[RFC PATCH 1/1] filter-options: Expand abbreviated numbers

[Josh Steadmon <steadmon@google.com>]

When communicating with a remote server or a subprocess, use expanded
numbers rather than abbreviated numbers in the object filter spec (e.g.
"limit:blob=1k" becomes "limit:blob=1024").

Update the protocol docs to note that clients should always perform this
expansion, to allow for more compatibility between server
implementations.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 Documentation/technical/protocol-v2.txt |  5 ++++-
 builtin/clone.c                         |  6 +++++-
 builtin/fetch.c                         |  7 ++++++-
 fetch-pack.c                            | 15 ++++++++++++---
 list-objects-filter-options.c           | 20 ++++++++++++++++++--
 list-objects-filter-options.h           | 17 +++++++++++++++--
 t/t6112-rev-list-filters-objects.sh     | 17 +++++++++++++++++
 transport-helper.c                      | 13 +++++++++----
 upload-pack.c                           |  7 +++++--
 9 files changed, 91 insertions(+), 16 deletions(-)

diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index 09e4e0273f..d001372404 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -296,7 +296,10 @@ included in the client's request:
 	Request that various objects from the packfile be omitted
 	using one of several filtering techniques. These are intended
 	for use with partial clone and partial fetch operations. See
-	`rev-list` for possible "filter-spec" values.
+	`rev-list` for possible "filter-spec" values. Clients MUST
+	translate abbreviated numbers (e.g. "1k") into fully-expanded
+	numbers (e.g. "1024") on the client side, so that the server
+	does not need to implement unit parsing.
 
 If the 'ref-in-want' feature is advertised, the following argument can
 be included in the client's request as well as the potential addition of
diff --git a/builtin/clone.c b/builtin/clone.c
index 15b142d646..8e05e8ad6c 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -1130,9 +1130,13 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 				     option_upload_pack);
 
 	if (filter_options.choice) {
+		struct strbuf expanded_filter_spec = STRBUF_INIT;
+		expand_list_objects_filter_spec(&filter_options,
+						&expanded_filter_spec);
 		transport_set_option(transport, TRANS_OPT_LIST_OBJECTS_FILTER,
-				     filter_options.filter_spec);
+				     expanded_filter_spec.buf);
 		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 e0140327aa..8b8bb64921 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1172,6 +1172,7 @@ static void add_negotiation_tips(struct git_transport_options *smart_options)
 static struct transport *prepare_transport(struct remote *remote, int deepen)
 {
 	struct transport *transport;
+
 	transport = transport_get(remote, NULL);
 	transport_set_verbosity(transport, verbosity, progress);
 	transport->family = family;
@@ -1191,9 +1192,13 @@ 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,
-			   filter_options.filter_spec);
+			   expanded_filter_spec.buf);
 		set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
+		strbuf_release(&expanded_filter_spec);
 	}
 	if (negotiation_tip.nr) {
 		if (transport->smart_options)
diff --git a/fetch-pack.c b/fetch-pack.c
index 9691046e64..485632fabe 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -329,9 +329,14 @@ static int find_common(struct fetch_negotiator *negotiator,
 			packet_buf_write(&req_buf, "deepen-not %s", s->string);
 		}
 	}
-	if (server_supports_filtering && args->filter_options.choice)
+	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",
-				 args->filter_options.filter_spec);
+				 expanded_filter_spec.buf);
+		strbuf_release(&expanded_filter_spec);
+	}
 	packet_buf_flush(&req_buf);
 	state_len = req_buf.len;
 
@@ -1155,9 +1160,13 @@ 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;
 		print_verbose(args, _("Server supports filter"));
+		expand_list_objects_filter_spec(&args->filter_options,
+						&expanded_filter_spec);
 		packet_buf_write(&req_buf, "filter %s",
-				 args->filter_options.filter_spec);
+				 expanded_filter_spec.buf);
+		strbuf_release(&expanded_filter_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 5285e7674d..9efb3e9902 100644
--- a/list-objects-filter-options.c
+++ b/list-objects-filter-options.c
@@ -18,8 +18,9 @@
  * See Documentation/rev-list-options.txt for allowed values for <arg>.
  *
  * Capture the given arg as the "filter_spec".  This can be forwarded to
- * subordinate commands when necessary.  We also "intern" the arg for
- * the convenience of the current command.
+ * subordinate commands when necessary (although it's better to pass it through
+ * expand_list_objects_filter_spec() first).  We also "intern" the arg for the
+ * convenience of the current command.
  */
 static int gently_parse_list_objects_filter(
 	struct list_objects_filter_options *filter_options,
@@ -111,6 +112,21 @@ 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)
+{
+	strbuf_init(expanded_spec, strlen(filter->filter_spec));
+	if (filter->choice == LOFC_BLOB_LIMIT)
+		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);
+}
+
 void list_objects_filter_release(
 	struct list_objects_filter_options *filter_options)
 {
diff --git a/list-objects-filter-options.h b/list-objects-filter-options.h
index 477cd97029..e3adc78ebf 100644
--- a/list-objects-filter-options.h
+++ b/list-objects-filter-options.h
@@ -2,6 +2,7 @@
 #define LIST_OBJECTS_FILTER_OPTIONS_H
 
 #include "parse-options.h"
+#include "strbuf.h"
 
 /*
  * The list of defined filters for list-objects.
@@ -20,8 +21,9 @@ struct list_objects_filter_options {
 	/*
 	 * 'filter_spec' is the raw argument value given on the command line
 	 * or protocol request.  (The part after the "--keyword=".)  For
-	 * commands that launch filtering sub-processes, this value should be
-	 * passed to them as received by the current process.
+	 * 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.
 	 */
 	char *filter_spec;
 
@@ -62,6 +64,17 @@ int opt_parse_list_objects_filter(const struct option *opt,
 	  N_("object filtering"), 0, \
 	  opt_parse_list_objects_filter }
 
+/*
+ * Translates abbreviated numbers in the filter's filter_spec into their
+ * fully-expanded forms (e.g., "limit:blob=1k" becomes "limit:blob=1024").
+ *
+ * This form should be used instead of the raw filter_spec field 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);
+
 void list_objects_filter_release(
 	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 18b0b14d5a..f96f551fb5 100755
--- a/t/t6112-rev-list-filters-objects.sh
+++ b/t/t6112-rev-list-filters-objects.sh
@@ -437,4 +437,21 @@ test_expect_success 'rev-list W/ missing=allow-any' '
 	git -C r1 rev-list --quiet --missing=allow-any --objects HEAD
 '
 
+# Test expansion of filter specs.
+
+test_expect_success 'expand blob limit in protocol' '
+	git -C r2 config --local uploadpack.allowfilter 1 &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -c protocol.version=2 clone \
+		--filter=blob:limit=1k "file://$(pwd)/r2" limit &&
+	! grep "blob:limit=1k" trace &&
+	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 bf225c698f..01404bfac5 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -679,10 +679,15 @@ static int fetch(struct transport *transport,
 	if (data->transport_options.update_shallow)
 		set_helper_option(transport, "update-shallow", "true");
 
-	if (data->transport_options.filter_options.choice)
-		set_helper_option(
-			transport, "filter",
-			data->transport_options.filter_options.filter_spec);
+	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);
+	}
 
 	if (data->transport_options.negotiation_tips)
 		warning("Ignoring --negotiation-tip because the protocol does not support it.");
diff --git a/upload-pack.c b/upload-pack.c
index 5e81f1ff24..1c6d73e5a2 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -140,14 +140,17 @@ static void create_pack_file(const struct object_array *have_obj,
 	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 (pack_objects.use_shell) {
 			struct strbuf buf = STRBUF_INIT;
-			sq_quote_buf(&buf, filter_options.filter_spec);
+			sq_quote_buf(&buf, expanded_filter_spec.buf);
 			argv_array_pushf(&pack_objects.args, "--filter=%s", buf.buf);
 			strbuf_release(&buf);
 		} else {
 			argv_array_pushf(&pack_objects.args, "--filter=%s",
-					 filter_options.filter_spec);
+					 expanded_filter_spec.buf);
 		}
 	}
 
-- 
2.20.0.405.gbc1bbc6f85-goog