Merge branch 'ej/cat-file-remote-object-info' into seen

"git cat-file --batch" and friends can optionally ask a remote
server about objects it does not have.

* ej/cat-file-remote-object-info:
  cat-file: add remote-object-info to batch-command
  transport: add client support for object-info
  serve: advertise object-info feature
  fetch-pack: move fetch initialization
  fetch-pack: refactor packet writing
  t1006: split test utility functions into new "lib-cat-file.sh"
  cat-file: add declaration of variable i inside its for loop
  git-compat-util: add strtoul_ul() with error handling

Author: gitster

Documentation/git-cat-file.adoc

@@ -168,6 +168,13 @@ info <object>::
 	Print object info for object reference `<object>`. This corresponds to the
 	output of `--batch-check`.
 
+remote-object-info <remote> <object>...::
+	Print object info for object references `<object>` at specified
+	`<remote>` without downloading objects from the remote.
+	Raise an error when the `object-info` capability is not supported by the remote.
+	Raise an error when no object references are provided.
+	This command may be combined with `--buffer`.
+
 flush::
 	Used with `--buffer` to execute all preceding commands that were issued
 	since the beginning or since the last flush was issued. When `--buffer`
@@ -309,21 +316,23 @@ newline. The available atoms are:
 	The full hex representation of the object name.
 
 `objecttype`::
-	The type of the object (the same as `cat-file -t` reports).
+	The type of the object (the same as `cat-file -t` reports). See
+	`CAVEATS` below. Not supported by `remote-object-info`.
 
 `objectsize`::
 	The size, in bytes, of the object (the same as `cat-file -s`
 	reports).
 
 `objectsize:disk`::
 	The size, in bytes, that the object takes up on disk. See the
-	note about on-disk sizes in the `CAVEATS` section below.
+	note about on-disk sizes in the `CAVEATS` section below. Not
+	supported by `remote-object-info`.
 
 `deltabase`::
 	If the object is stored as a delta on-disk, this expands to the
 	full hex representation of the delta base object name.
 	Otherwise, expands to the null OID (all zeroes). See `CAVEATS`
-	below.
+	below. Not supported by `remote-object-info`.
 
 `rest`::
 	If this atom is used in the output string, input lines are split
@@ -333,7 +342,10 @@ newline. The available atoms are:
 	line) are output in place of the `%(rest)` atom.
 
 If no format is specified, the default format is `%(objectname)
-%(objecttype) %(objectsize)`.
+%(objecttype) %(objectsize)`, except for `remote-object-info` commands which use
+`%(objectname) %(objectsize)` for now because "%(objecttype)" is not supported yet.
+WARNING: When "%(objecttype)" is supported, the default format WILL be unified, so
+DO NOT RELY on the current default format to stay the same!!!
 
 If `--batch` is specified, or if `--batch-command` is used with the `contents`
 command, the object information is followed by the object contents (consisting
@@ -422,6 +434,10 @@ scripting purposes.
 CAVEATS
 -------
 
+Note that since %(objecttype), %(objectsize:disk) and %(deltabase) are
+currently not supported by the `remote-object-info` command, we will raise
+an error and exit when they appear in the format string.
+
 Note that the sizes of objects on disk are reported accurately, but care
 should be taken in drawing conclusions about which refs or objects are
 responsible for disk usage. The size of a packed non-delta object may be

Makefile

@@ -1031,6 +1031,7 @@ 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

builtin/cat-file.c

@@ -29,6 +29,18 @@
 #include "promisor-remote.h"
 #include "mailmap.h"
 #include "write-or-die.h"
+#include "alias.h"
+#include "remote.h"
+#include "transport.h"
+
+/* Maximum length for a remote URL. While no universal standard exists,
+ * 8K is assumed to be a reasonable limit.
+ */
+#define MAX_REMOTE_URL_LEN (8*1024)
+/* Maximum number of objects allowed in a single remote-object-info request. */
+#define MAX_ALLOWED_OBJ_LIMIT 10000
+/* Maximum input size permitted for the remote-object-info command. */
+#define MAX_REMOTE_OBJ_INFO_LINE (MAX_REMOTE_URL_LEN + MAX_ALLOWED_OBJ_LIMIT * (GIT_MAX_HEXSZ + 1))
 
 enum batch_mode {
 	BATCH_MODE_CONTENTS,
@@ -51,6 +63,8 @@ struct batch_options {
 };
 
 static const char *force_path;
+static struct object_info *remote_object_info;
+static struct oid_array object_info_oids = OID_ARRAY_INIT;
 
 static struct string_list mailmap = STRING_LIST_INIT_NODUP;
 static int use_mailmap;
@@ -627,6 +641,61 @@ static void batch_one_object(const char *obj_name,
 	object_context_release(&ctx);
 }
 
+static int get_remote_info(struct batch_options *opt, int argc, const char **argv)
+{
+	int retval = 0;
+	struct remote *remote = NULL;
+	struct object_id oid;
+	struct string_list object_info_options = STRING_LIST_INIT_NODUP;
+	static struct transport *gtransport;
+
+	/*
+	 * Change the format to "%(objectname) %(objectsize)" when
+	 * remote-object-info command is used. Once we start supporting objecttype
+	 * the default format should change to DEFAULT_FORMAT.
+	*/
+	if (!opt->format)
+		opt->format = "%(objectname) %(objectsize)";
+
+	remote = remote_get(argv[0]);
+	if (!remote)
+		die(_("must supply valid remote when using remote-object-info"));
+
+	oid_array_clear(&object_info_oids);
+	for (size_t i = 1; i < argc; i++) {
+		if (get_oid_hex(argv[i], &oid))
+			die(_("Not a valid object name %s"), argv[i]);
+		oid_array_append(&object_info_oids, &oid);
+	}
+	if (!object_info_oids.nr)
+		die(_("remote-object-info requires objects"));
+
+	gtransport = transport_get(remote, NULL);
+	if (gtransport->smart_options) {
+		CALLOC_ARRAY(remote_object_info, object_info_oids.nr);
+		gtransport->smart_options->object_info = 1;
+		gtransport->smart_options->object_info_oids = &object_info_oids;
+
+		/* 'objectsize' is the only option currently supported */
+		if (!strstr(opt->format, "%(objectsize)"))
+			die(_("%s is currently not supported with remote-object-info"), opt->format);
+
+		string_list_append(&object_info_options, "size");
+
+		if (object_info_options.nr > 0) {
+			gtransport->smart_options->object_info_options = &object_info_options;
+			gtransport->smart_options->object_info_data = remote_object_info;
+			retval = transport_fetch_refs(gtransport, NULL);
+		}
+	} else {
+		retval = -1;
+	}
+
+	string_list_clear(&object_info_options, 0);
+	transport_disconnect(gtransport);
+	return retval;
+}
+
 struct object_cb_data {
 	struct batch_options *opt;
 	struct expand_data *expand;
@@ -694,28 +763,68 @@ static void parse_cmd_info(struct batch_options *opt,
 	batch_one_object(line, output, opt, data);
 }
 
+static void parse_cmd_remote_object_info(struct batch_options *opt,
+					 const char *line, struct strbuf *output,
+					 struct expand_data *data)
+{
+	int count;
+	const char **argv;
+	char *line_to_split;
+
+	if (strlen(line) >= MAX_REMOTE_OBJ_INFO_LINE)
+		die(_("remote-object-info command input overflow "
+			"(no more than %d objects are allowed)"),
+			MAX_ALLOWED_OBJ_LIMIT);
+
+	line_to_split = xstrdup(line);
+	count = split_cmdline(line_to_split, &argv);
+	if (count < 0)
+		die(_("split remote-object-info command"));
+
+	if (get_remote_info(opt, count, argv))
+		goto cleanup;
+
+	data->skip_object_info = 1;
+	for (size_t i = 0; i < object_info_oids.nr; i++) {
+		data->oid = object_info_oids.oid[i];
+		if (remote_object_info[i].sizep) {
+			/*
+			 * When reaching here, it means remote-object-info can retrieve
+			 * information from server without downloading them.
+			 */
+			data->size = *remote_object_info[i].sizep;
+			opt->batch_mode = BATCH_MODE_INFO;
+			batch_object_write(argv[i+1], output, opt, data, NULL, 0);
+		}
+	}
+	data->skip_object_info = 0;
+
+cleanup:
+	for (size_t i = 0; i < object_info_oids.nr; i++)
+		free_object_info_contents(&remote_object_info[i]);
+	free(line_to_split);
+	free(argv);
+	free(remote_object_info);
+}
+
 static void dispatch_calls(struct batch_options *opt,
 		struct strbuf *output,
 		struct expand_data *data,
 		struct queued_cmd *cmd,
 		int nr)
 {
-	int i;
-
 	if (!opt->buffer_output)
 		die(_("flush is only for --buffer mode"));
 
-	for (i = 0; i < nr; i++)
+	for (size_t i = 0; i < nr; i++)
 		cmd[i].fn(opt, cmd[i].line, output, data);
 
 	fflush(stdout);
 }
 
 static void free_cmds(struct queued_cmd *cmd, size_t *nr)
 {
-	size_t i;
-
-	for (i = 0; i < *nr; i++)
+	for (size_t i = 0; i < *nr; i++)
 		FREE_AND_NULL(cmd[i].line);
 
 	*nr = 0;
@@ -729,6 +838,7 @@ static const struct parse_cmd {
 } commands[] = {
 	{ "contents", parse_cmd_contents, 1},
 	{ "info", parse_cmd_info, 1},
+	{ "remote-object-info", parse_cmd_remote_object_info, 1},
 	{ "flush", NULL, 0},
 };
 
@@ -741,7 +851,6 @@ static void batch_objects_command(struct batch_options *opt,
 	size_t alloc = 0, nr = 0;
 
 	while (strbuf_getdelim_strip_crlf(&input, stdin, opt->input_delim) != EOF) {
-		int i;
 		const struct parse_cmd *cmd = NULL;
 		const char *p = NULL, *cmd_end;
 		struct queued_cmd call = {0};
@@ -751,7 +860,7 @@ static void batch_objects_command(struct batch_options *opt,
 		if (isspace(*input.buf))
 			die(_("whitespace before command: '%s'"), input.buf);
 
-		for (i = 0; i < ARRAY_SIZE(commands); i++) {
+		for (size_t i = 0; i < ARRAY_SIZE(commands); i++) {
 			if (!skip_prefix(input.buf, commands[i].name, &cmd_end))
 				continue;
 

connect.c

@@ -697,6 +697,40 @@ int server_supports(const char *feature)
 	return !!server_feature_value(feature, NULL);
 }
 
+void write_command_and_capabilities(struct strbuf *req_buf, const char *command,
+				    const struct string_list *server_options)
+{
+	const char *hash_name;
+	int advertise_sid;
+
+	git_config_get_bool("transfer.advertisesid", &advertise_sid);
+
+	ensure_server_supports_v2(command);
+	packet_buf_write(req_buf, "command=%s", command);
+	if (server_supports_v2("agent"))
+		packet_buf_write(req_buf, "agent=%s", git_user_agent_sanitized());
+	if (advertise_sid && server_supports_v2("session-id"))
+		packet_buf_write(req_buf, "session-id=%s", trace2_session_id());
+	if (server_options && server_options->nr) {
+		ensure_server_supports_v2("server-option");
+		for (size_t i = 0; i < server_options->nr; i++)
+			packet_buf_write(req_buf, "server-option=%s",
+					 server_options->items[i].string);
+	}
+
+	if (server_feature_v2("object-format", &hash_name)) {
+		const int hash_algo = hash_algo_by_name(hash_name);
+		if (hash_algo_by_ptr(the_hash_algo) != hash_algo)
+			die(_("mismatched algorithms: client %s; server %s"),
+				the_hash_algo->name, hash_name);
+		packet_buf_write(req_buf, "object-format=%s", the_hash_algo->name);
+	} else if (hash_algo_by_ptr(the_hash_algo) != GIT_HASH_SHA1) {
+		die(_("the server does not support algorithm '%s'"),
+			the_hash_algo->name);
+	}
+	packet_buf_delim(req_buf);
+}
+
 enum protocol {
 	PROTO_LOCAL = 1,
 	PROTO_FILE,

connect.h

@@ -30,4 +30,12 @@ void check_stateless_delimiter(int stateless_rpc,
 			       struct packet_reader *reader,
 			       const char *error);
 
+/*
+ * Writes a command along with the requested
+ * server capabilities/features into a request buffer.
+ */
+struct string_list;
+void write_command_and_capabilities(struct strbuf *req_buf, const char *command,
+				    const struct string_list *server_options);
+
 #endif