Function deduceDatabaseType

lib-src/sqlite/shell.c:14424–14457

** Try to deduce the type of file for zName based on its content. Return ** one of the SHELL_OPEN_* constants. ** ** If the file does not exist or is empty but its name looks like a ZIP ** archive and the dfltZip flag is true, then assume it is a ZIP archive. ** Otherwise, assume an ordinary database regardless of the filename if ** the type cannot be determined from content. */

** the type cannot be determined from content.
*/
int deduceDatabaseType(const char *zName, int dfltZip){
  FILE *f = fopen(zName, "rb");
  size_t n;
  int rc = SHELL_OPEN_UNSPEC;
  char zBuf[100];
  if( f==0 ){
    if( dfltZip && sqlite3_strlike("%.zip",zName,0)==0 ){
       return SHELL_OPEN_ZIPFILE;
    }else{
       return SHELL_OPEN_NORMAL;
    }
  }
  n = fread(zBuf, 16, 1, f);
  if( n==1 && memcmp(zBuf, "SQLite format 3", 16)==0 ){
    fclose(f);
    return SHELL_OPEN_NORMAL;
  }
  fseek(f, -25, SEEK_END);
  n = fread(zBuf, 25, 1, f);
  if( n==1 && memcmp(zBuf, "Start-Of-SQLite3-", 17)==0 ){
    rc = SHELL_OPEN_APPENDVFS;
  }else{
    fseek(f, -22, SEEK_END);
    n = fread(zBuf, 22, 1, f);
    if( n==1 && zBuf[0]==0x50 && zBuf[1]==0x4b && zBuf[2]==0x05
       && zBuf[3]==0x06 ){
      rc = SHELL_OPEN_ZIPFILE;
    }else if( n==0 && dfltZip && sqlite3_strlike("%.zip",zName,0)==0 ){
      rc = SHELL_OPEN_ZIPFILE;
    }
  }
  fclose(f);
  return rc;  
}

#ifdef SQLITE_ENABLE_DESERIALIZE
/*