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The original point of the GIT_REF_PARANOIA flag was to include broken
refs in iterations, so that possibly-destructive operations would not
silently ignore them (and would generally instead try to operate on the
oids and fail when the objects could not be accessed).
We already turned this on by default for some dangerous operations, like
"repack -ad" (where missing a reachability tip would mean dropping the
associated history). But it was not on for general use, even though it
could easily result in the spreading of corruption (e.g., imagine
cloning a repository which simply omits some of its refs because
their objects are missing; the result quietly succeeds even though you
did not clone everything!).
This patch turns on GIT_REF_PARANOIA by default. So a clone as mentioned
above would actually fail (upload-pack tells us about the broken ref,
and when we ask for the objects, pack-objects fails to deliver them).
This may be inconvenient when working with a corrupted repository, but:
- we are better off to err on the side of complaining about
corruption, and then provide mechanisms for explicitly loosening
safety.
- this is only one type of corruption anyway. If we are missing any
other objects in the history that _aren't_ ref tips, then we'd
behave similarly (happily show the ref, but then barf when we
started traversing).
We retain the GIT_REF_PARANOIA variable, but simply default it to "1"
instead of "0". That gives the user an escape hatch for loosening this
when working with a corrupt repository. It won't work across a remote
connection to upload-pack (because we can't necessarily set environment
variables on the remote), but there the client has other options (e.g.,
choosing which refs to fetch).
As a bonus, this also makes ref iteration faster in general (because we
don't have to call has_object_file() for each ref), though probably not
noticeably so in the general case. In a repo with a million refs, it
shaved a few hundred milliseconds off of upload-pack's advertisement;
that's noticeable, but most repos are not nearly that large.
The possible downside here is that any operation which iterates refs but
doesn't ever open their objects may now quietly claim to have X when the
object is corrupted (e.g., "git rev-list new-branch --not --all" will
treat a broken ref as uninteresting). But again, that's not really any
different than corruption below the ref level. We might have
refs/heads/old-branch as non-corrupt, but we are not actively checking
that we have the entire reachable history. Or the pointed-to object
could even be corrupted on-disk (but our "do we have it" check would
still succeed). In that sense, this is merely bringing ref-corruption in
line with general object corruption.
One alternative implementation would be to actually check for broken
refs, and then _immediately die_ if we see any. That would cause the
"rev-list --not --all" case above to abort immediately. But in many ways
that's the worst of all worlds:
- it still spends time looking up the objects an extra time
- it still doesn't catch corruption below the ref level
- it's even more inconvenient; with the current implementation of
GIT_REF_PARANOIA for something like upload-pack, we can make
the advertisement and let the client choose a non-broken piece of
history. If we bail as soon as we see a broken ref, they cannot even
see the advertisement.
The test changes here show some of the fallout. A non-destructive "git
repack -adk" now fails by default (but we can override it). Deleting a
broken ref now actually tells the hooks the correct "before" state,
rather than a confusing null oid.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Dangling symrefs aren't actually a corruption problem. It's perfectly
fine for refs/remotes/origin/HEAD to point to an unborn branch. And in
particular, if you are trying to establish reachability, a symref that
points nowhere doesn't matter either way. Any ref it could point to will
be examined during the rest of the traversal.
It's possible that a symref pointing nowhere _could_ be a sign that the
ref it was meant to point to was deleted accidentally (e.g., via
corruption). But there is no particular reason to think that is true for
any given case, and in the meantime, GIT_REF_PARANOIA kicking in
automatically for some operations means they'll fail unnecessarily.
So let's loosen it just a bit. The new test in t5312 shows off an
example that is safe, but currently fails (and no longer does after this
patch).
Note that we don't do anything if the caller explicitly asked for
DO_FOR_EACH_INCLUDE_BROKEN. In that case they may be looking for
dangling symrefs themselves, and setting GIT_REF_PARANOIA should not
_loosen_ things from what the caller asked for.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When repacking or pruning in a corrupted repository, our tests in t5312
argue that it is OK to complete the operation or bail, as long as we
don't actually delete the objects pointed to by the corruption.
This isn't a wrong line of reasoning, but the tests are a bit permissive
by using test_might_fail. The fact is that we _do_ bail currently, and
if we ever stopped doing so, that would be worthy of a human
investigating. So let's switch these to test_must_fail.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In t5312, we create a state with a broken ref, and then make sure that
destructive repacks don't silently ignore the breakage (where a
destructive repack is one that might drop objects). But we don't check
the behavior of non-destructive repacks at all (i.e., ones where we'd
keep unreachable objects).
So let's add a test to confirm the current behavior, which is that
they are allowed (i.e., ignoring the breakage and considering any
objects it points to as unreachable). This may change in the future, but
we'd like for the test suite to alert us to that fact.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Some tests in t5312 create an illegally-named ref, and then see how
various operations handle it. But between those operations, we also do
some more setup (e.g., repacking), and we are subtly depending on how
those setup steps react to the illegal ref.
To future-proof us against those behaviors changing, let's instead
create and clean up our bogus ref on demand in the tests that need it.
This has two small extra advantages:
- the tests are more stand-alone; we do not need an extra test to clean
up the ref before moving on to other parts of the script
- the creation and cleanup is together in one helper function. Because
these depend on touching the refs in the filesystem directly, they
may need to be tweaked for a world with alternate backends (they have
not been noticed so far in the reftable work because with a non-file
backend the tests don't fail; they simply become uninteresting noops
because the broken ref isn't read at all).
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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t5312 has several uses of the "verbose" helper, as described in
8ad1652418 (t5304: use helper to report failure of "test foo = bar",
2014-10-10). Back then the "-x" trace option for tests was new, and was
not as pleasant to use (e.g., some tests failed under "-x", we did not
support BASH_XTRACEFD, etc).
These days it is clear that "-x" is the preferred way to get extra
output, and we don't need to mark up individual tests. Let's get rid of
the uses of "verbose" here, as one step toward eradicating it totally.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Carefully excluding t5310, which is developed independently of the
current patch series at the time of writing, we now use `main` as
default branch in t5[0-4]*. This trick was performed via
$ (cd t &&
sed -i -e 's/master/main/g' -e 's/MASTER/MAIN/g' \
-e 's/Master/Main/g' -- t5[0-4]*.sh &&
git checkout HEAD -- t5310\*)
This allows us to define `GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main`
for those tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In addition to the manual adjustment to let the `linux-gcc` CI job run
the test suite with `master` and then with `main`, this patch makes sure
that GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME is set in all test scripts
that currently rely on the initial branch name being `master by default.
To determine which test scripts to mark up, the first step was to
force-set the default branch name to `master` in
- all test scripts that contain the keyword `master`,
- t4211, which expects `t/t4211/history.export` with a hard-coded ref to
initialize the default branch,
- t5560 because it sources `t/t556x_common` which uses `master`,
- t8002 and t8012 because both source `t/annotate-tests.sh` which also
uses `master`)
This trick was performed by this command:
$ sed -i '/^ *\. \.\/\(test-lib\|lib-\(bash\|cvs\|git-svn\)\|gitweb-lib\)\.sh$/i\
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master\
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME\
' $(git grep -l master t/t[0-9]*.sh) \
t/t4211*.sh t/t5560*.sh t/t8002*.sh t/t8012*.sh
After that, careful, manual inspection revealed that some of the test
scripts containing the needle `master` do not actually rely on a
specific default branch name: either they mention `master` only in a
comment, or they initialize that branch specificially, or they do not
actually refer to the current default branch. Therefore, the
aforementioned modification was undone in those test scripts thusly:
$ git checkout HEAD -- \
t/t0027-auto-crlf.sh t/t0060-path-utils.sh \
t/t1011-read-tree-sparse-checkout.sh \
t/t1305-config-include.sh t/t1309-early-config.sh \
t/t1402-check-ref-format.sh t/t1450-fsck.sh \
t/t2024-checkout-dwim.sh \
t/t2106-update-index-assume-unchanged.sh \
t/t3040-subprojects-basic.sh t/t3301-notes.sh \
t/t3308-notes-merge.sh t/t3423-rebase-reword.sh \
t/t3436-rebase-more-options.sh \
t/t4015-diff-whitespace.sh t/t4257-am-interactive.sh \
t/t5323-pack-redundant.sh t/t5401-update-hooks.sh \
t/t5511-refspec.sh t/t5526-fetch-submodules.sh \
t/t5529-push-errors.sh t/t5530-upload-pack-error.sh \
t/t5548-push-porcelain.sh \
t/t5552-skipping-fetch-negotiator.sh \
t/t5572-pull-submodule.sh t/t5608-clone-2gb.sh \
t/t5614-clone-submodules-shallow.sh \
t/t7508-status.sh t/t7606-merge-custom.sh \
t/t9302-fast-import-unpack-limit.sh
We excluded one set of test scripts in these commands, though: the range
of `git p4` tests. The reason? `git p4` stores the (foreign) remote
branch in the branch called `p4/master`, which is obviously not the
default branch. Manual analysis revealed that only five of these tests
actually require a specific default branch name to pass; They were
modified thusly:
$ sed -i '/^ *\. \.\/lib-git-p4\.sh$/i\
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master\
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME\
' t/t980[0167]*.sh t/t9811*.sh
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Alternate refs backends might store reflogs somewhere other than
.git/logs. Change most test code that directly accesses .git/logs to
instead use git reflog commands.
There are still a few tests which need direct access to reflogs: to
check reflog permissions, to manually create reflogs from scratch, to
save/restore reflogs, to check the format of raw reflog data, and to
remove not just reflog contents, but the reflogs themselves. All cases
which don't need direct access have been modified.
Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we delete a ref, we have to rewrite the entire
packed-refs file. We take this opportunity to "curate" the
packed-refs file and drop any entries that are crufty or
broken.
Dropping broken entries (e.g., with bogus names, or ones
that point to missing objects) is actively a bad idea, as it
means that we lose any notion that the data was there in the
first place. Aside from the general hackiness that we might
lose any information about ref "foo" while deleting an
unrelated ref "bar", this may seriously hamper any attempts
by the user at recovering from the corruption in "foo".
They will lose the sha1 and name of "foo"; the exact pointer
may still be useful even if they recover missing objects
from a different copy of the repository. But worse, once the
ref is gone, there is no trace of the corruption. A
follow-up "git prune" may delete objects, even though it
would otherwise bail when seeing corruption.
We could just drop the "broken" bits from
curate_packed_refs, and continue to drop the "crufty" bits:
refs whose loose counterpart exists in the filesystem. This
is not wrong to do, and it does have the advantage that we
may write out a slightly smaller packed-refs file. But it
has two disadvantages:
1. It is a potential source of races or mistakes with
respect to these refs that are otherwise unrelated to
the operation. To my knowledge, there aren't any active
problems in this area, but it seems like an unnecessary
risk.
2. We have to spend time looking up the matching loose
refs for every item in the packed-refs file. If you
have a large number of packed refs that do not change,
that outweighs the benefit from writing out a smaller
packed-refs file (it doesn't get smaller, and you do a
bunch of directory traversal to find that out).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If we are repacking with "-ad", we will drop any unreachable
objects. Likewise, using "-Ad --unpack-unreachable=<time>"
will drop any old, unreachable objects. In these cases, we
want to make sure the reachability we compute with "--all"
is complete. We can do this by passing GIT_REF_PARANOIA=1 in
the environment to pack-objects.
Note that "-Ad" is safe already, because it only loosens
unreachable objects. It is up to "git prune" to avoid
deleting them.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Prune should know about broken objects at the tips of refs,
so that we can feed them to our traversal rather than
ignoring them. It's better for us to abort the operation on
the broken object than it is to start deleting objects with
an incomplete view of the reachability namespace.
Note that for missing objects, aborting is the best we can
do. For a badly-named ref, we technically could use its sha1
as a reachability tip. However, the iteration code just
feeds us a null sha1, so there would be a reasonable amount
of code involved to pass down our wishes. It's not really
worth trying to do better, because this is a case that
should happen extremely rarely, and the message we provide:
fatal: unable to parse object: refs/heads/bogus:name
is probably enough to point the user in the right direction.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we are doing a destructive operation like "git prune",
we want to be extra careful that the set of reachable tips
we compute is valid. If there is any corruption or oddity,
we are better off aborting the operation and letting the
user figure things out rather than plowing ahead and
possibly deleting some data that cannot be recovered.
The tests here include:
1. Pruning objects mentioned only be refs with invalid
names. This used to abort prior to d0f810f (refs.c:
allow listing and deleting badly named refs,
2014-09-03), but since then we silently ignore the tip.
Likewise, we test repacking that can drop objects
(either "-ad", which drops anything unreachable,
or "-Ad --unpack-unreachable=<time>", which tries to
optimize out a loose object write that would be
directly pruned).
2. Pruning objects when some refs point to missing
objects. We don't know whether any dangling objects
would have been reachable from the missing objects. We
are better to keep them around, as they are better than
nothing for helping the user recover history.
3. Packed refs that point to missing objects can sometimes
be dropped. By itself, this is more of an annoyance
(you do not have the object anyway; even if you can
recover it from elsewhere, all you are losing is a
placeholder for your state at the time of corruption).
But coupled with (2), if we drop the ref and then go
on to prune, we may lose unrecoverable objects.
Note that we use test_might_fail for some of the operations.
In some cases, it would be appropriate to abort the
operation, and in others, it might be acceptable to continue
but taking the information into account. The tests don't
care either way, and check only for data loss.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Jeff King
Johannes Schindelin
David Turner