Re: [PATCH v3 07/12] unpack-trees: stop recursing into sparse directories

From: Derrick Stolee <redacted>

When walking trees using traverse_trees_recursive() and
unpack_callback(), we must not attempt to walk into a sparse directory
entry. There are no index entries within that directory to compare to
the tree object at that position, so skip over the entries of that tree.

This code is used in many places, so the only way to test it is to start
removing the command_requres_full_index option from one builtin at a
time and carefully test that its use of unpack_trees() behaves correctly
with a sparse-index. Such tests will be added by later changes.

Signed-off-by: Derrick Stolee <redacted>
---
 diff-lib.c     | 6 ++++++
 unpack-trees.c | 7 +++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/diff-lib.c b/diff-lib.c
index b73cc1859a49..d5e7e01132ee 100644
--- a/diff-lib.c
+++ b/diff-lib.c

@@ -322,6 +322,9 @@ static void show_new_file(struct rev_info *revs,
        unsigned int mode;
        unsigned dirty_submodule = 0;

+       if (S_ISSPARSEDIR(new_file->ce_mode))
+               return;
+

        /*
         * New file in the index: it might actually be different in
         * the working tree.

@@ -343,6 +346,9 @@ static int show_modified(struct rev_info *revs,
        const struct object_id *oid;
        unsigned dirty_submodule = 0;

+       if (S_ISSPARSEDIR(new_entry->ce_mode))
+               return 0;
+

        if (get_stat_data(new_entry, &oid, &mode, cached, match_missing,
                          &dirty_submodule, &revs->diffopt) < 0) {
                if (report_missing)

diff --git a/unpack-trees.c b/unpack-trees.c
index ef6a2b1c951c..703b0bdc9dfd 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c

@@ -1261,6 +1261,7 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
        struct unpack_trees_options *o = info->data;
        const struct name_entry *p = names;
+       unsigned unpack_tree = 1;

        /* Find first entry with a real name (we could use "mask" too) */
        while (!p->mode)

@@ -1307,7 +1308,8 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
                }
        }

-       if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
+       if (unpack_tree &&
+           unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
                return -1;

        if (o->merge && src[0]) {

@@ -1337,7 +1339,8 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
                        }
                }

-               if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
+               if (unpack_tree &&
+                   traverse_trees_recursive(n, dirmask, mask & ~dirmask,
                                             names, info) < 0)
                        return -1;
                return mask;
--

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