[XrdCl] Document xrdcp return codes, closes #628

docs/man/xrdcp.1

@@ -462,6 +462,22 @@ XRD_PREFERIPV4
 If set the client tries first IPv4 address (turned off by default).
 .RE
 
+.SH RETURN CODES
+.RE
+\fB50\fR  : generic error (e.g. config, internal, data, OS)
+
+\fB51\fR  : socket related error
+
+\fB52\fR  : pastmaster related error
+
+\fB53\fR  : XRootD related error
+
+\fB54\fR  : redirection error
+
+\fB254\fR : command line option error
+
+\fB255\fR : problem with source / destination (e.g. multiple sources were given, but target is not a directory)
+
 .SH NOTES
 Documentation for all components associated with \fBxrdcp\fR can be found at
 http://xrootd.org/docs.html

src/XrdCl/XrdClCopy.cc

@@ -652,8 +652,9 @@ int main( int argc, char **argv )
       char *cwd = getcwd( buf, FILENAME_MAX );
       if( !cwd )
       {
-        std::cerr <<  strerror( errno ) << std::endl;
-        return errno;
+        XRootDStatus st( stError, XProtocol::mapError( errno ), errno, strerror( errno ) );
+        std::cerr <<  st.GetErrorMessage() << std::endl;
+        return st.GetShellCode();
       }
       dest += cwd;
       dest += '/';
@@ -755,8 +756,9 @@ int main( int argc, char **argv )
         char *cwd = getcwd( buf, FILENAME_MAX );
         if( !cwd )
         {
-          std::cerr <<  strerror( errno ) << std::endl;
-          return errno;
+          XRootDStatus st( stError, XProtocol::mapError( errno ), errno, strerror( errno ) );
+          std::cerr <<  st.GetErrorMessage() << std::endl;
+          return st.GetShellCode();
         }
         source = "file://" + std::string( cwd ) + '/' + source;
       }