lshal: add HelpCommand

Add *Command::usage() function for each Command and let
Lshal class to call them.

Suppress output from getopt_long and write our own
error message to customized error stream (for testing).

Test: lshal_test
Test: lshal --help

Change-Id: I8f5847c84a3e01af29fa85871479cab3baeb5312

1 files changed, 16 insertions, 4 deletions

diff --git a/cmds/lshal/DebugCommand.cpp b/cmds/lshal/DebugCommand.cpp
index e657bcf4e6..d21764ce3e 100644
--- a/cmds/lshal/DebugCommand.cpp
+++ b/cmds/lshal/DebugCommand.cpp
@@ -21,9 +21,8 @@
 namespace android {
 namespace lshal {
 
-Status DebugCommand::parseArgs(const std::string &command, const Arg &arg) {
+Status DebugCommand::parseArgs(const Arg &arg) {
     if (optind >= arg.argc) {
-        mLshal.usage(command);
         return USAGE;
     }
     mInterfaceName = arg.argv[optind];
@@ -34,8 +33,8 @@ Status DebugCommand::parseArgs(const std::string &command, const Arg &arg) {
     return OK;
 }
 
-Status DebugCommand::main(const std::string &command, const Arg &arg) {
-    Status status = parseArgs(command, arg);
+Status DebugCommand::main(const Arg &arg) {
+    Status status = parseArgs(arg);
     if (status != OK) {
         return status;
     }
@@ -46,6 +45,19 @@ Status DebugCommand::main(const std::string &command, const Arg &arg) {
             mLshal.err());
 }
 
+void DebugCommand::usage() const {
+
+    static const std::string debug =
+            "debug:\n"
+            "    lshal debug <interface> [options [options [...]]] \n"
+            "        Print debug information of a specified interface.\n"
+            "        <inteface>: Format is `android.hardware.foo@1.0::IFoo/default`.\n"
+            "            If instance name is missing `default` is used.\n"
+            "        options: space separated options to IBase::debug.\n";
+
+    mLshal.err() << debug;
+}
+
 }  // namespace lshal
 }  // namespace android