<td>The compression type used to compress the zonefile index structure.
All values that are valid for the <i>compressionTypeContent</i> parameter,
except for "zstd_global_dict", are also valid for this option.

<tr valign=top><td>encryptionType<td>"none"
<td>The encryption type to use. At present the only valid values are
"none" (no encryption) and "xor" (an insecure mock encryption method
useful for testing only).








<tr valign=top><td>encryptionKey<td>""
<td>The encryption key to use. The encryption key must be specified as an
even number of hexadecimal that will be converted to a binary key before
use. It is the responsibility of the caller to specify a key of the optimal
length for each encryption algorithm (e.g. 16 bytes (32 hex digits) for
a 128-bit encryption, or 32 bytes (64 digits) for a 256-bit method).
................................................................................

This creates two virtual tables in the database schema. One read-only table
named "z1", with a schema equivalent to:

>     CREATE TABLE z1(  -- this whole table is read-only
>       k INTEGER PRIMARY KEY,     -- key value
>       v BLOB,                    -- associated blob of data
>       file TEXT,                 -- file this key is read from 
>       sz INTEGER                 -- size of blob of data in bytes
>     );

And a read-write table named "z1_files" with a schema like:

>     CREATE TABLE z1_files(
>       filename TEXT PRIMARY KEY,
>       ekey BLOB,         -- encryption key
>       fileid INTEGER,    -- read-only
>       header JSON HIDDEN -- read-only
>     );

Both tables are initially empty. To add a zonefile to the index, insert a
row into the "z1_files" table:

>     INSERT INTO z1_files(filename) VALUES(<filename>);

<td>The compression type used to compress the zonefile index structure.
All values that are valid for the <i>compressionTypeContent</i> parameter,
except for "zstd_global_dict", are also valid for this option.

<tr valign=top><td>encryptionType<td>"none"
<td>The encryption type to use. At present the only valid values are
"none" (no encryption) and "xor" (an insecure mock encryption method
useful for testing only). Enhanced implementations may support any or
all of the following encryption schemes:
<ul>
  <li> "AES_128_CTR"
  <li> "AES_128_CBC"
  <li> "AES_256_CTR"
  <li> "AES_256_CBC"
</ul>

<tr valign=top><td>encryptionKey<td>""
<td>The encryption key to use. The encryption key must be specified as an
even number of hexadecimal that will be converted to a binary key before
use. It is the responsibility of the caller to specify a key of the optimal
length for each encryption algorithm (e.g. 16 bytes (32 hex digits) for
a 128-bit encryption, or 32 bytes (64 digits) for a 256-bit method).
................................................................................

This creates two virtual tables in the database schema. One read-only table
named "z1", with a schema equivalent to:

>     CREATE TABLE z1(  -- this whole table is read-only
>       k INTEGER PRIMARY KEY,     -- key value
>       v BLOB,                    -- associated blob of data
>       fileid INTEGER,            -- file id (rowid value for z1_files)
>       sz INTEGER                 -- size of blob of data in bytes
>     );

And a read-write table named "z1_files" with a schema like:

>     CREATE TABLE z1_files(
>       filename TEXT PRIMARY KEY,
>       ekey BLOB,         -- encryption key

>       header JSON HIDDEN -- read-only
>     );

Both tables are initially empty. To add a zonefile to the index, insert a
row into the "z1_files" table:

>     INSERT INTO z1_files(filename) VALUES(<filename>);

  return SQLITE_OK;
}

/*
** Search the key-store passed as the first argument for an encryption
** key to use with the file with file-id iFileid in zonefile table zTab
** in database zDb. If successful, set (*pzKey) to point to the key
** buffer and return the size of the key in bytes.
**
** If no key is found, return 0. The final value of (*pzKey) is undefined
** in this case.
*/
static int zonefileKeyFind(
  ZonefileGlobal *pGlobal,
  const char *zDb,                /* Database containing zonefile table */
  const char *zTab,               /* Name of zonefile table */
  i64 iFileid,                    /* File-id to configure key for */
................................................................................
    0,
    zfLz4CompressBound, zfLz4hcCompress, 
    zfGenericUncompressSize, zfLz4Uncompress
  },
#endif /* SQLITE_HAVE_LZ4 */
};









static int zonefileCompress(
  const char *zName,              /* Name of requested compression method */
  ZonefileCompress **pp,          /* OUT: Pointer to compression object */
  char **pzErr                    /* OUT: Error message */
){
  int i;
  assert( *pzErr==0 );
................................................................................
      return SQLITE_OK;
    }
  }
  *pzErr = sqlite3_mprintf("unknown compression scheme: \"%s\"", zName);
  return SQLITE_ERROR;
}








static ZonefileCompress *zonefileCompressByValue(int eType){
  int i;
  for(i=0; i<sizeof(aZonefileCompress)/sizeof(aZonefileCompress[0]); i++){
    if( aZonefileCompress[i].eType==eType ){
      return &aZonefileCompress[i];
    }
  }
................................................................................
  va_start(ap, zFmt);
  zMsg = sqlite3_vmprintf(zFmt, ap);
  sqlite3_result_error(ctx, zMsg, -1);
  sqlite3_free(zMsg);
  va_end(ap);
}





static void zonefileTransferError(sqlite3_context *pCtx){
  sqlite3 *db = sqlite3_context_db_handle(pCtx);
  const char *zErr = sqlite3_errmsg(db);
  sqlite3_result_error(pCtx, zErr, -1);
}














static int zonefilePrepare(
  sqlite3 *db,
  sqlite3_stmt **ppStmt,
  char **pzErr,
  const char *zFmt,
  ...
){
  int rc;
  va_list ap;
  char *zSql;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
................................................................................
    default:
      assert( eType==SQLITE_NULL);
  }

  return 0;
}





int zonefileIsAutoFrame(sqlite3_value *pFrame){
  return (
      sqlite3_value_type(pFrame)==SQLITE_INTEGER 
   && sqlite3_value_int64(pFrame)==-1
  );
}

#define SQLITE_ZONEFILE_AES_128_CTR 1
#define SQLITE_ZONEFILE_AES_128_CBC 2
#define SQLITE_ZONEFILE_AES_256_CTR 3
#define SQLITE_ZONEFILE_AES_256_CBC 4











static int zonefileEncryption(const char *zName, int *peType, char **pzErr){
  struct Encryption {
    const char *zName;
    int eType;
  } a[] = {
    {"NONE", 0}, 
    {"AES_128_CTR", SQLITE_ZONEFILE_AES_128_CTR}, 
................................................................................
    }
  }

  *pzErr = sqlite3_mprintf("unknown encryption method: %s", zName);
  return SQLITE_ERROR;
}









static int zonefileGetParams(
  sqlite3_context *pCtx,          /* Leave any error message here */
  const char *zJson,              /* JSON configuration parameter (or NULL) */
  ZonefileParam *p                /* Populate this object before returning */
){
  sqlite3 *db = sqlite3_context_db_handle(pCtx);
  sqlite3_stmt *pStmt = 0;
................................................................................
  char *zErr = 0;
  int rc = SQLITE_OK;
  int rc2;

  memset(p, 0, sizeof(ZonefileParam));
  p->maxAutoFrameSize = ZONEFILE_DEFAULT_MAXAUTOFRAMESIZE;
  p->encryptionType = ZONEFILE_DEFAULT_ENCRYPTION;
  p->pCmpData = p->pCmpIdx = zonefileCompressByValue(0);

  rc = zonefilePrepare(db, &pStmt, &zErr,"SELECT key, value FROM json_each(?)");
  if( rc==SQLITE_OK ){
    sqlite3_bind_text(pStmt, 1, zJson, -1, SQLITE_STATIC);
  }
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
    const char *zKey = (const char*)sqlite3_column_text(pStmt, 0);
................................................................................
    }
    pBuf->a = aNew;
    pBuf->nAlloc = nNew;
  }
  return SQLITE_OK;
}




static void zonefileBufferFree(ZonefileBuffer *pBuf){
  sqlite3_free(pBuf->a);
  memset(pBuf, 0, sizeof(ZonefileBuffer));
}





static u64 zonefileGet64(u8 *aBuf){
  return (((u64)aBuf[0]) << 56)
       + (((u64)aBuf[1]) << 48)
       + (((u64)aBuf[2]) << 40)
       + (((u64)aBuf[3]) << 32) 
       + (((u64)aBuf[4]) << 24)
       + (((u64)aBuf[5]) << 16)
       + (((u64)aBuf[6]) <<  8)
       + (((u64)aBuf[7]) <<  0);
}





static void zonefileAppend32(ZonefileBuffer *pBuf, u32 v){
  zonefilePut32(&pBuf->a[pBuf->n], v);
  pBuf->n += 4;
}





static void zonefileAppend64(ZonefileBuffer *pBuf, u64 v){
  zonefileAppend32(pBuf, v>>32);
  zonefileAppend32(pBuf, v & 0xFFFFFFFF);
}





static void zonefileAppendBlob(ZonefileBuffer *pBuf, const u8 *p, int n){
  memcpy(&pBuf->a[pBuf->n], p, n);
  pBuf->n += n;
}






static int zonefileFileWrite(FILE *pFd, const u8 *aBuf, int nBuf){
  size_t res = fwrite(aBuf, 1, nBuf, pFd);
  return res!=(size_t)nBuf ? SQLITE_ERROR : SQLITE_OK;
}






static int zonefileFileRead(FILE *pFd, u8 *aBuf, int nBuf, i64 iOff){
  int rc = fseek(pFd, (long)iOff, SEEK_SET);
  if( rc==0 ){
    rc = fread(aBuf, 1, nBuf, pFd);
    rc = (rc==nBuf) ? SQLITE_OK : SQLITE_ERROR;


  }
  return rc;
}









static FILE *zonefileFileOpen(const char *zFile, int bWrite, char **pzErr){
  FILE *pFd = fopen(zFile, bWrite ? "wb" : "rb");
  if( pFd==0 ){
    *pzErr = sqlite3_mprintf("failed to open file \"%s\" for %s",
        zFile, bWrite ? "writing" : "reading"
    );
  }
  return pFd;
}




static void zonefileFileClose(FILE *pFd){
  if( pFd ) fclose(pFd);
}











static int zonefileAppendData(
  sqlite3_context *pCtx,          /* Leave any error message here */
  ZonefileCompress *pMethod,      /* Compression method object */
  void *pCmp,                     /* Compression handle */
  ZonefileCodec *pCodec,          /* Compression method, if any */
  ZonefileBuffer *pTo,            /* Append new data here */
  ZonefileBuffer *pFrom           /* Input buffer */
................................................................................
      if( zonefileFileWrite(pFd, buf, n) ) return SQLITE_ERROR;
      nRem -= n;
    }
  }
  return SQLITE_OK;
}





static int zonefileHexChar(char c){
  if( c>='0' && c<='9' ) return c-'0';
  c = c & ~0x20;
  if( c>='A' && c<='F' ) return c-('A'-10);
  return -1;
}















static int zonefileDecodeEncryptionKey(ZonefileParam *p, int *pn, char **pzErr){
  if( p->debugEncryptionKeyText==0 ){
    u8 *z = (u8*)p->encryptionKey;
    int n = *pn;
    int i;
    if( n&0x01 ) goto bad_format;
    for(i=0; i<n; i+=2){
................................................................................
  sqlite3_free(aSample);
  sqlite3_free(sParam.encryptionKey);
  if( rc==SQLITE_NOMEM ){
    sqlite3_result_error_nomem(pCtx);
  }
}




typedef struct ZonefileFilesTab ZonefileFilesTab;
struct ZonefileFilesTab {
  sqlite3_vtab base;              /* Base class - must be first */
  sqlite3 *db;
  char *zBase;                    /* Name of this table */
  char *zDb;                      /* Database containing this table */
  ZonefileGlobal *pGlobal;        /* Global object */
  sqlite3_stmt *pInsert;          /* Insert into the %_shadow_file table */
  sqlite3_stmt *pInsertIdx;       /* Insert into the %_shadow_idx table */
  sqlite3_stmt *pDeleteIdx;       /* Delete by fileid from %_shadow_idx table */
  sqlite3_stmt *pDelete;          /* Delete by rowid from %_shadow_file table */
};




typedef struct ZonefileFilesCsr ZonefileFilesCsr;
struct ZonefileFilesCsr {
  sqlite3_vtab_cursor base;       /* Base class - must be first */
  sqlite3_stmt *pSelect;
};

/*
................................................................................
** zonefile_files virtual table module xEof method.
*/
static int zffEof(sqlite3_vtab_cursor *cur){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  return pCsr->pSelect==0;
}





static void zonefileHeaderDeserialize(u8 *aBuf, ZonefileHeader *pHdr){
  pHdr->magicNumber = zonefileGet32(&aBuf[0]);
  pHdr->compressionTypeIndexData = aBuf[4];
  pHdr->compressionTypeContent = aBuf[5];
  pHdr->byteOffsetDictionary = zonefileGet32(&aBuf[6]);
  pHdr->byteOffsetFrames = zonefileGet32(&aBuf[10]);
  pHdr->numFrames = zonefileGet32(&aBuf[14]);
................................................................................
  pHdr->numKeys = zonefileGet32(&aBuf[18]);
  pHdr->encryptionType = aBuf[22];
  pHdr->encryptionKeyIdx = aBuf[23];
  pHdr->extendedHeaderVersion = aBuf[24];
  pHdr->extendedHeaderSize = aBuf[25];
}

static void zonefileJsonHeader(sqlite3_context *pCtx, const char *zFile){

  char *zErr = 0;
  FILE *pFd = zonefileFileOpen(zFile, 0, &zErr);
  if( pFd ){
    int rc;
    ZonefileHeader hdr = { 0 };










    u8 aBuf[ZONEFILE_SZ_HEADER];

    rc = zonefileFileRead(pFd, aBuf, ZONEFILE_SZ_HEADER, 0);
    if( rc==SQLITE_OK ){
      zonefileHeaderDeserialize(aBuf, &hdr);


    }


    if( rc!=SQLITE_OK ){
      zonefileCtxError(pCtx, "failed to read header from file: \"%s\"", zFile);






















    }else{




      char *zJson = sqlite3_mprintf("{"
          "\"magicNumber\":%u,"
          "\"compressionTypeIndexData\":%u,"
          "\"compressionTypeContent\":%u,"
          "\"byteOffsetDictionary\":%u,"
          "\"byteOffsetFrames\":%u,"
          "\"numFrames\":%u,"
          "\"numKeys\":%u,"
          "\"encryptionType\":%u,"
          "\"encryptionKeyIdx\":%u,"
          "\"extendedHeaderVersion\":%u,"
          "\"extendedHeaderSize\":%u}",
          (u32)hdr.magicNumber,
          (u32)hdr.compressionTypeIndexData,
          (u32)hdr.compressionTypeContent,
          (u32)hdr.byteOffsetDictionary,
          (u32)hdr.byteOffsetFrames,
          (u32)hdr.numFrames,
          (u32)hdr.numKeys,
          (u32)hdr.encryptionType,
          (u32)hdr.encryptionKeyIdx,
          (u32)hdr.extendedHeaderVersion,
          (u32)hdr.extendedHeaderSize
      );
      if( zJson ){
        sqlite3_result_text(pCtx, zJson, -1, SQLITE_TRANSIENT);
        sqlite3_free(zJson);
      }else{
        sqlite3_result_error_nomem(pCtx);
      }
    }
    fclose(pFd);
  }else{
    sqlite3_result_error(pCtx, zErr, -1);
    sqlite3_free(zErr);
  }


}

/* 
** zonefile_files virtual table module xColumn method.
*/
static int zffColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
................................................................................
static int zffRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  *pRowid = sqlite3_column_int64(pCsr->pSelect, 1);
  return SQLITE_OK;
}

/*
** Read and decode a Zonefile header from the start of the file opened
** by file-handle pFd. If successful, populate object (*pHdr) before
** returning SQLITE_OK. Otherwise, if an error occurs, set output
** parameter (*pzErr) to point to an English language error message and
** return an SQLite error code.
**
** It is the responsibility of the caller to eventually free any error
** message returned via (*pzErr) using sqlite3_free().



*/
static int zonefileReadHeader(
  FILE *pFd,                      /* File to read from */
  const char *zFile,              /* Name of file opened by pFd */
  ZonefileHeader *pHdr,           /* Populate this object before returning */
  char **pzErr                    /* OUT: Error message */
){
  u8 aBuf[ZONEFILE_SZ_HEADER];
  int rc = zonefileFileRead(pFd, aBuf, ZONEFILE_SZ_HEADER, 0);
  if( rc==SQLITE_OK ){
    zonefileHeaderDeserialize(aBuf, pHdr);
    if( pHdr->magicNumber!=ZONEFILE_MAGIC_NUMBER ){
      rc = SQLITE_ERROR;
    }
  }

  if( rc!=SQLITE_OK ){
    *pzErr = sqlite3_mprintf(
        "failed to read zonefile header from file \"%s\"", zFile
    );
  }

  return rc;
}

static int zonefileUncompress(
  ZonefileCompress *pMethod,
  void *pCmp,

  u8 *aIn, int nIn,
  u8 **paOut, int *pnOut
){
  int rc;
  int nOut = pMethod->xUncompressSize(pCmp, aIn, nIn);
  u8 *aOut = sqlite3_malloc(nOut);

  assert( pMethod->eType!=ZONEFILE_COMPRESSION_NONE );
  if( aOut==0 ){
................................................................................
  }

  *paOut = aOut;
  *pnOut = nOut;
  return rc;
}










static int zfFindCompress(int eType, ZonefileCompress **pp, char **pzErr){
  int rc = SQLITE_OK;
  ZonefileCompress *pCmp;
  pCmp = zonefileCompressByValue(eType);
  if( pCmp==0 ){
    *pzErr = sqlite3_mprintf("unsupported compression method: %d", eType);
    rc = SQLITE_ERROR;
  }else if( pCmp->eType==ZONEFILE_COMPRESSION_NONE ){
    pCmp = 0;
  }
  *pp = pCmp;
  return rc;
}














static int zonefileLoadIndex(
  ZonefileHeader *pHdr,
  FILE *pFd,

  u8 **paIdx, int *pnIdx,
  char **pzErr

){
  ZonefileCompress *pCmp = 0;
  int rc;
  u8 *aIdx = 0;
  int nIdx = 0;
    
  rc = zfFindCompress(pHdr->compressionTypeIndexData, &pCmp, pzErr);
  if( rc==SQLITE_OK ){
    if( pHdr->byteOffsetDictionary ){
      nIdx = pHdr->byteOffsetDictionary - ZONEFILE_SZ_HEADER;
    }else{
      nIdx = pHdr->byteOffsetFrames - ZONEFILE_SZ_HEADER;
    }
    nIdx -= pHdr->extendedHeaderSize;
................................................................................
    /* Read the zonefile header */
    if( rc==SQLITE_OK ){
      rc = zonefileReadHeader(pFd, zFile, &hdr, &zErr);
    }

    /* Find the compression method and open the compressor handle. */
    if( rc==SQLITE_OK ){
      rc = zfFindCompress(hdr.compressionTypeContent, &pCmpMethod, &zErr);
    }
    if( pCmpMethod ){
      int nDict = 0;
      u8 *aDict = 0;
      assert( rc==SQLITE_OK );
      if( hdr.byteOffsetDictionary ){
        nDict = hdr.byteOffsetFrames - hdr.byteOffsetDictionary;

  return SQLITE_OK;
}

/*
** Search the key-store passed as the first argument for an encryption
** key to use with the file with file-id iFileid in zonefile table zTab
** in database zDb. If successful, set (*paKey) to point to the key
** buffer and return the size of the key in bytes.
**
** If no key is found, return 0. The final value of (*paKey) is undefined
** in this case.
*/
static int zonefileKeyFind(
  ZonefileGlobal *pGlobal,
  const char *zDb,                /* Database containing zonefile table */
  const char *zTab,               /* Name of zonefile table */
  i64 iFileid,                    /* File-id to configure key for */
................................................................................
    0,
    zfLz4CompressBound, zfLz4hcCompress, 
    zfGenericUncompressSize, zfLz4Uncompress
  },
#endif /* SQLITE_HAVE_LZ4 */
};

/*
** Find the ZonefileCompress object for the compression scheme named
** by zName. If successful, set output variable (*pp) to point to the
** object and return SQLITE_OK. Otherwise, return SQLITE_ERROR and
** leave output variable (*pzErr) pointing to an English language error
** message. It is the reponsibility of the caller to eventually free
** the error message buffer using sqlite3_free().
*/
static int zonefileCompress(
  const char *zName,              /* Name of requested compression method */
  ZonefileCompress **pp,          /* OUT: Pointer to compression object */
  char **pzErr                    /* OUT: Error message */
){
  int i;
  assert( *pzErr==0 );
................................................................................
      return SQLITE_OK;
    }
  }
  *pzErr = sqlite3_mprintf("unknown compression scheme: \"%s\"", zName);
  return SQLITE_ERROR;
}

/*
** Find a compression routine based on its associated integer constant
** (defined as part of the zonefile file format). If successful, return
** a pointer to the associated ZonefileCompression object. Or, if the
** nominated compression scheme is not supported in this build, return 
** NULL.
*/
static ZonefileCompress *zonefileCompressByValue(int eType){
  int i;
  for(i=0; i<sizeof(aZonefileCompress)/sizeof(aZonefileCompress[0]); i++){
    if( aZonefileCompress[i].eType==eType ){
      return &aZonefileCompress[i];
    }
  }
................................................................................
  va_start(ap, zFmt);
  zMsg = sqlite3_vmprintf(zFmt, ap);
  sqlite3_result_error(ctx, zMsg, -1);
  sqlite3_free(zMsg);
  va_end(ap);
}

/*
** Retrieve the error message from the database handle associated with
** context object pCtx and copy it into pCtx itself.
*/
static void zonefileTransferError(sqlite3_context *pCtx){
  sqlite3 *db = sqlite3_context_db_handle(pCtx);
  const char *zErr = sqlite3_errmsg(db);
  sqlite3_result_error(pCtx, zErr, -1);
}

/*
** Create an SQL statement from the printf() style format string passed
** as the 4th argument and any trailing arguments. Attempt to prepare
** it against database handle db. If successful, set output variable
** (*ppStmt) to point to the new statement handle and return SQLITE_OK.
** In this case it is the responsibility of the caller to eventually
** release the statement handle using sqlite3_finalize().
**
** Or, if an error occurs, return an SQLite error code and optionally
** set output parameter (*pzErr) to point to a buffer containing an
** English language error message. The caller must eventually free any
** such buffer using sqlite3_free().
*/
static int zonefilePrepare(
  sqlite3 *db,                    /* Database handle */
  sqlite3_stmt **ppStmt,          /* OUT: New statement handle */
  char **pzErr,                   /* OUT: Error message */
  const char *zFmt,               /* printf() style formatting string */
  ...
){
  int rc;
  va_list ap;
  char *zSql;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
................................................................................
    default:
      assert( eType==SQLITE_NULL);
  }

  return 0;
}

/*
** Return true if the value object passed as the only argument contains
** integer value -1. False otherwise.
*/
int zonefileIsAutoFrame(sqlite3_value *pFrame){
  return (
      sqlite3_value_type(pFrame)==SQLITE_INTEGER 
   && sqlite3_value_int64(pFrame)==-1
  );
}

#define SQLITE_ZONEFILE_AES_128_CTR 1
#define SQLITE_ZONEFILE_AES_128_CBC 2
#define SQLITE_ZONEFILE_AES_256_CTR 3
#define SQLITE_ZONEFILE_AES_256_CBC 4

/*
** Argument zName is the name of an encryption scheme. If it is recognized
** output variable (*peType) is set to the corresponding integer constant
** (defined as part of the zonefile file format) and SQLITE_OK is returned.
** Or, if the named encryption method is not recognized, SQLITE_ERROR is
** returned and (*pzErr) set to point to a buffer containing an English
** language error message. In this case it is the responsibility of
** the caller to eventually free the error message buffer using a call
** to sqlite3_free().
*/
static int zonefileEncryption(const char *zName, int *peType, char **pzErr){
  struct Encryption {
    const char *zName;
    int eType;
  } a[] = {
    {"NONE", 0}, 
    {"AES_128_CTR", SQLITE_ZONEFILE_AES_128_CTR}, 
................................................................................
    }
  }

  *pzErr = sqlite3_mprintf("unknown encryption method: %s", zName);
  return SQLITE_ERROR;
}

/*
** Interpret the "json paramaters" argument passed to an invocation of
** the zonefile_write() SQL function. Populate the ZonefileParam indicated
** by the 3rd argument to this function with the results.
**
** If successful, return SQLITE_OK. Otherwise, return an SQLite error
** code and leave an error message in context object pCtx.
*/
static int zonefileGetParams(
  sqlite3_context *pCtx,          /* Leave any error message here */
  const char *zJson,              /* JSON configuration parameter (or NULL) */
  ZonefileParam *p                /* Populate this object before returning */
){
  sqlite3 *db = sqlite3_context_db_handle(pCtx);
  sqlite3_stmt *pStmt = 0;
................................................................................
  char *zErr = 0;
  int rc = SQLITE_OK;
  int rc2;

  memset(p, 0, sizeof(ZonefileParam));
  p->maxAutoFrameSize = ZONEFILE_DEFAULT_MAXAUTOFRAMESIZE;
  p->encryptionType = ZONEFILE_DEFAULT_ENCRYPTION;
  p->pCmpData = p->pCmpIdx = zonefileCompressByValue(ZONEFILE_COMPRESSION_NONE);

  rc = zonefilePrepare(db, &pStmt, &zErr,"SELECT key, value FROM json_each(?)");
  if( rc==SQLITE_OK ){
    sqlite3_bind_text(pStmt, 1, zJson, -1, SQLITE_STATIC);
  }
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
    const char *zKey = (const char*)sqlite3_column_text(pStmt, 0);
................................................................................
    }
    pBuf->a = aNew;
    pBuf->nAlloc = nNew;
  }
  return SQLITE_OK;
}

/*
** Free the memory allocation associated with buffer pBuf.
*/
static void zonefileBufferFree(ZonefileBuffer *pBuf){
  sqlite3_free(pBuf->a);
  memset(pBuf, 0, sizeof(ZonefileBuffer));
}

/*
** Read and return a 64-bit unsigned integer in big-endian format from 
** buffer aBuf.
*/
static u64 zonefileGet64(u8 *aBuf){
  return (((u64)aBuf[0]) << 56)
       + (((u64)aBuf[1]) << 48)
       + (((u64)aBuf[2]) << 40)
       + (((u64)aBuf[3]) << 32) 
       + (((u64)aBuf[4]) << 24)
       + (((u64)aBuf[5]) << 16)
       + (((u64)aBuf[6]) <<  8)
       + (((u64)aBuf[7]) <<  0);
}

/*
** Append a 32-bit big-endian integer with value v to buffer pBuf. Space
** must have already been reserved in the buffer using zonefileBufferGrow().
*/
static void zonefileAppend32(ZonefileBuffer *pBuf, u32 v){
  zonefilePut32(&pBuf->a[pBuf->n], v);
  pBuf->n += 4;
}

/*
** Append a 64-bit big-endian integer with value v to buffer pBuf. Space
** must have already been reserved in the buffer using zonefileBufferGrow().
*/
static void zonefileAppend64(ZonefileBuffer *pBuf, u64 v){
  zonefileAppend32(pBuf, v>>32);
  zonefileAppend32(pBuf, v & 0xFFFFFFFF);
}

/*
** Append the n bytse of data in buffer p to buffer pBuf. Space must have
** already been reserved in the buffer using zonefileBufferGrow().
*/
static void zonefileAppendBlob(ZonefileBuffer *pBuf, const u8 *p, int n){
  memcpy(&pBuf->a[pBuf->n], p, n);
  pBuf->n += n;
}

/*
** Write nBuf bytes of data from buffer aBuf to the file opened by 
** file-handle pFd. Return SQLITE_OK if successful, or SQLITE_ERROR
** otherwise.
*/
static int zonefileFileWrite(FILE *pFd, const u8 *aBuf, int nBuf){
  size_t res = fwrite(aBuf, 1, nBuf, pFd);
  return res!=(size_t)nBuf ? SQLITE_ERROR : SQLITE_OK;
}

/*
** Read nBuf bytes of data from offset iOff of the file opened by 
** file-handle pFd into buffer aBuf. Return SQLITE_OK if successful, or
** SQLITE_ERROR otherwise.
*/
static int zonefileFileRead(FILE *pFd, u8 *aBuf, int nBuf, i64 iOff){
  int rc = fseek(pFd, (long)iOff, SEEK_SET);
  if( rc==0 ){
    rc = fread(aBuf, 1, nBuf, pFd);
    rc = (rc==nBuf) ? SQLITE_OK : SQLITE_ERROR;
  }else{
    rc = SQLITE_ERROR;
  }
  return rc;
}

/*
** Open the file identified by path zFile for writing (if bWrite==1) or
** reading (if bWrite==0). If successful, return a pointer to the new
** file-handle object. Otherwise, return NULL and set output variable
** (*pzErr) to point to a buffer containing an English language error
** message. It is the responsibility of the caller to eventually free
** any error message buffer using sqlite3_free().
*/
static FILE *zonefileFileOpen(const char *zFile, int bWrite, char **pzErr){
  FILE *pFd = fopen(zFile, bWrite ? "wb" : "rb");
  if( pFd==0 ){
    *pzErr = sqlite3_mprintf("failed to open file \"%s\" for %s",
        zFile, bWrite ? "writing" : "reading"
    );
  }
  return pFd;
}

/*
** Close the file handle passed as the only argument.
*/
static void zonefileFileClose(FILE *pFd){
  if( pFd ) fclose(pFd);
}

/*
** Append the contents of buffer pFrom to buffer pTo. If successful, return
** SQLITE_OK. Otherwise, return an SQLite error code and leave an error
** message in context object pCtx.
**
** If argument pMethod is not NULL, then it is used along with pCmp to 
** compress the data before appending it to pFrom. Similarly, if argument
** pCodec is not NULL, then it is used to encrypt the data before it is
** appended.
*/
static int zonefileAppendData(
  sqlite3_context *pCtx,          /* Leave any error message here */
  ZonefileCompress *pMethod,      /* Compression method object */
  void *pCmp,                     /* Compression handle */
  ZonefileCodec *pCodec,          /* Compression method, if any */
  ZonefileBuffer *pTo,            /* Append new data here */
  ZonefileBuffer *pFrom           /* Input buffer */
................................................................................
      if( zonefileFileWrite(pFd, buf, n) ) return SQLITE_ERROR;
      nRem -= n;
    }
  }
  return SQLITE_OK;
}

/*
** If character c is not a hexadecimal digit, return -1. Otherwise, return
** the value of the hex digit (a value between 0 and 15).
*/
static int zonefileHexChar(char c){
  if( c>='0' && c<='9' ) return c-'0';
  c = c & ~0x20;
  if( c>='A' && c<='F' ) return c-('A'-10);
  return -1;
}

/*
** String ZonefileParam.encryptionKey currently contains a string specified
** for the encryptionKey attribute of a JSON object passed to SQL function
** zonefile_write(). The string is (*pn) bytes in size.
**
** If the ZonefileParam.debugEncryptionKeyText flag is true this function
** is a no-op. Otherwise, an attempt is made to overwrite the hex string in
** ZonefileParam.encryptionKey with the corresponding binary data. If
** successful, SQLITE_OK is returned and (*pn) is set to the number of
** bytes in the binary key. Otherwise, if an error occurs, an SQLite error
** code is returned and (*pzErr) set to point to an English language error
** message. It is the responsibility of the caller to eventually free any
** error message buffer using sqlite3_free().
*/
static int zonefileDecodeEncryptionKey(ZonefileParam *p, int *pn, char **pzErr){
  if( p->debugEncryptionKeyText==0 ){
    u8 *z = (u8*)p->encryptionKey;
    int n = *pn;
    int i;
    if( n&0x01 ) goto bad_format;
    for(i=0; i<n; i+=2){
................................................................................
  sqlite3_free(aSample);
  sqlite3_free(sParam.encryptionKey);
  if( rc==SQLITE_NOMEM ){
    sqlite3_result_error_nomem(pCtx);
  }
}

/*
** Virtual table type for zonefile_files virtual tables.
*/
typedef struct ZonefileFilesTab ZonefileFilesTab;
struct ZonefileFilesTab {
  sqlite3_vtab base;              /* Base class - must be first */
  sqlite3 *db;
  char *zBase;                    /* Name of this table */
  char *zDb;                      /* Database containing this table */
  ZonefileGlobal *pGlobal;        /* Global object */
  sqlite3_stmt *pInsert;          /* Insert into the %_shadow_file table */
  sqlite3_stmt *pInsertIdx;       /* Insert into the %_shadow_idx table */
  sqlite3_stmt *pDeleteIdx;       /* Delete by fileid from %_shadow_idx table */
  sqlite3_stmt *pDelete;          /* Delete by rowid from %_shadow_file table */
};

/*
** Virtual table cursor type for zonefile_files virtual tables.
*/
typedef struct ZonefileFilesCsr ZonefileFilesCsr;
struct ZonefileFilesCsr {
  sqlite3_vtab_cursor base;       /* Base class - must be first */
  sqlite3_stmt *pSelect;
};

/*
................................................................................
** zonefile_files virtual table module xEof method.
*/
static int zffEof(sqlite3_vtab_cursor *cur){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  return pCsr->pSelect==0;
}

/*
** Deserialize the ZONEFILE_SZ_HEADER byte zonefile header in the
** buffer. Populate (*pHdr) with the results.
*/
static void zonefileHeaderDeserialize(u8 *aBuf, ZonefileHeader *pHdr){
  pHdr->magicNumber = zonefileGet32(&aBuf[0]);
  pHdr->compressionTypeIndexData = aBuf[4];
  pHdr->compressionTypeContent = aBuf[5];
  pHdr->byteOffsetDictionary = zonefileGet32(&aBuf[6]);
  pHdr->byteOffsetFrames = zonefileGet32(&aBuf[10]);
  pHdr->numFrames = zonefileGet32(&aBuf[14]);
................................................................................
  pHdr->numKeys = zonefileGet32(&aBuf[18]);
  pHdr->encryptionType = aBuf[22];
  pHdr->encryptionKeyIdx = aBuf[23];
  pHdr->extendedHeaderVersion = aBuf[24];
  pHdr->extendedHeaderSize = aBuf[25];
}


/*
** Read and decode a Zonefile header from the start of the file opened
** by file-handle pFd. If successful, populate object (*pHdr) before
** returning SQLITE_OK. Otherwise, if an error occurs, set output
** parameter (*pzErr) to point to an English language error message and
** return an SQLite error code.
**
** It is the responsibility of the caller to eventually free any error
** message returned via (*pzErr) using sqlite3_free().
*/
static int zonefileReadHeader(
  FILE *pFd,                      /* File to read from */
  const char *zFile,              /* Name of file opened by pFd */
  ZonefileHeader *pHdr,           /* Populate this object before returning */
  char **pzErr                    /* OUT: Error message */
){
  u8 aBuf[ZONEFILE_SZ_HEADER];

  int rc = zonefileFileRead(pFd, aBuf, ZONEFILE_SZ_HEADER, 0);
  if( rc==SQLITE_OK ){
    zonefileHeaderDeserialize(aBuf, pHdr);
    if( pHdr->magicNumber!=ZONEFILE_MAGIC_NUMBER ){
      rc = SQLITE_ERROR;
    }
  }

  if( rc!=SQLITE_OK ){

    *pzErr = sqlite3_mprintf(
        "failed to read zonefile header from file \"%s\"", zFile
    );
  }

  return rc;
}

/*
** Read the zonefile header from file zFile and set the result of pCtx
** to a JSON object that represents the contents. Or, if an error occurs,
** leave an error message in pCtx. This function is called whenever the
** "header" column of a zonefile_files virtual table is requested.
*/
static void zonefileJsonHeader(sqlite3_context *pCtx, const char *zFile){
  char *zErr = 0;
  int rc = SQLITE_OK;
  ZonefileHeader hdr = {0};

  FILE *pFd = zonefileFileOpen(zFile, 0, &zErr);
  if( pFd ){
    rc = zonefileReadHeader(pFd, zFile, &hdr, &zErr);
  }else{
    rc = SQLITE_ERROR;
  }

  if( rc==SQLITE_OK ){
    char *zJson = sqlite3_mprintf("{"
        "\"magicNumber\":%u,"
        "\"compressionTypeIndexData\":%u,"
        "\"compressionTypeContent\":%u,"
        "\"byteOffsetDictionary\":%u,"
        "\"byteOffsetFrames\":%u,"
        "\"numFrames\":%u,"
        "\"numKeys\":%u,"
        "\"encryptionType\":%u,"
        "\"encryptionKeyIdx\":%u,"
        "\"extendedHeaderVersion\":%u,"
        "\"extendedHeaderSize\":%u}",
        (u32)hdr.magicNumber,
        (u32)hdr.compressionTypeIndexData,
        (u32)hdr.compressionTypeContent,
        (u32)hdr.byteOffsetDictionary,
        (u32)hdr.byteOffsetFrames,
        (u32)hdr.numFrames,
        (u32)hdr.numKeys,
        (u32)hdr.encryptionType,
        (u32)hdr.encryptionKeyIdx,
        (u32)hdr.extendedHeaderVersion,
        (u32)hdr.extendedHeaderSize
          );
    if( zJson ){
      sqlite3_result_text(pCtx, zJson, -1, SQLITE_TRANSIENT);
      sqlite3_free(zJson);
    }else{
      sqlite3_result_error_nomem(pCtx);
    }


  }else{
    sqlite3_result_error(pCtx, zErr, -1);
    sqlite3_free(zErr);
  }

  zonefileFileClose(pFd);
}

/* 
** zonefile_files virtual table module xColumn method.
*/
static int zffColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
................................................................................
static int zffRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  ZonefileFilesCsr *pCsr = (ZonefileFilesCsr*)cur;
  *pRowid = sqlite3_column_int64(pCsr->pSelect, 1);
  return SQLITE_OK;
}

/*
** Uncompress buffer aIn/nIn using the compression routines pMethod
** and the compressor instance pCmp into space obtained from 
** sqlite3_malloc(). If successful, return SQLITE_OK and set output
** parameters (*paOut) and (*pnOut) to point to the allocated buffer
** and its size in bytes respectively. In this case it is the 

** responsibility of the caller to eventually free buffer (*paOut)
** using sqlite3_free().
**
** Or, if an error occurs, set both output parameters to zero and
** return an SQLite error code.
*/
























static int zonefileUncompress(
  ZonefileCompress *pMethod,      /* Compression routines */

  void *pCmp,                     /* Compressor instance */
  u8 *aIn, int nIn,               /* Input buffer */
  u8 **paOut, int *pnOut          /* Output buffer */
){
  int rc;
  int nOut = pMethod->xUncompressSize(pCmp, aIn, nIn);
  u8 *aOut = sqlite3_malloc(nOut);

  assert( pMethod->eType!=ZONEFILE_COMPRESSION_NONE );
  if( aOut==0 ){
................................................................................
  }

  *paOut = aOut;
  *pnOut = nOut;
  return rc;
}

/*
** Attempt to find the compression methods object for the compression method
** identified by integer constant eType (defined as part of the zonefile file
** format). If successful, set output parameter (*pp) to point to the object
** and return SQLITE_OK. Otherwise, return an SQLite error code and set
** (*pzErr) to point to a buffer containing an English language error
** message. It is the responsibility of the caller to eventually free any
** error message buffer using sqlite3_free().
*/
static int zonefileFindCompress(int eType, ZonefileCompress **pp, char **pzErr){
  int rc = SQLITE_OK;
  ZonefileCompress *pCmp;
  pCmp = zonefileCompressByValue(eType);
  if( pCmp==0 ){
    *pzErr = sqlite3_mprintf("unsupported compression method: %d", eType);
    rc = SQLITE_ERROR;
  }else if( pCmp->eType==ZONEFILE_COMPRESSION_NONE ){
    pCmp = 0;
  }
  *pp = pCmp;
  return rc;
}

/*
** Argument pHdr points to a deserialized zonefile header read from the
** zonefile opened by file handle pFd. This function attempts to read
** the entire zonefile-index structure into space obtained from 
** sqlite3_malloc(). If successful, it sets output parameters (*paIdx)
** and (*pnIdx) to point to the buffer and its size in bytes respectively
** before returning SQLITE_OK.
**
** Otherwise, if an error occurs, an SQLite error code is returned and
** output parameter (*pzErr) may be set to point to a buffer containing an
** English language error message. It is the responsibility of the caller to
** eventually free any error message buffer using sqlite3_free().
*/
static int zonefileLoadIndex(
  ZonefileHeader *pHdr,           /* Deserialized header read from file */

  FILE *pFd,                      /* File to read from */
  u8 **paIdx, int *pnIdx,         /* OUT: Buffer containing zonefile index */

  char **pzErr                    /* OUT: Error message */
){
  ZonefileCompress *pCmp = 0;
  int rc;
  u8 *aIdx = 0;
  int nIdx = 0;
    
  rc = zonefileFindCompress(pHdr->compressionTypeIndexData, &pCmp, pzErr);
  if( rc==SQLITE_OK ){
    if( pHdr->byteOffsetDictionary ){
      nIdx = pHdr->byteOffsetDictionary - ZONEFILE_SZ_HEADER;
    }else{
      nIdx = pHdr->byteOffsetFrames - ZONEFILE_SZ_HEADER;
    }
    nIdx -= pHdr->extendedHeaderSize;
................................................................................
    /* Read the zonefile header */
    if( rc==SQLITE_OK ){
      rc = zonefileReadHeader(pFd, zFile, &hdr, &zErr);
    }

    /* Find the compression method and open the compressor handle. */
    if( rc==SQLITE_OK ){
      rc = zonefileFindCompress(hdr.compressionTypeContent, &pCmpMethod, &zErr);
    }
    if( pCmpMethod ){
      int nDict = 0;
      u8 *aDict = 0;
      assert( rc==SQLITE_OK );
      if( hdr.byteOffsetDictionary ){
        nDict = hdr.byteOffsetFrames - hdr.byteOffsetDictionary;

  UPDATE cc_files SET ekey = '0123456789';
  SELECT quote(dd.v)==quote(cc.v) FROM cc JOIN dd USING (k)
} {1 1 1}

close [open test.zonefile w+]
do_catchsql_test 3.4 {
  SELECT header FROM cc_files
} {1 {failed to read header from file: "test.zonefile"}}

forcedelete test.zonefile
do_catchsql_test 3.5 {
  SELECT header FROM cc_files
} {1 {failed to open file "test.zonefile" for reading}}

do_execsql_test 3.6 {

  UPDATE cc_files SET ekey = '0123456789';
  SELECT quote(dd.v)==quote(cc.v) FROM cc JOIN dd USING (k)
} {1 1 1}

close [open test.zonefile w+]
do_catchsql_test 3.4 {
  SELECT header FROM cc_files
} {1 {failed to read zonefile header from file "test.zonefile"}}

forcedelete test.zonefile
do_catchsql_test 3.5 {
  SELECT header FROM cc_files
} {1 {failed to open file "test.zonefile" for reading}}

do_execsql_test 3.6 {