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>
Bruno Albuquerque committed
Apr 20, 2021 at 16:38 UTC
a2ba162cda2acc171c3e36acbbc854792b093cb7
6 files changed
+183
Documentation/technical/protocol-v2.txt
+31
@@ -514,3 +514,34 @@ packet-line, and must not contain non-printable or whitespace characters. The
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current implementation uses trace2 session IDs (see
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link:api-trace2.html[api-trace2] for details), but this may change and users of
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the session ID should not rely on this fact.
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+
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+object-info
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+~~~~~~~~~~~
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+
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+`object-info` is the command to retrieve information about one or more objects.
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+Its main purpose is to allow a client to make decisions based on this
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+information without having to fully fetch objects. Object size is the only
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+information that is currently supported.
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+
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+An `object-info` request takes the following arguments:
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+
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+ size
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+ Requests size information to be returned for each listed object id.
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+
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+ oid <oid>
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+ Indicates to the server an object which the client wants to obtain
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+ information for.
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+
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+The response of `object-info` is a list of the the requested object ids
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+and associated requested information, each separated by a single space.
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+
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+ output = info flush-pkt
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+
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+ info = PKT-LINE(attrs) LF)
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+ *PKT-LINE(obj-info LF)
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+
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+ attrs = attr | attrs SP attrs
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+
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+ attr = "size"
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+
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+ obj-info = obj-id SP obj-size
Makefile
+1
@@ -961,6 +961,7 @@ LIB_OBJS += progress.o
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LIB_OBJS += promisor-remote.o
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LIB_OBJS += prompt.o
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LIB_OBJS += protocol.o
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+LIB_OBJS += protocol-caps.o
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LIB_OBJS += prune-packed.o
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LIB_OBJS += quote.o
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LIB_OBJS += range-diff.o
protocol-caps.c
new
+113
@@ -0,0 +1,113 @@
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+#include "git-compat-util.h"
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+#include "protocol-caps.h"
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+#include "gettext.h"
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+#include "pkt-line.h"
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+#include "strvec.h"
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+#include "hash.h"
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+#include "object.h"
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+#include "object-store.h"
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+#include "string-list.h"
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+#include "strbuf.h"
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+
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+struct requested_info {
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+ unsigned size : 1;
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+};
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+
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+/*
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+ * Parses oids from the given line and collects them in the given
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+ * oid_str_list. Returns 1 if parsing was successful and 0 otherwise.
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+ */
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+static int parse_oid(const char *line, struct string_list *oid_str_list)
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+{
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+ const char *arg;
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+
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+ if (!skip_prefix(line, "oid ", &arg))
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+ return 0;
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+
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+ string_list_append(oid_str_list, arg);
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+
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+ return 1;
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+}
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+
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+/*
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+ * Validates and send requested info back to the client. Any errors detected
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+ * are returned as they are detected.
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+ */
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+static void send_info(struct repository *r, struct packet_writer *writer,
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+ struct string_list *oid_str_list,
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+ struct requested_info *info)
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+{
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+ struct string_list_item *item;
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+ struct strbuf send_buffer = STRBUF_INIT;
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+
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+ if (!oid_str_list->nr)
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+ return;
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+
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+ if (info->size)
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+ packet_writer_write(writer, "size");
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+
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+ for_each_string_list_item (item, oid_str_list) {
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+ const char *oid_str = item->string;
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+ struct object_id oid;
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+ unsigned long object_size;
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+
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+ if (get_oid_hex(oid_str, &oid) < 0) {
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+ packet_writer_error(
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+ writer,
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+ "object-info: protocol error, expected to get oid, not '%s'",
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+ oid_str);
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+ continue;
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+ }
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+
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+ strbuf_addstr(&send_buffer, oid_str);
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+
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+ if (info->size) {
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+ if (oid_object_info(r, &oid, &object_size) < 0) {
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+ strbuf_addstr(&send_buffer, " ");
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+ } else {
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+ strbuf_addf(&send_buffer, " %lu", object_size);
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+ }
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+ }
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+
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+ packet_writer_write(writer, "%s",
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+ strbuf_detach(&send_buffer, NULL));
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+ }
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+}
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+
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+int cap_object_info(struct repository *r, struct strvec *keys,
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+ struct packet_reader *request)
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+{
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+ struct requested_info info;
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+ struct packet_writer writer;
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+ struct string_list oid_str_list = STRING_LIST_INIT_DUP;
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+
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+ packet_writer_init(&writer, 1);
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+
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+ while (packet_reader_read(request) == PACKET_READ_NORMAL) {
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+ if (!strcmp("size", request->line)) {
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+ info.size = 1;
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+ continue;
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+ }
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+
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+ if (parse_oid(request->line, &oid_str_list))
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+ continue;
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+
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+ packet_writer_error(&writer,
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+ "object-info: unexpected line: '%s'",
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+ request->line);
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+ }
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+
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+ if (request->status != PACKET_READ_FLUSH) {
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+ packet_writer_error(
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+ &writer, "object-info: expected flush after arguments");
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+ die(_("object-info: expected flush after arguments"));
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+ }
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+
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+ send_info(r, &writer, &oid_str_list, &info);
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+
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+ string_list_clear(&oid_str_list, 1);
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+
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+ packet_flush(1);
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+
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+ return 0;
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+}
protocol-caps.h
new
+10
@@ -0,0 +1,10 @@
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+#ifndef PROTOCOL_CAPS_H
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+#define PROTOCOL_CAPS_H
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+
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+struct repository;
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+struct strvec;
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+struct packet_reader;
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+int cap_object_info(struct repository *r, struct strvec *keys,
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+ struct packet_reader *request);
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+
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+#endif /* PROTOCOL_CAPS_H */
\ No newline at end of file
serve.c
+2
@@ -5,6 +5,7 @@
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#include "version.h"
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#include "strvec.h"
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#include "ls-refs.h"
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+#include "protocol-caps.h"
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#include "serve.h"
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#include "upload-pack.h"
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@@ -78,6 +79,7 @@ static struct protocol_capability capabilities[] = {
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{ "server-option", always_advertise, NULL },
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{ "object-format", object_format_advertise, NULL },
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{ "session-id", session_id_advertise, NULL },
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+ { "object-info", always_advertise, cap_object_info },
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};
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static void advertise_capabilities(void)
t/t5701-git-serve.sh
+26
@@ -19,6 +19,7 @@ test_expect_success 'test capability advertisement' '
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fetch=shallow
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server-option
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object-format=$(test_oid algo)
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+ object-info
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0000
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EOF
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@@ -240,4 +241,29 @@ test_expect_success 'unexpected lines are not allowed in fetch request' '
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grep "unexpected line: .this-is-not-a-command." err
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'
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+# Test the basics of object-info
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+#
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+test_expect_success 'basics of object-info' '
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+ test-tool pkt-line pack >in <<-EOF &&
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+ command=object-info
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+ object-format=$(test_oid algo)
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+ 0001
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+ size
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+ oid $(git rev-parse two:two.t)
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+ oid $(git rev-parse two:two.t)
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+ 0000
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+ EOF
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+
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+ cat >expect <<-EOF &&
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+ size
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+ $(git rev-parse two:two.t) $(wc -c <two.t | xargs)
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+ $(git rev-parse two:two.t) $(wc -c <two.t | xargs)
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+ 0000
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+ EOF
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+
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+ test-tool serve-v2 --stateless-rpc <in >out &&
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+ test-tool pkt-line unpack <out >actual &&
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+ test_cmp expect actual
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+'
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+
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test_done