[PATCH v2 2/2] fetch: in partial clone, check presence of targets

[Jonathan Tan]

When fetching an object that is known as a promisor object to the local
repository, the connectivity check in quickfetch() in builtin/fetch.c
succeeds, causing object transfer to be bypassed. However, this should
not happen if that object is merely promised and not actually present.

Because this happens, when a user invokes "git fetch origin <sha-1>" on
the command-line, the <sha-1> object may not actually be fetched even
though the command returns an exit code of 0. This is a similar issue
(but with a different cause) to the one fixed by a0c9016abd
("upload-pack: send refs' objects despite "filter"", 2018-07-09).

Therefore, update quickfetch() to also directly check for the presence
of all objects to be fetched. Its documentation and name are also
updated to better reflect what it does.

Signed-off-by: Jonathan Tan <jonathanta...@google.com>
---
 builtin/fetch.c          | 15 +++++++++++++--
 t/t5616-partial-clone.sh | 17 +++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 61bec5d21..b9e74c129 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -924,10 +924,11 @@ static int store_updated_refs(const char *raw_url, const 
char *remote_name,
  * everything we are going to fetch already exists and is connected
  * locally.
  */
-static int quickfetch(struct ref *ref_map)
+static int check_exist_and_connected(struct ref *ref_map)
 {
        struct ref *rm = ref_map;
        struct check_connected_options opt = CHECK_CONNECTED_INIT;
+       struct ref *r;
 
        /*
         * If we are deepening a shallow clone we already have these
@@ -938,13 +939,23 @@ static int quickfetch(struct ref *ref_map)
         */
        if (deepen)
                return -1;
+
+       /*
+        * check_connected() allows objects to merely be promised, but
+        * we need all direct targets to exist.
+        */
+       for (r = rm; r; r = r->next) {
+               if (!has_object_file(&r->old_oid))
+                       return -1;
+       }
+
        opt.quiet = 1;
        return check_connected(iterate_ref_map, &rm, &opt);
 }
 
 static int fetch_refs(struct transport *transport, struct ref *ref_map)
 {
-       int ret = quickfetch(ref_map);
+       int ret = check_exist_and_connected(ref_map);
        if (ret)
                ret = transport_fetch_refs(transport, ref_map);
        if (!ret)
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index bbbe7537d..359d27d02 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -170,6 +170,23 @@ test_expect_success 'partial clone fetches blobs pointed 
to by refs even if norm
        git -C dst fsck
 '
 
+test_expect_success 'fetch what is specified on CLI even if already promised' '
+       rm -rf src dst.git &&
+       git init src &&
+       test_commit -C src foo &&
+       test_config -C src uploadpack.allowfilter 1 &&
+       test_config -C src uploadpack.allowanysha1inwant 1 &&
+
+       git hash-object --stdin <src/foo.t >blob &&
+
+       git clone --bare --filter=blob:none "file://$(pwd)/src" dst.git &&
+       git -C dst.git rev-list --objects --quiet --missing=print HEAD 
>missing_before &&
+       grep "?$(cat blob)" missing_before &&
+       git -C dst.git fetch origin $(cat blob) &&
+       git -C dst.git rev-list --objects --quiet --missing=print HEAD 
>missing_after &&
+       ! grep "?$(cat blob)" missing_after
+'
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
-- 
2.19.0.444.g18242da7ef-goog