[#2788] add RAII struct for exhausting options

Author: andrei-pavel

src/lib/process/d_controller.cc

@@ -254,6 +254,10 @@ DControllerBase::parseArgs(int argc, char* argv[]) {
     opterr = 0;
     optind = 1;
     std::string opts("dvVWc:t:" + getCustomOpts());
+
+    // Defer exhausting of arguments to the end.
+    ExhaustOptions e(argc, argv, opts);
+
     while ((ch = getopt(argc, argv, opts.c_str())) != -1) {
         switch (ch) {
         case 'd':
@@ -297,10 +301,6 @@ DControllerBase::parseArgs(int argc, char* argv[]) {
             char const saved_optopt(optopt);
             std::string const saved_optarg(optarg ? optarg : std::string());
 
-            // Exhaust all remaining options in case parseArgs() is called again.
-            while (getopt(argc, argv, opts.c_str()) != -1) {
-            }
-
             // We hit an invalid option.
             isc_throw(InvalidUsage, "unsupported option: -" << saved_optopt <<
                       (saved_optarg.empty() ? std::string() : " " + saved_optarg));
@@ -314,10 +314,6 @@ DControllerBase::parseArgs(int argc, char* argv[]) {
                 char const saved_optopt(optopt);
                 std::string const saved_optarg(optarg ? optarg : std::string());
 
-                // Exhaust all remaining options in case parseArgs() is called again.
-                while (getopt(argc, argv, opts.c_str()) != -1) {
-                }
-
                 // We hit an invalid option.
                 isc_throw(InvalidUsage, "unsupported option: -" << saved_optopt <<
                         (saved_optarg.empty() ? std::string() : " " + saved_optarg));

src/lib/process/d_controller.h

@@ -652,9 +652,25 @@ class DControllerBase : public Daemon {
     /// @brief Singleton instance value.
     static DControllerBasePtr controller_;
 
-// DControllerTest is named a friend class to facilitate unit testing while
-// leaving the intended member scopes intact.
-friend class DControllerTest;
+    // DControllerTest is named a friend class to facilitate unit testing while
+    // leaving the intended member scopes intact.
+    friend class DControllerTest;
+
+    /// @brief Structure used in parseArgs() to reset arguments in case parseArgs() is called again.
+    struct ExhaustOptions {
+        ExhaustOptions(int argc, char* argv[], std::string opts)
+            : argc_(argc), argv_(argv), opts_(opts) {
+        }
+        ~ExhaustOptions() {
+            while (getopt(argc_, argv_, opts_.c_str()) != -1) {
+            }
+        }
+
+    private:
+        int argc_;
+        char** argv_;
+        std::string opts_;
+    };
 };
 
 }  // namespace process