git/builtin/cat-file.c

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#define USE_THE_INDEX_VARIABLE
#include "cache.h"
#include "alloc.h"
#include "config.h"
#include "builtin.h"
#include "diff.h"
#include "hex.h"
#include "ident.h"
#include "parse-options.h"
#include "userdiff.h"
#include "streaming.h"
#include "tree-walk.h"
#include "oid-array.h"
#include "packfile.h"
#include "object-store.h"
#include "replace-object.h"
#include "promisor-remote.h"
#include "mailmap.h"

enum batch_mode {
	BATCH_MODE_CONTENTS,
	BATCH_MODE_INFO,
	BATCH_MODE_QUEUE_AND_DISPATCH,
};

struct batch_options {
	int enabled;
	int follow_symlinks;
	enum batch_mode batch_mode;
	int buffer_output;
	int all_objects;
	int unordered;
	int transform_mode; /* may be 'w' or 'c' for --filters or --textconv */
	int nul_terminated;
	const char *format;
};

static const char *force_path;

static struct string_list mailmap = STRING_LIST_INIT_NODUP;
static int use_mailmap;

static char *replace_idents_using_mailmap(char *, size_t *);

static char *replace_idents_using_mailmap(char *object_buf, size_t *size)
{
	struct strbuf sb = STRBUF_INIT;
	const char *headers[] = { "author ", "committer ", "tagger ", NULL };

	strbuf_attach(&sb, object_buf, *size, *size + 1);
	apply_mailmap_to_header(&sb, headers, &mailmap);
	*size = sb.len;
	return strbuf_detach(&sb, NULL);
}

static int filter_object(const char *path, unsigned mode,
			 const struct object_id *oid,
			 char **buf, unsigned long *size)
{
	enum object_type type;

	*buf = read_object_file(oid, &type, size);
	if (!*buf)
		return error(_("cannot read object %s '%s'"),
			     oid_to_hex(oid), path);
	if ((type == OBJ_BLOB) && S_ISREG(mode)) {
		struct strbuf strbuf = STRBUF_INIT;
		struct checkout_metadata meta;

		init_checkout_metadata(&meta, NULL, NULL, oid);
		if (convert_to_working_tree(&the_index, path, *buf, *size, &strbuf, &meta)) {
			free(*buf);
			*size = strbuf.len;
			*buf = strbuf_detach(&strbuf, NULL);
		}
	}

	return 0;
}

static int stream_blob(const struct object_id *oid)
{
	if (stream_blob_to_fd(1, oid, NULL, 0))
		die("unable to stream %s to stdout", oid_to_hex(oid));
	return 0;
}

static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
			int unknown_type)
{
	int ret;
	struct object_id oid;
	enum object_type type;
	char *buf;
	unsigned long size;
	struct object_context obj_context;
	struct object_info oi = OBJECT_INFO_INIT;
	struct strbuf sb = STRBUF_INIT;
	unsigned flags = OBJECT_INFO_LOOKUP_REPLACE;
	unsigned get_oid_flags = GET_OID_RECORD_PATH | GET_OID_ONLY_TO_DIE;
	const char *path = force_path;
	const int opt_cw = (opt == 'c' || opt == 'w');
	if (!path && opt_cw)
		get_oid_flags |= GET_OID_REQUIRE_PATH;

	if (unknown_type)
		flags |= OBJECT_INFO_ALLOW_UNKNOWN_TYPE;

	if (get_oid_with_context(the_repository, obj_name, get_oid_flags, &oid,
				 &obj_context))
		die("Not a valid object name %s", obj_name);

	if (!path)
		path = obj_context.path;
	if (obj_context.mode == S_IFINVALID)
		obj_context.mode = 0100644;

	buf = NULL;
	switch (opt) {
	case 't':
		oi.type_name = &sb;
		if (oid_object_info_extended(the_repository, &oid, &oi, flags) < 0)
			die("git cat-file: could not get object info");
		if (sb.len) {
			printf("%s\n", sb.buf);
			strbuf_release(&sb);
			ret = 0;
			goto cleanup;
		}
		break;

	case 's':
		oi.sizep = &size;

		if (use_mailmap) {
			oi.typep = &type;
			oi.contentp = (void**)&buf;
		}

		if (oid_object_info_extended(the_repository, &oid, &oi, flags) < 0)
			die("git cat-file: could not get object info");

		if (use_mailmap && (type == OBJ_COMMIT || type == OBJ_TAG)) {
			size_t s = size;
			buf = replace_idents_using_mailmap(buf, &s);
			size = cast_size_t_to_ulong(s);
		}

		printf("%"PRIuMAX"\n", (uintmax_t)size);
		ret = 0;
		goto cleanup;

	case 'e':
		return !has_object_file(&oid);

	case 'w':

		if (filter_object(path, obj_context.mode,
				  &oid, &buf, &size)) {
			ret = -1;
			goto cleanup;
		}
		break;

	case 'c':
		if (textconv_object(the_repository, path, obj_context.mode,
				    &oid, 1, &buf, &size))
			break;
		/* else fallthrough */

	case 'p':
		type = oid_object_info(the_repository, &oid, NULL);
		if (type < 0)
			die("Not a valid object name %s", obj_name);

		/* custom pretty-print here */
		if (type == OBJ_TREE) {
			const char *ls_args[3] = { NULL };
			ls_args[0] =  "ls-tree";
			ls_args[1] =  obj_name;
			ret = cmd_ls_tree(2, ls_args, NULL);
			goto cleanup;
		}

		if (type == OBJ_BLOB) {
			ret = stream_blob(&oid);
			goto cleanup;
		}
		buf = read_object_file(&oid, &type, &size);
		if (!buf)
			die("Cannot read object %s", obj_name);

		if (use_mailmap) {
			size_t s = size;
			buf = replace_idents_using_mailmap(buf, &s);
			size = cast_size_t_to_ulong(s);
		}

		/* otherwise just spit out the data */
		break;

	case 0:
	{
		enum object_type exp_type_id = type_from_string(exp_type);

		if (exp_type_id == OBJ_BLOB) {
			struct object_id blob_oid;
			if (oid_object_info(the_repository, &oid, NULL) == OBJ_TAG) {
				char *buffer = read_object_file(&oid, &type,
								&size);
				const char *target;
				if (!skip_prefix(buffer, "object ", &target) ||
				    get_oid_hex(target, &blob_oid))
					die("%s not a valid tag", oid_to_hex(&oid));
				free(buffer);
			} else
				oidcpy(&blob_oid, &oid);

			if (oid_object_info(the_repository, &blob_oid, NULL) == OBJ_BLOB) {
				ret = stream_blob(&blob_oid);
				goto cleanup;
			}
			/*
			 * we attempted to dereference a tag to a blob
			 * and failed; there may be new dereference
			 * mechanisms this code is not aware of.
			 * fall-back to the usual case.
			 */
		}
		buf = read_object_with_reference(the_repository, &oid,
						 exp_type_id, &size, NULL);

		if (use_mailmap) {
			size_t s = size;
			buf = replace_idents_using_mailmap(buf, &s);
			size = cast_size_t_to_ulong(s);
		}
		break;
	}
	default:
		die("git cat-file: unknown option: %s", exp_type);
	}

	if (!buf)
		die("git cat-file %s: bad file", obj_name);

	write_or_die(1, buf, size);
	ret = 0;
cleanup:
	free(buf);
	free(obj_context.path);
	return ret;
}

struct expand_data {
	struct object_id oid;
	enum object_type type;
	unsigned long size;
	off_t disk_size;
	const char *rest;
	struct object_id delta_base_oid;

	/*
	 * If mark_query is true, we do not expand anything, but rather
	 * just mark the object_info with items we wish to query.
	 */
	int mark_query;

	/*
	 * Whether to split the input on whitespace before feeding it to
	 * get_sha1; this is decided during the mark_query phase based on
	 * whether we have a %(rest) token in our format.
	 */
	int split_on_whitespace;

	/*
	 * After a mark_query run, this object_info is set up to be
	 * passed to oid_object_info_extended. It will point to the data
	 * elements above, so you can retrieve the response from there.
	 */
	struct object_info info;

	/*
	 * This flag will be true if the requested batch format and options
	 * don't require us to call oid_object_info, which can then be
	 * optimized out.
	 */
	unsigned skip_object_info : 1;
};

static int is_atom(const char *atom, const char *s, int slen)
{
	int alen = strlen(atom);
	return alen == slen && !memcmp(atom, s, alen);
}

static void expand_atom(struct strbuf *sb, const char *atom, int len,
			void *vdata)
{
	struct expand_data *data = vdata;

	if (is_atom("objectname", atom, len)) {
		if (!data->mark_query)
			strbuf_addstr(sb, oid_to_hex(&data->oid));
	} else if (is_atom("objecttype", atom, len)) {
		if (data->mark_query)
			data->info.typep = &data->type;
		else
			strbuf_addstr(sb, type_name(data->type));
	} else if (is_atom("objectsize", atom, len)) {
		if (data->mark_query)
			data->info.sizep = &data->size;
		else
			strbuf_addf(sb, "%"PRIuMAX , (uintmax_t)data->size);
	} else if (is_atom("objectsize:disk", atom, len)) {
		if (data->mark_query)
			data->info.disk_sizep = &data->disk_size;
		else
			strbuf_addf(sb, "%"PRIuMAX, (uintmax_t)data->disk_size);
	} else if (is_atom("rest", atom, len)) {
		if (data->mark_query)
			data->split_on_whitespace = 1;
		else if (data->rest)
			strbuf_addstr(sb, data->rest);
	} else if (is_atom("deltabase", atom, len)) {
		if (data->mark_query)
			data->info.delta_base_oid = &data->delta_base_oid;
		else
			strbuf_addstr(sb,
				      oid_to_hex(&data->delta_base_oid));
	} else
		die("unknown format element: %.*s", len, atom);
}

static size_t expand_format(struct strbuf *sb, const char *start, void *data)
{
	const char *end;

	if (*start != '(')
		return 0;
	end = strchr(start + 1, ')');
	if (!end)
		die("format element '%s' does not end in ')'", start);

	expand_atom(sb, start + 1, end - start - 1, data);

	return end - start + 1;
}

static void batch_write(struct batch_options *opt, const void *data, int len)
{
	if (opt->buffer_output) {
		if (fwrite(data, 1, len, stdout) != len)
			die_errno("unable to write to stdout");
	} else
		write_or_die(1, data, len);
}

static void print_object_or_die(struct batch_options *opt, struct expand_data *data)
{
	const struct object_id *oid = &data->oid;

	assert(data->info.typep);

	if (data->type == OBJ_BLOB) {
		if (opt->buffer_output)
			fflush(stdout);
		if (opt->transform_mode) {
			char *contents;
			unsigned long size;

			if (!data->rest)
				die("missing path for '%s'", oid_to_hex(oid));

			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->transform_mode == 'c') {
				enum object_type type;
				if (!textconv_object(the_repository,
						     data->rest, 0100644, oid,
						     1, &contents, &size))
					contents = read_object_file(oid,
								    &type,
								    &size);
				if (!contents)
					die("could not convert '%s' %s",
					    oid_to_hex(oid), data->rest);
			} else
				BUG("invalid transform_mode: %c", opt->transform_mode);
			batch_write(opt, contents, size);
			free(contents);
		} else {
			stream_blob(oid);
		}
	}
	else {
		enum object_type type;
		unsigned long size;
		void *contents;

		contents = read_object_file(oid, &type, &size);

		if (use_mailmap) {
			size_t s = size;
			contents = replace_idents_using_mailmap(contents, &s);
			size = cast_size_t_to_ulong(s);
		}

		if (!contents)
			die("object %s disappeared", oid_to_hex(oid));
		if (type != data->type)
			die("object %s changed type!?", oid_to_hex(oid));
		if (data->info.sizep && size != data->size && !use_mailmap)
			die("object %s changed size!?", oid_to_hex(oid));

		batch_write(opt, contents, size);
		free(contents);
	}
}

static void print_default_format(struct strbuf *scratch, struct expand_data *data)
{
	strbuf_addf(scratch, "%s %s %"PRIuMAX"\n", oid_to_hex(&data->oid),
		    type_name(data->type),
		    (uintmax_t)data->size);
}

/*
 * If "pack" is non-NULL, then "offset" is the byte offset within the pack from
 * which the object may be accessed (though note that we may also rely on
 * data->oid, too). If "pack" is NULL, then offset is ignored.
 */
static void batch_object_write(const char *obj_name,
			       struct strbuf *scratch,
			       struct batch_options *opt,
			       struct expand_data *data,
			       struct packed_git *pack,
			       off_t offset)
{
	if (!data->skip_object_info) {
		int ret;

		if (use_mailmap)
			data->info.typep = &data->type;

		if (pack)
			ret = packed_object_info(the_repository, pack, offset,
						 &data->info);
		else
			ret = oid_object_info_extended(the_repository,
						       &data->oid, &data->info,
						       OBJECT_INFO_LOOKUP_REPLACE);
		if (ret < 0) {
			printf("%s missing\n",
			       obj_name ? obj_name : oid_to_hex(&data->oid));
			fflush(stdout);
			return;
		}

		if (use_mailmap && (data->type == OBJ_COMMIT || data->type == OBJ_TAG)) {
			size_t s = data->size;
			char *buf = NULL;

			buf = repo_read_object_file(the_repository, &data->oid, &data->type,
						    &data->size);
			buf = replace_idents_using_mailmap(buf, &s);
			data->size = cast_size_t_to_ulong(s);

			free(buf);
		}
	}

	strbuf_reset(scratch);

	if (!opt->format) {
		print_default_format(scratch, data);
	} else {
		strbuf_expand(scratch, opt->format, expand_format, data);
		strbuf_addch(scratch, '\n');
	}

	batch_write(opt, scratch->buf, scratch->len);

	if (opt->batch_mode == BATCH_MODE_CONTENTS) {
		print_object_or_die(opt, data);
		batch_write(opt, "\n", 1);
	}
}

static void batch_one_object(const char *obj_name,
			     struct strbuf *scratch,
			     struct batch_options *opt,
			     struct expand_data *data)
{
	struct object_context ctx;
	int flags = opt->follow_symlinks ? GET_OID_FOLLOW_SYMLINKS : 0;
	enum get_oid_result result;

	result = get_oid_with_context(the_repository, obj_name,
				      flags, &data->oid, &ctx);
	if (result != FOUND) {
		switch (result) {
		case MISSING_OBJECT:
			printf("%s missing\n", obj_name);
			break;
		case SHORT_NAME_AMBIGUOUS:
			printf("%s ambiguous\n", obj_name);
			break;
		case DANGLING_SYMLINK:
			printf("dangling %"PRIuMAX"\n%s\n",
			       (uintmax_t)strlen(obj_name), obj_name);
			break;
		case SYMLINK_LOOP:
			printf("loop %"PRIuMAX"\n%s\n",
			       (uintmax_t)strlen(obj_name), obj_name);
			break;
		case NOT_DIR:
			printf("notdir %"PRIuMAX"\n%s\n",
			       (uintmax_t)strlen(obj_name), obj_name);
			break;
		default:
			BUG("unknown get_sha1_with_context result %d\n",
			       result);
			break;
		}
		fflush(stdout);
		return;
	}

	if (ctx.mode == 0) {
		printf("symlink %"PRIuMAX"\n%s\n",
		       (uintmax_t)ctx.symlink_path.len,
		       ctx.symlink_path.buf);
		fflush(stdout);
		return;
	}

	batch_object_write(obj_name, scratch, opt, data, NULL, 0);
}

struct object_cb_data {
	struct batch_options *opt;
	struct expand_data *expand;
	struct oidset *seen;
	struct strbuf *scratch;
};

static int batch_object_cb(const struct object_id *oid, void *vdata)
{
	struct object_cb_data *data = vdata;
	oidcpy(&data->expand->oid, oid);
	batch_object_write(NULL, data->scratch, data->opt, data->expand,
			   NULL, 0);
	return 0;
}

static int collect_loose_object(const struct object_id *oid,
				const char *path,
				void *data)
{
	oid_array_append(data, oid);
	return 0;
}

static int collect_packed_object(const struct object_id *oid,
				 struct packed_git *pack,
				 uint32_t pos,
				 void *data)
{
	oid_array_append(data, oid);
	return 0;
}

static int batch_unordered_object(const struct object_id *oid,
				  struct packed_git *pack, off_t offset,
				  void *vdata)
{
	struct object_cb_data *data = vdata;

	if (oidset_insert(data->seen, oid))
		return 0;

	oidcpy(&data->expand->oid, oid);
	batch_object_write(NULL, data->scratch, data->opt, data->expand,
			   pack, offset);
	return 0;
}

static int batch_unordered_loose(const struct object_id *oid,
				 const char *path,
				 void *data)
{
	return batch_unordered_object(oid, NULL, 0, data);
}

static int batch_unordered_packed(const struct object_id *oid,
				  struct packed_git *pack,
				  uint32_t pos,
				  void *data)
{
	return batch_unordered_object(oid, pack,
				      nth_packed_object_offset(pack, pos),
				      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 (1) {
		int i, ret;
		const struct parse_cmd *cmd = NULL;
		const char *p = NULL, *cmd_end;
		struct queued_cmd call = {0};

		if (opt->nul_terminated)
			ret = strbuf_getline_nul(&input, stdin);
		else
			ret = strbuf_getline(&input, stdin);

		if (ret)
			break;

		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_cmds(queued_cmd, &nr);
	free(queued_cmd);
	strbuf_release(&input);
}

#define DEFAULT_FORMAT "%(objectname) %(objecttype) %(objectsize)"

static int batch_objects(struct batch_options *opt)
{
	struct strbuf input = STRBUF_INIT;
	struct strbuf output = STRBUF_INIT;
	struct expand_data data;
	int save_warning;
	int retval = 0;

	/*
	 * Expand once with our special mark_query flag, which will prime the
	 * object_info to be handed to oid_object_info_extended for each
	 * object.
	 */
	memset(&data, 0, sizeof(data));
	data.mark_query = 1;
	strbuf_expand(&output,
		      opt->format ? opt->format : DEFAULT_FORMAT,
		      expand_format,
		      &data);
	data.mark_query = 0;
	strbuf_release(&output);
	if (opt->transform_mode)
		data.split_on_whitespace = 1;

	if (opt->format && !strcmp(opt->format, DEFAULT_FORMAT))
		opt->format = NULL;
	/*
	 * 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->batch_mode == BATCH_MODE_CONTENTS)
		data.info.typep = &data.type;

	if (opt->all_objects) {
		struct object_cb_data cb;
		struct object_info empty = OBJECT_INFO_INIT;

		if (!memcmp(&data.info, &empty, sizeof(empty)))
			data.skip_object_info = 1;

		if (has_promisor_remote())
			warning("This repository uses promisor remotes. Some objects may not be loaded.");

		read_replace_refs = 0;

		cb.opt = opt;
		cb.expand = &data;
		cb.scratch = &output;

		if (opt->unordered) {
			struct oidset seen = OIDSET_INIT;

			cb.seen = &seen;

			for_each_loose_object(batch_unordered_loose, &cb, 0);
			for_each_packed_object(batch_unordered_packed, &cb,
					       FOR_EACH_OBJECT_PACK_ORDER);

			oidset_clear(&seen);
		} else {
			struct oid_array sa = OID_ARRAY_INIT;

			for_each_loose_object(collect_loose_object, &sa, 0);
			for_each_packed_object(collect_packed_object, &sa, 0);

			oid_array_for_each_unique(&sa, batch_object_cb, &cb);

			oid_array_clear(&sa);
		}

		strbuf_release(&output);
		return 0;
	}

	/*
	 * We are going to call get_sha1 on a potentially very large number of
	 * objects. In most large cases, these will be actual object sha1s. The
	 * cost to double-check that each one is not also a ref (just so we can
	 * warn) ends up dwarfing the actual cost of the object lookups
	 * themselves. We can work around it by just turning off the warning.
	 */
	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 (1) {
		int ret;
		if (opt->nul_terminated)
			ret = strbuf_getline_nul(&input, stdin);
		else
			ret = strbuf_getline(&input, stdin);

		if (ret == EOF)
			break;

		if (data.split_on_whitespace) {
			/*
			 * Split at first whitespace, tying off the beginning
			 * of the string and saving the remainder (or NULL) in
			 * data.rest.
			 */
			char *p = strpbrk(input.buf, " \t");
			if (p) {
				while (*p && strchr(" \t", *p))
					*p++ = '\0';
			}
			data.rest = p;
		}

		batch_one_object(input.buf, &output, opt, &data);
	}

 cleanup:
	strbuf_release(&input);
	strbuf_release(&output);
	warn_on_object_refname_ambiguity = save_warning;
	return retval;
}

static int git_cat_file_config(const char *var, const char *value, void *cb)
{
	if (userdiff_config(var, value) < 0)
		return -1;

	return git_default_config(var, value, cb);
}

static int batch_option_callback(const struct option *opt,
				 const char *arg,
				 int unset)
{
	struct batch_options *bo = opt->value;

	BUG_ON_OPT_NEG(unset);

	if (bo->enabled) {
		return error(_("only one batch option may be specified"));
	}

	bo->enabled = 1;

	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;
}

int cmd_cat_file(int argc, const char **argv, const char *prefix)
{
	int opt = 0;
	int opt_cw = 0;
	int opt_epts = 0;
	const char *exp_type = NULL, *obj_name = NULL;
	struct batch_options batch = {0};
	int unknown_type = 0;

	const char * const usage[] = {
		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-command) [--batch-all-objects]\n"
		   "             [--buffer] [--follow-symlinks] [--unordered]\n"
		   "             [--textconv | --filters] [-z]"),
		N_("git cat-file (--textconv | --filters)\n"
		   "             [<rev>:<path|tree-ish> | --path=<path|tree-ish> <rev>]"),
		NULL
	};
	const struct option options[] = {
		/* Simple queries */
		OPT_GROUP(N_("Check object existence or emit object contents")),
		OPT_CMDMODE('e', NULL, &opt,
			    N_("check if <object> exists"), 'e'),
		OPT_CMDMODE('p', NULL, &opt, N_("pretty-print <object> content"), 'p'),

		OPT_GROUP(N_("Emit [broken] object attributes")),
		OPT_CMDMODE('t', NULL, &opt, N_("show object type (one of 'blob', 'tree', 'commit', 'tag', ...)"), 't'),
		OPT_CMDMODE('s', NULL, &opt, N_("show object size"), 's'),
		OPT_BOOL(0, "allow-unknown-type", &unknown_type,
			  N_("allow -s and -t to work with broken/corrupt objects")),
		OPT_BOOL(0, "use-mailmap", &use_mailmap, N_("use mail map file")),
		OPT_ALIAS(0, "mailmap", "use-mailmap"),
		/* Batch mode */
		OPT_GROUP(N_("Batch objects requested on stdin (or --batch-all-objects)")),
		OPT_CALLBACK_F(0, "batch", &batch, N_("format"),
			N_("show full <object> or <rev> contents"),
			PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
			batch_option_callback),
		OPT_CALLBACK_F(0, "batch-check", &batch, N_("format"),
			N_("like --batch, but don't emit <contents>"),
			PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
			batch_option_callback),
		OPT_BOOL('z', NULL, &batch.nul_terminated, N_("stdin is NUL-terminated")),
		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 */
		OPT_GROUP(N_("Change or optimize batch output")),
		OPT_BOOL(0, "buffer", &batch.buffer_output, N_("buffer --batch output")),
		OPT_BOOL(0, "follow-symlinks", &batch.follow_symlinks,
			 N_("follow in-tree symlinks")),
		OPT_BOOL(0, "unordered", &batch.unordered,
			 N_("do not order objects before emitting them")),
		/* Textconv options, stand-ole*/
		OPT_GROUP(N_("Emit object (blob or tree) with conversion or filter (stand-alone, or with batch)")),
		OPT_CMDMODE(0, "textconv", &opt,
			    N_("run textconv on object's content"), 'c'),
		OPT_CMDMODE(0, "filters", &opt,
			    N_("run filters on object's content"), 'w'),
		OPT_STRING(0, "path", &force_path, N_("blob|tree"),
			   N_("use a <path> for (--textconv | --filters); Not with 'batch'")),
		OPT_END()
	};

	git_config(git_cat_file_config, NULL);

	batch.buffer_output = -1;

	argc = parse_options(argc, argv, prefix, options, usage, 0);
	opt_cw = (opt == 'c' || opt == 'w');
	opt_epts = (opt == 'e' || opt == 'p' || opt == 't' || opt == 's');

	if (use_mailmap)
		read_mailmap(&mailmap);

	/* --batch-all-objects? */
	if (opt == 'b')
		batch.all_objects = 1;

	/* Option compatibility */
	if (force_path && !opt_cw)
		usage_msg_optf(_("'%s=<%s>' needs '%s' or '%s'"),
			       usage, options,
			       "--path", _("path|tree-ish"), "--filters",
			       "--textconv");

	/* Option compatibility with batch mode */
	if (batch.enabled)
		;
	else if (batch.follow_symlinks)
		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
			       "--follow-symlinks");
	else if (batch.buffer_output >= 0)
		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
			       "--buffer");
	else if (batch.all_objects)
		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
			       "--batch-all-objects");
	else if (batch.nul_terminated)
		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
			       "-z");

	/* Batch defaults */
	if (batch.buffer_output < 0)
		batch.buffer_output = batch.all_objects;

	/* Return early if we're in batch mode? */
	if (batch.enabled) {
		if (opt_cw)
			batch.transform_mode = opt;
		else if (opt && opt != 'b')
			usage_msg_optf(_("'-%c' is incompatible with batch mode"),
				       usage, options, opt);
		else if (argc)
			usage_msg_opt(_("batch modes take no arguments"), usage,
				      options);

		return batch_objects(&batch);
	}

	if (opt) {
		if (!argc && opt == 'c')
			usage_msg_optf(_("<rev> required with '%s'"),
				       usage, options, "--textconv");
		else if (!argc && opt == 'w')
			usage_msg_optf(_("<rev> required with '%s'"),
				       usage, options, "--filters");
		else if (!argc && opt_epts)
			usage_msg_optf(_("<object> required with '-%c'"),
				       usage, options, opt);
		else if (argc == 1)
			obj_name = argv[0];
		else
			usage_msg_opt(_("too many arguments"), usage, options);
	} else if (!argc) {
		usage_with_options(usage, options);
	} else if (argc != 2) {
		usage_msg_optf(_("only two arguments allowed in <type> <object> mode, not %d"),
			      usage, options, argc);
	} else if (argc) {
		exp_type = argv[0];
		obj_name = argv[1];
	}

	if (unknown_type && opt != 't' && opt != 's')
		die("git cat-file --allow-unknown-type: use with -s or -t");
	return cat_one_file(opt, exp_type, obj_name, unknown_type);
}