Add some basic configuration checks

Avoid some segmentation faults caused by ill-formatted configuration files

src/core/libs/INIReader.cc

@@ -81,3 +81,23 @@ int INIReader::ValueHandler(void* user, const char* section, const char* name,
     reader->_values[MakeKey(section, name)] = value;
     return 1;
 }
+
+
+bool INIReader::HasSection(const std::string& section) const
+{
+    const std::string key = MakeKey(section, "");
+    auto pos = _values.lower_bound(key);
+    if (pos == _values.end())
+        {
+            return false;
+        }
+    // Does the key at the lower_bound pos start with "section"?
+    return pos->first.compare(0, key.length(), key) == 0;
+}
+
+
+bool INIReader::HasValue(const std::string& section, const std::string& name) const
+{
+    std::string key = MakeKey(section, name);
+    return _values.count(key);
+}

src/core/libs/INIReader.h

@@ -58,6 +58,12 @@ public:
     //! Get an integer (long) value from INI file, returning default_value if not found.
     int64_t GetInteger(const std::string& section, const std::string& name, int64_t default_value);
 
+    //! Return true if the given section exists (section must contain at least one name=value pair).
+    bool HasSection(const std::string& section) const;
+
+    //! Return true if a value exists with the given section and field names.
+    bool HasValue(const std::string& section, const std::string& name) const;
+
 private:
     static std::string MakeKey(const std::string& section, const std::string& name);
     static int ValueHandler(void* user, const char* section, const char* name,

src/core/receiver/control_thread.cc

@@ -83,6 +83,41 @@ ControlThread::ControlThread()
         {
             configuration_ = std::make_shared<FileConfiguration>(FLAGS_c);
         }
+    // Basic configuration checks
+    auto aux = std::dynamic_pointer_cast<FileConfiguration>(configuration_);
+    conf_file_has_section_ = aux->has_section();
+
+    conf_file_has_mandatory_globals_ = (configuration_->property("GNSS-SDR.internal_fs_sps", 0) == 0 ? false : true);
+
+    const std::string empty_implementation;
+    std::string src_impl = configuration_->property("SignalSource.implementation", empty_implementation);
+    int src_count = configuration_->property("Receiver.sources_count", 1);
+    if (src_impl.empty() && (src_count != 1))
+        {
+            int num_src = 0;
+            for (int i = 0; i < src_count; i++)
+                {
+                    std::string src_impl_multiple = configuration_->property("SignalSource" + std::to_string(i) + ".implementation", empty_implementation);
+                    if (!src_impl_multiple.empty())
+                        {
+                            num_src++;
+                        }
+                }
+            if (num_src != src_count)
+                {
+                    src_impl = std::string("");
+                }
+        }
+    conf_has_signal_sources_ = !src_impl.empty();
+
+    std::string pvt_impl = configuration_->property("PVT.implementation", empty_implementation);
+    conf_has_pvt_ = !pvt_impl.empty();
+
+    std::string obs_impl = configuration_->property("Observables.implementation", empty_implementation);
+    conf_has_observables_ = !obs_impl.empty();
+
+    well_formatted_configuration_ = conf_file_has_section_ && conf_file_has_mandatory_globals_ && conf_has_signal_sources_ && conf_has_observables_ && conf_has_pvt_;
+
     restart_ = false;
     init();
 }
@@ -91,6 +126,12 @@ ControlThread::ControlThread()
 ControlThread::ControlThread(std::shared_ptr<ConfigurationInterface> configuration)
 {
     configuration_ = std::move(configuration);
+    conf_file_has_section_ = true;
+    conf_file_has_mandatory_globals_ = true;
+    conf_has_signal_sources_ = true;
+    conf_has_observables_ = true;
+    conf_has_pvt_ = true;
+    well_formatted_configuration_ = true;
     restart_ = false;
     init();
 }
@@ -104,6 +145,8 @@ void ControlThread::init()
     // Instantiates a control queue, a GNSS flowgraph, and a control message factory
     control_queue_ = std::make_shared<Concurrent_Queue<pmt::pmt_t>>();
     cmd_interface_.set_msg_queue(control_queue_);  // set also the queue pointer for the telecommand thread
+    if (well_formatted_configuration_)
+        {
             try
                 {
                     flowgraph_ = std::make_shared<GNSSFlowgraph>(configuration_, control_queue_);
@@ -112,6 +155,12 @@ void ControlThread::init()
                 {
                     std::cout << "Caught bad lexical cast with error " << e.what() << '\n';
                 }
+        }
+    else
+        {
+            flowgraph_ = nullptr;
+        }
+
     stop_ = false;
     processed_control_messages_ = 0;
     applied_actions_ = 0;
@@ -285,6 +334,11 @@ void ControlThread::event_dispatcher(bool &valid_event, pmt::pmt_t &msg)
 int ControlThread::run()
 {
     // Connect the flowgraph
+    if (!flowgraph_)
+        {
+            print_help_at_exit();
+            return 0;
+        }
     try
         {
             flowgraph_->connect();
@@ -1145,3 +1199,37 @@ void ControlThread::keyboard_listener()
                 }
         }
 }
+
+
+void ControlThread::print_help_at_exit() const
+{
+    std::cerr << "Error: the configuration file is not well formatted\n";
+    if (!conf_file_has_section_)
+        {
+            std::cerr << " * The section label has not been found if the configuration file\n"
+                      << "   Please add the [GNSS-SDR] label at the top of your configuration file\n"
+                      << "   A configuration example is available at https://gnss-sdr.org/my-first-fix/\n";
+            return;
+        }
+    if (!conf_file_has_mandatory_globals_)
+        {
+            std::cerr << " * Have you forgotten to set the mandatory global parameter GNSS-SDR.internal_fs_sps in your conf file?\n"
+                      << "   Documentation about this parameter at https://gnss-sdr.org/docs/sp-blocks/global-parameters/\n"
+                      << "   A configuration example is available at https://gnss-sdr.org/my-first-fix/\n";
+        }
+    if (!conf_has_signal_sources_)
+        {
+            std::cerr << " * The configuration file must define at least one SignalSource.implementation\n"
+                      << "   Documentation of SignalSource block implementations at https://gnss-sdr.org/docs/sp-blocks/signal-source/\n";
+        }
+    if (!conf_has_observables_)
+        {
+            std::cerr << " * The configuration file must define an Observables.implementation\n"
+                      << "   Documentation of the Observables block at https://gnss-sdr.org/docs/sp-blocks/observables/\n";
+        }
+    if (!conf_has_pvt_)
+        {
+            std::cerr << " * The configuration file must define a PVT.implementation\n"
+                      << "   Documentation of the PVT block at https://gnss-sdr.org/docs/sp-blocks/pvt/\n";
+        }
+}

src/core/receiver/control_thread.h

@@ -153,6 +153,7 @@ private:
     void telecommand_listener();
     void keyboard_listener();
     void sysv_queue_listener();
+    void print_help_at_exit() const;
 
     // default filename for assistance data
     const std::string eph_default_xml_filename_ = "./gps_ephemeris.xml";
@@ -203,6 +204,12 @@ private:
     unsigned int applied_actions_;
     int msqid_;
 
+    bool well_formatted_configuration_;
+    bool conf_file_has_section_;
+    bool conf_file_has_mandatory_globals_;
+    bool conf_has_signal_sources_;
+    bool conf_has_observables_;
+    bool conf_has_pvt_;
     bool receiver_on_standby_;
     bool stop_;
     bool restart_;

src/core/receiver/file_configuration.cc

@@ -60,6 +60,12 @@ void FileConfiguration::init()
 }
 
 
+bool FileConfiguration::has_section() const
+{
+    return ini_reader_->HasSection("GNSS-SDR");
+}
+
+
 std::string FileConfiguration::property(std::string property_name, std::string default_value) const
 {
     if (overrided_->is_present(property_name))

src/core/receiver/file_configuration.h

@@ -63,6 +63,7 @@ public:
     double property(std::string property_name, double default_value) const override;
     void set_property(std::string property_name, std::string value) override;
     bool is_present(const std::string& property_name) const;
+    bool has_section() const;
 
 private:
     void init();