Gives and informative message and exits the program when the source file is not found, instead of abort and core dumping

git-svn-id: https://svn.code.sf.net/p/gnss-sdr/code/trunk@210 64b25241-fba3-4117-9849-534c7e92360d

src/algorithms/signal_source/adapters/file_signal_source.cc

@@ -7,7 +7,7 @@
  *
  * -------------------------------------------------------------------------
  *
- * Copyright (C) 2010-2011  (see AUTHORS file for a list of contributors)
+ * Copyright (C) 2010-2012  (see AUTHORS file for a list of contributors)
  *
  * GNSS-SDR is a software defined Global Navigation
  *          Satellite Systems receiver
@@ -37,6 +37,7 @@
 #include <iostream>
 #include <fstream>
 #include <iomanip>
+#include <exception>
 #include <gflags/gflags.h>
 #include <glog/log_severity.h>
 #include <glog/logging.h>
@@ -89,8 +90,31 @@ FileSignalSource::FileSignalSource(ConfigurationInterface* configuration,
           << " unrecognized item type. Using short.";
       item_size_ = sizeof(short);
     }
-
+  try
+  {
       file_source_ = gr_make_file_source(item_size_, filename_.c_str(), repeat_);
+  }
+  catch (const std::exception &e)
+  {
+      std::cerr
+      << "The receiver was configured to work with a file signal source "
+      << std::endl
+      << "but the specified file is unreachable by GNSS-SDR."
+      << std::endl
+      << "Please modify the configuration at "
+      << "conf/gnss-sdr.conf (the default configuration file)"
+      << std::endl
+      << "and point SignalSource.filename to a valid file,"
+      << std::endl
+      << "or specify your own receiver and source with the flag"
+      << std::endl
+      <<"gnss-sdr --config_file=my_GNSS_SDR_configuration"
+      << std::endl;
+      LOG_AT_LEVEL(INFO) << "file_signal_source: Unable to open the samples file "
+          << filename_.c_str() << ", exiting the program.";
+      exit(1);
+  }
+
   DLOG(INFO) << "file_source(" << file_source_->unique_id() << ")";
 
   if (samples_ == 0)