[PATCH 05/12] check_connected: relay errors to alternate descriptor

[Jeff King <peff@peff.net>]

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>
---
 connected.c | 11 +++++++++--
 connected.h |  7 +++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/connected.c b/connected.c
index 2a51eac..5f5c8bd 100644
--- a/connected.c
+++ b/connected.c
@@ -31,8 +31,11 @@ int check_connected(sha1_iterate_fn fn, void *cb_data,
 		opt = &defaults;
 	transport = opt->transport;
 
-	if (fn(cb_data, sha1))
+	if (fn(cb_data, sha1)) {
+		if (opt->err_fd)
+			close(opt->err_fd);
 		return err;
+	}
 
 	if (transport && transport->smart_options &&
 	    transport->smart_options->self_contained_and_connected &&
@@ -59,7 +62,11 @@ int check_connected(sha1_iterate_fn fn, void *cb_data,
 	rev_list.git_cmd = 1;
 	rev_list.in = -1;
 	rev_list.no_stdout = 1;
-	rev_list.no_stderr = opt->quiet;
+	if (opt->err_fd)
+		rev_list.err = opt->err_fd;
+	else
+		rev_list.no_stderr = opt->quiet;
+
 	if (start_command(&rev_list))
 		return error(_("Could not run 'git rev-list'"));
 
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 }
-- 
2.9.1.434.g748be50