Merge branch 'en/fast-imexport-nested-tags'

Updates to fast-import/export.

* en/fast-imexport-nested-tags:
  fast-export: handle nested tags
  t9350: add tests for tags of things other than a commit
  fast-export: allow user to request tags be marked with --mark-tags
  fast-export: add support for --import-marks-if-exists
  fast-import: add support for new 'alias' command
  fast-import: allow tags to be identified by mark labels
  fast-import: fix handling of deleted tags
  fast-export: fix exporting a tag and nothing else

Documentation/git-fast-export.txt

@@ -75,11 +75,20 @@ produced incorrect results if you gave these options.
 	Before processing any input, load the marks specified in
 	<file>.  The input file must exist, must be readable, and
 	must use the same format as produced by --export-marks.
+
+--mark-tags::
+	In addition to labelling blobs and commits with mark ids, also
+	label tags.  This is useful in conjunction with
+	`--export-marks` and `--import-marks`, and is also useful (and
+	necessary) for exporting of nested tags.  It does not hurt
+	other cases and would be the default, but many fast-import
+	frontends are not prepared to accept tags with mark
+	identifiers.
 +
-Any commits that have already been marked will not be exported again.
-If the backend uses a similar --import-marks file, this allows for
-incremental bidirectional exporting of the repository by keeping the
-marks the same across runs.
+Any commits (or tags) that have already been marked will not be
+exported again.  If the backend uses a similar --import-marks file,
+this allows for incremental bidirectional exporting of the repository
+by keeping the marks the same across runs.
 
 --fake-missing-tagger::
 	Some old repositories have tags without a tagger.  The

Documentation/git-fast-import.txt

@@ -337,6 +337,13 @@ and control the current import process.  More detailed discussion
 	`commit` command.  This command is optional and is not
 	needed to perform an import.
 
+`alias`::
+	Record that a mark refers to a given object without first
+	creating any new object.  Using --import-marks and referring
+	to missing marks will cause fast-import to fail, so aliases
+	can provide a way to set otherwise pruned commits to a valid
+	value (e.g. the nearest non-pruned ancestor).
+
 `checkpoint`::
 	Forces fast-import to close the current packfile, generate its
 	unique SHA-1 checksum and index, and start a new packfile.
@@ -774,6 +781,7 @@ lightweight (non-annotated) tags see the `reset` command below.
 
 ....
 	'tag' SP <name> LF
+	mark?
 	'from' SP <commit-ish> LF
 	original-oid?
 	'tagger' (SP <name>)? SP LT <email> GT SP <when> LF
@@ -913,6 +921,21 @@ a data chunk which does not have an LF as its last byte.
 +
 The `LF` after `<delim> LF` is optional (it used to be required).
 
+`alias`
+~~~~~~~
+Record that a mark refers to a given object without first creating any
+new object.
+
+....
+	'alias' LF
+	mark
+	'to' SP <commit-ish> LF
+	LF?
+....
+
+For a detailed description of `<commit-ish>` see above under `from`.
+
+
 `checkpoint`
 ~~~~~~~~~~~~
 Forces fast-import to close the current packfile, start a new one, and to

builtin/fast-export.c

@@ -40,6 +40,7 @@ static int no_data;
 static int full_tree;
 static int reference_excluded_commits;
 static int show_original_ids;
+static int mark_tags;
 static struct string_list extra_refs = STRING_LIST_INIT_NODUP;
 static struct string_list tag_refs = STRING_LIST_INIT_NODUP;
 static struct refspec refspecs = REFSPEC_INIT_FETCH;
@@ -842,25 +843,40 @@ static void handle_tag(const char *name, struct tag *tag)
 			free(buf);
 			return;
 		case REWRITE:
-			if (tagged->type != OBJ_COMMIT) {
-				die("tag %s tags unexported %s!",
-				    oid_to_hex(&tag->object.oid),
-				    type_name(tagged->type));
-			}
-			p = rewrite_commit((struct commit *)tagged);
-			if (!p) {
-				printf("reset %s\nfrom %s\n\n",
-				       name, oid_to_hex(&null_oid));
-				free(buf);
-				return;
+			if (tagged->type == OBJ_TAG && !mark_tags) {
+				die(_("Error: Cannot export nested tags unless --mark-tags is specified."));
+			} else if (tagged->type == OBJ_COMMIT) {
+				p = rewrite_commit((struct commit *)tagged);
+				if (!p) {
+					printf("reset %s\nfrom %s\n\n",
+					       name, oid_to_hex(&null_oid));
+					free(buf);
+					return;
+				}
+				tagged_mark = get_object_mark(&p->object);
+			} else {
+				/* tagged->type is either OBJ_BLOB or OBJ_TAG */
+				tagged_mark = get_object_mark(tagged);
 			}
-			tagged_mark = get_object_mark(&p->object);
 		}
 	}
 
+	if (tagged->type == OBJ_TAG) {
+		printf("reset %s\nfrom %s\n\n",
+		       name, oid_to_hex(&null_oid));
+	}
 	if (starts_with(name, "refs/tags/"))
 		name += 10;
-	printf("tag %s\nfrom :%d\n", name, tagged_mark);
+	printf("tag %s\n", name);
+	if (mark_tags) {
+		mark_next_object(&tag->object);
+		printf("mark :%"PRIu32"\n", last_idnum);
+	}
+	if (tagged_mark)
+		printf("from :%d\n", tagged_mark);
+	else
+		printf("from %s\n", oid_to_hex(&tagged->oid));
+
 	if (show_original_ids)
 		printf("original-oid %s\n", oid_to_hex(&tag->object.oid));
 	printf("%.*s%sdata %d\n%.*s\n",
@@ -1047,11 +1063,16 @@ static void export_marks(char *file)
 		error("Unable to write marks file %s.", file);
 }
 
-static void import_marks(char *input_file)
+static void import_marks(char *input_file, int check_exists)
 {
 	char line[512];
-	FILE *f = xfopen(input_file, "r");
+	FILE *f;
+	struct stat sb;
+
+	if (check_exists && stat(input_file, &sb))
+		return;
 
+	f = xfopen(input_file, "r");
 	while (fgets(line, sizeof(line), f)) {
 		uint32_t mark;
 		char *line_end, *mark_end;
@@ -1115,7 +1136,9 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	struct rev_info revs;
 	struct object_array commits = OBJECT_ARRAY_INIT;
 	struct commit *commit;
-	char *export_filename = NULL, *import_filename = NULL;
+	char *export_filename = NULL,
+	     *import_filename = NULL,
+	     *import_filename_if_exists = NULL;
 	uint32_t lastimportid;
 	struct string_list refspecs_list = STRING_LIST_INIT_NODUP;
 	struct string_list paths_of_changed_objects = STRING_LIST_INIT_DUP;
@@ -1135,6 +1158,10 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 			     N_("Dump marks to this file")),
 		OPT_STRING(0, "import-marks", &import_filename, N_("file"),
 			     N_("Import marks from this file")),
+		OPT_STRING(0, "import-marks-if-exists",
+			     &import_filename_if_exists,
+			     N_("file"),
+			     N_("Import marks from this file if it exists")),
 		OPT_BOOL(0, "fake-missing-tagger", &fake_missing_tagger,
 			 N_("Fake a tagger when tags lack one")),
 		OPT_BOOL(0, "full-tree", &full_tree,
@@ -1149,6 +1176,8 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 			 &reference_excluded_commits, N_("Reference parents which are not in fast-export stream by object id")),
 		OPT_BOOL(0, "show-original-ids", &show_original_ids,
 			    N_("Show original object ids of blobs/commits")),
+		OPT_BOOL(0, "mark-tags", &mark_tags,
+			    N_("Label tags with mark ids")),
 
 		OPT_END()
 	};
@@ -1182,8 +1211,12 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	if (use_done_feature)
 		printf("feature done\n");
 
+	if (import_filename && import_filename_if_exists)
+		die(_("Cannot pass both --import-marks and --import-marks-if-exists"));
 	if (import_filename)
-		import_marks(import_filename);
+		import_marks(import_filename, 0);
+	else if (import_filename_if_exists)
+		import_marks(import_filename_if_exists, 1);
 	lastimportid = last_idnum;
 
 	if (import_filename && revs.prune_data.nr)

fast-import.c

@@ -2489,18 +2489,14 @@ static void parse_from_existing(struct branch *b)
 	}
 }
 
-static int parse_from(struct branch *b)
+static int parse_objectish(struct branch *b, const char *objectish)
 {
-	const char *from;
 	struct branch *s;
 	struct object_id oid;
 
-	if (!skip_prefix(command_buf.buf, "from ", &from))
-		return 0;
-
 	oidcpy(&oid, &b->branch_tree.versions[1].oid);
 
-	s = lookup_branch(from);
+	s = lookup_branch(objectish);
 	if (b == s)
 		die("Can't create a branch from itself: %s", b->name);
 	else if (s) {
@@ -2508,8 +2504,8 @@ static int parse_from(struct branch *b)
 		oidcpy(&b->oid, &s->oid);
 		oidcpy(&b->branch_tree.versions[0].oid, t);
 		oidcpy(&b->branch_tree.versions[1].oid, t);
-	} else if (*from == ':') {
-		uintmax_t idnum = parse_mark_ref_eol(from);
+	} else if (*objectish == ':') {
+		uintmax_t idnum = parse_mark_ref_eol(objectish);
 		struct object_entry *oe = find_mark(idnum);
 		if (oe->type != OBJ_COMMIT)
 			die("Mark :%" PRIuMAX " not a commit", idnum);
@@ -2523,13 +2519,13 @@ static int parse_from(struct branch *b)
 			} else
 				parse_from_existing(b);
 		}
-	} else if (!get_oid(from, &b->oid)) {
+	} else if (!get_oid(objectish, &b->oid)) {
 		parse_from_existing(b);
 		if (is_null_oid(&b->oid))
 			b->delete = 1;
 	}
 	else
-		die("Invalid ref name or SHA1 expression: %s", from);
+		die("Invalid ref name or SHA1 expression: %s", objectish);
 
 	if (b->branch_tree.tree && !oideq(&oid, &b->branch_tree.versions[1].oid)) {
 		release_tree_content_recursive(b->branch_tree.tree);
@@ -2540,6 +2536,26 @@ static int parse_from(struct branch *b)
 	return 1;
 }
 
+static int parse_from(struct branch *b)
+{
+	const char *from;
+
+	if (!skip_prefix(command_buf.buf, "from ", &from))
+		return 0;
+
+	return parse_objectish(b, from);
+}
+
+static int parse_objectish_with_prefix(struct branch *b, const char *prefix)
+{
+	const char *base;
+
+	if (!skip_prefix(command_buf.buf, prefix, &base))
+		return 0;
+
+	return parse_objectish(b, base);
+}
+
 static struct hash_list *parse_merge(unsigned int *count)
 {
 	struct hash_list *list = NULL, **tail = &list, *n;
@@ -2714,6 +2730,7 @@ static void parse_new_tag(const char *arg)
 		first_tag = t;
 	last_tag = t;
 	read_next_command();
+	parse_mark();
 
 	/* from ... */
 	if (!skip_prefix(command_buf.buf, "from ", &from))
@@ -2770,7 +2787,7 @@ static void parse_new_tag(const char *arg)
 	strbuf_addbuf(&new_data, &msg);
 	free(tagger);
 
-	if (store_object(OBJ_TAG, &new_data, NULL, &t->oid, 0))
+	if (store_object(OBJ_TAG, &new_data, NULL, &t->oid, next_mark))
 		t->pack_id = MAX_PACK_ID;
 	else
 		t->pack_id = pack_id;
@@ -2779,6 +2796,7 @@ static void parse_new_tag(const char *arg)
 static void parse_reset_branch(const char *arg)
 {
 	struct branch *b;
+	const char *tag_name;
 
 	b = lookup_branch(arg);
 	if (b) {
@@ -2794,6 +2812,32 @@ static void parse_reset_branch(const char *arg)
 		b = new_branch(arg);
 	read_next_command();
 	parse_from(b);
+	if (b->delete && skip_prefix(b->name, "refs/tags/", &tag_name)) {
+		/*
+		 * Elsewhere, we call dump_branches() before dump_tags(),
+		 * and dump_branches() will handle ref deletions first, so
+		 * in order to make sure the deletion actually takes effect,
+		 * we need to remove the tag from our list of tags to update.
+		 *
+		 * NEEDSWORK: replace list of tags with hashmap for faster
+		 * deletion?
+		 */
+		struct tag *t, *prev = NULL;
+		for (t = first_tag; t; t = t->next_tag) {
+			if (!strcmp(t->name, tag_name))
+				break;
+			prev = t;
+		}
+		if (t) {
+			if (prev)
+				prev->next_tag = t->next_tag;
+			else
+				first_tag = t->next_tag;
+			if (!t->next_tag)
+				last_tag = prev;
+			/* There is no mem_pool_free(t) function to call. */
+		}
+	}
 	if (command_buf.len > 0)
 		unread_command_buf = 1;
 }
@@ -3060,6 +3104,28 @@ static void parse_progress(void)
 	skip_optional_lf();
 }
 
+static void parse_alias(void)
+{
+	struct object_entry *e;
+	struct branch b;
+
+	skip_optional_lf();
+	read_next_command();
+
+	/* mark ... */
+	parse_mark();
+	if (!next_mark)
+		die(_("Expected 'mark' command, got %s"), command_buf.buf);
+
+	/* to ... */
+	memset(&b, 0, sizeof(b));
+	if (!parse_objectish_with_prefix(&b, "to "))
+		die(_("Expected 'to' command, got %s"), command_buf.buf);
+	e = find_object(&b.oid);
+	assert(e);
+	insert_mark(next_mark, e);
+}
+
 static char* make_fast_import_path(const char *path)
 {
 	if (!relative_marks_paths || is_absolute_path(path))
@@ -3187,6 +3253,8 @@ static int parse_one_feature(const char *feature, int from_stream)
 		option_import_marks(arg, from_stream, 1);
 	} else if (skip_prefix(feature, "export-marks=", &arg)) {
 		option_export_marks(arg);
+	} else if (!strcmp(feature, "alias")) {
+		; /* Don't die - this feature is supported */
 	} else if (!strcmp(feature, "get-mark")) {
 		; /* Don't die - this feature is supported */
 	} else if (!strcmp(feature, "cat-blob")) {
@@ -3343,6 +3411,8 @@ int cmd_main(int argc, const char **argv)
 			parse_checkpoint();
 		else if (!strcmp("done", command_buf.buf))
 			break;
+		else if (!strcmp("alias", command_buf.buf))
+			parse_alias();
 		else if (starts_with(command_buf.buf, "progress "))
 			parse_progress();
 		else if (skip_prefix(command_buf.buf, "feature ", &v))

t/t9300-fast-import.sh

@@ -85,6 +85,36 @@ test_expect_success 'A: create pack from stdin' '
 	An annotated tag that annotates a blob.
 	EOF
 
+	tag to-be-deleted
+	from :3
+	data <<EOF
+	Another annotated tag that annotates a blob.
+	EOF
+
+	reset refs/tags/to-be-deleted
+	from 0000000000000000000000000000000000000000
+
+	tag nested
+	mark :6
+	from :4
+	data <<EOF
+	Tag of our lovely commit
+	EOF
+
+	reset refs/tags/nested
+	from 0000000000000000000000000000000000000000
+
+	tag nested
+	mark :7
+	from :6
+	data <<EOF
+	Tag of tag of our lovely commit
+	EOF
+
+	alias
+	mark :8
+	to :5
+
 	INPUT_END
 	git fast-import --export-marks=marks.out <input &&
 	git whatchanged master
@@ -157,12 +187,19 @@ test_expect_success 'A: verify tag/series-A-blob' '
 	test_cmp expect actual
 '
 
+test_expect_success 'A: verify tag deletion is successful' '
+	test_must_fail git rev-parse --verify refs/tags/to-be-deleted
+'
+
 test_expect_success 'A: verify marks output' '
 	cat >expect <<-EOF &&
 	:2 $(git rev-parse --verify master:file2)
 	:3 $(git rev-parse --verify master:file3)
 	:4 $(git rev-parse --verify master:file4)
 	:5 $(git rev-parse --verify master^0)
+	:6 $(git cat-file tag nested | grep object | cut -d" " -f 2)
+	:7 $(git rev-parse --verify nested)
+	:8 $(git rev-parse --verify master^0)
 	EOF
 	test_cmp expect marks.out
 '

t/t9350-fast-export.sh

@@ -53,6 +53,33 @@ test_expect_success 'fast-export | fast-import' '
 
 '
 
+test_expect_success 'fast-export ^muss^{commit} muss' '
+	git fast-export --tag-of-filtered-object=rewrite ^muss^{commit} muss >actual &&
+	cat >expected <<-EOF &&
+	tag muss
+	from $(git rev-parse --verify muss^{commit})
+	$(git cat-file tag muss | grep tagger)
+	data 9
+	valentin
+
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'fast-export --mark-tags ^muss^{commit} muss' '
+	git fast-export --mark-tags --tag-of-filtered-object=rewrite ^muss^{commit} muss >actual &&
+	cat >expected <<-EOF &&
+	tag muss
+	mark :1
+	from $(git rev-parse --verify muss^{commit})
+	$(git cat-file tag muss | grep tagger)
+	data 9
+	valentin
+
+	EOF
+	test_cmp expected actual
+'
+
 test_expect_success 'fast-export master~2..master' '
 
 	git fast-export master~2..master >actual &&
@@ -513,10 +540,41 @@ test_expect_success 'tree_tag'        '
 '
 
 # NEEDSWORK: not just check return status, but validate the output
+# Note that these tests DO NOTHING other than print a warning that
+# they are ommitting the one tag we asked them to export (because the
+# tags resolve to a tree).  They exist just to make sure we do not
+# abort but instead just warn.
 test_expect_success 'tree_tag-obj'    'git fast-export tree_tag-obj'
 test_expect_success 'tag-obj_tag'     'git fast-export tag-obj_tag'
 test_expect_success 'tag-obj_tag-obj' 'git fast-export tag-obj_tag-obj'
 
+test_expect_success 'handling tags of blobs' '
+	git tag -a -m "Tag of a blob" blobtag $(git rev-parse master:file) &&
+	git fast-export blobtag >actual &&
+	cat >expect <<-EOF &&
+	blob
+	mark :1
+	data 9
+	die Luft
+
+	tag blobtag
+	from :1
+	tagger $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data 14
+	Tag of a blob
+
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'handling nested tags' '
+	git tag -a -m "This is a nested tag" nested muss &&
+	git fast-export --mark-tags nested >output &&
+	grep "^from $ZERO_OID$" output &&
+	grep "^tag nested$" output >tag_lines &&
+	test_line_count = 2 tag_lines
+'
+
 test_expect_success 'directory becomes symlink'        '
 	git init dirtosymlink &&
 	git init result &&
@@ -567,17 +625,15 @@ test_expect_success 'fast-export quotes pathnames' '
 '
 
 test_expect_success 'test bidirectionality' '
-	>marks-cur &&
-	>marks-new &&
 	git init marks-test &&
-	git fast-export --export-marks=marks-cur --import-marks=marks-cur --branches | \
-	git --git-dir=marks-test/.git fast-import --export-marks=marks-new --import-marks=marks-new &&
+	git fast-export --export-marks=marks-cur --import-marks-if-exists=marks-cur --branches | \
+	git --git-dir=marks-test/.git fast-import --export-marks=marks-new --import-marks-if-exists=marks-new &&
 	(cd marks-test &&
 	git reset --hard &&
 	echo Wohlauf > file &&
 	git commit -a -m "back in time") &&
-	git --git-dir=marks-test/.git fast-export --export-marks=marks-new --import-marks=marks-new --branches | \
-	git fast-import --export-marks=marks-cur --import-marks=marks-cur
+	git --git-dir=marks-test/.git fast-export --export-marks=marks-new --import-marks-if-exists=marks-new --branches | \
+	git fast-import --export-marks=marks-cur --import-marks-if-exists=marks-cur
 '
 
 cat > expected << EOF