Make most command-line tools return useful error codes on well-known exceptions.

include/osrm/error_codes.hpp

@@ -0,0 +1,37 @@
+#ifndef OSRM_ERRORCODES_HPP
+#define OSRM_ERRORCODES_HPP
+
+#include <string>
+
+namespace osrm
+{
+
+/**
+ * Various error codes that can be returned by OSRM internal functions.
+ * Note: often, these translate into return codes from `int main()` functions.
+ *       Thus, do not change the order - if adding new codes, append them to the
+ *       end, so the code values do not change for users that are checking for
+ *       certain values.
+ */
+enum ErrorCode
+{
+    InvalidFingerprint = 2, // Start at 2 to avoid colliding with POSIX EXIT_FAILURE
+    IncompatibleFileVersion,
+    FileOpenError,
+    FileReadError,
+    FileWriteError,
+    FileIOError,
+    UnexpectedEndOfFile,
+    IncompatibleDataset,
+    UnknownAlgorithm
+#ifndef NDEBUG
+    // Leave this at the end.  In debug mode, we assert that the size of
+    // this enum matches the number of messages we have documented, and __ENDMARKER__
+    // is used as the "count" value.
+    ,
+    __ENDMARKER__
+#endif
+};
+}
+
+#endif // OSRM_ERRORCODES_HPP

include/osrm/exception.hpp

@@ -33,6 +33,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 namespace osrm
 {
 using util::exception;
+using util::RuntimeError;
 }
 
 #endif