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git/t/t3210-pack-refs.sh
Michael Haggerty ab292bc4f3 repack_without_ref(): silence errors for dangling packed refs
Stop emitting an error message when deleting a packed reference if we
find another dangling packed reference that is overridden by a loose
reference.  See the previous commit for a longer explanation of the
issue.

We have to be careful to make sure that the invalid packed reference
really *is* overridden by a loose reference; otherwise what we have
found is repository corruption, which we *should* report.

Please note that this approach is vulnerable to a race condition
similar to the race conditions already known to affect packed
references [1]:

* Process 1 tries to peel packed reference X as part of deleting
  another packed reference.  It discovers that X does not refer to a
  valid object (because the object that it referred to has been
  garbage collected).

* Process 2 tries to delete reference X.  It starts by deleting the
  loose reference X.

* Process 1 checks whether there is a loose reference X.  There is not
  (it has just been deleted by process 2), so process 1 reports a
  spurious error "X does not point to a valid object!"

The worst case seems relatively harmless, and the fix is identical to
the fix that will be needed for the other race conditions (namely
holding a lock on the packed-refs file during *all* reference
deletions), so we leave the cleaning up of all of them as a future
project.

[1] http://thread.gmane.org/gmane.comp.version-control.git/211956

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-05-01 15:33:10 -07:00

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#!/bin/sh
#
# Copyright (c) 2005 Amos Waterland
# Copyright (c) 2006 Christian Couder
#
test_description='git pack-refs should not change the branch semantic
This test runs git pack-refs and git show-ref and checks that the branch
semantic is still the same.
'
. ./test-lib.sh
echo '[core] logallrefupdates = true' >>.git/config
test_expect_success \
'prepare a trivial repository' \
'echo Hello > A &&
git update-index --add A &&
git commit -m "Initial commit." &&
HEAD=$(git rev-parse --verify HEAD)'
SHA1=
test_expect_success \
'see if git show-ref works as expected' \
'git branch a &&
SHA1=`cat .git/refs/heads/a` &&
echo "$SHA1 refs/heads/a" >expect &&
git show-ref a >result &&
test_cmp expect result'
test_expect_success \
'see if a branch still exists when packed' \
'git branch b &&
git pack-refs --all &&
rm -f .git/refs/heads/b &&
echo "$SHA1 refs/heads/b" >expect &&
git show-ref b >result &&
test_cmp expect result'
test_expect_success 'git branch c/d should barf if branch c exists' '
git branch c &&
git pack-refs --all &&
rm -f .git/refs/heads/c &&
test_must_fail git branch c/d
'
test_expect_success \
'see if a branch still exists after git pack-refs --prune' \
'git branch e &&
git pack-refs --all --prune &&
echo "$SHA1 refs/heads/e" >expect &&
git show-ref e >result &&
test_cmp expect result'
test_expect_success 'see if git pack-refs --prune remove ref files' '
git branch f &&
git pack-refs --all --prune &&
! test -f .git/refs/heads/f
'
test_expect_success 'see if git pack-refs --prune removes empty dirs' '
git branch r/s/t &&
git pack-refs --all --prune &&
! test -e .git/refs/heads/r
'
test_expect_success \
'git branch g should work when git branch g/h has been deleted' \
'git branch g/h &&
git pack-refs --all --prune &&
git branch -d g/h &&
git branch g &&
git pack-refs --all &&
git branch -d g'
test_expect_success 'git branch i/j/k should barf if branch i exists' '
git branch i &&
git pack-refs --all --prune &&
test_must_fail git branch i/j/k
'
test_expect_success \
'test git branch k after branch k/l/m and k/lm have been deleted' \
'git branch k/l &&
git branch k/lm &&
git branch -d k/l &&
git branch k/l/m &&
git branch -d k/l/m &&
git branch -d k/lm &&
git branch k'
test_expect_success \
'test git branch n after some branch deletion and pruning' \
'git branch n/o &&
git branch n/op &&
git branch -d n/o &&
git branch n/o/p &&
git branch -d n/op &&
git pack-refs --all --prune &&
git branch -d n/o/p &&
git branch n'
test_expect_success \
'see if up-to-date packed refs are preserved' \
'git branch q &&
git pack-refs --all --prune &&
git update-ref refs/heads/q refs/heads/q &&
! test -f .git/refs/heads/q'
test_expect_success 'pack, prune and repack' '
git tag foo &&
git pack-refs --all --prune &&
git show-ref >all-of-them &&
git pack-refs &&
git show-ref >again &&
test_cmp all-of-them again
'
test_expect_success 'explicit pack-refs with dangling packed reference' '
git commit --allow-empty -m "soon to be garbage-collected" &&
git pack-refs --all &&
git reset --hard HEAD^ &&
git reflog expire --expire=all --all &&
git prune --expire=all &&
git pack-refs --all 2>result &&
test_cmp /dev/null result
'
test_expect_success 'delete ref with dangling packed version' '
git checkout -b lamb &&
git commit --allow-empty -m "future garbage" &&
git pack-refs --all &&
git reset --hard HEAD^ &&
git checkout master &&
git reflog expire --expire=all --all &&
git prune --expire=all &&
git branch -d lamb 2>result &&
test_cmp /dev/null result
'
test_expect_success 'delete ref while another dangling packed ref' '
git branch lamb &&
git commit --allow-empty -m "future garbage" &&
git pack-refs --all &&
git reset --hard HEAD^ &&
git reflog expire --expire=all --all &&
git prune --expire=all &&
git branch -d lamb 2>result &&
test_cmp /dev/null result
'
test_done