Return constant file suffix string pointers.

src/cdi.h

@@ -320,7 +320,7 @@ int     streamInqTimestep(int streamID, int tsID);
 int     streamInqCurTimestepID(int streamID);
 
 char   *streamFilename(int streamID);
-char   *streamFilesuffix(int filetype);
+const char *streamFilesuffix(int filetype);
 off_t   streamNvals(int streamID);
 
 int     streamInqNvars ( int streamID );

src/stream.c

@@ -308,11 +308,14 @@ int streamInqByteorder(int streamID)
 }
 
 
-char *streamFilesuffix(int filetype)
+const char *streamFilesuffix(int filetype)
 {
   // static char *fileSuffix[] = {"", ".grb", ".g2", ".nc", ".nc", ".nc4", ".nc4", ".srv", ".ext", ".ieg"};
-  static char *fileSuffix[] = {"", ".grb", ".grb", ".nc", ".nc", ".nc", ".nc", ".srv", ".ext", ".ieg"};
-  int size = (int) (sizeof(fileSuffix)/sizeof(char *));
+  /* note: the 2nd dimenstion of the fileSuffix array must be equal to or
+   * larger than the length of the longest suffix (dot and \0 terminator
+   * included) */
+  static const char fileSuffix[][5] = {"", ".grb", ".grb", ".nc", ".nc", ".nc", ".nc", ".srv", ".ext", ".ieg"};
+  int size = (int)(sizeof(fileSuffix)/sizeof(fileSuffix[0]));
 
   if ( filetype > 0 && filetype < size )
     return (fileSuffix[filetype]);