Add version schema check.

Author: techrah

ceshim.c

@@ -491,6 +491,11 @@ static int ceshimPagerLock(ceshim_file *p){
         }else{
           // restore some data
           rc = ceshimLoadHeader(p);
+          if( rc==SQLITE_OK && pInfo->ceshimHeader.schema > CESHIM_FILE_SCHEMA_NO ){
+            // The file schema# is larger than this version can handle.
+            // A newer version is needed to read this file.
+            rc = CESHIM_ERROR_EXT_VERSION_TOO_OLD;
+          }
           if( rc==SQLITE_OK ) rc = ceshimLoadMMTbl(p);
           if( rc==SQLITE_OK ) rc = ceshimLoadPagemapData(p, 0);
         }

ceshim.h

@@ -9,9 +9,10 @@
 #ifndef ceshim_h
 #define ceshim_h
 
-#define CESHIM_ERROR                       400
+#define CESHIM_ERROR                       111
 #define CESHIM_ERROR_PAGE_SIZE_TOO_SMALL   (CESHIM_ERROR | (1<<8))
 #define CESHIM_ERROR_MALFORMED_KEY         (CESHIM_ERROR | (2<<8))
+#define CESHIM_ERROR_EXT_VERSION_TOO_OLD   (CESHIM_ERROR | (3<<8))
 
 int ceshim_register(
   const char *zName,                /* Name of the newly constructed VFS */