builtin-fast-export.c - pub/scm/git/git - Git at Google

 /*
  * "git fast-export" builtin command
  *
  * Copyright (C) 2007 Johannes E. Schindelin
  */
 #include "builtin.h"
 #include "cache.h"
 #include "commit.h"
 #include "object.h"
 #include "tag.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "log-tree.h"
 #include "revision.h"
 #include "decorate.h"
 #include "string-list.h"
 #include "utf8.h"
 #include "parse-options.h"

 static const char *fast_export_usage[] = {
 	"git fast-export [rev-list-opts]",
 	NULL
 };

 static int progress;
 static enum { ABORT, VERBATIM, WARN, STRIP } signed_tag_mode = ABORT;
 static enum { ERROR, DROP, REWRITE } tag_of_filtered_mode = ABORT;
 static int fake_missing_tagger;
 static int no_data;

 static int parse_opt_signed_tag_mode(const struct option *opt,
 				     const char *arg, int unset)
 {
 	if (unset || !strcmp(arg, "abort"))
 		signed_tag_mode = ABORT;
 	else if (!strcmp(arg, "verbatim") || !strcmp(arg, "ignore"))
 		signed_tag_mode = VERBATIM;
 	else if (!strcmp(arg, "warn"))
 		signed_tag_mode = WARN;
 	else if (!strcmp(arg, "strip"))
 		signed_tag_mode = STRIP;
 	else
 		return error("Unknown signed-tag mode: %s", arg);
 	return 0;
 }

 static int parse_opt_tag_of_filtered_mode(const struct option *opt,
 					  const char *arg, int unset)
 {
 	if (unset || !strcmp(arg, "abort"))
 		tag_of_filtered_mode = ABORT;
 	else if (!strcmp(arg, "drop"))
 		tag_of_filtered_mode = DROP;
 	else if (!strcmp(arg, "rewrite"))
 		tag_of_filtered_mode = REWRITE;
 	else
 		return error("Unknown tag-of-filtered mode: %s", arg);
 	return 0;
 }

 static struct decoration idnums;
 static uint32_t last_idnum;

 static int has_unshown_parent(struct commit *commit)
 {
 	struct commit_list *parent;

 	for (parent = commit->parents; parent; parent = parent->next)
 		if (!(parent->item->object.flags & SHOWN) &&
 		    !(parent->item->object.flags & UNINTERESTING))
 			return 1;
 	return 0;
 }

 /* Since intptr_t is C99, we do not use it here */
 static inline uint32_t *mark_to_ptr(uint32_t mark)
 {
 	return ((uint32_t *)NULL) + mark;
 }

 static inline uint32_t ptr_to_mark(void * mark)
 {
 	return (uint32_t *)mark - (uint32_t *)NULL;
 }

 static inline void mark_object(struct object *object, uint32_t mark)
 {
 	add_decoration(&idnums, object, mark_to_ptr(mark));
 }

 static inline void mark_next_object(struct object *object)
 {
 	mark_object(object, ++last_idnum);
 }

 static int get_object_mark(struct object *object)
 {
 	void *decoration = lookup_decoration(&idnums, object);
 	if (!decoration)
 		return 0;
 	return ptr_to_mark(decoration);
 }

 static void show_progress(void)
 {
 	static int counter = 0;
 	if (!progress)
 		return;
 	if ((++counter % progress) == 0)
 		printf("progress %d objects\n", counter);
 }

 static void handle_object(const unsigned char *sha1)
 {
 	unsigned long size;
 	enum object_type type;
 	char *buf;
 	struct object *object;

 	if (no_data)
 		return;

 	if (is_null_sha1(sha1))
 		return;

 	object = parse_object(sha1);
 	if (!object)
 		die ("Could not read blob %s", sha1_to_hex(sha1));

 	if (object->flags & SHOWN)
 		return;

 	buf = read_sha1_file(sha1, &type, &size);
 	if (!buf)
 		die ("Could not read blob %s", sha1_to_hex(sha1));

 	mark_next_object(object);

 	printf("blob\nmark :%"PRIu32"\ndata %lu\n", last_idnum, size);
 	if (size && fwrite(buf, size, 1, stdout) != 1)
 		die_errno ("Could not write blob '%s'", sha1_to_hex(sha1));
 	printf("\n");

 	show_progress();

 	object->flags |= SHOWN;
 	free(buf);
 }

 static void show_filemodify(struct diff_queue_struct *q,
 			    struct diff_options *options, void *data)
 {
 	int i;
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filespec *ospec = q->queue[i]->one;
 		struct diff_filespec *spec = q->queue[i]->two;

 		switch (q->queue[i]->status) {
 		case DIFF_STATUS_DELETED:
 			printf("D %s\n", spec->path);
 			break;

 		case DIFF_STATUS_COPIED:
 		case DIFF_STATUS_RENAMED:
 			printf("%c \"%s\" \"%s\"\n", q->queue[i]->status,
 			       ospec->path, spec->path);

 			if (!hashcmp(ospec->sha1, spec->sha1) &&
 			    ospec->mode == spec->mode)
 				break;
 			/* fallthrough */

 		case DIFF_STATUS_TYPE_CHANGED:
 		case DIFF_STATUS_MODIFIED:
 		case DIFF_STATUS_ADDED:
 			/*
 			 * Links refer to objects in another repositories;
 			 * output the SHA-1 verbatim.
 			 */
 			if (no_data || S_ISGITLINK(spec->mode))
 				printf("M %06o %s %s\n", spec->mode,
 				       sha1_to_hex(spec->sha1), spec->path);
 			else {
 				struct object *object = lookup_object(spec->sha1);
 				printf("M %06o :%d %s\n", spec->mode,
 				       get_object_mark(object), spec->path);
 			}
 			break;

 		default:
 			die("Unexpected comparison status '%c' for %s, %s",
 				q->queue[i]->status,
 				ospec->path ? ospec->path : "none",
 				spec->path ? spec->path : "none");
 		}
 	}
 }

 static const char *find_encoding(const char *begin, const char *end)
 {
 	const char *needle = "\nencoding ";
 	char *bol, *eol;

 	bol = memmem(begin, end ? end - begin : strlen(begin),
 		     needle, strlen(needle));
 	if (!bol)
 		return git_commit_encoding;
 	bol += strlen(needle);
 	eol = strchrnul(bol, '\n');
 	*eol = '\0';
 	return bol;
 }

 static void handle_commit(struct commit *commit, struct rev_info *rev)
 {
 	int saved_output_format = rev->diffopt.output_format;
 	const char *author, *author_end, *committer, *committer_end;
 	const char *encoding, *message;
 	char *reencoded = NULL;
 	struct commit_list *p;
 	int i;

 	rev->diffopt.output_format = DIFF_FORMAT_CALLBACK;

 	parse_commit(commit);
 	author = strstr(commit->buffer, "\nauthor ");
 	if (!author)
 		die ("Could not find author in commit %s",
 		     sha1_to_hex(commit->object.sha1));
 	author++;
 	author_end = strchrnul(author, '\n');
 	committer = strstr(author_end, "\ncommitter ");
 	if (!committer)
 		die ("Could not find committer in commit %s",
 		     sha1_to_hex(commit->object.sha1));
 	committer++;
 	committer_end = strchrnul(committer, '\n');
 	message = strstr(committer_end, "\n\n");
 	encoding = find_encoding(committer_end, message);
 	if (message)
 		message += 2;

 	if (commit->parents &&
 	    get_object_mark(&commit->parents->item->object) != 0) {
 		parse_commit(commit->parents->item);
 		diff_tree_sha1(commit->parents->item->tree->object.sha1,
 			       commit->tree->object.sha1, "", &rev->diffopt);
 	}
 	else
 		diff_root_tree_sha1(commit->tree->object.sha1,
 				    "", &rev->diffopt);

 	/* Export the referenced blobs, and remember the marks. */
 	for (i = 0; i < diff_queued_diff.nr; i++)
 		if (!S_ISGITLINK(diff_queued_diff.queue[i]->two->mode))
 			handle_object(diff_queued_diff.queue[i]->two->sha1);

 	mark_next_object(&commit->object);
 	if (!is_encoding_utf8(encoding))
 		reencoded = reencode_string(message, "UTF-8", encoding);
 	if (!commit->parents)
 		printf("reset %s\n", (const char*)commit->util);
 	printf("commit %s\nmark :%"PRIu32"\n%.*s\n%.*s\ndata %u\n%s",
 	       (const char *)commit->util, last_idnum,
 	       (int)(author_end - author), author,
 	       (int)(committer_end - committer), committer,
 	       (unsigned)(reencoded
 			  ? strlen(reencoded) : message
 			  ? strlen(message) : 0),
 	       reencoded ? reencoded : message ? message : "");
 	free(reencoded);

 	for (i = 0, p = commit->parents; p; p = p->next) {
 		int mark = get_object_mark(&p->item->object);
 		if (!mark)
 			continue;
 		if (i == 0)
 			printf("from :%d\n", mark);
 		else
 			printf("merge :%d\n", mark);
 		i++;
 	}

 	log_tree_diff_flush(rev);
 	rev->diffopt.output_format = saved_output_format;

 	printf("\n");

 	show_progress();
 }

 static void handle_tail(struct object_array *commits, struct rev_info *revs)
 {
 	struct commit *commit;
 	while (commits->nr) {
 		commit = (struct commit *)commits->objects[commits->nr - 1].item;
 		if (has_unshown_parent(commit))
 			return;
 		handle_commit(commit, revs);
 		commits->nr--;
 	}
 }

 static void handle_tag(const char *name, struct tag *tag)
 {
 	unsigned long size;
 	enum object_type type;
 	char *buf;
 	const char *tagger, *tagger_end, *message;
 	size_t message_size = 0;
 	struct object *tagged;
 	int tagged_mark;
 	struct commit *p;

 	/* Trees have no identifer in fast-export output, thus we have no way
 	 * to output tags of trees, tags of tags of trees, etc.  Simply omit
 	 * such tags.
 	 */
 	tagged = tag->tagged;
 	while (tagged->type == OBJ_TAG) {
 		tagged = ((struct tag *)tagged)->tagged;
 	}
 	if (tagged->type == OBJ_TREE) {
 		warning("Omitting tag %s,\nsince tags of trees (or tags of tags of trees, etc.) are not supported.",
 			sha1_to_hex(tag->object.sha1));
 		return;
 	}

 	buf = read_sha1_file(tag->object.sha1, &type, &size);
 	if (!buf)
 		die ("Could not read tag %s", sha1_to_hex(tag->object.sha1));
 	message = memmem(buf, size, "\n\n", 2);
 	if (message) {
 		message += 2;
 		message_size = strlen(message);
 	}
 	tagger = memmem(buf, message ? message - buf : size, "\ntagger ", 8);
 	if (!tagger) {
 		if (fake_missing_tagger)
 			tagger = "tagger Unspecified Tagger "
 				"<unspecified-tagger> 0 +0000";
 		else
 			tagger = "";
 		tagger_end = tagger + strlen(tagger);
 	} else {
 		tagger++;
 		tagger_end = strchrnul(tagger, '\n');
 	}

 	/* handle signed tags */
 	if (message) {
 		const char *signature = strstr(message,
 					       "\n-----BEGIN PGP SIGNATURE-----\n");
 		if (signature)
 			switch(signed_tag_mode) {
 			case ABORT:
 				die ("Encountered signed tag %s; use "
 				     "--signed-tag=<mode> to handle it.",
 				     sha1_to_hex(tag->object.sha1));
 			case WARN:
 				warning ("Exporting signed tag %s",
 					 sha1_to_hex(tag->object.sha1));
 				/* fallthru */
 			case VERBATIM:
 				break;
 			case STRIP:
 				message_size = signature + 1 - message;
 				break;
 			}
 	}

 	/* handle tag->tagged having been filtered out due to paths specified */
 	tagged = tag->tagged;
 	tagged_mark = get_object_mark(tagged);
 	if (!tagged_mark) {
 		switch(tag_of_filtered_mode) {
 		case ABORT:
 			die ("Tag %s tags unexported object; use "
 			     "--tag-of-filtered-object=<mode> to handle it.",
 			     sha1_to_hex(tag->object.sha1));
 		case DROP:
 			/* Ignore this tag altogether */
 			return;
 		case REWRITE:
 			if (tagged->type != OBJ_COMMIT) {
 				die ("Tag %s tags unexported %s!",
 				     sha1_to_hex(tag->object.sha1),
 				     typename(tagged->type));
 			}
 			p = (struct commit *)tagged;
 			for (;;) {
 				if (p->parents && p->parents->next)
 					break;
 				if (p->object.flags & UNINTERESTING)
 					break;
 				if (!(p->object.flags & TREESAME))
 					break;
 				if (!p->parents)
 					die ("Can't find replacement commit for tag %s\n",
 					     sha1_to_hex(tag->object.sha1));
 				p = p->parents->item;
 			}
 			tagged_mark = get_object_mark(&p->object);
 		}
 	}

 	if (!prefixcmp(name, "refs/tags/"))
 		name += 10;
 	printf("tag %s\nfrom :%d\n%.*s%sdata %d\n%.*s\n",
 	       name, tagged_mark,
 	       (int)(tagger_end - tagger), tagger,
 	       tagger == tagger_end ? "" : "\n",
 	       (int)message_size, (int)message_size, message ? message : "");
 }

 static void get_tags_and_duplicates(struct object_array *pending,
 				    struct string_list *extra_refs)
 {
 	struct tag *tag;
 	int i;

 	for (i = 0; i < pending->nr; i++) {
 		struct object_array_entry *e = pending->objects + i;
 		unsigned char sha1[20];
 		struct commit *commit = commit;
 		char *full_name;

 		if (dwim_ref(e->name, strlen(e->name), sha1, &full_name) != 1)
 			continue;

 		switch (e->item->type) {
 		case OBJ_COMMIT:
 			commit = (struct commit *)e->item;
 			break;
 		case OBJ_TAG:
 			tag = (struct tag *)e->item;

 			/* handle nested tags */
 			while (tag && tag->object.type == OBJ_TAG) {
 				parse_object(tag->object.sha1);
 				string_list_append(full_name, extra_refs)->util = tag;
 				tag = (struct tag *)tag->tagged;
 			}
 			if (!tag)
 				die ("Tag %s points nowhere?", e->name);
 			switch(tag->object.type) {
 			case OBJ_COMMIT:
 				commit = (struct commit *)tag;
 				break;
 			case OBJ_BLOB:
 				handle_object(tag->object.sha1);
 				continue;
 			default: /* OBJ_TAG (nested tags) is already handled */
 				warning("Tag points to object of unexpected type %s, skipping.",
 					typename(tag->object.type));
 				continue;
 			}
 			break;
 		default:
 			warning("%s: Unexpected object of type %s, skipping.",
 				e->name,
 				typename(e->item->type));
 			continue;
 		}
 		if (commit->util)
 			/* more than one name for the same object */
 			string_list_append(full_name, extra_refs)->util = commit;
 		else
 			commit->util = full_name;
 	}
 }

 static void handle_tags_and_duplicates(struct string_list *extra_refs)
 {
 	struct commit *commit;
 	int i;

 	for (i = extra_refs->nr - 1; i >= 0; i--) {
 		const char *name = extra_refs->items[i].string;
 		struct object *object = extra_refs->items[i].util;
 		switch (object->type) {
 		case OBJ_TAG:
 			handle_tag(name, (struct tag *)object);
 			break;
 		case OBJ_COMMIT:
 			/* create refs pointing to already seen commits */
 			commit = (struct commit *)object;
 			printf("reset %s\nfrom :%d\n\n", name,
 			       get_object_mark(&commit->object));
 			show_progress();
 			break;
 		}
 	}
 }

 static void export_marks(char *file)
 {
 	unsigned int i;
 	uint32_t mark;
 	struct object_decoration *deco = idnums.hash;
 	FILE *f;
 	int e = 0;

 	f = fopen(file, "w");
 	if (!f)
 		error("Unable to open marks file %s for writing.", file);

 	for (i = 0; i < idnums.size; i++) {
 		if (deco->base && deco->base->type == 1) {
 			mark = ptr_to_mark(deco->decoration);
 			if (fprintf(f, ":%"PRIu32" %s\n", mark,
 				sha1_to_hex(deco->base->sha1)) < 0) {
 			    e = 1;
 			    break;
 			}
 		}
 		deco++;
 	}

 	e |= ferror(f);
 	e |= fclose(f);
 	if (e)
 		error("Unable to write marks file %s.", file);
 }

 static void import_marks(char *input_file)
 {
 	char line[512];
 	FILE *f = fopen(input_file, "r");
 	if (!f)
 		die_errno("cannot read '%s'", input_file);

 	while (fgets(line, sizeof(line), f)) {
 		uint32_t mark;
 		char *line_end, *mark_end;
 		unsigned char sha1[20];
 		struct object *object;

 		line_end = strchr(line, '\n');
 		if (line[0] != ':' || !line_end)
 			die("corrupt mark line: %s", line);
 		*line_end = '\0';

 		mark = strtoumax(line + 1, &mark_end, 10);
 		if (!mark || mark_end == line + 1
 			|| *mark_end != ' ' || get_sha1(mark_end + 1, sha1))
 			die("corrupt mark line: %s", line);

 		object = parse_object(sha1);
 		if (!object)
 			die ("Could not read blob %s", sha1_to_hex(sha1));

 		if (object->flags & SHOWN)
 			error("Object %s already has a mark", sha1);

 		mark_object(object, mark);
 		if (last_idnum < mark)
 			last_idnum = mark;

 		object->flags |= SHOWN;
 	}
 	fclose(f);
 }

 int cmd_fast_export(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info revs;
 	struct object_array commits = { 0, 0, NULL };
 	struct string_list extra_refs = { NULL, 0, 0, 0 };
 	struct commit *commit;
 	char *export_filename = NULL, *import_filename = NULL;
 	struct option options[] = {
 		OPT_INTEGER(0, "progress", &progress,
 			    "show progress after <n> objects"),
 		OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, "mode",
 			     "select handling of signed tags",
 			     parse_opt_signed_tag_mode),
 		OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, "mode",
 			     "select handling of tags that tag filtered objects",
 			     parse_opt_tag_of_filtered_mode),
 		OPT_STRING(0, "export-marks", &export_filename, "FILE",
 			     "Dump marks to this file"),
 		OPT_STRING(0, "import-marks", &import_filename, "FILE",
 			     "Import marks from this file"),
 		OPT_BOOLEAN(0, "fake-missing-tagger", &fake_missing_tagger,
 			     "Fake a tagger when tags lack one"),
 		{ OPTION_NEGBIT, 0, "data", &no_data, NULL,
 			"Skip output of blob data",
 			PARSE_OPT_NOARG | PARSE_OPT_NEGHELP, NULL, 1 },
 		OPT_END()
 	};

 	if (argc == 1)
 		usage_with_options (fast_export_usage, options);

 	/* we handle encodings */
 	git_config(git_default_config, NULL);

 	init_revisions(&revs, prefix);
 	revs.topo_order = 1;
 	revs.show_source = 1;
 	revs.rewrite_parents = 1;
 	argc = setup_revisions(argc, argv, &revs, NULL);
 	argc = parse_options(argc, argv, prefix, options, fast_export_usage, 0);
 	if (argc > 1)
 		usage_with_options (fast_export_usage, options);

 	if (import_filename)
 		import_marks(import_filename);

 	get_tags_and_duplicates(&revs.pending, &extra_refs);

 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
 	revs.diffopt.format_callback = show_filemodify;
 	DIFF_OPT_SET(&revs.diffopt, RECURSIVE);
 	while ((commit = get_revision(&revs))) {
 		if (has_unshown_parent(commit)) {
 			add_object_array(&commit->object, NULL, &commits);
 		}
 		else {
 			handle_commit(commit, &revs);
 			handle_tail(&commits, &revs);
 		}
 	}

 	handle_tags_and_duplicates(&extra_refs);

 	if (export_filename)
 		export_marks(export_filename);

 	return 0;
 }
	/*
	* "git fast-export" builtin command
	*
	* Copyright (C) 2007 Johannes E. Schindelin
	*/
	#include "builtin.h"
	#include "cache.h"
	#include "commit.h"
	#include "object.h"
	#include "tag.h"
	#include "diff.h"
	#include "diffcore.h"
	#include "log-tree.h"
	#include "revision.h"
	#include "decorate.h"
	#include "string-list.h"
	#include "utf8.h"
	#include "parse-options.h"

	static const char *fast_export_usage[] = {
	"git fast-export [rev-list-opts]",
	NULL
	};

	static int progress;
	static enum { ABORT, VERBATIM, WARN, STRIP } signed_tag_mode = ABORT;
	static enum { ERROR, DROP, REWRITE } tag_of_filtered_mode = ABORT;
	static int fake_missing_tagger;
	static int no_data;

	static int parse_opt_signed_tag_mode(const struct option *opt,
	const char *arg, int unset)
	{
	if (unset \|\| !strcmp(arg, "abort"))
	signed_tag_mode = ABORT;
	else if (!strcmp(arg, "verbatim") \|\| !strcmp(arg, "ignore"))
	signed_tag_mode = VERBATIM;
	else if (!strcmp(arg, "warn"))
	signed_tag_mode = WARN;
	else if (!strcmp(arg, "strip"))
	signed_tag_mode = STRIP;
	else
	return error("Unknown signed-tag mode: %s", arg);
	return 0;
	}

	static int parse_opt_tag_of_filtered_mode(const struct option *opt,
	const char *arg, int unset)
	{
	if (unset \|\| !strcmp(arg, "abort"))
	tag_of_filtered_mode = ABORT;
	else if (!strcmp(arg, "drop"))
	tag_of_filtered_mode = DROP;
	else if (!strcmp(arg, "rewrite"))
	tag_of_filtered_mode = REWRITE;
	else
	return error("Unknown tag-of-filtered mode: %s", arg);
	return 0;
	}

	static struct decoration idnums;
	static uint32_t last_idnum;

	static int has_unshown_parent(struct commit *commit)
	{
	struct commit_list *parent;

	for (parent = commit->parents; parent; parent = parent->next)
	if (!(parent->item->object.flags & SHOWN) &&
	!(parent->item->object.flags & UNINTERESTING))
	return 1;
	return 0;
	}

	/* Since intptr_t is C99, we do not use it here */
	static inline uint32_t *mark_to_ptr(uint32_t mark)
	{
	return ((uint32_t *)NULL) + mark;
	}

	static inline uint32_t ptr_to_mark(void * mark)
	{
	return (uint32_t )mark - (uint32_t )NULL;
	}

	static inline void mark_object(struct object *object, uint32_t mark)
	{
	add_decoration(&idnums, object, mark_to_ptr(mark));
	}

	static inline void mark_next_object(struct object *object)
	{
	mark_object(object, ++last_idnum);
	}

	static int get_object_mark(struct object *object)
	{
	void *decoration = lookup_decoration(&idnums, object);
	if (!decoration)
	return 0;
	return ptr_to_mark(decoration);
	}

	static void show_progress(void)
	{
	static int counter = 0;
	if (!progress)
	return;
	if ((++counter % progress) == 0)
	printf("progress %d objects\n", counter);
	}

	static void handle_object(const unsigned char *sha1)
	{
	unsigned long size;
	enum object_type type;
	char *buf;
	struct object *object;

	if (no_data)
	return;

	if (is_null_sha1(sha1))
	return;

	object = parse_object(sha1);
	if (!object)
	die ("Could not read blob %s", sha1_to_hex(sha1));

	if (object->flags & SHOWN)
	return;

	buf = read_sha1_file(sha1, &type, &size);
	if (!buf)
	die ("Could not read blob %s", sha1_to_hex(sha1));

	mark_next_object(object);

	printf("blob\nmark :%"PRIu32"\ndata %lu\n", last_idnum, size);
	if (size && fwrite(buf, size, 1, stdout) != 1)
	die_errno ("Could not write blob '%s'", sha1_to_hex(sha1));
	printf("\n");

	show_progress();

	object->flags \|= SHOWN;
	free(buf);
	}

	static void show_filemodify(struct diff_queue_struct *q,
	struct diff_options options, void data)
	{
	int i;
	for (i = 0; i < q->nr; i++) {
	struct diff_filespec *ospec = q->queue[i]->one;
	struct diff_filespec *spec = q->queue[i]->two;

	switch (q->queue[i]->status) {
	case DIFF_STATUS_DELETED:
	printf("D %s\n", spec->path);
	break;

	case DIFF_STATUS_COPIED:
	case DIFF_STATUS_RENAMED:
	printf("%c \"%s\" \"%s\"\n", q->queue[i]->status,
	ospec->path, spec->path);

	if (!hashcmp(ospec->sha1, spec->sha1) &&
	ospec->mode == spec->mode)
	break;
	/* fallthrough */

	case DIFF_STATUS_TYPE_CHANGED:
	case DIFF_STATUS_MODIFIED:
	case DIFF_STATUS_ADDED:
	/*
	* Links refer to objects in another repositories;
	* output the SHA-1 verbatim.
	*/
	if (no_data \|\| S_ISGITLINK(spec->mode))
	printf("M %06o %s %s\n", spec->mode,
	sha1_to_hex(spec->sha1), spec->path);
	else {
	struct object *object = lookup_object(spec->sha1);
	printf("M %06o :%d %s\n", spec->mode,
	get_object_mark(object), spec->path);
	}
	break;

	default:
	die("Unexpected comparison status '%c' for %s, %s",
	q->queue[i]->status,
	ospec->path ? ospec->path : "none",
	spec->path ? spec->path : "none");
	}
	}
	}

	static const char find_encoding(const char begin, const char *end)
	{
	const char *needle = "\nencoding ";
	char bol, eol;

	bol = memmem(begin, end ? end - begin : strlen(begin),
	needle, strlen(needle));
	if (!bol)
	return git_commit_encoding;
	bol += strlen(needle);
	eol = strchrnul(bol, '\n');
	*eol = '\0';
	return bol;
	}

	static void handle_commit(struct commit commit, struct rev_info rev)
	{
	int saved_output_format = rev->diffopt.output_format;
	const char author, author_end, committer, committer_end;
	const char encoding, message;
	char *reencoded = NULL;
	struct commit_list *p;
	int i;

	rev->diffopt.output_format = DIFF_FORMAT_CALLBACK;

	parse_commit(commit);
	author = strstr(commit->buffer, "\nauthor ");
	if (!author)
	die ("Could not find author in commit %s",
	sha1_to_hex(commit->object.sha1));
	author++;
	author_end = strchrnul(author, '\n');
	committer = strstr(author_end, "\ncommitter ");
	if (!committer)
	die ("Could not find committer in commit %s",
	sha1_to_hex(commit->object.sha1));
	committer++;
	committer_end = strchrnul(committer, '\n');
	message = strstr(committer_end, "\n\n");
	encoding = find_encoding(committer_end, message);
	if (message)
	message += 2;

	if (commit->parents &&
	get_object_mark(&commit->parents->item->object) != 0) {
	parse_commit(commit->parents->item);
	diff_tree_sha1(commit->parents->item->tree->object.sha1,
	commit->tree->object.sha1, "", &rev->diffopt);
	}
	else
	diff_root_tree_sha1(commit->tree->object.sha1,
	"", &rev->diffopt);

	/* Export the referenced blobs, and remember the marks. */
	for (i = 0; i < diff_queued_diff.nr; i++)
	if (!S_ISGITLINK(diff_queued_diff.queue[i]->two->mode))
	handle_object(diff_queued_diff.queue[i]->two->sha1);

	mark_next_object(&commit->object);
	if (!is_encoding_utf8(encoding))
	reencoded = reencode_string(message, "UTF-8", encoding);
	if (!commit->parents)
	printf("reset %s\n", (const char*)commit->util);
	printf("commit %s\nmark :%"PRIu32"\n%.s\n%.s\ndata %u\n%s",
	(const char *)commit->util, last_idnum,
	(int)(author_end - author), author,
	(int)(committer_end - committer), committer,
	(unsigned)(reencoded
	? strlen(reencoded) : message
	? strlen(message) : 0),
	reencoded ? reencoded : message ? message : "");
	free(reencoded);

	for (i = 0, p = commit->parents; p; p = p->next) {
	int mark = get_object_mark(&p->item->object);
	if (!mark)
	continue;
	if (i == 0)
	printf("from :%d\n", mark);
	else
	printf("merge :%d\n", mark);
	i++;
	}

	log_tree_diff_flush(rev);
	rev->diffopt.output_format = saved_output_format;

	printf("\n");

	show_progress();
	}

	static void handle_tail(struct object_array commits, struct rev_info revs)
	{
	struct commit *commit;
	while (commits->nr) {
	commit = (struct commit *)commits->objects[commits->nr - 1].item;
	if (has_unshown_parent(commit))
	return;
	handle_commit(commit, revs);
	commits->nr--;
	}
	}

	static void handle_tag(const char name, struct tag tag)
	{
	unsigned long size;
	enum object_type type;
	char *buf;
	const char tagger, tagger_end, *message;
	size_t message_size = 0;
	struct object *tagged;
	int tagged_mark;
	struct commit *p;

	/* Trees have no identifer in fast-export output, thus we have no way
	* to output tags of trees, tags of tags of trees, etc. Simply omit
	* such tags.
	*/
	tagged = tag->tagged;
	while (tagged->type == OBJ_TAG) {
	tagged = ((struct tag *)tagged)->tagged;
	}
	if (tagged->type == OBJ_TREE) {
	warning("Omitting tag %s,\nsince tags of trees (or tags of tags of trees, etc.) are not supported.",
	sha1_to_hex(tag->object.sha1));
	return;
	}

	buf = read_sha1_file(tag->object.sha1, &type, &size);
	if (!buf)
	die ("Could not read tag %s", sha1_to_hex(tag->object.sha1));
	message = memmem(buf, size, "\n\n", 2);
	if (message) {
	message += 2;
	message_size = strlen(message);
	}
	tagger = memmem(buf, message ? message - buf : size, "\ntagger ", 8);
	if (!tagger) {
	if (fake_missing_tagger)
	tagger = "tagger Unspecified Tagger "
	"<unspecified-tagger> 0 +0000";
	else
	tagger = "";
	tagger_end = tagger + strlen(tagger);
	} else {
	tagger++;
	tagger_end = strchrnul(tagger, '\n');
	}

	/* handle signed tags */
	if (message) {
	const char *signature = strstr(message,
	"\n-----BEGIN PGP SIGNATURE-----\n");
	if (signature)
	switch(signed_tag_mode) {
	case ABORT:
	die ("Encountered signed tag %s; use "
	"--signed-tag=<mode> to handle it.",
	sha1_to_hex(tag->object.sha1));
	case WARN:
	warning ("Exporting signed tag %s",
	sha1_to_hex(tag->object.sha1));
	/* fallthru */
	case VERBATIM:
	break;
	case STRIP:
	message_size = signature + 1 - message;
	break;
	}
	}

	/* handle tag->tagged having been filtered out due to paths specified */
	tagged = tag->tagged;
	tagged_mark = get_object_mark(tagged);
	if (!tagged_mark) {
	switch(tag_of_filtered_mode) {
	case ABORT:
	die ("Tag %s tags unexported object; use "
	"--tag-of-filtered-object=<mode> to handle it.",
	sha1_to_hex(tag->object.sha1));
	case DROP:
	/* Ignore this tag altogether */
	return;
	case REWRITE:
	if (tagged->type != OBJ_COMMIT) {
	die ("Tag %s tags unexported %s!",
	sha1_to_hex(tag->object.sha1),
	typename(tagged->type));
	}
	p = (struct commit *)tagged;
	for (;;) {
	if (p->parents && p->parents->next)
	break;
	if (p->object.flags & UNINTERESTING)
	break;
	if (!(p->object.flags & TREESAME))
	break;
	if (!p->parents)
	die ("Can't find replacement commit for tag %s\n",
	sha1_to_hex(tag->object.sha1));
	p = p->parents->item;
	}
	tagged_mark = get_object_mark(&p->object);
	}
	}

	if (!prefixcmp(name, "refs/tags/"))
	name += 10;
	printf("tag %s\nfrom :%d\n%.s%sdata %d\n%.s\n",
	name, tagged_mark,
	(int)(tagger_end - tagger), tagger,
	tagger == tagger_end ? "" : "\n",
	(int)message_size, (int)message_size, message ? message : "");
	}

	static void get_tags_and_duplicates(struct object_array *pending,
	struct string_list *extra_refs)
	{
	struct tag *tag;
	int i;

	for (i = 0; i < pending->nr; i++) {
	struct object_array_entry *e = pending->objects + i;
	unsigned char sha1[20];
	struct commit *commit = commit;
	char *full_name;

	if (dwim_ref(e->name, strlen(e->name), sha1, &full_name) != 1)
	continue;

	switch (e->item->type) {
	case OBJ_COMMIT:
	commit = (struct commit *)e->item;
	break;
	case OBJ_TAG:
	tag = (struct tag *)e->item;

	/* handle nested tags */
	while (tag && tag->object.type == OBJ_TAG) {
	parse_object(tag->object.sha1);
	string_list_append(full_name, extra_refs)->util = tag;
	tag = (struct tag *)tag->tagged;
	}
	if (!tag)
	die ("Tag %s points nowhere?", e->name);
	switch(tag->object.type) {
	case OBJ_COMMIT:
	commit = (struct commit *)tag;
	break;
	case OBJ_BLOB:
	handle_object(tag->object.sha1);
	continue;
	default: /* OBJ_TAG (nested tags) is already handled */
	warning("Tag points to object of unexpected type %s, skipping.",
	typename(tag->object.type));
	continue;
	}
	break;
	default:
	warning("%s: Unexpected object of type %s, skipping.",
	e->name,
	typename(e->item->type));
	continue;
	}
	if (commit->util)
	/* more than one name for the same object */
	string_list_append(full_name, extra_refs)->util = commit;
	else
	commit->util = full_name;
	}
	}

	static void handle_tags_and_duplicates(struct string_list *extra_refs)
	{
	struct commit *commit;
	int i;

	for (i = extra_refs->nr - 1; i >= 0; i--) {
	const char *name = extra_refs->items[i].string;
	struct object *object = extra_refs->items[i].util;
	switch (object->type) {
	case OBJ_TAG:
	handle_tag(name, (struct tag *)object);
	break;
	case OBJ_COMMIT:
	/* create refs pointing to already seen commits */
	commit = (struct commit *)object;
	printf("reset %s\nfrom :%d\n\n", name,
	get_object_mark(&commit->object));
	show_progress();
	break;
	}
	}
	}

	static void export_marks(char *file)
	{
	unsigned int i;
	uint32_t mark;
	struct object_decoration *deco = idnums.hash;
	FILE *f;
	int e = 0;

	f = fopen(file, "w");
	if (!f)
	error("Unable to open marks file %s for writing.", file);

	for (i = 0; i < idnums.size; i++) {
	if (deco->base && deco->base->type == 1) {
	mark = ptr_to_mark(deco->decoration);
	if (fprintf(f, ":%"PRIu32" %s\n", mark,
	sha1_to_hex(deco->base->sha1)) < 0) {
	e = 1;
	break;
	}
	}
	deco++;
	}

	e \|= ferror(f);
	e \|= fclose(f);
	if (e)
	error("Unable to write marks file %s.", file);
	}

	static void import_marks(char *input_file)
	{
	char line[512];
	FILE *f = fopen(input_file, "r");
	if (!f)
	die_errno("cannot read '%s'", input_file);

	while (fgets(line, sizeof(line), f)) {
	uint32_t mark;
	char line_end, mark_end;
	unsigned char sha1[20];
	struct object *object;

	line_end = strchr(line, '\n');
	if (line[0] != ':' \|\| !line_end)
	die("corrupt mark line: %s", line);
	*line_end = '\0';

	mark = strtoumax(line + 1, &mark_end, 10);
	if (!mark \|\| mark_end == line + 1
	\|\| *mark_end != ' ' \|\| get_sha1(mark_end + 1, sha1))
	die("corrupt mark line: %s", line);

	object = parse_object(sha1);
	if (!object)
	die ("Could not read blob %s", sha1_to_hex(sha1));

	if (object->flags & SHOWN)
	error("Object %s already has a mark", sha1);

	mark_object(object, mark);
	if (last_idnum < mark)
	last_idnum = mark;

	object->flags \|= SHOWN;
	}
	fclose(f);
	}

	int cmd_fast_export(int argc, const char *argv, const char prefix)
	{
	struct rev_info revs;
	struct object_array commits = { 0, 0, NULL };
	struct string_list extra_refs = { NULL, 0, 0, 0 };
	struct commit *commit;
	char export_filename = NULL, import_filename = NULL;
	struct option options[] = {
	OPT_INTEGER(0, "progress", &progress,
	"show progress after <n> objects"),
	OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, "mode",
	"select handling of signed tags",
	parse_opt_signed_tag_mode),
	OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, "mode",
	"select handling of tags that tag filtered objects",
	parse_opt_tag_of_filtered_mode),
	OPT_STRING(0, "export-marks", &export_filename, "FILE",
	"Dump marks to this file"),
	OPT_STRING(0, "import-marks", &import_filename, "FILE",
	"Import marks from this file"),
	OPT_BOOLEAN(0, "fake-missing-tagger", &fake_missing_tagger,
	"Fake a tagger when tags lack one"),
	{ OPTION_NEGBIT, 0, "data", &no_data, NULL,
	"Skip output of blob data",
	PARSE_OPT_NOARG \| PARSE_OPT_NEGHELP, NULL, 1 },
	OPT_END()
	};

	if (argc == 1)
	usage_with_options (fast_export_usage, options);

	/* we handle encodings */
	git_config(git_default_config, NULL);

	init_revisions(&revs, prefix);
	revs.topo_order = 1;
	revs.show_source = 1;
	revs.rewrite_parents = 1;
	argc = setup_revisions(argc, argv, &revs, NULL);
	argc = parse_options(argc, argv, prefix, options, fast_export_usage, 0);
	if (argc > 1)
	usage_with_options (fast_export_usage, options);

	if (import_filename)
	import_marks(import_filename);

	get_tags_and_duplicates(&revs.pending, &extra_refs);

	if (prepare_revision_walk(&revs))
	die("revision walk setup failed");
	revs.diffopt.format_callback = show_filemodify;
	DIFF_OPT_SET(&revs.diffopt, RECURSIVE);
	while ((commit = get_revision(&revs))) {
	if (has_unshown_parent(commit)) {
	add_object_array(&commit->object, NULL, &commits);
	}
	else {
	handle_commit(commit, &revs);
	handle_tail(&commits, &revs);
	}
	}

	handle_tags_and_duplicates(&extra_refs);

	if (export_filename)
	export_marks(export_filename);

	return 0;
	}