vcs-svn: Error out for v3 dumps

By ignoring the Text-Delta and Prop-Delta node fields, current svn-fe
happily mistakes deltas for full text and instead of cleanly erroring
out, it produces a valid but semantically bogus fast-import stream
when fed a dump file in the modern "svnadmin dump --deltas" format.

Dump file parsers are supposed to ignore header fields they don't
understand (to allow for backward-compatible extensions), but they are
also supposed to check the SVN-fs-dump-format-version header to
prevent misinterpretation of non backward-compatible extensions.
Do so.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9010-svn-fe.sh

@@ -4,29 +4,44 @@ test_description='check svn dumpfile importer'
 
 . ./lib-git-svn.sh
 
-test_dump() {
-	label=$1
-	dump=$2
-	test_expect_success "$dump" '
-		svnadmin create "$label-svn" &&
-		svnadmin load "$label-svn" < "$TEST_DIRECTORY/$dump" &&
-		svn_cmd export "file://$PWD/$label-svn" "$label-svnco" &&
-		git init "$label-git" &&
-		test-svn-fe "$TEST_DIRECTORY/$dump" >"$label.fe" &&
-		(
-			cd "$label-git" &&
-			git fast-import < ../"$label.fe"
-		) &&
-		(
-			cd "$label-svnco" &&
-			git init &&
-			git add . &&
-			git fetch "../$label-git" master &&
-			git diff --exit-code FETCH_HEAD
-		)
-	'
+reinit_git () {
+	rm -fr .git &&
+	git init
 }
 
-test_dump simple t9135/svn.dump
+>empty
+
+test_expect_success 'empty dump' '
+	reinit_git &&
+	echo "SVN-fs-dump-format-version: 2" >input &&
+	test-svn-fe input >stream &&
+	git fast-import <stream
+'
+
+test_expect_success 'v3 dumps not supported' '
+	reinit_git &&
+	echo "SVN-fs-dump-format-version: 3" >input &&
+	test_must_fail test-svn-fe input >stream &&
+	test_cmp empty stream
+'
+
+test_expect_success 't9135/svn.dump' '
+	svnadmin create simple-svn &&
+	svnadmin load simple-svn <"$TEST_DIRECTORY/t9135/svn.dump" &&
+	svn_cmd export "file://$PWD/simple-svn" simple-svnco &&
+	git init simple-git &&
+	test-svn-fe "$TEST_DIRECTORY/t9135/svn.dump" >simple.fe &&
+	(
+		cd simple-git &&
+		git fast-import <../simple.fe
+	) &&
+	(
+		cd simple-svnco &&
+		git init &&
+		git add . &&
+		git fetch ../simple-git master &&
+		git diff --exit-code FETCH_HEAD
+	)
+'
 
 test_done

vcs-svn/svndump.c

@@ -51,14 +51,14 @@ static struct {
 } rev_ctx;
 
 static struct {
-	uint32_t uuid, url;
+	uint32_t version, uuid, url;
 } dump_ctx;
 
 static struct {
 	uint32_t svn_log, svn_author, svn_date, svn_executable, svn_special, uuid,
 		revision_number, node_path, node_kind, node_action,
 		node_copyfrom_path, node_copyfrom_rev, text_content_length,
-		prop_content_length, content_length;
+		prop_content_length, content_length, svn_fs_dump_format_version;
 } keys;
 
 static void reset_node_ctx(char *fname)
@@ -85,6 +85,7 @@ static void reset_rev_ctx(uint32_t revision)
 static void reset_dump_ctx(uint32_t url)
 {
 	dump_ctx.url = url;
+	dump_ctx.version = 1;
 	dump_ctx.uuid = ~0;
 }
 
@@ -105,6 +106,7 @@ static void init_keys(void)
 	keys.text_content_length = pool_intern("Text-content-length");
 	keys.prop_content_length = pool_intern("Prop-content-length");
 	keys.content_length = pool_intern("Content-length");
+	keys.svn_fs_dump_format_version = pool_intern("SVN-fs-dump-format-version");
 }
 
 static void read_props(void)
@@ -206,7 +208,12 @@ void svndump_read(const char *url)
 		*val++ = '\0';
 		key = pool_intern(t);
 
-		if (key == keys.uuid) {
+		if (key == keys.svn_fs_dump_format_version) {
+			dump_ctx.version = atoi(val);
+			if (dump_ctx.version > 2)
+				die("expected svn dump format version <= 2, found %d",
+				    dump_ctx.version);
+		} else if (key == keys.uuid) {
 			dump_ctx.uuid = pool_intern(val);
 		} else if (key == keys.revision_number) {
 			if (active_ctx == NODE_CTX)