object-info: support for retrieving object info

Sometimes it is useful to get information of an object without having to download it completely. Add the "object-info" capability that lets the client ask for object-related information with their full hexadecimal object names. Only sizes are returned for now. Signed-off-by: Bruno Albuquerque <bga@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-20 16:38:31 -07:00
parent d1b10fc6d8
commit a2ba162cda
6 changed files with 183 additions and 0 deletions
--- a/protocol-caps.c
+++ b/protocol-caps.c
@ -0,0 +1,113 @@
+#include "git-compat-util.h"
+#include "protocol-caps.h"
+#include "gettext.h"
+#include "pkt-line.h"
+#include "strvec.h"
+#include "hash.h"
+#include "object.h"
+#include "object-store.h"
+#include "string-list.h"
+#include "strbuf.h"
+
+struct requested_info {
+	unsigned size : 1;
+};
+
+/*
+ * Parses oids from the given line and collects them in the given
+ * oid_str_list. Returns 1 if parsing was successful and 0 otherwise.
+ */
+static int parse_oid(const char *line, struct string_list *oid_str_list)
+{
+	const char *arg;
+
+	if (!skip_prefix(line, "oid ", &arg))
+		return 0;
+
+	string_list_append(oid_str_list, arg);
+
+	return 1;
+}
+
+/*
+ * Validates and send requested info back to the client. Any errors detected
+ * are returned as they are detected.
+ */
+static void send_info(struct repository *r, struct packet_writer *writer,
+		      struct string_list *oid_str_list,
+		      struct requested_info *info)
+{
+	struct string_list_item *item;
+	struct strbuf send_buffer = STRBUF_INIT;
+
+	if (!oid_str_list->nr)
+		return;
+
+	if (info->size)
+		packet_writer_write(writer, "size");
+
+	for_each_string_list_item (item, oid_str_list) {
+		const char *oid_str = item->string;
+		struct object_id oid;
+		unsigned long object_size;
+
+		if (get_oid_hex(oid_str, &oid) < 0) {
+			packet_writer_error(
+				writer,
+				"object-info: protocol error, expected to get oid, not '%s'",
+				oid_str);
+			continue;
+		}
+
+		strbuf_addstr(&send_buffer, oid_str);
+
+		if (info->size) {
+			if (oid_object_info(r, &oid, &object_size) < 0) {
+				strbuf_addstr(&send_buffer, " ");
+			} else {
+				strbuf_addf(&send_buffer, " %lu", object_size);
+			}
+		}
+
+		packet_writer_write(writer, "%s",
+				    strbuf_detach(&send_buffer, NULL));
+	}
+}
+
+int cap_object_info(struct repository *r, struct strvec *keys,
+		    struct packet_reader *request)
+{
+	struct requested_info info;
+	struct packet_writer writer;
+	struct string_list oid_str_list = STRING_LIST_INIT_DUP;
+
+	packet_writer_init(&writer, 1);
+
+	while (packet_reader_read(request) == PACKET_READ_NORMAL) {
+		if (!strcmp("size", request->line)) {
+			info.size = 1;
+			continue;
+		}
+
+		if (parse_oid(request->line, &oid_str_list))
+			continue;
+
+		packet_writer_error(&writer,
+				    "object-info: unexpected line: '%s'",
+				    request->line);
+	}
+
+	if (request->status != PACKET_READ_FLUSH) {
+		packet_writer_error(
+			&writer, "object-info: expected flush after arguments");
+		die(_("object-info: expected flush after arguments"));
+	}
+
+	send_info(r, &writer, &oid_str_list, &info);
+
+	string_list_clear(&oid_str_list, 1);
+
+	packet_flush(1);
+
+	return 0;
+}