Notes:

  *  Using 32-bit frame numbers (not 16-bit).


  *  The ZonefileHeader object is 26 bytes in size. Which means that the
     ZoneFileIndex will not be 8-byte aligned. Problem?












  *  The offsets in the ZoneFileIndex.byteOffsetZoneFrame[] array are
     relative to the offset in ZoneFileHeader.byteOffsetFrames. This is
     necessary as we may not know the offset of the start of the frame data
     until after the ZoneFileIndex structure is compressed.

Notes:

  *  Contrary to the spec, the implementation uses 32-bit (not 16-bit) frame
     numbers. So the KeyOffsetPair structure becomes:


     KeyOffsetPair
     {
       uint64  key;
       uint32  frameNo;
       uint32  frameByteOffset;
     };

     Also, the ZonefileHeader.numFrames field is now 32-bit. Which makes
     the ZonefileHeader structure 26 bytes in size. The implementation
     pads this out to 32 bytes so that the ZoneFileIndex is 8-byte aligned.

  *  Multi-byte integer values are big-endian.

  *  The offsets in the ZoneFileIndex.byteOffsetZoneFrame[] array are
     relative to the offset in ZoneFileHeader.byteOffsetFrames. This is
     necessary as we may not know the offset of the start of the frame data
     until after the ZoneFileIndex structure is compressed.

  *  Currently there is no support for encryption or compression.

  "  ofst INTEGER,"              \
  "  sz INTEGER"                 \
  ")"

#define ZONEFILE_FILES_SCHEMA    \
  "CREATE TABLE z2("             \
  "  filename TEXT,"             \
  "  priority INTEGER,"          \
  "  ekey BLOB,"                 \
  "  header JSON HIDDEN"         \
  ")"


#include <stdio.h>
#include <string.h>
................................................................................
*/
static int zffColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  switch( i ){
    case 0: /* filename */
      sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pSelect, 0));
      break;
    case 1: /* priority */
      break;
    case 2: /* ekey */
      break;
    case 3: { /* header */
      const char *zFile = (const char*)sqlite3_column_text(pCsr->pSelect, 0);
      zonefileJsonHeader(ctx, zFile);
      break;
    }
  }
  return SQLITE_OK;
}
................................................................................
**
** A delete specifies a single argument - the rowid of the row to remove.
** 
** Update and insert operations pass:
**
**   1. The "old" rowid, or NULL.
**   2. The "new" rowid.
**   3. Values for each of the 4 columns: (filename,priority,ekey,header)
*/
static int zffUpdate(
  sqlite3_vtab *pVtab, 
  int nVal, 
  sqlite3_value **apVal, 
  sqlite_int64 *pRowid
){
................................................................................
          "  fileid INTEGER,"
          "  frame INTEGER,"
          "  ofst INTEGER,"
          "  sz INTEGER"
          ");"
          "CREATE TABLE %Q.'%q_shadow_file'(" 
          "  filename TEXT,"
          "  priority INTEGER,"
          "  fileid INTEGER PRIMARY KEY"
          ");" 
          "CREATE VIRTUAL TABLE %Q.'%q_files' USING zonefile_files;",
          zDb, zName, zDb, zName, zDb, zName
      );
  
      if( zSql==0 ){

  "  ofst INTEGER,"              \
  "  sz INTEGER"                 \
  ")"

#define ZONEFILE_FILES_SCHEMA    \
  "CREATE TABLE z2("             \
  "  filename TEXT,"             \

  "  ekey BLOB,"                 \
  "  header JSON HIDDEN"         \
  ")"


#include <stdio.h>
#include <string.h>
................................................................................
*/
static int zffColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  switch( i ){
    case 0: /* filename */
      sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pSelect, 0));
      break;


    case 1: /* ekey */
      break;
    case 2: { /* header */
      const char *zFile = (const char*)sqlite3_column_text(pCsr->pSelect, 0);
      zonefileJsonHeader(ctx, zFile);
      break;
    }
  }
  return SQLITE_OK;
}
................................................................................
**
** A delete specifies a single argument - the rowid of the row to remove.
** 
** Update and insert operations pass:
**
**   1. The "old" rowid, or NULL.
**   2. The "new" rowid.
**   3. Values for each of the 3 columns: (filename,ekey,header)
*/
static int zffUpdate(
  sqlite3_vtab *pVtab, 
  int nVal, 
  sqlite3_value **apVal, 
  sqlite_int64 *pRowid
){
................................................................................
          "  fileid INTEGER,"
          "  frame INTEGER,"
          "  ofst INTEGER,"
          "  sz INTEGER"
          ");"
          "CREATE TABLE %Q.'%q_shadow_file'(" 
          "  filename TEXT,"

          "  fileid INTEGER PRIMARY KEY"
          ");" 
          "CREATE VIRTUAL TABLE %Q.'%q_files' USING zonefile_files;",
          zDb, zName, zDb, zName, zDb, zName
      );
  
      if( zSql==0 ){