Apply some v2.48 regression bugfixes (#5376)

Now that most of the Git contributors are back from the holidays, there
is an influx of bug fixes. This is precisely why I held off from rushing
Git for Windows v2.48.0 out the door.

These bug fixes are mostly taken from upstream's branches; In some
cases, though, I had to apply them directly from the Git mailing list
because they did not make it into git/git yet.

I deem those bug fixes necessary to get Git for Windows into a somewhat
healthy state again.

builtin/fetch.c

@@ -1618,9 +1618,9 @@ static void report_set_head(const char *remote, const char *head_name,
 }
 
 static int set_head(const struct ref *remote_refs, int follow_remote_head,
-		const char *no_warn_branch)
+		const char *no_warn_branch, int mirror)
 {
-	int result = 0, create_only, is_bare, was_detached;
+	int result = 0, create_only, baremirror, was_detached;
 	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT,
 		      b_local_head = STRBUF_INIT;
 	const char *remote = gtransport->remote->name;
@@ -1655,17 +1655,17 @@ static int set_head(const struct ref *remote_refs, int follow_remote_head,
 
 	if (!head_name)
 		goto cleanup;
-	is_bare = is_bare_repository();
-	create_only = follow_remote_head == FOLLOW_REMOTE_ALWAYS ? 0 : !is_bare;
-	if (is_bare) {
+	baremirror = is_bare_repository() && mirror;
+	create_only = follow_remote_head == FOLLOW_REMOTE_ALWAYS ? 0 : !baremirror;
+	if (baremirror) {
 		strbuf_addstr(&b_head, "HEAD");
 		strbuf_addf(&b_remote_head, "refs/heads/%s", head_name);
 	} else {
 		strbuf_addf(&b_head, "refs/remotes/%s/HEAD", remote);
 		strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", remote, head_name);
 	}
 		/* make sure it's valid */
-	if (!is_bare && !refs_ref_exists(refs, b_remote_head.buf)) {
+	if (!baremirror && !refs_ref_exists(refs, b_remote_head.buf)) {
 		result = 1;
 		goto cleanup;
 	}
@@ -1925,7 +1925,8 @@ static int do_fetch(struct transport *transport,
 		}
 	}
 	if (set_head(remote_refs, transport->remote->follow_remote_head,
-		transport->remote->no_warn_branch))
+		transport->remote->no_warn_branch,
+		transport->remote->mirror))
 		;
 		/*
 		 * Way too many cases where this can go wrong

grep.c

@@ -1646,6 +1646,8 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
 
 	bol = gs->buf;
 	left = gs->size;
+	if (left && gs->buf[left-1] == '\n')
+		left--;
 	while (left) {
 		const char *eol;
 		int hit;

refs.c

@@ -1318,13 +1318,21 @@ int ref_transaction_update(struct ref_transaction *transaction,
 	return 0;
 }
 
-int ref_transaction_update_reflog(struct ref_transaction *transaction,
-				  const char *refname,
-				  const struct object_id *new_oid,
-				  const struct object_id *old_oid,
-				  const char *committer_info, unsigned int flags,
-				  const char *msg, unsigned int index,
-				  struct strbuf *err)
+/*
+ * Similar to`ref_transaction_update`, but this function is only for adding
+ * a reflog update. Supports providing custom committer information. The index
+ * field can be utiltized to order updates as desired. When not used, the
+ * updates default to being ordered by refname.
+ */
+static int ref_transaction_update_reflog(struct ref_transaction *transaction,
+					 const char *refname,
+					 const struct object_id *new_oid,
+					 const struct object_id *old_oid,
+					 const char *committer_info,
+					 unsigned int flags,
+					 const char *msg,
+					 uint64_t index,
+					 struct strbuf *err)
 {
 	struct ref_update *update;
 
@@ -2805,7 +2813,7 @@ static int migrate_one_ref(const char *refname, const char *referent UNUSED, con
 }
 
 struct reflog_migration_data {
-	unsigned int index;
+	uint64_t index;
 	const char *refname;
 	struct ref_store *old_refs;
 	struct ref_transaction *transaction;

refs.h

@@ -771,20 +771,6 @@ int ref_transaction_update(struct ref_transaction *transaction,
 			   unsigned int flags, const char *msg,
 			   struct strbuf *err);
 
-/*
- * Similar to`ref_transaction_update`, but this function is only for adding
- * a reflog update. Supports providing custom committer information. The index
- * field can be utiltized to order updates as desired. When not used, the
- * updates default to being ordered by refname.
- */
-int ref_transaction_update_reflog(struct ref_transaction *transaction,
-				  const char *refname,
-				  const struct object_id *new_oid,
-				  const struct object_id *old_oid,
-				  const char *committer_info, unsigned int flags,
-				  const char *msg, unsigned int index,
-				  struct strbuf *err);
-
 /*
  * Add a reference creation to transaction. new_oid is the value that
  * the reference should have after the update; it must not be

refs/refs-internal.h

@@ -120,7 +120,7 @@ struct ref_update {
 	 * when migrating reflogs and we want to ensure we carry over the
 	 * same order.
 	 */
-	unsigned int index;
+	uint64_t index;
 
 	/*
 	 * If this ref_update was split off of a symref update via
@@ -203,7 +203,7 @@ struct ref_transaction {
 	enum ref_transaction_state state;
 	void *backend_data;
 	unsigned int flags;
-	unsigned int max_index;
+	uint64_t max_index;
 };
 
 /*

refs/reftable-backend.c

@@ -942,7 +942,7 @@ struct write_transaction_table_arg {
 	size_t updates_nr;
 	size_t updates_alloc;
 	size_t updates_expected;
-	unsigned int max_index;
+	uint64_t max_index;
 };
 
 struct reftable_transaction_data {
@@ -1444,7 +1444,9 @@ static int write_transaction_table(struct reftable_writer *writer, void *cb_data
 	 * multiple entries. Each entry will contain a different update_index,
 	 * so set the limits accordingly.
 	 */
-	reftable_writer_set_limits(writer, ts, ts + arg->max_index);
+	ret = reftable_writer_set_limits(writer, ts, ts + arg->max_index);
+	if (ret < 0)
+		goto done;
 
 	for (i = 0; i < arg->updates_nr; i++) {
 		struct reftable_transaction_update *tx_update = &arg->updates[i];
@@ -1766,7 +1768,9 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
 	deletion_ts = creation_ts = reftable_stack_next_update_index(arg->be->stack);
 	if (arg->delete_old)
 		creation_ts++;
-	reftable_writer_set_limits(writer, deletion_ts, creation_ts);
+	ret = reftable_writer_set_limits(writer, deletion_ts, creation_ts);
+	if (ret < 0)
+		goto done;
 
 	/*
 	 * Add the new reference. If this is a rename then we also delete the
@@ -2298,7 +2302,9 @@ static int write_reflog_existence_table(struct reftable_writer *writer,
 	if (ret <= 0)
 		goto done;
 
-	reftable_writer_set_limits(writer, ts, ts);
+	ret = reftable_writer_set_limits(writer, ts, ts);
+	if (ret < 0)
+		goto done;
 
 	/*
 	 * The existence entry has both old and new object ID set to the
@@ -2357,7 +2363,9 @@ static int write_reflog_delete_table(struct reftable_writer *writer, void *cb_da
 	uint64_t ts = reftable_stack_next_update_index(arg->stack);
 	int ret;
 
-	reftable_writer_set_limits(writer, ts, ts);
+	ret = reftable_writer_set_limits(writer, ts, ts);
+	if (ret < 0)
+		goto out;
 
 	ret = reftable_stack_init_log_iterator(arg->stack, &it);
 	if (ret < 0)
@@ -2434,7 +2442,9 @@ static int write_reflog_expiry_table(struct reftable_writer *writer, void *cb_da
 		if (arg->records[i].value_type == REFTABLE_LOG_UPDATE)
 			live_records++;
 
-	reftable_writer_set_limits(writer, ts, ts);
+	ret = reftable_writer_set_limits(writer, ts, ts);
+	if (ret < 0)
+		return ret;
 
 	if (!is_null_oid(&arg->update_oid)) {
 		struct reftable_ref_record ref = {0};

reftable/reftable-error.h

@@ -30,6 +30,7 @@ enum reftable_error {
 
 	/* Misuse of the API:
 	 *  - on writing a record with NULL refname.
+	 *  - on writing a record before setting the writer limits.
 	 *  - on writing a reftable_ref_record outside the table limits
 	 *  - on writing a ref or log record before the stack's
 	 * next_update_inde*x

reftable/reftable-writer.h

@@ -124,17 +124,21 @@ int reftable_writer_new(struct reftable_writer **out,
 			int (*flush_func)(void *),
 			void *writer_arg, const struct reftable_write_options *opts);
 
-/* Set the range of update indices for the records we will add. When writing a
-   table into a stack, the min should be at least
-   reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
-
-   For transactional updates to a stack, typically min==max, and the
-   update_index can be obtained by inspeciting the stack. When converting an
-   existing ref database into a single reftable, this would be a range of
-   update-index timestamps.
+/*
+ * Set the range of update indices for the records we will add. When writing a
+ * table into a stack, the min should be at least
+ * reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
+ *
+ * For transactional updates to a stack, typically min==max, and the
+ * update_index can be obtained by inspeciting the stack. When converting an
+ * existing ref database into a single reftable, this would be a range of
+ * update-index timestamps.
+ *
+ * The function should be called before adding any records to the writer. If not
+ * it will fail with REFTABLE_API_ERROR.
  */
-void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
-				uint64_t max);
+int reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
+			       uint64_t max);
 
 /*
   Add a reftable_ref_record. The record should have names that come after

reftable/stack.c

@@ -1058,8 +1058,10 @@ static int stack_write_compact(struct reftable_stack *st,
 
 	for (size_t i = first; i <= last; i++)
 		st->stats.bytes += st->readers[i]->size;
-	reftable_writer_set_limits(wr, st->readers[first]->min_update_index,
-				   st->readers[last]->max_update_index);
+	err = reftable_writer_set_limits(wr, st->readers[first]->min_update_index,
+					 st->readers[last]->max_update_index);
+	if (err < 0)
+		goto done;
 
 	err = reftable_merged_table_new(&mt, st->readers + first, subtabs_len,
 					st->opts.hash_id);

reftable/writer.c

@@ -179,11 +179,20 @@ int reftable_writer_new(struct reftable_writer **out,
 	return 0;
 }
 
-void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
-				uint64_t max)
+int reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
+			       uint64_t max)
 {
+	/*
+	 * The limits should be set before any records are added to the writer.
+	 * Check if any records were added by checking if `last_key` was set.
+	 */
+	if (w->last_key.len)
+		return REFTABLE_API_ERROR;
+
 	w->min_update_index = min;
 	w->max_update_index = max;
+
+	return 0;
 }
 
 static void writer_release(struct reftable_writer *w)

t/t5505-remote.sh

@@ -589,6 +589,16 @@ test_expect_success 'add --mirror setting HEAD' '
 	)
 '
 
+test_expect_success 'non-mirror fetch does not interfere with mirror' '
+	mkdir headnotmain &&
+	(
+		cd headnotmain &&
+		git init --bare -b notmain &&
+		git remote add -f other ../two &&
+		test "$(git symbolic-ref HEAD)" = "refs/heads/notmain"
+	)
+'
+
 test_expect_success 'add --mirror=fetch' '
 	mkdir mirror-fetch &&
 	git init -b main mirror-fetch/parent &&

t/t5510-fetch.sh

@@ -81,6 +81,19 @@ test_expect_success "fetch test remote HEAD" '
 	branch=$(git rev-parse refs/remotes/origin/main) &&
 	test "z$head" = "z$branch"'
 
+test_expect_success "fetch test remote HEAD in bare repository" '
+	cd "$D" &&
+	git init --bare barerepo &&
+	cd barerepo &&
+	git remote add upstream ../two &&
+	git fetch upstream &&
+	git rev-parse --verify refs/remotes/upstream/HEAD &&
+	git rev-parse --verify refs/remotes/upstream/main &&
+	head=$(git rev-parse refs/remotes/upstream/HEAD) &&
+	branch=$(git rev-parse refs/remotes/upstream/main) &&
+	test "z$head" = "z$branch"'
+
+
 test_expect_success "fetch test remote HEAD change" '
 	cd "$D" &&
 	cd two &&

t/unit-tests/t-reftable-stack.c

@@ -103,7 +103,8 @@ static void t_read_file(void)
 static int write_test_ref(struct reftable_writer *wr, void *arg)
 {
 	struct reftable_ref_record *ref = arg;
-	reftable_writer_set_limits(wr, ref->update_index, ref->update_index);
+	check(!reftable_writer_set_limits(wr, ref->update_index,
+					  ref->update_index));
 	return reftable_writer_add_ref(wr, ref);
 }
 
@@ -143,7 +144,8 @@ static int write_test_log(struct reftable_writer *wr, void *arg)
 {
 	struct write_log_arg *wla = arg;
 
-	reftable_writer_set_limits(wr, wla->update_index, wla->update_index);
+	check(!reftable_writer_set_limits(wr, wla->update_index,
+					  wla->update_index));
 	return reftable_writer_add_log(wr, wla->log);
 }
 
@@ -961,7 +963,7 @@ static void t_reflog_expire(void)
 
 static int write_nothing(struct reftable_writer *wr, void *arg UNUSED)
 {
-	reftable_writer_set_limits(wr, 1, 1);
+	check(!reftable_writer_set_limits(wr, 1, 1));
 	return 0;
 }