On Wed, Apr 21, 2021 at 5:29 AM Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> wrote: > > > On Fri, Dec 11 2020, Elijah Newren via GitGitGadget wrote: > > > While creating the last commit, I found a number of other cases where > > git would segfault when faced with trees that have duplicate entries. > > None of these segfaults are in the diffcore-rename code (they all occur > > in cache-tree and unpack-trees). Further, to my knowledge, no one has > > ever been adversely affected by these bugs, and given that it has been > > 15 years and folks have fixed a few other issues with historical > > duplicate entries (as noted in the last commit), I am not sure we will > > ever run into anyone having problems with these. So I am not sure these > > are worth fixing, but it doesn't hurt to at least document these > > failures in the same test file that is concerned with duplicate tree > > entries. > > [...] > > +test_expect_failure 'fast-forward from duplicate entries to non-duplicate' ' > > + git merge update > > +' > > + > > test_done > > Per https://lore.kernel.org/git/87lf9b3mth.fsf@xxxxxxxxxxxxxxxxxxx/ > isn't the noise of having a segfault from "git" worth fixing in itself > though? I.e. something like this, so we at least se why it fails: > > diff --git a/t/t4058-diff-duplicates.sh b/t/t4058-diff-duplicates.sh > index 54614b814db..ed91d9f7fe9 100755 > --- a/t/t4058-diff-duplicates.sh > +++ b/t/t4058-diff-duplicates.sh > @@ -182,8 +182,10 @@ test_expect_success 'switch to base branch and force status to be clean' ' > test_must_be_empty actual > ' > > -test_expect_failure 'fast-forward from duplicate entries to non-duplicate' ' > - git merge update > +test_expect_success 'fast-forward from duplicate entries to non-duplicate' ' > + ! git merge update 2>err && > + grep "^BUG: " err && > + grep -F "should have entry at o->src_index->cache[1]" err > ' > > test_done > diff --git a/unpack-trees.c b/unpack-trees.c > index 8a1afbc1e49..230cb073fe1 100644 > --- a/unpack-trees.c > +++ b/unpack-trees.c > @@ -789,8 +789,11 @@ static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names, > */ > for (i = 0; i < nr_entries; i++) { > int new_ce_len, len, rc; > + int j = pos + i; > > - src[0] = o->src_index->cache[pos + i]; > + src[0] = o->src_index->cache[j]; > + if (!src[0]) > + BUG("should have entry at o->src_index->cache[%d]", j); > > len = ce_namelen(src[0]); > new_ce_len = cache_entry_size(len); > Seems reasonable to me. Are you planning to add a commit message and turn it into a proper patch? If so, I'll give my Thumbs-up-by or whatever we need. :-)
