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@xxxxxxxxxx>
---
This version is a small change with just style fixes.
Documentation/technical/protocol-v2.txt | 31 +++++++
Makefile | 1 +
protocol-caps.c | 113 ++++++++++++++++++++++++
protocol-caps.h | 10 +++
serve.c | 2 +
t/t5701-git-serve.sh | 26 ++++++
6 files changed, 183 insertions(+)
create mode 100644 protocol-caps.c
create mode 100644 protocol-caps.h
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index a7c806a73e..f4ed141774 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -514,3 +514,34 @@ packet-line, and must not contain non-printable or whitespace characters. The
current implementation uses trace2 session IDs (see
link:api-trace2.html[api-trace2] for details), but this may change and users of
the session ID should not rely on this fact.
+
+object-info
+~~~~~~~~~~~
+
+`object-info` is the command to retrieve information about one or more objects.
+Its main purpose is to allow a client to make decisions based on this
+information without having to fully fetch objects. Object size is the only
+information that is currently supported.
+
+An `object-info` request takes the following arguments:
+
+ size
+ Requests size information to be returned for each listed object id.
+
+ oid <oid>
+ Indicates to the server an object which the client wants to obtain
+ information for.
+
+The response of `object-info` is a list of the the requested object ids
+and associated requested information, each separated by a single space.
+
+ output = info flush-pkt
+
+ info = PKT-LINE(attrs) LF)
+ *PKT-LINE(obj-info LF)
+
+ attrs = attr | attrs SP attrs
+
+ attr = "size"
+
+ obj-info = obj-id SP obj-size
diff --git a/Makefile b/Makefile
index 21c0bf1667..3225e37b63 100644
--- a/Makefile
+++ b/Makefile
@@ -961,6 +961,7 @@ LIB_OBJS += progress.o
LIB_OBJS += promisor-remote.o
LIB_OBJS += prompt.o
LIB_OBJS += protocol.o
+LIB_OBJS += protocol-caps.o
LIB_OBJS += prune-packed.o
LIB_OBJS += quote.o
LIB_OBJS += range-diff.o
diff --git a/protocol-caps.c b/protocol-caps.c
new file mode 100644
index 0000000000..13a9e63a04
--- /dev/null
+++ 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;
+}
diff --git a/protocol-caps.h b/protocol-caps.h
new file mode 100644
index 0000000000..6351648e37
--- /dev/null
+++ b/protocol-caps.h
@@ -0,0 +1,10 @@
+#ifndef PROTOCOL_CAPS_H
+#define PROTOCOL_CAPS_H
+
+struct repository;
+struct strvec;
+struct packet_reader;
+int cap_object_info(struct repository *r, struct strvec *keys,
+ struct packet_reader *request);
+
+#endif /* PROTOCOL_CAPS_H */
\ No newline at end of file
diff --git a/serve.c b/serve.c
index ac20c72763..aa8209f147 100644
--- a/serve.c
+++ b/serve.c
@@ -5,6 +5,7 @@
#include "version.h"
#include "strvec.h"
#include "ls-refs.h"
+#include "protocol-caps.h"
#include "serve.h"
#include "upload-pack.h"
@@ -78,6 +79,7 @@ static struct protocol_capability capabilities[] = {
{ "server-option", always_advertise, NULL },
{ "object-format", object_format_advertise, NULL },
{ "session-id", session_id_advertise, NULL },
+ { "object-info", always_advertise, cap_object_info },
};
static void advertise_capabilities(void)
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 509f379d49..73e74a9c54 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -19,6 +19,7 @@ test_expect_success 'test capability advertisement' '
fetch=shallow
server-option
object-format=$(test_oid algo)
+ object-info
0000
EOF
@@ -240,4 +241,29 @@ test_expect_success 'unexpected lines are not allowed in fetch request' '
grep "unexpected line: .this-is-not-a-command." err
'
+# Test the basics of object-info
+#
+test_expect_success 'basics of object-info' '
+ test-tool pkt-line pack >in <<-EOF &&
+ command=object-info
+ object-format=$(test_oid algo)
+ 0001
+ size
+ oid $(git rev-parse two:two.t)
+ oid $(git rev-parse two:two.t)
+ 0000
+ EOF
+
+ cat >expect <<-EOF &&
+ size
+ $(git rev-parse two:two.t) $(wc -c <two.t | xargs)
+ $(git rev-parse two:two.t) $(wc -c <two.t | xargs)
+ 0000
+ EOF
+
+ test-tool serve-v2 --stateless-rpc <in >out &&
+ test-tool pkt-line unpack <out >actual &&
+ test_cmp expect actual
+'
+
test_done
--
2.31.1.368.gbe11c130af-goog
