--- a/hglib.lua	Fri Sep 16 15:50:45 2016 +0800
+++ b/hglib.lua	Fri Sep 16 16:07:39 2016 +0800
@@ -128,7 +128,7 @@
 	end
 end
 
-function Client:runcommand(command)
+function Client:runcommand(command, input)
 	if not self.capabilities.runcommand then
 		return nil, '', 'runcommand is not supported by this command server', ''
 	end
@@ -138,6 +138,11 @@
 	local o = ''
 	local e = ''
 	local d = ''
+	local function write_input(length)
+		write_block(self.wh, input:sub(1, length))
+		self.wh:flush()
+		input = input:sub(length + 1)
+	end
 	while true do
 		local channel, message = read_channel(self.rh)
 		if channel == 'r' then
@@ -148,6 +153,10 @@
 			e = e .. message
 		elseif channel == 'd' then
 			d = d .. message
+		elseif channel == 'I' and input ~= nil then
+			write_input(message)
+		elseif channel == 'L' and input ~= nil then
+			write_input(math.min(input:find('\n') or message, message))
 		elseif channel:lower() ~= channel then
 			e = e .. '\nhglib: unexpected data on required channel "' .. channel .. '"'
 			return nil, o, e, d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spec/data/foo.patch	Fri Sep 16 16:07:39 2016 +0800
@@ -0,0 +1,14 @@
+# HG changeset patch
+# User John Smith <john@example.com>
+# Date 1474010779 -28800
+#      Fri Sep 16 15:26:19 2016 +0800
+# Node ID 39d84331d692c8b0beb94da7cba0c5af83ee070d
+# Parent  0000000000000000000000000000000000000000
+First patch ever, I don't know what I'm doing!
+
+diff --git a/foo b/foo
+new file mode 100644
+--- /dev/null
++++ b/foo
+@@ -0,0 +1,1 @@
++bar

--- a/spec/hglib_spec.lua	Fri Sep 16 15:50:45 2016 +0800
+++ b/spec/hglib_spec.lua	Fri Sep 16 16:07:39 2016 +0800
@@ -80,4 +80,35 @@
 		assert.are_equal('', d)
 		assert.are_equal(0, code)
 	end)
+
+	it('can use runcommand to import a patch and run summary', function()
+		local client = hglib.Client.open()
+		do
+			local code, o, e, d = client:runcommand({'init', 'testrepo'})
+			finally(function() os.execute('rm -r testrepo') end)
+			assert.are_equal('', o)
+			assert.are_equal('', e)
+			assert.are_equal('', d)
+			assert.are_equal(0, code)
+		end
+		do
+			local pf = assert(io.open('spec/data/foo.patch', 'rb'))
+			local patch = pf:read('*all')
+			pf:close()
+			local code, o, e, d = client:runcommand({'-R', 'testrepo', 'import', '-'}, patch)
+			assert.is_not_nil(o:find('applying patch from stdin'))
+			assert.are_equal('', e)
+			assert.are_equal('', d)
+			assert.are_equal(0, code)
+		end
+		do
+			local code, o, e, d = client:runcommand({'-R', 'testrepo', 'summary'})
+			assert.is_nil(o:find('empty repository'))
+			assert.is_not_nil(o:find('parent: 0:[0-9a-f]+ tip'))
+			assert.are_equal('', e)
+			assert.are_equal('', d)
+			assert.are_equal(0, code)
+		end
+		client:close()
+	end)
 end)