cgribexDecode: allocate cgribexp if needed.

src/grb_read.c

@@ -135,6 +135,7 @@ DecodeArgs grb_read_raw_data(stream_t *streamptr, int recID, int memtype, void *
 
   if ( recsize == 0 ) Error("Internal problem! Recordsize is zero for record %d at timestep %d", recID+1, tsID+1);
 
+  void *cgribexp = (gribbuffer && streamptr->record->cgribexp) ? streamptr->record->cgribexp : NULL;
   if (!gribbuffer) gribbuffer = Malloc(streamptr->record->buffersize);
   if (!data) data = Malloc(gridsize*(memtype == MEMTYPE_FLOAT ? sizeof(float) : sizeof(double)));
 
@@ -157,7 +158,7 @@ DecodeArgs grb_read_raw_data(stream_t *streamptr, int recID, int memtype, void *
     .outZip = &streamptr->tsteps[tsID].records[recID].zip,
     .filetype = streamptr->filetype,
     .memtype = memtype,
-    .cgribexp = streamptr->record->cgribexp,
+    .cgribexp = cgribexp,
     .gribbuffer = gribbuffer,
     .recsize = recsize,
     .data = data,

src/stream_cgribex.c

@@ -1297,7 +1297,8 @@ int cgribexDecode(int memtype, void *cgribex, void *gribbuffer, size_t gribsize,
 {
   int status = 0;
 
-  cgribexrec_t *cgribexp = (cgribexrec_t *) cgribex;
+  bool lalloc = cgribex == NULL;
+  cgribexrec_t *cgribexp = (cgribexrec_t *) (lalloc ? cgribexNew() : cgribex);
 
   int *isec0 = cgribexp->sec0;
   int *isec1 = cgribexp->sec1;
@@ -1352,6 +1353,8 @@ int cgribexDecode(int memtype, void *cgribex, void *gribbuffer, size_t gribsize,
         }
     }
 
+  if (lalloc) cgribexDelete(cgribexp);
+
   return status;
 }