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Author SHA1 Message Date
Junio C Hamano f6c075ad71 Merge branch 'jk/ref-paranoia'
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
2021-10-11 10:21:47 -07:00
Junio C Hamano 870de59af0 Merge branch 'ab/retire-refs-unused-funcs'
Code cleanup.

* ab/retire-refs-unused-funcs:
  refs/ref-cache.[ch]: remove "incomplete" from create_dir_entry()
  refs/ref-cache.c: remove "mkdir" parameter from find_containing_dir()
  refs/ref-cache.[ch]: remove unused add_ref_entry()
  refs/ref-cache.[ch]: remove unused remove_entry_from_dir()
  refs.[ch]: remove unused ref_storage_backend_exists()
2021-10-06 13:40:13 -07:00
Junio C Hamano 92382d14cd Merge branch 'hn/refs-errno-cleanup'
Futz with the way 'errno' is relied on in the refs API to carry the
failure modes up the call chain.

* hn/refs-errno-cleanup:
  refs: make errno output explicit for read_raw_ref_fn
  refs/files-backend: stop setting errno from lock_ref_oid_basic
  refs: remove EINVAL errno output from specification of read_raw_ref_fn
  refs file backend: move raceproof_create_file() here
2021-10-03 21:49:18 -07:00
Junio C Hamano 842d45d293 Merge branch 'ab/refs-files-cleanup'
Continued work on top of the hn/refs-errno-cleanup topic.

* ab/refs-files-cleanup:
  refs/files: remove unused "errno != ENOTDIR" condition
  refs/files: remove unused "errno == EISDIR" code
  refs/files: remove unused "oid" in lock_ref_oid_basic()
  refs API: remove OID argument to reflog_expire()
  reflog expire: don't lock reflogs using previously seen OID
  refs/files: add a comment about refs_reflog_exists() call
  refs: make repo_dwim_log() accept a NULL oid
  refs/debug: re-indent argument list for "prepare"
  refs/files: remove unused "skip" in lock_raw_ref() too
  refs/files: remove unused "extras/skip" in lock_ref_oid_basic()
  refs: drop unused "flags" parameter to lock_ref_oid_basic()
  refs/files: remove unused REF_DELETING in lock_ref_oid_basic()
  refs/packet: add missing BUG() invocations to reflog callbacks
2021-10-03 21:49:18 -07:00
Ævar Arnfjörð Bjarmason 750036c8f7 refs/ref-cache.[ch]: remove "incomplete" from create_dir_entry()
Remove the now-unused "incomplete" parameter from create_dir_entry(),
all its callers specify it as "1", so let's drop the "incomplete=0"
case. The last caller to use it was search_for_subdir(), but that code
was removed in the preceding commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 15:12:04 -07:00
Ævar Arnfjörð Bjarmason 5e4546d599 refs/ref-cache.c: remove "mkdir" parameter from find_containing_dir()
Remove the "mkdir" parameter from the find_containing_dir() function,
the add_ref_entry() function removed in the preceding commit was its
last user.

Since "mkdir" is always "0" we can also remove the parameter from
search_for_subdir(), which in turn means that we can delete most of
that function.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 15:12:04 -07:00
Ævar Arnfjörð Bjarmason 6a99fa2e9e refs/ref-cache.[ch]: remove unused add_ref_entry()
This function has not been used since 9dd389f3d8 (packed_ref_store:
get rid of the `ref_cache` entirely, 2017-09-25).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 15:12:04 -07:00
Ævar Arnfjörð Bjarmason 34e8a20d76 refs/ref-cache.[ch]: remove unused remove_entry_from_dir()
This function was missed in 9939b33d6a (packed-backend: rip out some
now-unused code, 2017-09-08), and has been orphaned since then. Let's
delete it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 15:12:04 -07:00
Jeff King 8dccb2244c refs: add DO_FOR_EACH_OMIT_DANGLING_SYMREFS flag
When the DO_FOR_EACH_INCLUDE_BROKEN flag is used, we include both actual
corrupt refs (illegal names, missing objects), but also symrefs that
point to nothing. This latter is not really a corruption, but just
something that may happen normally. For example, the symref at
refs/remotes/origin/HEAD may point to a tracking branch which is later
deleted. (The local HEAD may also be unborn, of course, but we do not
access it through ref iteration).

Most callers of for_each_ref() etc, do not care. They don't pass
INCLUDE_BROKEN, so don't see it at all. But for those which do pass it,
this somewhat-normal state causes extra warnings (e.g., from
for-each-ref) or even aborts operations (destructive repacks with
GIT_REF_PARANOIA set).

This patch just introduces the flag and the mechanism; there are no
callers yet (and hence no tests). Two things to note on the
implementation:

  - we actually skip any symref that does not resolve to a ref. This
    includes ones which point to an invalidly-named ref. You could argue
    this is a more serious breakage than simple dangling. But the
    overall effect is the same (we could not follow the symref), as well
    as the impact on things like REF_PARANOIA (either way, a symref we
    can't follow won't impact reachability, because we'll see the ref
    itself during iteration). The underlying resolution function doesn't
    distinguish these two cases (they both get REF_ISBROKEN).

  - we change the iterator in refs/files-backend.c where we check
    INCLUDE_BROKEN. There's a matching spot in refs/packed-backend.c,
    but we don't know need to do anything there. The packed backend does
    not support symrefs at all.

The resulting set of flags might be a bit easier to follow if we broke
this down into "INCLUDE_CORRUPT_REFS" and "INCLUDE_DANGLING_SYMREFS".
But there are a few reasons not do so:

  - adding a new OMIT_DANGLING_SYMREFS flag lets us leave existing
    callers intact, without changing their behavior (and some of them
    really do want to see the dangling symrefs; e.g., t5505 has a test
    which expects us to report when a symref becomes dangling)

  - they're not actually independent. You cannot say "include dangling
    symrefs" without also including refs whose objects are not
    reachable, because dangling symrefs by definition do not have an
    object. We could tweak the implementation to distinguish this, but
    in practice nobody wants to ask for that. Adding the OMIT flag keeps
    the implementation simple and makes sure we don't regress the
    current behavior.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27 12:36:45 -07:00
Jeff King 9aab952e85 refs-internal.h: reorganize DO_FOR_EACH_* flag documentation
The documentation for the DO_FOR_EACH_* flags is sprinkled over the
refs-internal.h file. We define the two flags in one spot, and then
describe them in more detail far away from there, in the definitions of
refs_ref_iterator_begin() and ref_iterator_advance_fn().

Let's try to organize this a bit better:

  - convert the #defines to an enum. This makes it clear that they are
    related, and that the enum shows the complete set of flags.

  - combine all descriptions for each flag in a single spot, next to the
    flag's definition

  - use the enum rather than a bare int for functions which take the
    flags. This helps readers realize which flags can be used.

  - clarify the mention of flags for ref_iterator_advance_fn(). It does
    not take flags itself, but is meant to depend on ones set up
    earlier.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27 12:36:45 -07:00
Jeff King bf708add2e refs-internal.h: move DO_FOR_EACH_* flags next to each other
There are currently two DO_FOR_EACH_* flags, which must not have their
bits overlap. Yet they're defined hundreds of lines apart. Let's move
them next to each other to make it clear that they are related and are a
complete set (which matters if you are adding a new flag and would like
to know what the next available bit is).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27 12:36:45 -07:00
René Scharfe 35cf94eaf6 refs/files-backend: remove unused open mode parameter
We only need to provide a mode if we are willing to let open(2) create
the file, which is not the case here, so drop the unnecessary parameter.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 17:40:28 -07:00
Han-Wen Nienhuys 5b12e16bb1 refs: make errno output explicit for read_raw_ref_fn
This makes it explicit how alternative ref backends should report errors in
read_raw_ref_fn.

read_raw_ref_fn needs to supply a credible errno for a number of cases. These
are primarily:

1) The files backend calls read_raw_ref from lock_raw_ref, and uses the
resulting error codes to create/remove directories as needed.

2) ENOENT should be translated in a zero OID, optionally with REF_ISBROKEN set,
returning the last successfully resolved symref. This is necessary so
read_raw_ref("HEAD") on an empty repo returns refs/heads/main (or the default branch
du-jour), and we know on which branch to create the first commit.

Make this information flow explicit by adding a failure_errno to the signature
of read_raw_ref. All errnos from the files backend are still propagated
unchanged, even though inspection suggests only ENOTDIR, EISDIR and ENOENT are
relevant.

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>
2021-08-25 13:30:26 -07:00
Han-Wen Nienhuys 1ae6ed230a refs/files-backend: stop setting errno from lock_ref_oid_basic
refs/files-backend.c::lock_ref_oid_basic() tries to signal how it failed
to its callers using errno.

It is safe to stop setting errno here, because the callers of this
file-scope static function are

* files_copy_or_rename_ref()
* files_create_symref()
* files_reflog_expire()

None of them looks at errno after seeing a negative return from
lock_ref_oid_basic() to make any decision, and no caller of these three
functions looks at errno after they signal a failure by returning a
negative value. In particular,

* files_copy_or_rename_ref() - here, calls are followed by error()
(which performs I/O) or write_ref_to_lockfile() (which calls
parse_object() which may perform I/O)

* files_create_symref() - here, calls are followed by error() or
create_symref_locked() (which performs I/O and does not inspect
errno)

* files_reflog_expire() - here, calls are followed by error() or
refs_reflog_exists() (which calls a function in a vtable that is not
documented to use and/or preserve 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>
2021-08-25 13:30:26 -07:00
Han-Wen Nienhuys 20d422cfd7 refs: remove EINVAL errno output from specification of read_raw_ref_fn
This commit does not change code; it documents the fact that an alternate ref
backend does not need to return EINVAL from read_raw_ref_fn to function
properly.

This is correct, because refs_read_raw_ref is only called from;

* resolve_ref_unsafe(), which does not care for the EINVAL errno result.

* refs_verify_refname_available(), which does not inspect errno.

* files-backend.c, where errno is overwritten on failure.

* packed-backend.c (is_packed_transaction_needed), which calls it for the
  packed ref backend, which never emits EINVAL.

A grep for EINVAL */*c reveals that no code checks errno against EINVAL after
reading references. In addition, the refs.h file does not mention errno at all.

A grep over resolve_ref_unsafe() turned up the following callers that inspect
errno:

* sequencer.c::print_commit_summary, which uses it for die_errno

* lock_ref_oid_basic(), which only treats EISDIR and ENOTDIR specially.

The files ref backend does use EINVAL. The files backend does not call into
the generic API (refs_read_raw), but into the files-specific function
(files_read_raw_ref), which we are not changing in this commit.

As the errno sideband is unintuitive and error-prone, remove EINVAL
value, as a step towards getting rid of the errno sideband altogether.

Spotted by Ævar Arnfjörð Bjarmason <avarab@gmail.com>.

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>
2021-08-25 13:30:26 -07:00
Ævar Arnfjörð Bjarmason 3fa2e91d17 refs file backend: move raceproof_create_file() here
Move the raceproof_create_file() API added to cache.h and
object-file.c in 177978f56a (raceproof_create_file(): new function,
2017-01-06) to its only user, refs/files-backend.c.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:30:26 -07:00
Ævar Arnfjörð Bjarmason 48cdcd9ca0 refs/files: remove unused "errno != ENOTDIR" condition
As a follow-up to the preceding commit where we removed the adjacent
"errno == EISDIR" condition in the same function, remove the
"last_errno != ENOTDIR" condition here.

It's not possible for us to hit this condition added in
5b2d8d6f21 (lock_ref_sha1_basic(): improve diagnostics for ref D/F
conflicts, 2015-05-11). Since a1c1d8170d (refs_resolve_ref_unsafe:
handle d/f conflicts for writes, 2017-10-06) we've explicitly caught
these in refs_resolve_ref_unsafe() before returning NULL:

	if (errno != ENOENT &&
	    errno != EISDIR &&
	    errno != ENOTDIR)
		return NULL;

We'd then always return the refname from refs_resolve_ref_unsafe()
even if we were in a broken state as explained in the preceding
commit. The elided context here is a call to refs_resolve_ref_unsafe().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 245fbba46d refs/files: remove unused "errno == EISDIR" code
When we lock a reference like "foo" we need to handle the case where
"foo" exists, but is an empty directory. That's what this code added
in bc7127ef0f (ref locking: allow 'foo' when 'foo/bar' used to exist
but not anymore., 2006-09-30) seems like it should be dealing with.

Except it doesn't, and we never take this branch. The reason is that
when bc7127ef0f was written this looked like:

	ref = resolve_ref([...]);
	if (!ref && errno == EISDIR) {
	[...]

And in resolve_ref() we had this code:

	fd = open(path, O_RDONLY);
	if (fd < 0)
		return NULL;

I.e. we would attempt to read "foo" with open(), which would fail with
EISDIR and we'd return NULL. We'd then take this branch, call
remove_empty_directories() and continue.

Since a1c1d8170d (refs_resolve_ref_unsafe: handle d/f conflicts for
writes, 2017-10-06) we don't. E.g. in the case of
files_copy_or_rename_ref() our callstack will look something like:

	[...] ->
	files_copy_or_rename_ref() ->
	lock_ref_oid_basic() ->
	refs_resolve_ref_unsafe()

At that point the first (now only) refs_resolve_ref_unsafe() call in
lock_ref_oid_basic() would do the equivalent of this in the resulting
call to refs_read_raw_ref() in refs_resolve_ref_unsafe():

	/* Via refs_read_raw_ref() */
	fd = open(path, O_RDONLY);
	if (fd < 0)
		/* get errno == EISDIR */
	/* later, in refs_resolve_ref_unsafe() */
	if ([...] && errno != EISDIR)
		return NULL;
	[...]
	/* returns the refs/heads/foo to the caller, even though it's a directory */
	return refname;

I.e. even though we got an "errno == EISDIR" we won't take this
branch, since in cases of EISDIR "resolved" is always
non-NULL. I.e. we pretend at this point as though everything's OK and
there is no "foo" directory.

We then proceed with the entire ref update and don't call
remove_empty_directories() until we call commit_ref_update(). See
5387c0d883 (commit_ref(): if there is an empty dir in the way, delete
it, 2016-05-05) for the addition of that code, and
a1c1d8170d (refs_resolve_ref_unsafe: handle d/f conflicts for writes,
2017-10-06) for the commit that changed the original codepath added in
bc7127ef0f to use this "EISDIR" handling.

Further historical commentary:

Before the two preceding commits the caller in files_reflog_expire()
was the only one out of our 4 callers that would pass non-NULL as an
oid. We would then set a (now gone) "resolve_flags" to
"RESOLVE_REF_READING" and just before that "errno != EISDIR" check do:

	if (resolve_flags & RESOLVE_REF_READING)
		return NULL;

There may have been some case where this ended up mattering and we
couldn't safely make this change before we removed the "oid"
parameter, but I don't think there was, see [1] for some discussion on
that.

In any case, now that we've removed the "oid" parameter in a preceding
commit we can be sure that this code is redundant, so let's remove it.

1. http://lore.kernel.org/git/871r801yp6.fsf@evledraar.gmail.com

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason ff7a2e4dbb refs/files: remove unused "oid" in lock_ref_oid_basic()
In the preceding commit the last caller that passed a non-NULL OID was
changed to pass NULL to lock_ref_oid_basic(). As noted in preceding
commits use of this API has been going away (we should use ref
transactions, or lock_raw_ref()), so we're unlikely to gain new
callers that want to pass the "oid".

So let's remove it, doing so means we can remove the "mustexist"
condition, and therefore anything except the "flags =
RESOLVE_REF_NO_RECURSE" case.

Furthermore, since the verify_lock() function we called did most of
its work when the "oid" was passed (as "old_oid") we can inline the
trivial part of it that remains in its only remaining caller. Without
a NULL "oid" passed it was equivalent to calling refs_read_ref_full()
followed by oidclr().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason cc40b5ce13 refs API: remove OID argument to reflog_expire()
Since the the preceding commit the "oid" parameter to reflog_expire()
is always NULL, but it was not cleaned up to reduce the size of the
diff. Let's do that subsequent API and documentation cleanup now.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason ae35e16cd4 reflog expire: don't lock reflogs using previously seen OID
During reflog expiry, the cmd_reflog_expire() function first iterates
over all reflogs in logs/*, and then one-by-one acquires the lock for
each one and expires it. This behavior has been with us since this
command was implemented in 4264dc15e1 ("git reflog expire",
2006-12-19).

Change this to stop calling lock_ref_oid_basic() with the OID we saw
when we looped over the logs, instead have it pass the OID it managed
to lock.

This mostly mitigates a race condition where e.g. "git gc" will fail
in a concurrently updated repository because the branch moved since
"git reflog expire --all" was started. I.e. with:

    error: cannot lock ref '<refname>': ref '<refname>' is at <OID-A> but expected <OID-B>

This behavior of passing in an "oid" was needed for an edge-case that
I've untangled in this and preceding commits though, namely that we
needed this OID because we'd:

 1. Lookup the reflog name/OID via dwim_log()
 2. With that OID, lock the reflog
 3. Later in builtin/reflog.c we use the OID we looked as input to
    lookup_commit_reference_gently(), assured that it's equal to the
    OID we got from dwim_log().

We can be sure that this change is safe to make because between
dwim_log (step #1) and lock_ref_oid_basic (step #2) there was no other
logic relevant to the OID or expiry run in the cmd_reflog_expire()
caller.

We can thus treat that code as a black box, before and after this
change it would get an OID that's been locked, the only difference is
that now we mostly won't be failing to get the lock due to the TOCTOU
race[0]. That failure was purely an implementation detail in how the
"current OID" was looked up, it was divorced from the locking
mechanism.

What do we mean with "mostly"? It mostly mitigates it because we'll
still run into cases where the ref is locked and being updated as we
want to expire it, and other git processes wanting to update the refs
will in turn race with us as we expire the reflog.

That remaining race can in turn be mitigated with the
core.filesRefLockTimeout setting, see 4ff0f01cb7 ("refs: retry
acquiring reference locks for 100ms", 2017-08-21). In practice if that
value is high enough we'll probably never have ref updates or reflog
expiry failing, since the clients involved will retry for far longer
than the time any of those operations could take.

See [1] for an initial report of how this impacted "git gc" and a
large discussion about this change in early 2019. In particular patch
looked good to Michael Haggerty, see his[2]. That message seems to not
have made it to the ML archive, its content is quoted in full in my
[3].

I'm leaving behind now-unused code the refs API etc. that takes the
now-NULL "unused_oid" argument, and other code that can be simplified now
that we never have on OID in that context, that'll be cleaned up in
subsequent commits, but for now let's narrowly focus on fixing the
"git gc" issue. As the modified assert() shows we always pass a NULL
oid to reflog_expire() now.

Unfortunately this sort of probabilistic contention is hard to turn
into a test. I've tested this by running the following three subshells
in concurrent terminals:

    (
        rm -rf /tmp/git &&
        git init /tmp/git &&
        while true
        do
            head -c 10 /dev/urandom | hexdump >/tmp/git/out &&
            git -C /tmp/git add out &&
            git -C /tmp/git commit -m"out"
        done
    )

    (
	rm -rf /tmp/git-clone &&
        git clone file:///tmp/git /tmp/git-clone &&
        while git -C /tmp/git-clone pull
        do
            date
        done
    )

    (
        while git -C /tmp/git-clone reflog expire --all
        do
            date
        done
    )

Before this change the "reflog expire" would fail really quickly with
the "but expected" error noted above.

After this change both the "pull" and "reflog expire" will run for a
while, but eventually fail because I get unlucky with
core.filesRefLockTimeout (the "reflog expire" is in a really tight
loop). As noted above that can in turn be mitigated with higher values
of core.filesRefLockTimeout than the 100ms default.

As noted in the commentary added in the preceding commit there's also
the case of branches being racily deleted, that can be tested by
adding this to the above:

    (
        while git -C /tmp/git-clone branch topic master &&
	      git -C /tmp/git-clone branch -D topic
        do
            date
        done
    )

With core.filesRefLockTimeout set to 10 seconds (it can probably be a
lot lower) I managed to run all four of these concurrently for about
an hour, and accumulated ~125k commits, auto-gc's and all, and didn't
have a single failure. The loops visibly stall while waiting for the
lock, but that's expected and desired behavior.

0. https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use
1. https://lore.kernel.org/git/87tvg7brlm.fsf@evledraar.gmail.com/
2. http://lore.kernel.org/git/b870a17d-2103-41b8-3cbc-7389d5fff33a@alum.mit.edu
3. https://lore.kernel.org/git/87pnqkco8v.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 7aa7829f75 refs/files: add a comment about refs_reflog_exists() call
Add a comment about why it is that we need to check for the the
existence of a reflog we're deleting after we've successfully acquired
the lock in files_reflog_expire(). As noted in [1] the lock protocol
for reflogs is somewhat intuitive.

This early exit code the comment applies to dates all the way back to
4264dc15e1 (git reflog expire, 2006-12-19).

1. https://lore.kernel.org/git/54DCDA42.2060800@alum.mit.edu/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 81bc122589 refs/debug: re-indent argument list for "prepare"
Re-indent this argument list that's been mis-indented since it was
added in 34c319970d (refs/debug: trace into reflog expiry too,
2021-04-23). This makes a subsequent change smaller.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 640d9d55c3 refs/files: remove unused "skip" in lock_raw_ref() too
Remove the unused "skip" parameter to lock_raw_ref(), it was never
used. We do use it when passing "skip" to the
refs_rename_ref_available() function in files_copy_or_rename_ref(),
but not here.

This is part of a larger series that modifies lock_ref_oid_basic()
extensively, there will be no more modifications of this function in
this series, but since the preceding commit removed this unused
parameter from lock_ref_oid_basic(), let's do it here too for
consistency.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 11e984da07 refs/files: remove unused "extras/skip" in lock_ref_oid_basic()
The lock_ref_oid_basic() function has gradually been replaced by use
of the file transaction API, there are only 4 remaining callers of
it.

None of those callers pass non-NULL "extras" and "skip" parameters,
the last such caller went away in 92b1551b1d (refs: resolve symbolic
refs first, 2016-04-25), so let's remove the parameters.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Jeff King 491ad946b2 refs: drop unused "flags" parameter to lock_ref_oid_basic()
In the last commit we removed the REF_DELETING flag from
lock_ref_oid_basic(). Since then all of the remaining callers do pass
REF_NO_DEREF, but that has been ignored completely since
7a418f3a17 (lock_ref_sha1_basic(): only handle REF_NODEREF mode,
2016-04-22).

So we can simply get rid of the parameter entirely.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-25 13:27:37 -07:00
Ævar Arnfjörð Bjarmason 212631ed50 refs/files: remove unused REF_DELETING in lock_ref_oid_basic()
The lock_ref_oid_basic() function has gradually been replaced by
most callers no longer performing a low-level "acquire lock,
update and release", and instead using the ref transaction API.
So there are only 4 remaining callers of lock_ref_oid_basic().

None of those callers pass REF_DELETING anymore, the last caller went
away in 92b1551b1d (refs: resolve symbolic refs first,
2016-04-25).

Before that we'd refactored and moved this code in:

 - 8df4e51138 (struct ref_update: move "have_old" into "flags",
   2015-02-17)

 - 7bd9bcf372 (refs: split filesystem-based refs code into a new
   file, 2015-11-09)

 - 165056b2fc (lock_ref_for_update(): new function, 2016-04-24)

We then finally stopped using it in 92b1551b1d (noted above). So let's
remove the handling of this parameter.

By itself this change doesn't benefit us much, but it's the start of
even more removal of unused code in and around this function in
subsequent commits.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-19 19:06:38 -07:00
Ævar Arnfjörð Bjarmason 881aebffcf refs/packet: add missing BUG() invocations to reflog callbacks
In e0cc8ac820 (packed_ref_store: make class into a subclass of
`ref_store`, 2017-06-23) a die() was added to packed_create_reflog(),
but not to any of the other reflog callbacks, let's do that.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-08-19 19:06:38 -07:00
Junio C Hamano aaf113ed95 Merge branch 'hn/refs-debug-empty-prefix'
Debugging aid.

* hn/refs-debug-empty-prefix:
  refs/debug: quote prefix
2021-07-28 13:18:04 -07:00
Han-Wen Nienhuys c510928a25 refs/debug: quote prefix
This makes the empty prefix ("") stand out better.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-19 14:32:34 -07:00
Junio C Hamano bd4232fac3 Merge branch 'ab/struct-init'
Code cleanup around struct_type_init() functions.

* ab/struct-init:
  string-list.h users: change to use *_{nodup,dup}()
  string-list.[ch]: add a string_list_init_{nodup,dup}()
  dir.[ch]: replace dir_init() with DIR_INIT
  *.c *_init(): define in terms of corresponding *_INIT macro
  *.h: move some *_INIT to designated initializers
2021-07-16 17:42:53 -07:00
Junio C Hamano f0ade787ac Merge branch 'hn/refs-iterator-peel-returns-boolean'
Tiny API tweak.

* hn/refs-iterator-peel-returns-boolean:
  refs: make explicit that ref_iterator_peel returns boolean
2021-07-16 17:42:49 -07:00
Ævar Arnfjörð Bjarmason bc40dfb10a string-list.h users: change to use *_{nodup,dup}()
Change all in-tree users of the string_list_init(LIST, BOOL) API to
use string_list_init_{nodup,dup}(LIST) instead.

As noted in the preceding commit let's leave the now-unused
string_list_init() wrapper in-place for any in-flight users, it can be
removed at some later date.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-01 12:32:22 -07:00
Han-Wen Nienhuys 617480d75b refs: make explicit that ref_iterator_peel returns boolean
Use -1 as error return value throughout.

This removes spurious differences in the GIT_TRACE_REFS output, depending on the
ref storage backend active.

Before, the cached ref_iterator (but only that iterator!) would return
peel_object() output directly. No callers relied on the peel_status values
beyond success/failure. All calls to these functions go through
peel_iterated_oid(), which returns peel_object() as a fallback, but also
squashing the error values.

The iteration interface already passes REF_ISSYMREF and REF_ISBROKEN through the
flags argument, so the additional error values in enum peel_status provide no
value.

The ref iteration interface provides a separate peel() function because certain
formats (eg. packed-refs and reftable) can store the peeled object next to the
tag SHA1. Passing the peeled SHA1 as an optional argument to each_ref_fn maps
more naturally to the implementation of ref databases. Changing the code in this
way is left for a future refactoring.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-20 07:54:12 +09:00
Junio C Hamano 16f91451fa Merge branch 'wc/packed-ref-removal-cleanup'
When "git update-ref -d" removes a ref that is packed, it left
empty directories under $GIT_DIR/refs/ for

* wc/packed-ref-removal-cleanup:
  refs: cleanup directories when deleting packed ref
2021-05-16 21:05:24 +09:00
Will Chandler 5f03e5126d refs: cleanup directories when deleting packed ref
When deleting a packed ref via 'update-ref -d', a lockfile is made in
the directory that would contain the loose copy of that ref, creating
any directories in the ref's path that do not exist. When the
transaction completes, the lockfile is deleted, but any empty parent
directories made when creating the lockfile are left in place.  These
empty directories are not removed by 'pack-refs' or other housekeeping
tasks and will accumulate over time.

When deleting a loose ref, we remove all empty parent directories at the
end of the transaction.

This commit applies the parent directory cleanup logic used when
deleting loose refs to packed refs as well.

Signed-off-by: Will Chandler <wfc@wfchandler.org>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-11 13:59:57 +09:00
Junio C Hamano aaa3c8065d Merge branch 'bc/hash-transition-interop-part-1'
SHA-256 transition.

* bc/hash-transition-interop-part-1:
  hex: print objects using the hash algorithm member
  hex: default to the_hash_algo on zero algorithm value
  builtin/pack-objects: avoid using struct object_id for pack hash
  commit-graph: don't store file hashes as struct object_id
  builtin/show-index: set the algorithm for object IDs
  hash: provide per-algorithm null OIDs
  hash: set, copy, and use algo field in struct object_id
  builtin/pack-redundant: avoid casting buffers to struct object_id
  Use the final_oid_fn to finalize hashing of object IDs
  hash: add a function to finalize object IDs
  http-push: set algorithm when reading object ID
  Always use oidread to read into struct object_id
  hash: add an algo member to struct object_id
2021-05-10 16:59:46 +09:00
Junio C Hamano a850356d1b Merge branch 'hn/trace-reflog-expiry'
The reflog expiry machinery has been taught to emit trace events.

* hn/trace-reflog-expiry:
  refs/debug: trace into reflog expiry too
2021-05-07 12:47:38 +09:00
brian m. carlson 14228447c9 hash: provide per-algorithm null OIDs
Up until recently, object IDs did not have an algorithm member, only a
hash.  Consequently, it was possible to share one null (all-zeros)
object ID among all hash algorithms.  Now that we're going to be
handling objects from multiple hash algorithms, it's important to make
sure that all object IDs have a correct algorithm field.

Introduce a per-algorithm null OID, and add it to struct hash_algo.
Introduce a wrapper function as well, and use it everywhere we used to
use the null_oid constant.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 16:31:39 +09:00
Han-Wen Nienhuys 34c319970d refs/debug: trace into reflog expiry too
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 15:59:39 +09:00
Han-Wen Nienhuys 2a2112a429 refs: print errno for read_raw_ref if GIT_TRACE_REFS is set
The ref backend API uses errno as a sideband error channel.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-12 14:42:37 -07:00
René Scharfe ca56dadb4b use CALLOC_ARRAY
Add and apply a semantic patch for converting code that open-codes
CALLOC_ARRAY to use it instead.  It shortens the code and infers the
element size automatically.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-13 16:00:09 -08:00
Martin Ågren 7f0dc7998b refs/files-backend: don't peek into `struct lock_file`
Similar to the previous commits, avoid peeking into the `struct
lock_file`. Use the lock file API instead. Note how we obtain the path
to the lock file if `fdopen_lock_file()` failed and that this is not a
problem: as documented in lockfile.h, failure to "fdopen" does not roll
back the lock file and we're free to, e.g., query it for its path.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-06 13:53:32 -08:00
Junio C Hamano c9a04f036f Merge branch 'hn/refs-trace-backend'
Developer support.

* hn/refs-trace-backend:
  refs: add GIT_TRACE_REFS debugging mechanism
2020-09-22 12:36:28 -07:00
Han-Wen Nienhuys 4441f42707 refs: add GIT_TRACE_REFS debugging mechanism
When set in the environment, GIT_TRACE_REFS makes git print operations and
results as they flow through the ref storage backend. This helps debug
discrepancies between different ref backends.

Example:

    $ GIT_TRACE_REFS="1" ./git branch
    15:42:09.769631 refs/debug.c:26         ref_store for .git
    15:42:09.769681 refs/debug.c:249        read_raw_ref: HEAD: 0000000000000000000000000000000000000000 (=> refs/heads/ref-debug) type 1: 0
    15:42:09.769695 refs/debug.c:249        read_raw_ref: refs/heads/ref-debug: 3a238e539b (=> refs/heads/ref-debug) type 0: 0
    15:42:09.770282 refs/debug.c:233        ref_iterator_begin: refs/heads/ (0x1)
    15:42:09.770290 refs/debug.c:189        iterator_advance: refs/heads/b4 (0)
    15:42:09.770295 refs/debug.c:189        iterator_advance: refs/heads/branch3 (0)

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-09 12:58:37 -07:00
Han-Wen Nienhuys 63c0567365 refs: move REF_LOG_ONLY to refs-internal.h
REF_LOG_ONLY is used in the transaction preparation: if a symref is involved in
a transaction, the referent of the symref should be updated, and the symref
itself should only be updated in the reflog.

Other ref backends will need to duplicate this logic too, so move it to a
central place.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-08 15:51:07 -07:00
Han-Wen Nienhuys 5085aef4c8 refs: move gitdir into base ref_store
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:04 -07:00
Han-Wen Nienhuys 4877c6c738 refs: fix comment about submodule ref_stores
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:03 -07:00
Han-Wen Nienhuys e39620f07e refs: split off reading loose ref data in separate function
This prepares for handling FETCH_HEAD (which is not a regular ref)
separately from the ref backend.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:03 -07:00
Han-Wen Nienhuys 25429fed5c refs: move the logic to add \t to reflog to the files backend
523fa69c (reflog: cleanse messages in the refs.c layer, 2020-07-10)
centralized reflog normalizaton.  However, the normalizaton added a
leading "\t" to the message. This is an artifact of the reflog
storage format in the files backend, so it should be added there.

Routines that parse back the reflog (such as grab_nth_branch_switch)
expect the "\t" to not be in the message, so without this fix, git
with reftable cannot process the "@{-1}" syntax.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-31 10:21:51 -07:00