[PATCH 3/7] list-objects.c: handle unexpected non-blob entries

[Taylor Blau]

Fix one of the cases described in the previous commit where a tree-entry
that is promised to a blob is in fact a non-blob.

When 'lookup_blob()' returns NULL, it is because Git has cached the
requested object as a non-blob. In this case, prevent a SIGSEGV by
'die()'-ing immediately before attempting to dereference the result.

Signed-off-by: Taylor Blau <m...@ttaylorr.com>
---
 list-objects.c                         | 5 +++++
 t/t6102-rev-list-unexpected-objects.sh | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/list-objects.c b/list-objects.c
index dc77361e11..ea04bbdee6 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -133,6 +133,11 @@ static void process_tree_contents(struct traversal_context 
*ctx,
                                        base, entry.path);
                else {
                        struct blob *b = lookup_blob(ctx->revs->repo, 
&entry.oid);
+                       if (!b) {
+                               die(_("entry '%s' in tree %s has blob mode, "
+                                     "but is not a blob"),
+                                   entry.path, oid_to_hex(&tree->object.oid));
+                       }
                        b->object.flags |= NOT_USER_GIVEN;
                        process_blob(ctx, b, base, entry.path);
                }
diff --git a/t/t6102-rev-list-unexpected-objects.sh 
b/t/t6102-rev-list-unexpected-objects.sh
index 472b08528a..76fe9be30f 100755
--- a/t/t6102-rev-list-unexpected-objects.sh
+++ b/t/t6102-rev-list-unexpected-objects.sh
@@ -19,8 +19,9 @@ test_expect_failure 'traverse unexpected non-blob entry 
(lone)' '
        test_must_fail git rev-list --objects $broken_tree
 '
 
-test_expect_failure 'traverse unexpected non-blob entry (seen)' '
-       test_must_fail git rev-list --objects $tree $broken_tree
+test_expect_success 'traverse unexpected non-blob entry (seen)' '
+       test_must_fail git rev-list --objects $tree $broken_tree >output 2>&1 &&
+       test_i18ngrep "is not a blob" output
 '
 
 test_expect_success 'setup unexpected non-tree entry' '
-- 
2.21.0.203.g358da99528