6 files changed, 100 insertions, 1 deletions
diff --git a/xmake/modules/devel/git/checkout.lua b/xmake/modules/devel/git/checkout.lua
index 12541e5ac..4a4c92bae 100644
--- a/xmake/modules/devel/git/checkout.lua
+++ b/xmake/modules/devel/git/checkout.lua
@@ -38,6 +38,9 @@ import("lib.detect.find_tool")
 --
 function main(commit, opt)
 
+    -- init options
+    opt = opt or {}
+
     -- find git
     local git = find_tool("git")
     if not git then
diff --git a/xmake/modules/devel/git/clean.lua b/xmake/modules/devel/git/clean.lua
index 2d80c2bac..4ed39a20f 100644
--- a/xmake/modules/devel/git/clean.lua
+++ b/xmake/modules/devel/git/clean.lua
@@ -37,6 +37,9 @@ import("lib.detect.find_tool")
 --
 function main(opt)
 
+    -- init options
+    opt = opt or {}
+
     -- find git
     local git = find_tool("git")
     if not git then
diff --git a/xmake/modules/devel/git/clone.lua b/xmake/modules/devel/git/clone.lua
index 75a652b1d..4a77abbf5 100644
--- a/xmake/modules/devel/git/clone.lua
+++ b/xmake/modules/devel/git/clone.lua
@@ -60,6 +60,11 @@ function main(url, opt)
         table.insert(argv, ifelse(type(opt.depth) == "number", tostring(opt.depth), opt.depth))
     end
 
+    -- recursive?
+    if opt.recursive then
+        table.insert(argv, "--recursive")
+    end
+
     -- set outputdir
     if opt.outputdir then
         table.insert(argv, path.translate(opt.outputdir))
diff --git a/xmake/modules/devel/git/ls_remote.lua b/xmake/modules/devel/git/ls_remote.lua
index 391b85caf..e946a054a 100644
--- a/xmake/modules/devel/git/ls_remote.lua
+++ b/xmake/modules/devel/git/ls_remote.lua
@@ -50,8 +50,16 @@ function main(reftype, url)
     -- init reference type
     reftype = reftype or "refs"
 
+    -- init arguments
+    local argv = {"ls-remote", "--" .. reftype, url or "."}
+
+    -- trace
+    if option.get("verbose") then
+        print("%s %s", git.program, os.args(argv))
+    end
+
     -- get refs
-    local data = os.iorunv(git.program, {"ls-remote", "--" .. reftype, url or "."})
+    local data = os.iorunv(git.program, argv)
 
     -- get commmits and tags
     local refs = {}
diff --git a/xmake/modules/devel/git/pull.lua b/xmake/modules/devel/git/pull.lua
index 3e0b67b30..4c274a70b 100644
--- a/xmake/modules/devel/git/pull.lua
+++ b/xmake/modules/devel/git/pull.lua
@@ -37,6 +37,9 @@ import("lib.detect.find_tool")
 --
 function main(opt)
 
+    -- init options
+    opt = opt or {}
+
     -- find git
     local git = find_tool("git")
     if not git then
diff --git a/xmake/modules/devel/git/submodule/update.lua b/xmake/modules/devel/git/submodule/update.lua
new file mode 100644
index 000000000..403bf112d
--- /dev/null
+++ b/xmake/modules/devel/git/submodule/update.lua
@@ -0,0 +1,77 @@
+--!A cross-platform build utility based on Lua
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+-- 
+-- Copyright (C) 2015 - 2019, TBOOX Open Source Group.
+--
+-- @author      ruki
+-- @file        update.lua
+--
+
+-- imports
+import("core.base.option")
+import("lib.detect.find_tool")
+
+-- update submodule 
+--
+-- @param opt       the argument options, e.g. repodir, init, remote, force, checkout, merge, rebase, recursive, reference, pathes
+--
+-- @code
+--
+-- import("devel.git.submodule")
+-- 
+-- submodule.update("master", {repodir = "/tmp/xmake", init = true, remote = true})
+-- submodule.update("v1.0.1", {repodir = "/tmp/xmake", recursive = true, reference = "xxx", pathes = "xxx"})
+--
+-- @endcode
+--
+function main(opt)
+
+    -- init options
+    opt = opt or {}
+
+    -- find git
+    local git = find_tool("git")
+    if not git then
+        return 
+    end
+
+    -- init argv
+    local argv = {"submodule", "update"}
+    for _, name in ipairs({"init", "remote", "force", "checkout", "merge", "rebase", "recursive"}) do
+        if opt[name] then
+            table.insert(argv, "--" .. name)
+        end
+    end
+    if opt.reference then
+        table.insert(argv, "--reference")
+        table.insert(argv, opt.reference)
+    end
+    if opt.pathes then
+        table.join2(argv, opt.pathes)
+    end
+
+    -- enter repository directory
+    local oldir = nil
+    if opt.repodir then
+        oldir = os.cd(opt.repodir)
+    end
+
+    -- submodule it
+    os.vrunv(git.program, argv)
+
+    -- leave repository directory
+    if oldir then
+        os.cd(oldir)
+    end
+end