list-objects-filter-options: make filter_spec a string_list

Make the filter_spec string a string_list rather than a raw C string.
The list of strings must be concatted together to make a complete
filter_spec. A future patch will use this capability to build "combine:"
filter specs gradually.

A strbuf would seem to be a more natural choice for this object, but it
unfortunately requires initialization besides just zero'ing out the
memory.  This results in all container structs, and all containers of
those structs, etc., to also require initialization. Initializing them
all would be more cumbersome that simply using a string_list, which
behaves properly when its contents are zero'd.

For the purposes of code simplification, change behavior in how filter
specs are conveyed over the protocol: do not normalize the tree:<depth>
filter specs since there should be no server in existence that supports
tree:# but not tree:#k etc.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

9 files changed, 78 insertions, 70 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
index 5b9ebe9947..a693e6ca44 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -1149,13 +1149,11 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		transport->server_options = &server_options;
 
 	if (filter_options.choice) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
-		expand_list_objects_filter_spec(&filter_options,
-						&expanded_filter_spec);
+		const char *spec =
+			expand_list_objects_filter_spec(&filter_options);
 		transport_set_option(transport, TRANS_OPT_LIST_OBJECTS_FILTER,
-				     expanded_filter_spec.buf);
+				     spec);
 		transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
-		strbuf_release(&expanded_filter_spec);
 	}
 
 	if (transport->smart_options && !deepen && !filter_options.choice)
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 4ba63d5ac6..dee89e1a19 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1188,13 +1188,10 @@ static struct transport *prepare_transport(struct remote *remote, int deepen)
 	if (update_shallow)
 		set_option(transport, TRANS_OPT_UPDATE_SHALLOW, "yes");
 	if (filter_options.choice) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
-		expand_list_objects_filter_spec(&filter_options,
-						&expanded_filter_spec);
-		set_option(transport, TRANS_OPT_LIST_OBJECTS_FILTER,
-			   expanded_filter_spec.buf);
+		const char *spec =
+			expand_list_objects_filter_spec(&filter_options);
+		set_option(transport, TRANS_OPT_LIST_OBJECTS_FILTER, spec);
 		set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
-		strbuf_release(&expanded_filter_spec);
 	}
 	if (negotiation_tip.nr) {
 		if (transport->smart_options)
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 660172b014..68acbe8fd2 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -466,8 +466,10 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 				die(_("object filtering requires --objects"));
 			if (filter_options.choice == LOFC_SPARSE_OID &&
 			    !filter_options.sparse_oid_value)
-				die(_("invalid sparse value '%s'"),
-				    filter_options.filter_spec);
+				die(
+					_("invalid sparse value '%s'"),
+					list_objects_filter_spec(
+						&filter_options));
 			continue;
 		}
 		if (!strcmp(arg, ("--no-" CL_ARG__FILTER))) {
diff --git a/fetch-pack.c b/fetch-pack.c
index 1c10f54e78..72e13b0a1d 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -339,12 +339,9 @@ static int find_common(struct fetch_negotiator *negotiator,
 		}
 	}
 	if (server_supports_filtering && args->filter_options.choice) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
-		expand_list_objects_filter_spec(&args->filter_options,
-						&expanded_filter_spec);
-		packet_buf_write(&req_buf, "filter %s",
-				 expanded_filter_spec.buf);
-		strbuf_release(&expanded_filter_spec);
+		const char *spec =
+			expand_list_objects_filter_spec(&args->filter_options);
+		packet_buf_write(&req_buf, "filter %s", spec);
 	}
 	packet_buf_flush(&req_buf);
 	state_len = req_buf.len;
@@ -1099,7 +1096,7 @@ static int add_haves(struct fetch_negotiator *negotiator,
 }
 
 static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
-			      const struct fetch_pack_args *args,
+			      struct fetch_pack_args *args,
 			      const struct ref *wants, struct oidset *common,
 			      int *haves_to_send, int *in_vain,
 			      int sideband_all)
@@ -1140,13 +1137,10 @@ static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
 	/* Add filter */
 	if (server_supports_feature("fetch", "filter", 0) &&
 	    args->filter_options.choice) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
+		const char *spec =
+			expand_list_objects_filter_spec(&args->filter_options);
 		print_verbose(args, _("Server supports filter"));
-		expand_list_objects_filter_spec(&args->filter_options,
-						&expanded_filter_spec);
-		packet_buf_write(&req_buf, "filter %s",
-				 expanded_filter_spec.buf);
-		strbuf_release(&expanded_filter_spec);
+		packet_buf_write(&req_buf, "filter %s", spec);
 	} else if (args->filter_options.choice) {
 		warning("filtering not recognized by server, ignoring");
 	}
diff --git a/list-objects-filter-options.c b/list-objects-filter-options.c
index 5fe2814841..01c0f13346 100644
--- a/list-objects-filter-options.c
+++ b/list-objects-filter-options.c
@@ -184,7 +184,7 @@ int parse_list_objects_filter(struct list_objects_filter_options *filter_options
 	struct strbuf buf = STRBUF_INIT;
 	if (filter_options->choice)
 		die(_("multiple filter-specs cannot be combined"));
-	filter_options->filter_spec = strdup(arg);
+	string_list_append(&filter_options->filter_spec, xstrdup(arg));
 	if (gently_parse_list_objects_filter(filter_options, arg, &buf))
 		die("%s", buf.buf);
 	return 0;
@@ -203,19 +203,36 @@ int opt_parse_list_objects_filter(const struct option *opt,
 	return parse_list_objects_filter(filter_options, arg);
 }
 
-void expand_list_objects_filter_spec(
-	const struct list_objects_filter_options *filter,
-	struct strbuf *expanded_spec)
+const char *list_objects_filter_spec(struct list_objects_filter_options *filter)
 {
-	strbuf_init(expanded_spec, strlen(filter->filter_spec));
-	if (filter->choice == LOFC_BLOB_LIMIT)
-		strbuf_addf(expanded_spec, "blob:limit=%lu",
+	if (!filter->filter_spec.nr)
+		BUG("no filter_spec available for this filter");
+	if (filter->filter_spec.nr != 1) {
+		struct strbuf concatted = STRBUF_INIT;
+		strbuf_add_separated_string_list(
+			&concatted, "", &filter->filter_spec);
+		string_list_clear(&filter->filter_spec, /*free_util=*/0);
+		string_list_append(
+			&filter->filter_spec, strbuf_detach(&concatted, NULL));
+	}
+
+	return filter->filter_spec.items[0].string;
+}
+
+const char *expand_list_objects_filter_spec(
+	struct list_objects_filter_options *filter)
+{
+	if (filter->choice == LOFC_BLOB_LIMIT) {
+		struct strbuf expanded_spec = STRBUF_INIT;
+		strbuf_addf(&expanded_spec, "blob:limit=%lu",
 			    filter->blob_limit_value);
-	else if (filter->choice == LOFC_TREE_DEPTH)
-		strbuf_addf(expanded_spec, "tree:%lu",
-			    filter->tree_exclude_depth);
-	else
-		strbuf_addstr(expanded_spec, filter->filter_spec);
+		string_list_clear(&filter->filter_spec, /*free_util=*/0);
+		string_list_append(
+			&filter->filter_spec,
+			strbuf_detach(&expanded_spec, NULL));
+	}
+
+	return list_objects_filter_spec(filter);
 }
 
 void list_objects_filter_release(
@@ -225,7 +242,7 @@ void list_objects_filter_release(
 
 	if (!filter_options)
 		return;
-	free(filter_options->filter_spec);
+	string_list_clear(&filter_options->filter_spec, /*free_util=*/0);
 	free(filter_options->sparse_oid_value);
 	for (sub = 0; sub < filter_options->sub_nr; sub++)
 		list_objects_filter_release(&filter_options->sub[sub]);
@@ -235,7 +252,7 @@ void list_objects_filter_release(
 
 void partial_clone_register(
 	const char *remote,
-	const struct list_objects_filter_options *filter_options)
+	struct list_objects_filter_options *filter_options)
 {
 	/*
 	 * Record the name of the partial clone remote in the
@@ -258,7 +275,7 @@ void partial_clone_register(
 	 * the default for subsequent fetches from this remote.
 	 */
 	core_partial_clone_filter_default =
-		xstrdup(filter_options->filter_spec);
+		xstrdup(expand_list_objects_filter_spec(filter_options));
 	git_config_set("core.partialclonefilter",
 		       core_partial_clone_filter_default);
 }
@@ -274,7 +291,8 @@ void partial_clone_get_default_filter_spec(
 	if (!core_partial_clone_filter_default)
 		return;
 
-	filter_options->filter_spec = strdup(core_partial_clone_filter_default);
+	string_list_append(&filter_options->filter_spec,
+			   core_partial_clone_filter_default);
 	gently_parse_list_objects_filter(filter_options,
 					 core_partial_clone_filter_default,
 					 &errbuf);
diff --git a/list-objects-filter-options.h b/list-objects-filter-options.h
index 789faef1e5..bb33303f9b 100644
--- a/list-objects-filter-options.h
+++ b/list-objects-filter-options.h
@@ -2,7 +2,7 @@
 #define LIST_OBJECTS_FILTER_OPTIONS_H
 
 #include "parse-options.h"
-#include "strbuf.h"
+#include "string-list.h"
 
 /*
  * The list of defined filters for list-objects.
@@ -24,8 +24,10 @@ struct list_objects_filter_options {
 	 * commands that launch filtering sub-processes, or for communication
 	 * over the network, don't use this value; use the result of
 	 * expand_list_objects_filter_spec() instead.
+	 * To get the raw filter spec given by the user, use the result of
+	 * list_objects_filter_spec().
 	 */
-	char *filter_spec;
+	struct string_list filter_spec;
 
 	/*
 	 * 'choice' is determined by parsing the filter-spec.  This indicates
@@ -76,13 +78,22 @@ int opt_parse_list_objects_filter(const struct option *opt,
 /*
  * Translates abbreviated numbers in the filter's filter_spec into their
  * fully-expanded forms (e.g., "limit:blob=1k" becomes "limit:blob=1024").
+ * Returns a string owned by the list_objects_filter_options object.
  *
- * This form should be used instead of the raw filter_spec field when
- * communicating with a remote process or subprocess.
+ * This form should be used instead of the raw list_objects_filter_spec()
+ * value when communicating with a remote process or subprocess.
  */
-void expand_list_objects_filter_spec(
-	const struct list_objects_filter_options *filter,
-	struct strbuf *expanded_spec);
+const char *expand_list_objects_filter_spec(
+	struct list_objects_filter_options *filter);
+
+/*
+ * Returns the filter spec string more or less in the form as the user
+ * entered it. This form of the filter_spec can be used in user-facing
+ * messages.  Returns a string owned by the list_objects_filter_options
+ * object.
+ */
+const char *list_objects_filter_spec(
+	struct list_objects_filter_options *filter);
 
 void list_objects_filter_release(
 	struct list_objects_filter_options *filter_options);
@@ -96,7 +107,7 @@ static inline void list_objects_filter_set_no_filter(
 
 void partial_clone_register(
 	const char *remote,
-	const struct list_objects_filter_options *filter_options);
+	struct list_objects_filter_options *filter_options);
 void partial_clone_get_default_filter_spec(
 	struct list_objects_filter_options *filter_options);
 
diff --git a/t/t6112-rev-list-filters-objects.sh b/t/t6112-rev-list-filters-objects.sh
index 05d4f2e9c2..27ba15719a 100755
--- a/t/t6112-rev-list-filters-objects.sh
+++ b/t/t6112-rev-list-filters-objects.sh
@@ -590,11 +590,4 @@ test_expect_success 'expand blob limit in protocol' '
 	grep "blob:limit=1024" trace
 '
 
-test_expect_success 'expand tree depth limit in protocol' '
-	GIT_TRACE_PACKET="$(pwd)/tree_trace" git -c protocol.version=2 clone \
-		--filter=tree:0k "file://$(pwd)/r2" tree &&
-	! grep "tree:0k" tree_trace &&
-	grep "tree:0" tree_trace
-'
-
 test_done
diff --git a/transport-helper.c b/transport-helper.c
index c7e17ec9cb..0a34544df0 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -682,13 +682,9 @@ static int fetch(struct transport *transport,
 		set_helper_option(transport, "update-shallow", "true");
 
 	if (data->transport_options.filter_options.choice) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
-		expand_list_objects_filter_spec(
-			&data->transport_options.filter_options,
-			&expanded_filter_spec);
-		set_helper_option(transport, "filter",
-				  expanded_filter_spec.buf);
-		strbuf_release(&expanded_filter_spec);
+		const char *spec = expand_list_objects_filter_spec(
+			&data->transport_options.filter_options);
+		set_helper_option(transport, "filter", spec);
 	}
 
 	if (data->transport_options.negotiation_tips)
diff --git a/upload-pack.c b/upload-pack.c
index 4d2129e7fc..d404d88941 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -140,18 +140,17 @@ static void create_pack_file(const struct object_array *have_obj,
 		argv_array_push(&pack_objects.args, "--delta-base-offset");
 	if (use_include_tag)
 		argv_array_push(&pack_objects.args, "--include-tag");
-	if (filter_options.filter_spec) {
-		struct strbuf expanded_filter_spec = STRBUF_INIT;
-		expand_list_objects_filter_spec(&filter_options,
-						&expanded_filter_spec);
+	if (filter_options.choice) {
+		const char *spec =
+			expand_list_objects_filter_spec(&filter_options);
 		if (pack_objects.use_shell) {
 			struct strbuf buf = STRBUF_INIT;
-			sq_quote_buf(&buf, expanded_filter_spec.buf);
+			sq_quote_buf(&buf, spec);
 			argv_array_pushf(&pack_objects.args, "--filter=%s", buf.buf);
 			strbuf_release(&buf);
 		} else {
 			argv_array_pushf(&pack_objects.args, "--filter=%s",
-					 expanded_filter_spec.buf);
+					 spec);
 		}
 	}