t/lib-git-daemon: try harder to find a port

As with the previous commit, try harder to find an open port to avoid
intermittent failures on busy/shared build systems.

By default, we make 3 attempts.  This may be overridden by setting
GIT_TEST_START_GIT_DAEMON_TRIES to a different value.

Signed-off-by: Todd Zullinger <tmz@pobox.com>

Author: tmzullinger

t/lib-git-daemon.sh

@@ -51,30 +51,44 @@ start_git_daemon() {
 		registered_stop_git_daemon_atexit_handler=AlreadyDone
 	fi
 
-	say >&3 "Starting git daemon ..."
-	mkfifo git_daemon_output
-	${LIB_GIT_DAEMON_COMMAND:-git daemon} \
-		--listen=127.0.0.1 --port="$LIB_GIT_DAEMON_PORT" \
-		--reuseaddr --verbose --pid-file="$GIT_DAEMON_PIDFILE" \
-		--base-path="$GIT_DAEMON_DOCUMENT_ROOT_PATH" \
-		"$@" "$GIT_DAEMON_DOCUMENT_ROOT_PATH" \
-		>&3 2>git_daemon_output &
-	GIT_DAEMON_PID=$!
-	{
-		read -r line <&7
-		printf "%s\n" "$line" >&4
-		cat <&7 >&4 &
-	} 7<git_daemon_output &&
+	i=0
+	while test $i -lt ${GIT_TEST_START_GIT_DAEMON_TRIES:-3}
+	do
+		say >&3 "Starting git daemon on port $LIB_GIT_DAEMON_PORT ..."
+		mkfifo git_daemon_output
+		${LIB_GIT_DAEMON_COMMAND:-git daemon} \
+			--listen=127.0.0.1 --port="$LIB_GIT_DAEMON_PORT" \
+			--reuseaddr --verbose --pid-file="$GIT_DAEMON_PIDFILE" \
+			--base-path="$GIT_DAEMON_DOCUMENT_ROOT_PATH" \
+			"$@" "$GIT_DAEMON_DOCUMENT_ROOT_PATH" \
+			>&3 2>git_daemon_output &
+		GIT_DAEMON_PID=$!
+		{
+			read -r line <&7
+			printf "%s\n" "$line" >&4
+			cat <&7 >&4 &
+		} 7<git_daemon_output &&
 
-	# Check expected output
-	if test x"$(expr "$line" : "\[[0-9]*\] \(.*\)")" != x"Ready to rumble"
-	then
-		kill "$GIT_DAEMON_PID"
-		wait "$GIT_DAEMON_PID"
-		unset GIT_DAEMON_PID
-		test_skip_or_die GIT_TEST_GIT_DAEMON \
-			"git daemon failed to start"
-	fi
+		# Check expected output
+		output="$(expr "$line" : "\[[0-9]*\] \(.*\)")"
+		# Return if found
+		test x"$output" = x"Ready to rumble" && return
+		# Increment port for retry if not found
+		LIB_GIT_DAEMON_PORT=$(($LIB_GIT_DAEMON_PORT + 1))
+		export LIB_GIT_DAEMON_PORT
+		GIT_DAEMON_HOST_PORT=127.0.0.1:$LIB_GIT_DAEMON_PORT
+		GIT_DAEMON_URL=git://$GIT_DAEMON_HOST_PORT
+		# unset GIT_DAEMON_PID; remove the fifo & pid file
+		GIT_DAEMON_PID=
+		rm -f git_daemon_output "$GIT_DAEMON_PIDFILE"
+	done
+
+	# Clean up and return failure
+	kill "$GIT_DAEMON_PID"
+	wait "$GIT_DAEMON_PID"
+	unset GIT_DAEMON_PID
+	test_skip_or_die GIT_TEST_GIT_DAEMON \
+		"git daemon failed to start"
 }
 
 stop_git_daemon() {