Add `lshal debug` command.

Supported command:
    lshal debug android.hardware.foo@1.0::IFoo option option

Test: adb unroot && lshal --debug ; echo $?
Test: adb unroot && lshal debug android.hardware.nfc@1.0::INfc ; echo $?
Test: adb root && lshal --debug ; echo $?
Test: adb root && lshal debug android.hardware.nfc@1.0::INfc ; echo $?

Bug: 37954458
Change-Id: Ia2f4c9c0d3fb0a7bb26e76f01d02f49dc426e7f8
diff --git a/cmds/lshal/DebugCommand.cpp b/cmds/lshal/DebugCommand.cpp
new file mode 100644
index 0000000..672cad6
--- /dev/null
+++ b/cmds/lshal/DebugCommand.cpp
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "DebugCommand.h"
+
+#include "Lshal.h"
+
+namespace android {
+namespace lshal {
+
+DebugCommand::DebugCommand(Lshal &lshal) : mLshal(lshal) {
+}
+
+Status DebugCommand::parseArgs(const std::string &command, const Arg &arg) {
+    if (optind >= arg.argc) {
+        mLshal.usage(command);
+        return USAGE;
+    }
+    mInterfaceName = arg.argv[optind];
+    ++optind;
+    for (; optind < arg.argc; ++optind) {
+        mOptions.push_back(arg.argv[optind]);
+    }
+    return OK;
+}
+
+Status DebugCommand::main(const std::string &command, const Arg &arg) {
+    Status status = parseArgs(command, arg);
+    if (status != OK) {
+        return status;
+    }
+    auto pair = splitFirst(mInterfaceName, '/');
+    return mLshal.emitDebugInfo(
+            pair.first, pair.second.empty() ? "default" : pair.second, mOptions,
+            mLshal.out().buf(),
+            mLshal.err());
+}
+
+}  // namespace lshal
+}  // namespace android
+