Hi Jinoh, On Fri, 6 Nov 2020, Jinoh Kang wrote: > Commit 3aef54e8b8 ("diff: munmap() file contents before running external > diff") introduced calls to diff_free_filespec_data in > run_external_diff, which may pass NULL pointers. Sorry for the breakage! Maybe the commit message could talk a bit about the circumstances when this happens? Of course, I (and every other reader...) could analyze your patch to guess what it is that triggers the bug, but it's really a good use of the commit message to describe it in plain English. > > Fix this and prevent any such bugs in the future by making > `diff_free_filespec_data(NULL)` a no-op. > > Fixes: 3aef54e8b8 ("diff: munmap() file contents before running external diff") I am unaware of any other commit having a `Fixes:` trailer in the commit message. In any case, I would have expected `Fixes:` to mention a ticket or a bug report, not the commit that fixed _a separate_ issue (but unfortunately introduced this regression). > Signed-off-by: Jinoh Kang <luke1337@xxxxxxxxx> > --- > diff.c | 3 +++ > t/t7800-difftool.sh | 23 +++++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/diff.c b/diff.c > index d24f47df99..ace4a1d387 100644 > --- a/diff.c > +++ b/diff.c > @@ -4115,6 +4115,9 @@ void diff_free_filespec_blob(struct diff_filespec *s) > > void diff_free_filespec_data(struct diff_filespec *s) > { > + if (!s) > + return; > + > diff_free_filespec_blob(s); > FREE_AND_NULL(s->cnt_data); We can write this in a more canonical way without wasting all that many lines: if (s) { diff_free_filespec_blob(s); FREE_AND_NULL(s->cnt_data); } > } > diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh > index 524f30f7dc..e9391abb54 100755 > --- a/t/t7800-difftool.sh > +++ b/t/t7800-difftool.sh > @@ -728,6 +728,29 @@ test_expect_success 'add -N and difftool -d' ' > git difftool --dir-diff --extcmd ls > ' > > +test_expect_success 'difftool --cached with unmerged files' ' > + test_when_finished git reset --hard && > + echo base >file && > + git add file && > + git commit -m base && This does not advance the committer date. Let's just use the helper function we invented to make this much easier: test_commit base This has also the advantage of already tagging the outcome. > + git checkout -B conflict-a && > + git checkout -B conflict-b && > + git checkout conflict-a && > + echo conflict-a >>file && > + git add file && > + git commit -m conflict-a && > + git checkout conflict-b && > + echo conflict-b >>file && > + git add file && > + git commit -m conflict-b && > + git checkout master && > + git merge conflict-a && > + test_must_fail git merge conflict-b && > + : >expect && > + git difftool --cached --no-prompt >actual && > + test_cmp expect actual Shouldn't this use the `test_must_be_empty` function instead? How about writing the test case this way: test_expect_success 'difftool --cached with unmerged files' ' test_when_finished git reset --hard && test_commit conflicting && test_commit conflict-a a conflicting.t && git reset --hard conflicting && test_commit conflict-b b conflicting.t && test_must_fail git merge conflict-a && git difftool --cached --no-prompt >out && test_must_be_empty out ' Ciao, Dscho > +' > + > test_expect_success 'outside worktree' ' > echo 1 >1 && > echo 2 >2 && > -- > 2.26.2 > >