check_connected: relay errors to alternate descriptor

Unless the "quiet" flag is given, check_connected sends any
errors to the stderr of the caller (because the child
rev-list inherits that descriptor). However, server-side
callers may want to send these over a sideband channel
instead.  Let's make that possible.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/connected.h b/connected.h
index 12594ef..5d88e26 100644
--- a/connected.h
+++ b/connected.h
@@ -23,6 +23,13 @@ struct check_connected_options {
 
 	/* Transport whose objects we are checking, if available. */
 	struct transport *transport;
+
+	/*
+	 * If non-zero, send error messages to this descriptor rather
+	 * than stderr. The descriptor is closed before check_connected
+	 * returns.
+	 */
+	int err_fd;
 };
 
 #define CHECK_CONNECTED_INIT { 0 }