filter-options: expand scaled numbers

When communicating with a remote server or a subprocess, use
expanded numbers rather than numbers with scaling suffix 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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/list-objects-filter-options.h b/list-objects-filter-options.h
index 477cd97..e3adc78 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);