Add --continue argument

The monitor will exit when key is pressed.
Add --continue argument and if it is set to "true", the monitor will
continue after key is pressed.

This is useful in cases to monitor a button presses.
E.g. It can be used to monitor ID button and start a system unit
everytime when the button is pressed.

This argument is optional so it does not break the current code.

Tested: With "--continue=true", the monitor does not exit when the key
        is pressed.
        Without the argument of if it is set to other strings, the
        monitor exits after the key is pressed.

Change-Id: I4f2ca16d7b26e10397181c83c2c5947ed5ce091f
Signed-off-by: Lei YU <mine260309@gmail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/argument.cpp b/argument.cpp
index 41cf6f7..d388001 100644
--- a/argument.cpp
+++ b/argument.cpp
@@ -37,6 +37,7 @@ const option ArgumentParser::options[] =
     { "key",      required_argument,  nullptr,   'k' },
     { "polarity", required_argument,  nullptr,   'r' },
     { "target",   required_argument,  nullptr,   't' },
+    { "continue", optional_argument,  nullptr,   'c' },
     { "help",     no_argument,        nullptr,   'h' },
     { 0, 0, 0, 0},
 };
@@ -60,7 +61,10 @@ ArgumentParser::ArgumentParser(int argc, char** argv)
 
         if (i->val)
         {
-            arguments[i->name] = (i->has_arg ? optarg : trueString);
+            // optinal argument may get nullptr for optarg
+            // make it empty string in such case
+            auto arg = (optarg == nullptr ? "" : optarg);
+            arguments[i->name] = (i->has_arg ? arg : trueString);
         }
     }
 }
@@ -90,6 +94,8 @@ void ArgumentParser::usage(char** argv)
                                             " This is 0 / 1 \n";
     std::cerr << "  --target=<systemd unit> Systemd unit to be called on GPIO"
                                             " state change\n";
+    std::cerr << "  --continue=[true]       Whether or not to continue"
+                                            " after key pressed\n";
 }
 } // namespace gpio
 } // namespace phosphor