Merge branch 'fc/remote-helper-refmap'

Allow remote-helper/fast-import based transport to rename the refs
while transferring the history.

* fc/remote-helper-refmap:
  transport-helper: remove unnecessary strbuf resets
  transport-helper: add support to delete branches
  fast-export: add support to delete refs
  fast-import: add support to delete refs
  transport-helper: add support to push symbolic refs
  transport-helper: add support for old:new refspec
  fast-export: add new --refspec option
  fast-export: improve argument parsing

Documentation/git-fast-export.txt

@@ -105,6 +105,10 @@ marks the same across runs.
 	in the commit (as opposed to just listing the files which are
 	different from the commit's first parent).
 
+--refspec::
+	Apply the specified refspec to each ref exported. Multiple of them can
+	be specified.
+
 [<git-rev-list-args>...]::
 	A list of arguments, acceptable to 'git rev-parse' and
 	'git rev-list', that specifies the specific objects and references

Documentation/git-fast-import.txt

@@ -483,6 +483,9 @@ Marks must be declared (via `mark`) before they can be used.
 * Any valid Git SHA-1 expression that resolves to a commit.  See
   ``SPECIFYING REVISIONS'' in linkgit:gitrevisions[7] for details.
 
+* The special null SHA-1 (40 zeros) specifies that the branch is to be
+  removed.
+
 The special case of restarting an incremental import from the
 current branch value should be written as:
 ----

builtin/fast-export.c

@@ -17,6 +17,7 @@
 #include "utf8.h"
 #include "parse-options.h"
 #include "quote.h"
+#include "remote.h"
 
 static const char *fast_export_usage[] = {
 	N_("git fast-export [rev-list-opts]"),
@@ -31,6 +32,8 @@ static int use_done_feature;
 static int no_data;
 static int full_tree;
 static struct string_list extra_refs = STRING_LIST_INIT_NODUP;
+static struct refspec *refspecs;
+static int refspecs_nr;
 
 static int parse_opt_signed_tag_mode(const struct option *opt,
 				     const char *arg, int unset)
@@ -525,6 +528,15 @@ static void get_tags_and_duplicates(struct rev_cmdline_info *info)
 		if (dwim_ref(e->name, strlen(e->name), sha1, &full_name) != 1)
 			continue;
 
+		if (refspecs) {
+			char *private;
+			private = apply_refspecs(refspecs, refspecs_nr, full_name);
+			if (private) {
+				free(full_name);
+				full_name = private;
+			}
+		}
+
 		commit = get_commit(e, full_name);
 		if (!commit) {
 			warning("%s: Unexpected object of type %s, skipping.",
@@ -661,6 +673,19 @@ static void import_marks(char *input_file)
 	fclose(f);
 }
 
+static void handle_deletes(void)
+{
+	int i;
+	for (i = 0; i < refspecs_nr; i++) {
+		struct refspec *refspec = &refspecs[i];
+		if (*refspec->src)
+			continue;
+
+		printf("reset %s\nfrom %s\n\n",
+				refspec->dst, sha1_to_hex(null_sha1));
+	}
+}
+
 int cmd_fast_export(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info revs;
@@ -668,6 +693,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	struct commit *commit;
 	char *export_filename = NULL, *import_filename = NULL;
 	uint32_t lastimportid;
+	struct string_list refspecs_list = STRING_LIST_INIT_NODUP;
 	struct option options[] = {
 		OPT_INTEGER(0, "progress", &progress,
 			    N_("show progress after <n> objects")),
@@ -688,6 +714,8 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "use-done-feature", &use_done_feature,
 			     N_("Use the done feature to terminate the stream")),
 		OPT_BOOL(0, "no-data", &no_data, N_("Skip output of blob data")),
+		OPT_STRING_LIST(0, "refspec", &refspecs_list, N_("refspec"),
+			     N_("Apply refspec to exported refs")),
 		OPT_END()
 	};
 
@@ -701,11 +729,27 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	revs.topo_order = 1;
 	revs.show_source = 1;
 	revs.rewrite_parents = 1;
+	argc = parse_options(argc, argv, prefix, options, fast_export_usage,
+			PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN);
 	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 (refspecs_list.nr) {
+		const char **refspecs_str;
+		int i;
+
+		refspecs_str = xmalloc(sizeof(*refspecs_str) * refspecs_list.nr);
+		for (i = 0; i < refspecs_list.nr; i++)
+			refspecs_str[i] = refspecs_list.items[i].string;
+
+		refspecs_nr = refspecs_list.nr;
+		refspecs = parse_fetch_refspec(refspecs_nr, refspecs_str);
+
+		string_list_clear(&refspecs_list, 1);
+		free(refspecs_str);
+	}
+
 	if (use_done_feature)
 		printf("feature done\n");
 
@@ -733,6 +777,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	}
 
 	handle_tags_and_duplicates();
+	handle_deletes();
 
 	if (export_filename && lastimportid != last_idnum)
 		export_marks(export_filename);
@@ -740,5 +785,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	if (use_done_feature)
 		printf("done\n");
 
+	free_refspec(refspecs_nr, refspecs);
+
 	return 0;
 }

fast-import.c

@@ -248,6 +248,7 @@ struct branch {
 	uintmax_t last_commit;
 	uintmax_t num_notes;
 	unsigned active : 1;
+	unsigned delete : 1;
 	unsigned pack_id : PACK_ID_BITS;
 	unsigned char sha1[20];
 };
@@ -1681,10 +1682,13 @@ static int update_branch(struct branch *b)
 	struct ref_lock *lock;
 	unsigned char old_sha1[20];
 
-	if (is_null_sha1(b->sha1))
-		return 0;
 	if (read_ref(b->name, old_sha1))
 		hashclr(old_sha1);
+	if (is_null_sha1(b->sha1)) {
+		if (b->delete)
+			delete_ref(b->name, old_sha1, 0);
+		return 0;
+	}
 	lock = lock_any_ref_for_update(b->name, old_sha1, 0, NULL);
 	if (!lock)
 		return error("Unable to lock %s", b->name);
@@ -2611,8 +2615,11 @@ static int parse_from(struct branch *b)
 			free(buf);
 		} else
 			parse_from_existing(b);
-	} else if (!get_sha1(from, b->sha1))
+	} else if (!get_sha1(from, b->sha1)) {
 		parse_from_existing(b);
+		if (is_null_sha1(b->sha1))
+			b->delete = 1;
+	}
 	else
 		die("Invalid ref name or SHA1 expression: %s", from);
 

t/t5801-remote-helpers.sh

@@ -87,13 +87,29 @@ test_expect_success 'push new branch by name' '
 	compare_refs local HEAD server refs/heads/new-name
 '
 
-test_expect_failure 'push new branch with old:new refspec' '
+test_expect_success 'push new branch with old:new refspec' '
 	(cd local &&
 	 git push origin new-name:new-refspec
 	) &&
 	compare_refs local HEAD server refs/heads/new-refspec
 '
 
+test_expect_success 'push new branch with HEAD:new refspec' '
+	(cd local &&
+	 git checkout new-name
+	 git push origin HEAD:new-refspec-2
+	) &&
+	compare_refs local HEAD server refs/heads/new-refspec-2
+'
+
+test_expect_success 'push delete branch' '
+	(cd local &&
+	 git push origin :new-name
+	) &&
+	test_must_fail git --git-dir="server/.git" \
+	 rev-parse --verify refs/heads/new-name
+'
+
 test_expect_success 'forced push' '
 	(cd local &&
 	git checkout -b force-test &&

t/t9300-fast-import.sh

@@ -2999,4 +2999,22 @@ test_expect_success 'T: ls root tree' '
 	test_cmp expect actual
 '
 
+test_expect_success 'T: delete branch' '
+	git branch to-delete &&
+	git fast-import <<-EOF &&
+	reset refs/heads/to-delete
+	from 0000000000000000000000000000000000000000
+	EOF
+	test_must_fail git rev-parse --verify refs/heads/to-delete
+'
+
+test_expect_success 'T: empty reset doesnt delete branch' '
+	git branch not-to-delete &&
+	git fast-import <<-EOF &&
+	reset refs/heads/not-to-delete
+	EOF
+	git show-ref &&
+	git rev-parse --verify refs/heads/not-to-delete
+'
+
 test_done

t/t9350-fast-export.sh

@@ -504,4 +504,22 @@ test_expect_success 'refs are updated even if no commits need to be exported' '
 	test_cmp expected actual
 '
 
+test_expect_success 'use refspec' '
+	git fast-export --refspec refs/heads/master:refs/heads/foobar master | \
+		grep "^commit " | sort | uniq > actual &&
+	echo "commit refs/heads/foobar" > expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'delete refspec' '
+	git branch to-delete &&
+	git fast-export --refspec :refs/heads/to-delete to-delete ^to-delete > actual &&
+	cat > expected <<-EOF &&
+	reset refs/heads/to-delete
+	from 0000000000000000000000000000000000000000
+
+	EOF
+	test_cmp expected actual
+'
+
 test_done

transport-helper.c

@@ -850,7 +850,7 @@ static int push_refs_with_export(struct transport *transport,
 	struct ref *ref;
 	struct child_process *helper, exporter;
 	struct helper_data *data = transport->data;
-	struct string_list revlist_args = STRING_LIST_INIT_NODUP;
+	struct string_list revlist_args = STRING_LIST_INIT_DUP;
 	struct strbuf buf = STRBUF_INIT;
 
 	if (!data->refspecs)
@@ -870,15 +870,10 @@ static int push_refs_with_export(struct transport *transport,
 
 	write_constant(helper->in, "export\n");
 
-	strbuf_reset(&buf);
-
 	for (ref = remote_refs; ref; ref = ref->next) {
 		char *private;
 		unsigned char sha1[20];
 
-		if (ref->deletion)
-			die("remote-helpers do not support ref deletion");
-
 		private = apply_refspecs(data->refspecs, data->refspec_nr, ref->name);
 		if (private && !get_sha1(private, sha1)) {
 			strbuf_addf(&buf, "^%s", private);
@@ -888,15 +883,34 @@ static int push_refs_with_export(struct transport *transport,
 		free(private);
 
 		if (ref->peer_ref) {
-			if (strcmp(ref->peer_ref->name, ref->name))
-				die("remote-helpers do not support old:new syntax");
-			string_list_append(&revlist_args, ref->peer_ref->name);
+			if (strcmp(ref->name, ref->peer_ref->name)) {
+				if (!ref->deletion) {
+					const char *name;
+					int flag;
+
+					/* Follow symbolic refs (mainly for HEAD). */
+					name = resolve_ref_unsafe(ref->peer_ref->name, sha1, 1, &flag);
+					if (!name || !(flag & REF_ISSYMREF))
+						name = ref->peer_ref->name;
+
+					strbuf_addf(&buf, "%s:%s", name, ref->name);
+				} else
+					strbuf_addf(&buf, ":%s", ref->name);
+
+				string_list_append(&revlist_args, "--refspec");
+				string_list_append(&revlist_args, buf.buf);
+				strbuf_release(&buf);
+			}
+			if (!ref->deletion)
+				string_list_append(&revlist_args, ref->peer_ref->name);
 		}
 	}
 
 	if (get_exporter(transport, &exporter, &revlist_args))
 		die("Couldn't run fast-export");
 
+	string_list_clear(&revlist_args, 1);
+
 	if (finish_command(&exporter))
 		die("Error while running fast-export");
 	if (push_update_refs_status(data, remote_refs, flags))