[PATCH v4 4/4] cache-tree: invalidate i-t-a paths after generating trees

[Nguyễn Thái Ngọc Duy]

Intent-to-add entries used to forbid writing trees so it was not a
problem. After commit 3f6d56d (commit: ignore intent-to-add entries
instead of refusing - 2012-02-07), we can generate trees from an index
with i-t-a entries.

However, the commit forgets to invalidate all paths leading to i-t-a
entries. With fully valid cache-tree (e.g. after commit or
write-tree), diff operations may prefer cache-tree to index and not
see i-t-a entries in the index, because cache-tree does not have them.

Reported-by: Jonathon Mah <m...@jonathonmah.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
---
 cache-tree.c          | 14 ++++++++++++--
 t/t2203-add-intent.sh | 20 ++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/cache-tree.c b/cache-tree.c
index 2c10b2e..37e4d00 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -244,6 +244,7 @@ static int update_one(struct cache_tree *it,
        struct strbuf buffer;
        int missing_ok = flags & WRITE_TREE_MISSING_OK;
        int dryrun = flags & WRITE_TREE_DRY_RUN;
+       int to_invalidate = 0;
        int i;
 
        *skip_count = 0;
@@ -333,6 +334,8 @@ static int update_one(struct cache_tree *it,
                        i += sub->count;
                        sha1 = sub->cache_tree->sha1;
                        mode = S_IFDIR;
+                       if (sub->cache_tree->entry_count < 0)
+                               to_invalidate = 1;
                }
                else {
                        sha1 = ce->sha1;
@@ -356,8 +359,15 @@ static int update_one(struct cache_tree *it,
                        continue;
                }
 
-               if (ce->ce_flags & CE_INTENT_TO_ADD)
+               /*
+                * CE_INTENT_TO_ADD entries exist on on-disk index but
+                * they are not part of generated trees. Invalidate up
+                * to root to force cache-tree users to read elsewhere.
+                */
+               if (ce->ce_flags & CE_INTENT_TO_ADD) {
+                       to_invalidate = 1;
                        continue;
+               }
 
                strbuf_grow(&buffer, entlen + 100);
                strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, 
'\0');
@@ -377,7 +387,7 @@ static int update_one(struct cache_tree *it,
        }
 
        strbuf_release(&buffer);
-       it->entry_count = i - *skip_count;
+       it->entry_count = to_invalidate ? -1 : i - *skip_count;
 #if DEBUG
        fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
                it->entry_count, it->subtree_nr,
diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
index ec35409..2a4a749 100755
--- a/t/t2203-add-intent.sh
+++ b/t/t2203-add-intent.sh
@@ -62,5 +62,25 @@ test_expect_success 'can "commit -a" with an i-t-a entry' '
        git commit -a -m all
 '
 
+test_expect_success 'cache-tree invalidates i-t-a paths' '
+       git reset --hard &&
+       mkdir dir &&
+       : >dir/foo &&
+       git add dir/foo &&
+       git commit -m foo &&
+
+       : >dir/bar &&
+       git add -N dir/bar &&
+       git diff --cached --name-only >actual &&
+       echo dir/bar >expect &&
+       test_cmp expect actual &&
+
+       git write-tree >/dev/null &&
+
+       git diff --cached --name-only >actual &&
+       echo dir/bar >expect &&
+       test_cmp expect actual
+'
+
 test_done
 
-- 
1.8.0.rc2.23.g1fb49df

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