** start of the description of what that command does.
*/
static const char *(azHelp[]) = {
#if defined(SQLITE_HAVE_ZLIB) && !defined(SQLITE_OMIT_VIRTUALTABLE)
  ".archive ...             Manage SQL archives",
  "   Each command must have exactly one of the following options:",
  "     -c, --create               Create a new archive",
  "     -u, --update               Update or add files to an existing archive",

  "     -t, --list                 List contents of archive",
  "     -x, --extract              Extract files from archive",
  "   Optional arguments:",
  "     -v, --verbose              Print each filename as it is processed",
  "     -f FILE, --file FILE       Operate on archive FILE (default is current db)",
  "     -a FILE, --append FILE     Operate on FILE opened using the apndvfs VFS",
  "     -C DIR, --directory DIR    Change to directory DIR to read/extract files",
................................................................................
  return SQLITE_ERROR;
}

/*
** Values for ArCommand.eCmd.
*/
#define AR_CMD_CREATE       1


#define AR_CMD_EXTRACT      2
#define AR_CMD_LIST         3
#define AR_CMD_UPDATE       4
#define AR_CMD_HELP         5

/*
** Other (non-command) switches.
*/
#define AR_SWITCH_VERBOSE     6
#define AR_SWITCH_FILE        7
#define AR_SWITCH_DIRECTORY   8
#define AR_SWITCH_APPEND      9
#define AR_SWITCH_DRYRUN     10

static int arProcessSwitch(ArCommand *pAr, int eSwitch, const char *zArg){
  switch( eSwitch ){
    case AR_CMD_CREATE:
    case AR_CMD_EXTRACT:
    case AR_CMD_LIST:
    case AR_CMD_UPDATE:

    case AR_CMD_HELP:
      if( pAr->eCmd ){
        return arErrorMsg(pAr, "multiple command options");
      }
      pAr->eCmd = eSwitch;
      break;

................................................................................
    const char *zLong;
    char cShort;
    u8 eSwitch;
    u8 bArg;
  } aSwitch[] = {
    { "create",    'c', AR_CMD_CREATE,       0 },
    { "extract",   'x', AR_CMD_EXTRACT,      0 },

    { "list",      't', AR_CMD_LIST,         0 },
    { "update",    'u', AR_CMD_UPDATE,       0 },
    { "help",      'h', AR_CMD_HELP,         0 },
    { "verbose",   'v', AR_SWITCH_VERBOSE,   0 },
    { "file",      'f', AR_SWITCH_FILE,      1 },
    { "append",    'a', AR_SWITCH_APPEND,    1 },
    { "directory", 'C', AR_SWITCH_DIRECTORY, 1 },
................................................................................
    }
  }
  return rc;
}


/*
** Implementation of .ar "create" and "update" commands.





**
** Create the "sqlar" table in the database if it does not already exist.
** Then add each file in the azFile[] array to the archive. Directories
** are added recursively. If argument bVerbose is non-zero, a message is
** printed on stdout for each file archived.
**
** The create command is the same as update, except that it drops
** any existing "sqlar" table before beginning.


*/
static int arCreateOrUpdateCommand(
  ArCommand *pAr,                 /* Command arguments and options */
  int bUpdate                     /* true for a --create.  false for --update */

){
  const char *zCreate = 
      "CREATE TABLE IF NOT EXISTS sqlar(\n"
      "  name TEXT PRIMARY KEY,  -- name of the file\n"
      "  mode INT,               -- access permissions\n"
      "  mtime INT,              -- last modification time\n"
      "  sz INT,                 -- original file size\n"
................................................................................
     "    mode,\n"
     "    mtime,\n"
     "    CASE substr(lsmode(mode),1,1)\n"
     "      WHEN '-' THEN length(data)\n"
     "      WHEN 'd' THEN 0\n"
     "      ELSE -1 END,\n"
     "    sqlar_compress(data)\n"
     "  FROM fsdir(%Q,%Q)\n"
     "  WHERE lsmode(mode) NOT LIKE '?%%';",

     "REPLACE INTO %s(name,mode,mtime,data)\n"
     "  SELECT\n"
     "    %s,\n"
     "    mode,\n"
     "    mtime,\n"
     "    data\n"
     "  FROM fsdir(%Q,%Q)\n"
     "  WHERE lsmode(mode) NOT LIKE '?%%';"
  };
  int i;                          /* For iterating through azFile[] */
  int rc;                         /* Return code */
  const char *zTab = 0;           /* SQL table into which to insert */
  char *zSql;
  char zTemp[50];


  arExecSql(pAr, "PRAGMA page_size=512");
  rc = arExecSql(pAr, "SAVEPOINT ar;");
  if( rc!=SQLITE_OK ) return rc;
  zTemp[0] = 0; 
  if( pAr->bZip ){
    /* Initialize the zipfile virtual table, if necessary */
................................................................................
    zTab = "sqlar";
    if( bUpdate==0 ){
      rc = arExecSql(pAr, zDrop);
      if( rc!=SQLITE_OK ) goto end_ar_transaction;
    }
    rc = arExecSql(pAr, zCreate);
  }











  for(i=0; i<pAr->nArg && rc==SQLITE_OK; i++){
    char *zSql2 = sqlite3_mprintf(zInsertFmt[pAr->bZip], zTab,
        pAr->bVerbose ? "shell_putsnl(name)" : "name",
        pAr->azArg[i], pAr->zDir);
    rc = arExecSql(pAr, zSql2);
    sqlite3_free(zSql2);
  }
end_ar_transaction:
  if( rc!=SQLITE_OK ){
    sqlite3_exec(pAr->db, "ROLLBACK TO ar; RELEASE ar;", 0, 0, 0);
  }else{
................................................................................
    rc = arExecSql(pAr, "RELEASE ar;");
    if( pAr->bZip && pAr->zFile ){
      zSql = sqlite3_mprintf("DROP TABLE %s", zTemp);
      arExecSql(pAr, zSql);
      sqlite3_free(zSql);
    }
  }

  return rc;
}

/*
** Implementation of ".ar" dot command.
*/
static int arDotCommand(
................................................................................
          cmd.zSrcTable = sqlite3_mprintf("zipfile(%Q)", cmd.zFile);
        }
      }
      cmd.bZip = 1;
    }else if( cmd.zFile ){
      int flags;
      if( cmd.bAppend ) eDbType = SHELL_OPEN_APPENDVFS;
      if( cmd.eCmd==AR_CMD_CREATE || cmd.eCmd==AR_CMD_UPDATE ){

        flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE;
      }else{
        flags = SQLITE_OPEN_READONLY;
      }
      cmd.db = 0;
      if( cmd.bDryRun ){
        utf8_printf(pState->out, "-- open database '%s'%s\n", cmd.zFile,
................................................................................
        goto end_ar_command;
      }
      cmd.zSrcTable = sqlite3_mprintf("sqlar");
    }

    switch( cmd.eCmd ){
      case AR_CMD_CREATE:
        rc = arCreateOrUpdateCommand(&cmd, 0);
        break;

      case AR_CMD_EXTRACT:
        rc = arExtractCommand(&cmd);
        break;

      case AR_CMD_LIST:
................................................................................
        rc = arListCommand(&cmd);
        break;

      case AR_CMD_HELP:
        arUsage(pState->out);
        break;





      default:
        assert( cmd.eCmd==AR_CMD_UPDATE );
        rc = arCreateOrUpdateCommand(&cmd, 1);
        break;
    }
  }
end_ar_command:
  if( cmd.db!=pState->db ){
    close_db(cmd.db);
  }

** start of the description of what that command does.
*/
static const char *(azHelp[]) = {
#if defined(SQLITE_HAVE_ZLIB) && !defined(SQLITE_OMIT_VIRTUALTABLE)
  ".archive ...             Manage SQL archives",
  "   Each command must have exactly one of the following options:",
  "     -c, --create               Create a new archive",
  "     -u, --update               Add files or update files with newer mtime",
  "     -i, --insert               Like -u but always add even if mtime unchanged",
  "     -t, --list                 List contents of archive",
  "     -x, --extract              Extract files from archive",
  "   Optional arguments:",
  "     -v, --verbose              Print each filename as it is processed",
  "     -f FILE, --file FILE       Operate on archive FILE (default is current db)",
  "     -a FILE, --append FILE     Operate on FILE opened using the apndvfs VFS",
  "     -C DIR, --directory DIR    Change to directory DIR to read/extract files",
................................................................................
  return SQLITE_ERROR;
}

/*
** Values for ArCommand.eCmd.
*/
#define AR_CMD_CREATE       1
#define AR_CMD_UPDATE       2
#define AR_CMD_INSERT       3
#define AR_CMD_EXTRACT      4
#define AR_CMD_LIST         5

#define AR_CMD_HELP         6

/*
** Other (non-command) switches.
*/
#define AR_SWITCH_VERBOSE     7
#define AR_SWITCH_FILE        8
#define AR_SWITCH_DIRECTORY   9
#define AR_SWITCH_APPEND     10
#define AR_SWITCH_DRYRUN     11

static int arProcessSwitch(ArCommand *pAr, int eSwitch, const char *zArg){
  switch( eSwitch ){
    case AR_CMD_CREATE:
    case AR_CMD_EXTRACT:
    case AR_CMD_LIST:
    case AR_CMD_UPDATE:
    case AR_CMD_INSERT:
    case AR_CMD_HELP:
      if( pAr->eCmd ){
        return arErrorMsg(pAr, "multiple command options");
      }
      pAr->eCmd = eSwitch;
      break;

................................................................................
    const char *zLong;
    char cShort;
    u8 eSwitch;
    u8 bArg;
  } aSwitch[] = {
    { "create",    'c', AR_CMD_CREATE,       0 },
    { "extract",   'x', AR_CMD_EXTRACT,      0 },
    { "insert",    'i', AR_CMD_INSERT,       0 },
    { "list",      't', AR_CMD_LIST,         0 },
    { "update",    'u', AR_CMD_UPDATE,       0 },
    { "help",      'h', AR_CMD_HELP,         0 },
    { "verbose",   'v', AR_SWITCH_VERBOSE,   0 },
    { "file",      'f', AR_SWITCH_FILE,      1 },
    { "append",    'a', AR_SWITCH_APPEND,    1 },
    { "directory", 'C', AR_SWITCH_DIRECTORY, 1 },
................................................................................
    }
  }
  return rc;
}


/*
** Implementation of .ar "create", "insert", and "update" commands.
**
**     create    ->     Create a new SQL archive
**     insert    ->     Insert or reinsert all files listed
**     update    ->     Insert files that have changed or that were not
**                      previously in the archive
**
** Create the "sqlar" table in the database if it does not already exist.
** Then add each file in the azFile[] array to the archive. Directories
** are added recursively. If argument bVerbose is non-zero, a message is
** printed on stdout for each file archived.
**
** The create command is the same as update, except that it drops
** any existing "sqlar" table before beginning.  The "insert" command
** always overwrites every file named on the command-line, where as
** "update" only overwrites if the size or mtime or mode has changed.
*/
static int arCreateOrUpdateCommand(
  ArCommand *pAr,                 /* Command arguments and options */
  int bUpdate,                    /* true for a --create. */
  int bOnlyIfChanged              /* Only update if file has changed */
){
  const char *zCreate = 
      "CREATE TABLE IF NOT EXISTS sqlar(\n"
      "  name TEXT PRIMARY KEY,  -- name of the file\n"
      "  mode INT,               -- access permissions\n"
      "  mtime INT,              -- last modification time\n"
      "  sz INT,                 -- original file size\n"
................................................................................
     "    mode,\n"
     "    mtime,\n"
     "    CASE substr(lsmode(mode),1,1)\n"
     "      WHEN '-' THEN length(data)\n"
     "      WHEN 'd' THEN 0\n"
     "      ELSE -1 END,\n"
     "    sqlar_compress(data)\n"
     "  FROM fsdir(%Q,%Q) AS disk\n"
     "  WHERE lsmode(mode) NOT LIKE '?%%'%s;"
     ,
     "REPLACE INTO %s(name,mode,mtime,data)\n"
     "  SELECT\n"
     "    %s,\n"
     "    mode,\n"
     "    mtime,\n"
     "    data\n"
     "  FROM fsdir(%Q,%Q) AS disk\n"
     "  WHERE lsmode(mode) NOT LIKE '?%%'%s;"
  };
  int i;                          /* For iterating through azFile[] */
  int rc;                         /* Return code */
  const char *zTab = 0;           /* SQL table into which to insert */
  char *zSql;
  char zTemp[50];
  char *zExists = 0;

  arExecSql(pAr, "PRAGMA page_size=512");
  rc = arExecSql(pAr, "SAVEPOINT ar;");
  if( rc!=SQLITE_OK ) return rc;
  zTemp[0] = 0; 
  if( pAr->bZip ){
    /* Initialize the zipfile virtual table, if necessary */
................................................................................
    zTab = "sqlar";
    if( bUpdate==0 ){
      rc = arExecSql(pAr, zDrop);
      if( rc!=SQLITE_OK ) goto end_ar_transaction;
    }
    rc = arExecSql(pAr, zCreate);
  }
  if( bOnlyIfChanged ){
    zExists = sqlite3_mprintf(
      " AND NOT EXISTS("
          "SELECT 1 FROM %s AS mem"
          " WHERE mem.name=disk.name"
          " AND mem.mtime=disk.mtime"
          " AND mem.mode=disk.mode)", zTab);
  }else{
    zExists = sqlite3_mprintf("");
  }
  if( zExists==0 ) rc = SQLITE_NOMEM;
  for(i=0; i<pAr->nArg && rc==SQLITE_OK; i++){
    char *zSql2 = sqlite3_mprintf(zInsertFmt[pAr->bZip], zTab,
        pAr->bVerbose ? "shell_putsnl(name)" : "name",
        pAr->azArg[i], pAr->zDir, zExists);
    rc = arExecSql(pAr, zSql2);
    sqlite3_free(zSql2);
  }
end_ar_transaction:
  if( rc!=SQLITE_OK ){
    sqlite3_exec(pAr->db, "ROLLBACK TO ar; RELEASE ar;", 0, 0, 0);
  }else{
................................................................................
    rc = arExecSql(pAr, "RELEASE ar;");
    if( pAr->bZip && pAr->zFile ){
      zSql = sqlite3_mprintf("DROP TABLE %s", zTemp);
      arExecSql(pAr, zSql);
      sqlite3_free(zSql);
    }
  }
  sqlite3_free(zExists);
  return rc;
}

/*
** Implementation of ".ar" dot command.
*/
static int arDotCommand(
................................................................................
          cmd.zSrcTable = sqlite3_mprintf("zipfile(%Q)", cmd.zFile);
        }
      }
      cmd.bZip = 1;
    }else if( cmd.zFile ){
      int flags;
      if( cmd.bAppend ) eDbType = SHELL_OPEN_APPENDVFS;
      if( cmd.eCmd==AR_CMD_CREATE || cmd.eCmd==AR_CMD_INSERT 
           || cmd.eCmd==AR_CMD_UPDATE ){
        flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE;
      }else{
        flags = SQLITE_OPEN_READONLY;
      }
      cmd.db = 0;
      if( cmd.bDryRun ){
        utf8_printf(pState->out, "-- open database '%s'%s\n", cmd.zFile,
................................................................................
        goto end_ar_command;
      }
      cmd.zSrcTable = sqlite3_mprintf("sqlar");
    }

    switch( cmd.eCmd ){
      case AR_CMD_CREATE:
        rc = arCreateOrUpdateCommand(&cmd, 0, 0);
        break;

      case AR_CMD_EXTRACT:
        rc = arExtractCommand(&cmd);
        break;

      case AR_CMD_LIST:
................................................................................
        rc = arListCommand(&cmd);
        break;

      case AR_CMD_HELP:
        arUsage(pState->out);
        break;

      case AR_CMD_INSERT:
        rc = arCreateOrUpdateCommand(&cmd, 1, 0);
        break;

      default:
        assert( cmd.eCmd==AR_CMD_UPDATE );
        rc = arCreateOrUpdateCommand(&cmd, 1, 1);
        break;
    }
  }
end_ar_command:
  if( cmd.db!=pState->db ){
    close_db(cmd.db);
  }