transport: add client support for object-info
Sometimes, it is beneficial to retrieve information about an object without downloading it entirely. The server-side logic for this functionality was implemented in commit "a2ba162cda (object-info: support for retrieving object info, 2021-04-20)." And the wire format is documented at https://git-scm.com/docs/protocol-v2#_object_info. Introduce client-side support for the object-info capability. Add its own function for object-info separate from existing fetch infrastructure. Currently, the client supports requesting a list of object IDs with the size feature from a v2 server. If the server does not advertise this feature (i.e., transfer.advertiseobjectinfo is set to false), the client returns an error and exit. Note that: 1. the entire request is written into req_buf before being sent to the remote. This approach follows the pattern used in the send_fetch_request() logic within 'fetch-pack.c'. Streaming the request is not addressed in this patch. 2. When the server does not recognize an OID, following the v2 protocol, the server returns "<OID> SP", when this happens, fetch_object_info() sets the corresponding size pointer to NULL so that callers can detect and handle it. Helped-by: Jonathan Tan <jonathantanmy@google.com> Helped-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Calvin Wan <calvinwan@google.com> Signed-off-by: Eric Ju <eric.peijian@gmail.com> Signed-off-by: Pablo Sabater <pabloosabaterr@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Calvin Wan committed
Jul 10, 2026 at 18:41 UTC
82e288a14848918784d5a88a9a2d97a6a5b207a2
9 files changed
+209
-2
Makefile
+1
index 1cec251f43..ec4df39a6b 100644
--- a/Makefile
+++ b/Makefile
@@ -1159,6 +1159,7 @@ LIB_OBJS += ewah/ewah_rlw.o
LIB_OBJS += exec-cmd.o
LIB_OBJS += fetch-negotiator.o
LIB_OBJS += fetch-pack.o
+LIB_OBJS += fetch-object-info.o
LIB_OBJS += fmt-merge-msg.o
LIB_OBJS += fsck.o
LIB_OBJS += fsmonitor.o
fetch-object-info.c
+109
new file mode 100644
index 0000000000..91685cb355
--- /dev/null
+++ b/fetch-object-info.c
@@ -0,0 +1,109 @@
+#include "git-compat-util.h"
+#include "gettext.h"
+#include "hex.h"
+#include "pkt-line.h"
+#include "connect.h"
+#include "oid-array.h"
+#include "odb.h"
+#include "fetch-object-info.h"
+#include "string-list.h"
+
+/* Sends object-info command and its arguments into the request buffer. */
+static void send_object_info_request(const int fd_out, struct object_info_args *args)
+{
+ struct strbuf req_buf = STRBUF_INIT;
+
+ write_command_and_capabilities(&req_buf, "object-info", args->server_options);
+
+ if (unsorted_string_list_has_string(args->object_info_options, "size"))
+ packet_buf_write(&req_buf, "size");
+ else
+ BUG("only size should be in object_info_options");
+
+ if (args->oids)
+ for (size_t i = 0; i < args->oids->nr; i++)
+ packet_buf_write(&req_buf, "oid %s", oid_to_hex(&args->oids->oid[i]));
+
+ packet_buf_flush(&req_buf);
+ if (write_in_full(fd_out, req_buf.buf, req_buf.len) < 0)
+ die_errno(_("unable to write request to remote"));
+
+ strbuf_release(&req_buf);
+}
+
+static size_t parse_object_size(const char *s, size_t *res)
+{
+ uintmax_t uim;
+
+ if (!s[0] || s[strspn(s, "0123456789")])
+ return -1;
+ errno = 0;
+ uim = strtoumax(s, NULL, 10);
+ if (errno || uim > SIZE_MAX)
+ return -1;
+ *res = uim;
+ return 0;
+}
+
+int fetch_object_info(const enum protocol_version version, struct object_info_args *args,
+ struct packet_reader *reader, struct object_info *object_info_data,
+ const int stateless_rpc, const int fd_out)
+{
+ int size_index = -1;
+
+ switch (version) {
+ case protocol_v2:
+ if (!server_supports_v2("object-info"))
+ die(_("object-info capability is not enabled on the server"));
+ send_object_info_request(fd_out, args);
+ break;
+ case protocol_v1:
+ case protocol_v0:
+ die(_("unsupported protocol version. expected v2"));
+ case protocol_unknown_version:
+ BUG("unknown protocol version");
+ }
+
+ for (size_t i = 0; i < args->object_info_options->nr; i++) {
+ if (packet_reader_read(reader) != PACKET_READ_NORMAL) {
+ check_stateless_delimiter(stateless_rpc, reader,
+ "stateless delimiter expected");
+ return -1;
+ }
+
+ if (!string_list_has_string(args->object_info_options, reader->line))
+ return -1;
+
+ if (!strcmp(reader->line, "size")) {
+ size_index = i;
+ for (size_t j = 0; j < args->oids->nr; j++)
+ object_info_data[j].sizep = xcalloc(1, sizeof(*object_info_data[j].sizep));
+ } else {
+ BUG("only size is supported");
+ }
+ }
+
+ for (size_t i = 0; packet_reader_read(reader) == PACKET_READ_NORMAL && i < args->oids->nr; i++) {
+ struct string_list object_info_values = STRING_LIST_INIT_DUP;
+
+ string_list_split(&object_info_values, reader->line, " ", -1);
+ if (size_index >= 0) {
+ if (!strcmp(object_info_values.items[1 + size_index].string, "")) {
+ FREE_AND_NULL(object_info_data[i].sizep);
+ string_list_clear(&object_info_values, 0);
+ continue;
+ }
+
+ if (parse_object_size(object_info_values.items[1 + size_index].string,
+ object_info_data[i].sizep))
+ die("object-info: ref %s has invalid size %s",
+ object_info_values.items[0].string,
+ object_info_values.items[1 + size_index].string);
+ }
+
+ string_list_clear(&object_info_values, 0);
+ }
+ check_stateless_delimiter(stateless_rpc, reader, "stateless delimiter expected");
+
+ return 0;
+}
fetch-object-info.h
+22
new file mode 100644
index 0000000000..d35284bd6b
--- /dev/null
+++ b/fetch-object-info.h
@@ -0,0 +1,22 @@
+#ifndef FETCH_OBJECT_INFO_H
+#define FETCH_OBJECT_INFO_H
+
+#include "pkt-line.h"
+#include "protocol.h"
+#include "odb.h"
+
+struct object_info_args {
+ struct string_list *object_info_options;
+ const struct string_list *server_options;
+ struct oid_array *oids;
+};
+
+/*
+ * Sends git-cat-file object-info command into the request buf and read the
+ * results from packets.
+ */
+int fetch_object_info(enum protocol_version version, struct object_info_args *args,
+ struct packet_reader *reader, struct object_info *object_info_data,
+ int stateless_rpc, int fd_out);
+
+#endif /* FETCH_OBJECT_INFO_H */
fetch-pack.h
+1
index 6d0dec7f41..0fba340a84 100644
--- a/fetch-pack.h
+++ b/fetch-pack.h
@@ -16,6 +16,7 @@ struct fetch_pack_args {
const struct string_list *deepen_not;
struct list_objects_filter_options filter_options;
const struct string_list *server_options;
+ struct object_info *object_info_data;
/*
* If not NULL, during packfile negotiation, fetch-pack will send "have"
meson.build
+1
index 3247697f74..145c6882eb 100644
--- a/meson.build
+++ b/meson.build
@@ -347,6 +347,7 @@ libgit_sources = [
'exec-cmd.c',
'fetch-negotiator.c',
'fetch-pack.c',
+ 'fetch-object-info.c',
'fmt-merge-msg.c',
'fsck.c',
'fsmonitor.c',
transport-helper.c
+11
-2
index 8a71354d50..f9c14d6f47 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -727,8 +727,7 @@ static int fetch_refs(struct transport *transport,
/*
* If we reach here, then the server, the client, and/or the transport
- * helper does not support protocol v2. --negotiate-only requires
- * protocol v2.
+ * helper does not support protocol v2. --negotiate-only.
*/
if (data->transport_options.acked_commits) {
warning(_("--negotiate-only requires protocol v2"));
@@ -784,6 +783,15 @@ static int fetch_refs(struct transport *transport,
return -1;
}
+static int fetch_object_info_helper(struct transport *transport)
+{
+ get_helper(transport);
+ if (process_connect(transport, 0))
+ return transport->vtable->fetch_object_info(transport);
+
+ die(_("object-info requires protocol v2"));
+}
+
struct push_update_ref_state {
struct ref *hint;
struct ref_push_report *report;
@@ -1330,6 +1338,7 @@ static struct transport_vtable vtable = {
.get_refs_list = get_refs_list,
.get_bundle_uri = get_bundle_uri,
.fetch_refs = fetch_refs,
+ .fetch_object_info = fetch_object_info_helper,
.push_refs = push_refs,
.connect = connect_helper,
.disconnect = release_helper
transport-internal.h
+8
index 051f3ab0dc..60db0bedcd 100644
--- a/transport-internal.h
+++ b/transport-internal.h
@@ -45,6 +45,14 @@ struct transport_vtable {
**/
int (*fetch_refs)(struct transport *transport, int refs_nr, struct ref **refs);
+ /*
+ * Fetch object info (only size currently) from remote without
+ * downloading the objects.
+ *
+ * Uses object-info capability of v2 protocol.
+ */
+ int (*fetch_object_info)(struct transport *transport);
+
/**
* Push the objects and refs. Send the necessary objects, and
* then, for any refs where peer_ref is set and
transport.c
+46
index 0f5ec30247..602b1c5512 100644
--- a/transport.c
+++ b/transport.c
@@ -1,3 +1,4 @@
+#include "compat/posix.h"
#define USE_THE_REPOSITORY_VARIABLE
#include "git-compat-util.h"
@@ -9,6 +10,7 @@
#include "hook.h"
#include "pkt-line.h"
#include "fetch-pack.h"
+#include "fetch-object-info.h"
#include "remote.h"
#include "connect.h"
#include "send-pack.h"
@@ -432,6 +434,48 @@ static int get_bundle_uri(struct transport *transport)
transport->bundles, stateless_rpc);
}
+static int fetch_object_info_via_pack(struct transport *transport)
+{
+ int ret = 0;
+ struct git_transport_data *data = transport->data;
+ struct packet_reader reader;
+ struct object_info_args args = { 0 };
+
+ args.server_options = transport->server_options;
+ args.oids = transport->smart_options->object_info_oids;
+ args.object_info_options = transport->smart_options->object_info_options;
+ string_list_sort(args.object_info_options);
+
+ connect_setup(transport, 0);
+ packet_reader_init(&reader, data->fd[0], NULL, 0,
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
+
+ data->version = discover_version(&reader);
+ transport->hash_algo = reader.hash_algo;
+
+ ret = fetch_object_info(data->version, &args, &reader,
+ data->options.object_info_data,
+ transport->stateless_rpc, data->fd[1]);
+
+ close(data->fd[0]);
+ if (data->fd[1] >= 0)
+ close(data->fd[1]);
+ if (finish_connect(data->conn))
+ ret = -1;
+ data->conn = NULL;
+
+ return ret;
+}
+
+int transport_fetch_object_info(struct transport *transport)
+{
+ if (!transport->vtable->fetch_object_info)
+ die(_("remote does not support object-info"));
+ return transport->vtable->fetch_object_info(transport);
+}
+
static int fetch_refs_via_pack(struct transport *transport,
int nr_heads, struct ref **to_fetch)
{
@@ -1004,6 +1048,7 @@ static struct transport_vtable taken_over_vtable = {
.get_refs_list = get_refs_via_connect,
.get_bundle_uri = get_bundle_uri,
.fetch_refs = fetch_refs_via_pack,
+ .fetch_object_info = fetch_object_info_via_pack,
.push_refs = git_transport_push,
.disconnect = disconnect_git
};
@@ -1169,6 +1214,7 @@ static struct transport_vtable builtin_smart_vtable = {
.get_refs_list = get_refs_via_connect,
.get_bundle_uri = get_bundle_uri,
.fetch_refs = fetch_refs_via_pack,
+ .fetch_object_info = fetch_object_info_via_pack,
.push_refs = git_transport_push,
.connect = connect_git,
.disconnect = disconnect_git
transport.h
+10
index 7e5867cffa..9e85a4cd35 100644
--- a/transport.h
+++ b/transport.h
@@ -6,6 +6,7 @@
#include "list-objects-filter-options.h"
#include "string-list.h"
#include "connect.h"
+#include "odb.h"
struct git_transport_options {
unsigned thin : 1;
@@ -55,6 +56,10 @@ struct git_transport_options {
* common commits to this oidset instead of fetching any packfiles.
*/
struct oidset *acked_commits;
+
+ struct oid_array *object_info_oids;
+ struct object_info *object_info_data;
+ struct string_list *object_info_options;
};
enum transport_family {
@@ -309,6 +314,11 @@ int transport_get_remote_bundle_uri(struct transport *transport);
const struct git_hash_algo *transport_get_hash_algo(struct transport *transport);
int transport_fetch_refs(struct transport *transport, struct ref *refs);
+/*
+ * Fetch the object info from remote
+ */
+int transport_fetch_object_info(struct transport *transport);
+
/*
* If this flag is set, unlocking will avoid to call non-async-signal-safe
* functions. This will necessarily leave behind some data structures which