Merge branch 'jc/cat-file-batch-commands'

"git cat-file" learns "--batch-command" mode, which is a more
flexible interface than the existing "--batch" or "--batch-check"
modes, to allow different kinds of inquiries made.

* jc/cat-file-batch-commands:
  cat-file: add --batch-command mode
  cat-file: add remove_timestamp helper
  cat-file: introduce batch_mode enum to replace print_contents
  cat-file: rename cmdmode to transform_mode

Author: gitster

Documentation/git-cat-file.txt

@@ -96,6 +96,33 @@ OPTIONS
 	need to specify the path, separated by whitespace.  See the
 	section `BATCH OUTPUT` below for details.
 
+--batch-command::
+--batch-command=<format>::
+	Enter a command mode that reads commands and arguments from stdin. May
+	only be combined with `--buffer`, `--textconv` or `--filters`. In the
+	case of `--textconv` or `--filters`, the input lines also need to specify
+	the path, separated by whitespace. See the section `BATCH OUTPUT` below
+	for details.
++
+`--batch-command` recognizes the following commands:
++
+--
+contents <object>::
+	Print object contents for object reference `<object>`. This corresponds to
+	the output of `--batch`.
+
+info <object>::
+	Print object info for object reference `<object>`. This corresponds to the
+	output of `--batch-check`.
+
+flush::
+	Used with `--buffer` to execute all preceding commands that were issued
+	since the beginning or since the last flush was issued. When `--buffer`
+	is used, no output will come until a `flush` is issued. When `--buffer`
+	is not used, commands are flushed each time without issuing `flush`.
+--
++
+
 --batch-all-objects::
 	Instead of reading a list of objects on stdin, perform the
 	requested batch operation on all objects in the repository and
@@ -110,7 +137,7 @@ OPTIONS
 	that a process can interactively read and write from
 	`cat-file`. With this option, the output uses normal stdio
 	buffering; this is much more efficient when invoking
-	`--batch-check` on a large number of objects.
+	`--batch-check` or `--batch-command` on a large number of objects.
 
 --unordered::
 	When `--batch-all-objects` is in use, visit objects in an
@@ -202,6 +229,13 @@ from stdin, one per line, and print information about them. By default,
 the whole line is considered as an object, as if it were fed to
 linkgit:git-rev-parse[1].
 
+When `--batch-command` is given, `cat-file` will read commands from stdin,
+one per line, and print information based on the command given. With
+`--batch-command`, the `info` command followed by an object will print
+information about the object the same way `--batch-check` would, and the
+`contents` command followed by an object prints contents in the same way
+`--batch` would.
+
 You can specify the information shown for each object by using a custom
 `<format>`. The `<format>` is copied literally to stdout for each
 object, with placeholders of the form `%(atom)` expanded, followed by a
@@ -237,9 +271,9 @@ newline. The available atoms are:
 If no format is specified, the default format is `%(objectname)
 %(objecttype) %(objectsize)`.
 
-If `--batch` is specified, the object information is followed by the
-object contents (consisting of `%(objectsize)` bytes), followed by a
-newline.
+If `--batch` is specified, or if `--batch-command` is used with the `contents`
+command, the object information is followed by the object contents (consisting
+of `%(objectsize)` bytes), followed by a newline.
 
 For example, `--batch` without a custom format would produce:
 

builtin/cat-file.c

@@ -17,14 +17,20 @@
 #include "object-store.h"
 #include "promisor-remote.h"
 
+enum batch_mode {
+	BATCH_MODE_CONTENTS,
+	BATCH_MODE_INFO,
+	BATCH_MODE_QUEUE_AND_DISPATCH,
+};
+
 struct batch_options {
 	int enabled;
 	int follow_symlinks;
-	int print_contents;
+	enum batch_mode batch_mode;
 	int buffer_output;
 	int all_objects;
 	int unordered;
-	int cmdmode; /* may be 'w' or 'c' for --filters or --textconv */
+	int transform_mode; /* may be 'w' or 'c' for --filters or --textconv */
 	const char *format;
 };
 
@@ -302,19 +308,19 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 	if (data->type == OBJ_BLOB) {
 		if (opt->buffer_output)
 			fflush(stdout);
-		if (opt->cmdmode) {
+		if (opt->transform_mode) {
 			char *contents;
 			unsigned long size;
 
 			if (!data->rest)
 				die("missing path for '%s'", oid_to_hex(oid));
 
-			if (opt->cmdmode == 'w') {
+			if (opt->transform_mode == 'w') {
 				if (filter_object(data->rest, 0100644, oid,
 						  &contents, &size))
 					die("could not convert '%s' %s",
 					    oid_to_hex(oid), data->rest);
-			} else if (opt->cmdmode == 'c') {
+			} else if (opt->transform_mode == 'c') {
 				enum object_type type;
 				if (!textconv_object(the_repository,
 						     data->rest, 0100644, oid,
@@ -326,7 +332,7 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 					die("could not convert '%s' %s",
 					    oid_to_hex(oid), data->rest);
 			} else
-				BUG("invalid cmdmode: %c", opt->cmdmode);
+				BUG("invalid transform_mode: %c", opt->transform_mode);
 			batch_write(opt, contents, size);
 			free(contents);
 		} else {
@@ -386,7 +392,7 @@ static void batch_object_write(const char *obj_name,
 	strbuf_addch(scratch, '\n');
 	batch_write(opt, scratch->buf, scratch->len);
 
-	if (opt->print_contents) {
+	if (opt->batch_mode == BATCH_MODE_CONTENTS) {
 		print_object_or_die(opt, data);
 		batch_write(opt, "\n", 1);
 	}
@@ -508,6 +514,135 @@ static int batch_unordered_packed(const struct object_id *oid,
 				      data);
 }
 
+typedef void (*parse_cmd_fn_t)(struct batch_options *, const char *,
+			       struct strbuf *, struct expand_data *);
+
+struct queued_cmd {
+	parse_cmd_fn_t fn;
+	char *line;
+};
+
+static void parse_cmd_contents(struct batch_options *opt,
+			     const char *line,
+			     struct strbuf *output,
+			     struct expand_data *data)
+{
+	opt->batch_mode = BATCH_MODE_CONTENTS;
+	batch_one_object(line, output, opt, data);
+}
+
+static void parse_cmd_info(struct batch_options *opt,
+			   const char *line,
+			   struct strbuf *output,
+			   struct expand_data *data)
+{
+	opt->batch_mode = BATCH_MODE_INFO;
+	batch_one_object(line, output, opt, data);
+}
+
+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++)
+		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++)
+		FREE_AND_NULL(cmd[i].line);
+
+	*nr = 0;
+}
+
+
+static const struct parse_cmd {
+	const char *name;
+	parse_cmd_fn_t fn;
+	unsigned takes_args;
+} commands[] = {
+	{ "contents", parse_cmd_contents, 1},
+	{ "info", parse_cmd_info, 1},
+	{ "flush", NULL, 0},
+};
+
+static void batch_objects_command(struct batch_options *opt,
+				    struct strbuf *output,
+				    struct expand_data *data)
+{
+	struct strbuf input = STRBUF_INIT;
+	struct queued_cmd *queued_cmd = NULL;
+	size_t alloc = 0, nr = 0;
+
+	while (!strbuf_getline(&input, stdin)) {
+		int i;
+		const struct parse_cmd *cmd = NULL;
+		const char *p = NULL, *cmd_end;
+		struct queued_cmd call = {0};
+
+		if (!input.len)
+			die(_("empty command in input"));
+		if (isspace(*input.buf))
+			die(_("whitespace before command: '%s'"), input.buf);
+
+		for (i = 0; i < ARRAY_SIZE(commands); i++) {
+			if (!skip_prefix(input.buf, commands[i].name, &cmd_end))
+				continue;
+
+			cmd = &commands[i];
+			if (cmd->takes_args) {
+				if (*cmd_end != ' ')
+					die(_("%s requires arguments"),
+					    commands[i].name);
+
+				p = cmd_end + 1;
+			} else if (*cmd_end) {
+				die(_("%s takes no arguments"),
+				    commands[i].name);
+			}
+
+			break;
+		}
+
+		if (!cmd)
+			die(_("unknown command: '%s'"), input.buf);
+
+		if (!strcmp(cmd->name, "flush")) {
+			dispatch_calls(opt, output, data, queued_cmd, nr);
+			free_cmds(queued_cmd, &nr);
+		} else if (!opt->buffer_output) {
+			cmd->fn(opt, p, output, data);
+		} else {
+			ALLOC_GROW(queued_cmd, nr + 1, alloc);
+			call.fn = cmd->fn;
+			call.line = xstrdup_or_null(p);
+			queued_cmd[nr++] = call;
+		}
+	}
+
+	if (opt->buffer_output &&
+	    nr &&
+	    !git_env_bool("GIT_TEST_CAT_FILE_NO_FLUSH_ON_EXIT", 0)) {
+		dispatch_calls(opt, output, data, queued_cmd, nr);
+		free_cmds(queued_cmd, &nr);
+	}
+
+	free(queued_cmd);
+	strbuf_release(&input);
+}
+
 static int batch_objects(struct batch_options *opt)
 {
 	struct strbuf input = STRBUF_INIT;
@@ -529,14 +664,14 @@ static int batch_objects(struct batch_options *opt)
 	strbuf_expand(&output, opt->format, expand_format, &data);
 	data.mark_query = 0;
 	strbuf_release(&output);
-	if (opt->cmdmode)
+	if (opt->transform_mode)
 		data.split_on_whitespace = 1;
 
 	/*
 	 * If we are printing out the object, then always fill in the type,
 	 * since we will want to decide whether or not to stream.
 	 */
-	if (opt->print_contents)
+	if (opt->batch_mode == BATCH_MODE_CONTENTS)
 		data.info.typep = &data.type;
 
 	if (opt->all_objects) {
@@ -590,6 +725,11 @@ static int batch_objects(struct batch_options *opt)
 	save_warning = warn_on_object_refname_ambiguity;
 	warn_on_object_refname_ambiguity = 0;
 
+	if (opt->batch_mode == BATCH_MODE_QUEUE_AND_DISPATCH) {
+		batch_objects_command(opt, &output, &data);
+		goto cleanup;
+	}
+
 	while (strbuf_getline(&input, stdin) != EOF) {
 		if (data.split_on_whitespace) {
 			/*
@@ -608,6 +748,7 @@ static int batch_objects(struct batch_options *opt)
 		batch_one_object(input.buf, &output, opt, &data);
 	}
 
+ cleanup:
 	strbuf_release(&input);
 	strbuf_release(&output);
 	warn_on_object_refname_ambiguity = save_warning;
@@ -635,7 +776,16 @@ static int batch_option_callback(const struct option *opt,
 	}
 
 	bo->enabled = 1;
-	bo->print_contents = !strcmp(opt->long_name, "batch");
+
+	if (!strcmp(opt->long_name, "batch"))
+		bo->batch_mode = BATCH_MODE_CONTENTS;
+	else if (!strcmp(opt->long_name, "batch-check"))
+		bo->batch_mode = BATCH_MODE_INFO;
+	else if (!strcmp(opt->long_name, "batch-command"))
+		bo->batch_mode = BATCH_MODE_QUEUE_AND_DISPATCH;
+	else
+		BUG("%s given to batch-option-callback", opt->long_name);
+
 	bo->format = arg;
 
 	return 0;
@@ -654,7 +804,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 		N_("git cat-file <type> <object>"),
 		N_("git cat-file (-e | -p) <object>"),
 		N_("git cat-file (-t | -s) [--allow-unknown-type] <object>"),
-		N_("git cat-file (--batch | --batch-check) [--batch-all-objects]\n"
+		N_("git cat-file (--batch | --batch-check | --batch-command) [--batch-all-objects]\n"
 		   "             [--buffer] [--follow-symlinks] [--unordered]\n"
 		   "             [--textconv | --filters]"),
 		N_("git cat-file (--textconv | --filters)\n"
@@ -683,6 +833,10 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 			N_("like --batch, but don't emit <contents>"),
 			PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
 			batch_option_callback),
+		OPT_CALLBACK_F(0, "batch-command", &batch, N_("format"),
+			N_("read commands from stdin"),
+			PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
+			batch_option_callback),
 		OPT_CMDMODE(0, "batch-all-objects", &opt,
 			    N_("with --batch[-check]: ignores stdin, batches all known objects"), 'b'),
 		/* Batch-specific options */
@@ -742,7 +896,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 	/* Return early if we're in batch mode? */
 	if (batch.enabled) {
 		if (opt_cw)
-			batch.cmdmode = opt;
+			batch.transform_mode = opt;
 		else if (opt && opt != 'b')
 			usage_msg_optf(_("'-%c' is incompatible with batch mode"),
 				       usage, options, opt);