration lands, but that's all internal to the reference code
itself.
So let's remove this output parameter. Not only isn't it used now, but
it's unlikely that we'll want it again in the future. We'd like to
slowly move the refs API to a more file-backend independent way of
communicating error codes, having it use a "failure_errno" was only
the first step in that direction. If this or any other function needs
to communicate what specifically is wrong with the requested "refname"
it'll be better to have the function set some output enum of
well-defined error states than piggy-backend on "errno".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When deleting refs from the loose-files refs backend, then we need to be
careful to also delete the same ref from the packed refs backend, if it
exists. If we don't, then deleting the loose ref would "uncover" the
packed ref. We thus always have to queue up deletions of refs for both
the loose and the packed refs backend. This is done in two separate
transactions, where the end result is that the reference-transaction
hook is executed twice for the deleted refs.
This behaviour is quite misleading: it's exposing implementation details
of how the files backend works to the user, in contrast to the logical
updates that we'd really want to expose via the hook. Worse yet, whether
the hook gets executed once or twice depends on how well-packed the
repository is: if the ref only exists as a loose ref, then we execute it
once, otherwise if it is also packed then we execute it twice.
Fix this behaviour and don't execute the reference-transaction hook at
all when refs in the packed-refs backend if it's driven by the files
backend. This works as expected even in case the refs to be deleted only
exist in the packed-refs backend because the loose-backend always queues
refs in its own transaction even if they don't exist such that they can
be locked for concurrent creation. And it also does the right thing in
case neither of the backends has the ref because that would cause the
transaction to fail completely.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reference-transaction hook is supposed to track logical changes to
references, but it currently also gets executed when packing refs in a
repository. This is unexpected and ultimately not all that useful:
packing refs is not supposed to result in any user-visible change to the
refs' state, and it ultimately is an implementation detail of how refs
stores work.
Fix this excessive execution of the hook when packing refs.
Reported-by: Waleed Khan <me@waleedkhan.name>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We do not currently have any flags when creating reference transactions,
but we'll add one to disable execution of the reference transaction hook
in some cases.
Allow passing flags to `ref_store_transaction_begin()` to prepare for
this change.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When deleting loose refs, then we also have to delete the refs in the
packed backend. This is done by calling `refs_delete_refs()`, which
then uses the packed-backend's logic to delete refs. This doesn't allow
us to exercise any control over the reference transaction which is being
created in the packed backend, which is required in a subsequent commit.
Extract a new function `packed_refs_delete_refs()`, which hosts most of
the logic to delete refs except for creating the transaction itself.
Like this, we can easily create the transaction in the files backend
and thus exert more control over it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix a logic error in refs_resolve_ref_unsafe() introduced in a recent
series of mine to abstract the refs API away from errno. See
96f6623ada (Merge branch 'ab/refs-errno-cleanup', 2021-11-29)for that
series.
In that series introduction of "failure_errno" to
refs_resolve_ref_unsafe came in ef18119dec (refs API: add a version
of refs_resolve_ref_unsafe() with "errno", 2021-10-16). There we'd set
"errno = 0" immediately before refs_read_raw_ref(), and then set
"failure_errno" to "errno" if errno was non-zero afterwards.
Then in the next commit 8b72fea7e9 (refs API: make
refs_read_raw_ref() not set errno, 2021-10-16) we started expecting
"refs_read_raw_ref()" to set "failure_errno". It would do that if
refs_read_raw_ref() failed, but it wouldn't be the same errno.
So we might set the "errno" here to any arbitrary bad value, and end
up e.g. returning NULL when we meant to return the refname from
refs_resolve_ref_unsafe(), or the other way around. Instrumenting this
code will reveal cases where refs_read_raw_ref() will fail, and
"errno" and "failure_errno" will be set to different values.
In practice I haven't found a case where this scary bug changed
anything in practice. The reason for that is that we'll not care about
the actual value of "errno" here per-se, but only whether:
1. We have an errno
2. If it's one of ENOENT, EISDIR or ENOTDIR. See the adjacent code
added in a1c1d8170d (refs_resolve_ref_unsafe: handle d/f
conflicts for writes, 2017-10-06)
I.e. if we clobber "failure_errno" with "errno", but it happened to be
one of those three, and we'll clobber it with another one of the three
we were OK.
Perhaps there are cases where the difference ended up mattering, but I
haven't found them. Instrumenting the test suite to fail if "errno"
and "failure_errno" are different shows a lot of failures, checking if
they're different *and* one is but not the other is outside that list
of three "errno" values yields no failures.
But let's fix the obvious bug. We should just stop paying attention to
"errno" in refs_resolve_ref_unsafe(). In addition let's change the
partial resetting of "errno" in files_read_raw_ref() to happen just
before the "return", to ensure that any such bug will be more easily
spotted in the future.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code refactoring in the reflog part of refs API.
* ab/reflog-prep:
reflog + refs-backend: move "verbose" out of the backend
refs files-backend: assume cb->newlog if !EXPIRE_REFLOGS_DRY_RUN
reflog: reduce scope of "struct rev_info"
reflog expire: don't use lookup_commit_reference_gently()
reflog expire: refactor & use "tip_commit" only for UE_NORMAL
reflog expire: use "switch" over enum values
reflog: change one->many worktree->refnames to use a string_list
reflog expire: narrow scope of "cb" in cmd_reflog_expire()
reflog delete: narrow scope of "cmd" passed to count_reflog_ent()
Move the handling of the "verbose" flag entirely out of
"refs/files-backend.c" and into "builtin/reflog.c". This allows the
backend to stop knowing about the EXPIRE_REFLOGS_VERBOSE flag.
The expire_reflog_ent() function shouldn't need to deal with the
implementation detail of whether or not we're emitting verbose output,
by doing this the --verbose output becomes backend-agnostic, so
reftable will get the same output.
I think the output is rather bad currently, and should e.g. be
implemented with some better future mode of progress.[ch], but that's
a topic for another improvement.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's not possible for "cb->newlog" to be NULL if
!EXPIRE_REFLOGS_DRY_RUN, since files_reflog_expire() would have
error()'d and taken the "goto failure" branch if it couldn't open the
file. By not using the "newlog" field private to "file-backend.c"'s
"struct expire_reflog_cb", we can move this verbosity logging to
"builtin/reflog.c" in a subsequent commit.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is consistent with the calling convention for ref backend creation, and
avoids storing ".git/packed-refs" (the name of a regular file) in a variable called
ref_store::gitdir.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test helper for refs subsystem learned to write bogus and/or
nonexistent object name to refs to simulate error situations we
want to test Git in.
* hn/allow-bogus-oid-in-ref-tests:
t1430: create valid symrefs using test-helper
t1430: remove refs using test-tool
refs: introduce REF_SKIP_REFNAME_VERIFICATION flag
refs: introduce REF_SKIP_OID_VERIFICATION flag
refs: update comment.
test-ref-store: plug memory leak in cmd_delete_refs
test-ref-store: parse symbolic flag constants
test-ref-store: remove force-create argument for create-reflog
Prepare tests on ref API to help testing reftable backends.
* hn/reflog-tests:
refs/debug: trim trailing LF from reflog message
test-ref-store: tweaks to for-each-reflog-ent format
t1405: check for_each_reflog_ent_reverse() more thoroughly
test-ref-store: don't add newline to reflog message
show-branch: show reflog message
This lets the ref-store test helper write non-existent or unparsable objects
into the ref storage.
Use this to make t1006 and t3800 independent of the files storage backend.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
REF_IS_PRUNING is right below this comment, so it clearly does not belong in
this comment. This was apparently introduced in commit 5ac95fee (Nov 5, 2017
"refs: tidy up and adjust visibility of the `ref_update` flags").
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
On iteration, the reflog message is always terminated by a newline. Trim it to
avoid clobbering the console with is this extra newline.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "remainder" of hn/refs-errno-cleanup topic.
* ab/refs-errno-cleanup: (21 commits)
refs API: post-migration API renaming [2/2]
refs API: post-migration API renaming [1/2]
refs API: don't expose "errno" in run_transaction_hook()
refs API: make expand_ref() & repo_dwim_log() not set errno
refs API: make resolve_ref_unsafe() not set errno
refs API: make refs_ref_exists() not set errno
refs API: make refs_resolve_refdup() not set errno
refs tests: ignore ignore errno in test-ref-store helper
refs API: ignore errno in worktree.c's find_shared_symref()
refs API: ignore errno in worktree.c's add_head_info()
refs API: make files_copy_or_rename_ref() et al not set errno
refs API: make loose_fill_ref_dir() not set errno
refs API: make resolve_gitlink_ref() not set errno
refs API: remove refs_read_ref_full() wrapper
refs/files: remove "name exist?" check in lock_ref_oid_basic()
reflog tests: add --updateref tests
refs API: make refs_rename_ref_available() static
refs API: make parse_loose_ref_contents() not set errno
refs API: make refs_read_raw_ref() not set errno
refs API: add a version of refs_resolve_ref_unsafe() with "errno"
...
There is only one caller, builtin/checkout.c, and it hardcodes
force_create=1.
This argument was introduced in abd0cd3a30 (refs: new public ref function:
safe_create_reflog, 2015-07-21), which promised to immediately use it in a
follow-on commit, but that never happened.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Follow through the work to use the repo interface to access
submodule objects in-process, instead of abusing the alternate
object database interface.
* jt/no-abuse-alternate-odb-for-submodules:
submodule: trace adding submodule ODB as alternate
submodule: pass repo to check_has_commit()
object-file: only register submodule ODB if needed
merge-{ort,recursive}: remove add_submodule_odb()
refs: peeling non-the_repository iterators is BUG
refs: teach arbitrary repo support to iterators
refs: plumb repo into ref stores
Rename the transitory refs_werrres_ref_unsafe() function to
refs_resolve_ref_unsafe(), now that all callers of the old function
have learned to pass in a "failure_errno" parameter.
The coccinelle semantic patch added in the preceding commit works, but
I couldn't figure out how to get spatch(1) to re-flow these argument
lists (and sometimes make lines way too long), so this rename was done
with:
perl -pi -e 's/refs_werrres_ref_unsafe/refs_resolve_ref_unsafe/g' \
$(git grep -l refs_werrres_ref_unsafe -- '*.c')
But after that "make contrib/coccinelle/refs.cocci.patch" comes up
empty, so the result would have been the same. Let's remove that
transitory semantic patch file, we won't need to retain it for any
other in-flight changes, refs_werrres_ref_unsafe() only existed within
this patch series.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
None of the callers of rename_ref() and copy_ref() care about errno,
and as seen in the context here we already emit our own non-errno
using error() in the case where we'd use it.
So let's have it explicitly ignore errno, and do the same in
commit_ref_update(), which is only used within other code in
files_copy_or_rename_ref() itself which doesn't care about errno
either.
It might actually be sensible to have the callers use errno if the
failure was filesystem-specific, and with the upcoming reftable
backend we don't want to rely on that sort of thing, so let's keep
ignoring that for now.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the refs_resolve_ref_unsafe() invoked in loose_fill_ref_dir()
to a form that ignores errno. The only eventual caller of this
function is create_ref_cache(), whose callers in turn don't have their
failure depend on any errno set here.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove the refs_read_ref_full() wrapper in favor of migrating various
refs.c API users to the underlying refs_werrres_ref_unsafe() function.
A careful reading of these callers shows that the callers of this
function did not care about "errno", by moving away from the
refs_resolve_ref_unsafe() wrapper we can be sure that nothing relies
on it anymore.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In lock_ref_oid_basic() we'll happily lock a reference that doesn't
exist yet. That's normal, and is how references are initially born,
but we don't need to retain checks here in lock_ref_oid_basic() about
the state of the ref, when what we're checking is either checked
already, or something we're about to discover by trying to lock the
ref with raceproof_create_file().
The one exception is the caller in files_reflog_expire(), who passes
us a "type" to find out if the reference is a symref or not. We can
move the that logic over to that caller, which can now defer its
discovery of whether or not the ref is a symref until it's needed. In
the preceding commit an exhaustive regression test was added for that
case in a new test in "t1417-reflog-updateref.sh".
The improved diagnostics here were added in
5b2d8d6f21 (lock_ref_sha1_basic(): improve diagnostics for ref D/F
conflicts, 2015-05-11), and then much of the surrounding code went
away recently in my 245fbba46d (refs/files: remove unused "errno ==
EISDIR" code, 2021-08-23).
The refs_resolve_ref_unsafe() code being removed here looks like it
should be tasked with doing that, but it's actually redundant to other
code.
The reason for that is as noted in 245fbba46d this once widely used
function now only has a handful of callers left, which all handle this
case themselves.
To the extent that we're racy between their check and ours removing
this check actually improves the situation, as we'll be doing fewer
things between the not-under-lock initial check and acquiring the
lock.
Why this is OK for all the remaining callers of lock_ref_oid_basic()
is noted below. There are only two of those callers:
* "git branch -[cm] <oldbranch> <newbranch>":
In files_copy_or_rename_ref() we'll call this when we copy or rename
refs via rename_ref() and copy_ref(). but only after we've checked
if the refname exists already via its own call to
refs_resolve_ref_unsafe() and refs_rename_ref_available().
As the updated comment to the latter here notes neither of those are
actually needed. If we delete not only this code but also
refs_rename_ref_available() we'll do just fine, we'll just emit a
less friendly error message if e.g. "git branch -m A B/C" would have
a D/F conflict with a "B" file.
Actually we'd probably die before that in case reflogs for the
branch existed, i.e. when the try to rename() or copy_file() the
relevant reflog, since if we've got a D/F conflict with a branch
name we'll probably also have the same with its reflogs (but not
necessarily, we might have reflogs, but it might not).
As some #leftoverbits that code seems buggy to me, i.e. the reflog
"protocol" should be to get a lock on the main ref, and then perform
ref and/or reflog operations. That code dates back to
c976d415e5 (git-branch: add options and tests for branch renaming,
2006-11-28) and probably pre-dated the solidifying of that
convention. But in any case, that edge case is not our bug or
problem right now.
* "git reflog expire <ref>":
In files_reflog_expire() we'll call this without previous ref
existence checking in files-backend.c, but that code is in turn
called by code that's just finished checking if the refname whose
reflog we're expiring exists.
See ae35e16cd4 (reflog expire: don't lock reflogs using previously
seen OID, 2021-08-23) for the current state of that code, and
5e6f003ca8 (reflog_expire(): ignore --updateref for symbolic
references, 2015-03-03) for the code we'd break if we only did a
"update = !!ref" here, which is covered by the aforementioned
regression test in "t1417-reflog-updateref.sh".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the refs_rename_ref_available() function into
"refs/files-backend.c". It is file-backend specific.
This function was added in 5fe7d825da (refs.c: pass a list of names
to skip to is_refname_available, 2014-05-01) as rename_ref_available()
and was only ever used in this one file-backend specific codepath. So
let's move it there.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the parse_loose_ref_contents() function to stop setting "errno"
and failure, and to instead pass up a "failure_errno" via a
parameter. This requires changing its callers to do the same.
The EINVAL error from parse_loose_ref_contents is used in files-backend
to create a custom error message.
In untangling this we discovered a tricky edge case. The
refs_read_special_head() function was relying on
parse_loose_ref_contents() setting EINVAL.
By converting it to use "saved_errno" we can migrate away from "errno"
in this part of the code entirely, and do away with an existing
"save_errno" pattern, its only purpose was to not clobber the "errno"
we previously needed at the end of files_read_raw_ref().
Let's assert that we can do that by not having files_read_raw_ref()
itself operate on *failure_errno in addition to passing it on. Instead
we'll assert that if we return non-zero we actually do set errno, thus
assuring ourselves and callers that they can trust the resulting
"failure_errno".
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a "failure_errno" to refs_read_raw_ref(), his allows
refs_werrres_ref_unsafe() to pass along its "failure_errno", as a
first step before its own callers are migrated to pass it further up
the chain.
We are leaving out out the refs_read_special_head() in
refs_read_raw_ref() for now, as noted in a subsequent commit moving it
to "failure_errno" will require some special consideration.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ref iteration code used to optionally allow dangling refs to be
shown, which has been tightened up.
* jk/ref-paranoia:
refs: drop "broken" flag from for_each_fullref_in()
ref-filter: drop broken-ref code entirely
ref-filter: stop setting FILTER_REFS_INCLUDE_BROKEN
repack, prune: drop GIT_REF_PARANOIA settings
refs: turn on GIT_REF_PARANOIA by default
refs: omit dangling symrefs when using GIT_REF_PARANOIA
refs: add DO_FOR_EACH_OMIT_DANGLING_SYMREFS flag
refs-internal.h: reorganize DO_FOR_EACH_* flag documentation
refs-internal.h: move DO_FOR_EACH_* flags next to each other
t5312: be more assertive about command failure
t5312: test non-destructive repack
t5312: create bogus ref as necessary
t5312: drop "verbose" helper
t5600: provide detached HEAD for corruption failures
t5516: don't use HEAD ref for invalid ref-deletion tests
t7900: clean up some more broken refs
There is currently no support for peeling the current ref of an iterator
iterating over a non-the_repository ref store, and none is needed. Thus,
for now, BUG() if that happens.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Note that should_pack_ref() is called when writing refs, which is only
supported for the_repository, hence the_repository is hardcoded there.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
