vcs-svn: implement text-delta handling

Handle input in Subversion's dumpfile format, version 3.  This is the
format produced by "svnrdump dump" and "svnadmin dump --deltas", and
the main difference between v3 dumpfiles and the dumpfiles already
handled is that these can include nodes whose properties and text are
expressed relative to some other node.

To handle such nodes, we find which node the text and properties are
based on, handle its property changes, use the cat-blob command to
request the basis blob from the fast-import backend, use the
svndiff0_apply() helper to apply the text delta on the fly, writing
output to a temporary file, and then measure that postimage file's
length and write its content to the fast-import stream.

The temporary postimage file is shared between delta-using nodes to
avoid some file system overhead.

The svn-fe interface needs to be more complicated to accomodate the
backward flow of information from the fast-import backend to svn-fe.
The backflow fd is not needed when parsing streams without deltas,
though, so existing scripts using svn-fe on v2 dumps should
continue to work.

NEEDSWORK: generalize interface so caller sets the backflow fd, close
temporary file before exiting

Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

1 files changed, 106 insertions, 2 deletions

diff --git a/t/t9010-svn-fe.sh b/t/t9010-svn-fe.sh
index 003395c5f6..f24f004fd5 100755
--- a/t/t9010-svn-fe.sh
+++ b/t/t9010-svn-fe.sh
@@ -674,7 +674,7 @@ test_expect_success PIPE 'change file mode and reiterate content' '
 	test_cmp hello actual.target
 '
 
-test_expect_success PIPE 'deltas not supported' '
+test_expect_success PIPE 'deltas supported' '
 	reinit_git &&
 	{
 		# (old) h + (inline) ello + (old) \n
@@ -735,7 +735,7 @@ test_expect_success PIPE 'deltas not supported' '
 		echo PROPS-END &&
 		cat delta
 	} >delta.dump &&
-	test_must_fail try_dump delta.dump
+	try_dump delta.dump
 '
 
 test_expect_success PIPE 'property deltas supported' '
@@ -942,6 +942,110 @@ test_expect_success PIPE 'deltas for typechange' '
 	test_cmp expect actual
 '
 
+test_expect_success PIPE 'deltas need not consume the whole preimage' '
+	reinit_git &&
+	cat >expect <<-\EOF &&
+	OBJID
+	:120000 100644 OBJID OBJID T	postimage
+	OBJID
+	:100644 120000 OBJID OBJID T	postimage
+	OBJID
+	:000000 100644 OBJID OBJID A	postimage
+	EOF
+	echo "first preimage" >expect.1 &&
+	printf target >expect.2 &&
+	printf lnk >expect.3 &&
+	{
+		printf "SVNQ%b%b%b" "QQ\017\001\017" "\0217" "first preimage\n" |
+		q_to_nul
+	} >delta.1 &&
+	{
+		properties svn:special "*" &&
+		echo PROPS-END
+	} >symlink.props &&
+	{
+		printf "SVNQ%b%b%b" "Q\002\013\004\012" "\0201\001\001\0211" "lnk target" |
+		q_to_nul
+	} >delta.2 &&
+	{
+		printf "SVNQ%b%b" "Q\004\003\004Q" "\001Q\002\002" |
+		q_to_nul
+	} >delta.3 &&
+	{
+		cat <<-\EOF &&
+		SVN-fs-dump-format-version: 3
+
+		Revision-number: 1
+		Prop-content-length: 10
+		Content-length: 10
+
+		PROPS-END
+
+		Node-path: postimage
+		Node-kind: file
+		Node-action: add
+		Text-delta: true
+		Prop-content-length: 10
+		EOF
+		echo Text-content-length: $(wc -c <delta.1) &&
+		echo Content-length: $((10 + $(wc -c <delta.1))) &&
+		echo &&
+		echo PROPS-END &&
+		cat delta.1 &&
+		cat <<-\EOF &&
+
+		Revision-number: 2
+		Prop-content-length: 10
+		Content-length: 10
+
+		PROPS-END
+
+		Node-path: postimage
+		Node-kind: file
+		Node-action: change
+		Text-delta: true
+		EOF
+		echo Prop-content-length: $(wc -c <symlink.props) &&
+		echo Text-content-length: $(wc -c <delta.2) &&
+		echo Content-length: $(($(wc -c <symlink.props) + $(wc -c <delta.2))) &&
+		echo &&
+		cat symlink.props &&
+		cat delta.2 &&
+		cat <<-\EOF &&
+
+		Revision-number: 3
+		Prop-content-length: 10
+		Content-length: 10
+
+		PROPS-END
+
+		Node-path: postimage
+		Node-kind: file
+		Node-action: change
+		Text-delta: true
+		Prop-content-length: 10
+		EOF
+		echo Text-content-length: $(wc -c <delta.3) &&
+		echo Content-length: $((10 + $(wc -c <delta.3))) &&
+		echo &&
+		echo PROPS-END &&
+		cat delta.3 &&
+		echo
+	} >deltapartial.dump &&
+	try_dump deltapartial.dump &&
+	{
+		git rev-list HEAD |
+		git diff-tree --root --stdin |
+		sed "s/$_x40/OBJID/g"
+	} >actual &&
+	test_cmp expect actual &&
+	git show HEAD:postimage >actual.3 &&
+	git show HEAD^:postimage >actual.2 &&
+	git show HEAD^^:postimage >actual.1 &&
+	test_cmp expect.1 actual.1 &&
+	test_cmp expect.2 actual.2 &&
+	test_cmp expect.3 actual.3
+'
 
 test_expect_success 'set up svn repo' '
 	svnconf=$PWD/svnconf &&