vcs-svn: set up channel to read fast-import cat-blob response

Set up some plumbing: teach the svndump lib to pass a file descriptor
number to the fast_export lib, representing where cat-blob/ls
responses can be read from, and add a get_response_line helper
function to the fast_export lib to read a line from that file.

Unfortunately this means that svn-fe needs file descriptor 3 to be
redirected from somewhere (preferrably the cat-blob stream of a
fast-import backend); otherwise it will fail:

	$ svndump <path> | svn-fe
	fatal: cannot read from file descriptor 3: Bad file descriptor

For the moment, "svn-fe 3</dev/null" works as a workaround but it
will not work for very long.  A fast-import backend that can retrieve
old commits is needed in order to be able to fulfill svn
"Node-copyfrom-rev" requests that refer to revs from a previous run.

[jn: with new change description]

Based-on-patch-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, 28 insertions, 0 deletions

diff --git a/vcs-svn/fast_export.c b/vcs-svn/fast_export.c
index 260cf50e7..70bd9597e 100644
--- a/vcs-svn/fast_export.c
+++ b/vcs-svn/fast_export.c
@@ -12,6 +12,24 @@
 #define MAX_GITSVN_LINE_LEN 4096
 
 static uint32_t first_commit_done;
+static struct line_buffer report_buffer = LINE_BUFFER_INIT;
+
+void fast_export_init(int fd)
+{
+	if (buffer_fdinit(&report_buffer, fd))
+		die_errno("cannot read from file descriptor %d", fd);
+}
+
+void fast_export_deinit(void)
+{
+	if (buffer_deinit(&report_buffer))
+		die_errno("error closing fast-import feedback stream");
+}
+
+void fast_export_reset(void)
+{
+	buffer_reset(&report_buffer);
+}
 
 void fast_export_delete(uint32_t depth, uint32_t *path)
 {
@@ -63,6 +81,16 @@ void fast_export_commit(uint32_t revision, uint32_t author, char *log,
 	printf("progress Imported commit %"PRIu32".\n\n", revision);
 }
 
+static const char *get_response_line(void)
+{
+	const char *line = buffer_read_line(&report_buffer);
+	if (line)
+		return line;
+	if (buffer_ferror(&report_buffer))
+		die_errno("error reading from fast-import");
+	die("unexpected end of fast-import feedback");
+}
+
 void fast_export_blob(uint32_t mode, uint32_t mark, uint32_t len, struct line_buffer *input)
 {
 	if (mode == REPO_MODE_LNK) {