lshal: add wait command

Waits for an interface to start (e.g. for scripting certain tests).

Fixes: 135956088
Test: the following
$ adb shell lshal wait android.hardware.nfc@1.0::INfc/foo
Service not found (missing permissions or not in VINTF manifest?).
$ echo $?
128
$ adb shell lshal wait android.hardware.nfc@1.0::INfc/default
$ echo $?
0
Test: lshal_test

Change-Id: I355fc33f9e46bac573a38425205e8db81f19a36e

cmds/lshal/Android.bp

@@ -36,6 +36,7 @@ cc_library_static {
         "TableEntry.cpp",
         "TextTable.cpp",
         "utils.cpp",
+        "WaitCommand.cpp",
     ],
     cflags: [
         "-Wall",

cmds/lshal/Lshal.cpp

@@ -26,7 +26,9 @@
 #include <hidl/HidlTransportUtils.h>
 
 #include "DebugCommand.h"
+#include "HelpCommand.h"
 #include "ListCommand.h"
+#include "WaitCommand.h"
 #include "PipeRelay.h"
 
 namespace android {
@@ -49,6 +51,7 @@ Lshal::Lshal(std::ostream &out, std::ostream &err,
     mRegisteredCommands.push_back({std::make_unique<ListCommand>(*this)});
     mRegisteredCommands.push_back({std::make_unique<DebugCommand>(*this)});
     mRegisteredCommands.push_back({std::make_unique<HelpCommand>(*this)});
+    mRegisteredCommands.push_back({std::make_unique<WaitCommand>(*this)});
 }
 
 void Lshal::forEachCommand(const std::function<void(const Command* c)>& f) const {

cmds/lshal/Lshal.h

@@ -24,7 +24,6 @@
 #include <utils/StrongPointer.h>
 
 #include "Command.h"
-#include "HelpCommand.h"
 #include "NullableOStream.h"
 #include "utils.h"
 

cmds/lshal/WaitCommand.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2019 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 "WaitCommand.h"
+
+#include "Lshal.h"
+
+#include <hidl/ServiceManagement.h>
+#include <hidl-util/FQName.h>
+
+namespace android {
+namespace lshal {
+
+std::string WaitCommand::getName() const {
+    return "wait";
+}
+
+std::string WaitCommand::getSimpleDescription() const {
+    return "Wait for HAL to start if it is not already started.";
+}
+
+Status WaitCommand::parseArgs(const Arg &arg) {
+    if (optind + 1 != arg.argc) {
+        return USAGE;
+    }
+
+    mInterfaceName = arg.argv[optind];
+    ++optind;
+    return OK;
+}
+
+Status WaitCommand::main(const Arg &arg) {
+    Status status = parseArgs(arg);
+    if (status != OK) {
+        return status;
+    }
+
+    auto [interface, instance] = splitFirst(mInterfaceName, '/');
+    instance = instance.empty() ? "default" : instance;
+
+    FQName fqName;
+    if (!FQName::parse(interface, &fqName) || fqName.isIdentifier() || !fqName.isFullyQualified()) {
+        mLshal.err() << "Invalid fully-qualified name '" << interface << "'\n\n";
+        return USAGE;
+    }
+
+    using android::hidl::manager::V1_0::IServiceManager;
+
+    using android::hardware::details::getRawServiceInternal;
+    auto service = getRawServiceInternal(interface, instance, true /*retry*/, false /*getStub*/);
+
+    if (service == nullptr) {
+        mLshal.err() << "Service not found (missing permissions or not in VINTF manifest?).\n";
+        return NO_INTERFACE;
+    }
+
+    return OK;
+}
+
+void WaitCommand::usage() const {
+    static const std::string debug =
+            "wait:\n"
+            "    lshal wait <interface/instance> \n"
+            "        For a HAL that is on the device, wait for the HAL to start.\n"
+            "        This will not start a HAL unless it is configured as a lazy HAL.\n"
+            "        <interface>: Format is `android.hardware.foo@1.0::IFoo/default`.\n"
+            "            If instance name is missing `default` is used.\n";
+
+    mLshal.err() << debug;
+}
+
+}  // namespace lshal
+}  // namespace android
+

cmds/lshal/WaitCommand.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <string>
+
+#include <android-base/macros.h>
+
+#include "Command.h"
+#include "utils.h"
+
+namespace android {
+namespace lshal {
+
+class Lshal;
+
+class WaitCommand : public Command {
+public:
+    explicit WaitCommand(Lshal &lshal) : Command(lshal) {}
+    ~WaitCommand() = default;
+    Status main(const Arg &arg) override;
+    void usage() const override;
+    std::string getSimpleDescription() const override;
+    std::string getName() const override;
+private:
+    Status parseArgs(const Arg &arg);
+
+    std::string mInterfaceName;
+
+    DISALLOW_COPY_AND_ASSIGN(WaitCommand);
+};
+
+
+}  // namespace lshal
+}  // namespace android