SQLite

}

/*
** Return a vector of device characteristics.
*/
static int winDeviceCharacteristics(sqlite3_file *id){
  UNUSED_PARAMETER(id);
  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN;
}

/****************************************************************************
********************************* Shared Memory *****************************
**
** The next subdivision of code manages the shared-memory primitives.
*/

  int exists = 1;               /* True if a journal file is present */
  int jrnlOpen = !!isOpen(pPager->jfd);

  assert( pPager!=0 );
  assert( pPager->useJournal );
  assert( isOpen(pPager->fd) );
  assert( pPager->state <= PAGER_SHARED );
  assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
    SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
  ));

  *pExists = 0;
  if( !jrnlOpen ){
    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
  }
  if( rc==SQLITE_OK && exists ){
    int locked;                 /* True if some process holds a RESERVED lock */

      rc = sqlite3JournalOpen(
          pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager)
      );
#else
      rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
      if( rc==SQLITE_OK ){
        int iDc = sqlite3OsDeviceCharacteristics(pPager->jfd);
        pPager->safeJrnlHandle = (iDc&SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)!=0;
      }
#endif
    }
    assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
  }

** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
*/
#define SQLITE_IOCAP_ATOMIC                 0x00000001
#define SQLITE_IOCAP_ATOMIC512              0x00000002
#define SQLITE_IOCAP_ATOMIC1K               0x00000004
#define SQLITE_IOCAP_ATOMIC2K               0x00000008
#define SQLITE_IOCAP_ATOMIC4K               0x00000010
#define SQLITE_IOCAP_ATOMIC8K               0x00000020
#define SQLITE_IOCAP_ATOMIC16K              0x00000040
#define SQLITE_IOCAP_ATOMIC32K              0x00000080
#define SQLITE_IOCAP_ATOMIC64K              0x00000100
#define SQLITE_IOCAP_SAFE_APPEND            0x00000200
#define SQLITE_IOCAP_SEQUENTIAL             0x00000400
#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800

/*
** CAPI3REF: File Locking Levels
**
** SQLite uses one of these integer values as the second
** argument to calls it makes to the xLock() and xUnlock() methods
** of an [sqlite3_io_methods] object.

    }

    case CMD_DEVCHAR: {
      struct DeviceFlag {
        char *zName;
        int iValue;
      } aFlag[] = {
        { "default",               -1 },
        { "atomic",                SQLITE_IOCAP_ATOMIC      },
        { "atomic512",             SQLITE_IOCAP_ATOMIC512   },
        { "atomic1k",              SQLITE_IOCAP_ATOMIC1K    },
        { "atomic2k",              SQLITE_IOCAP_ATOMIC2K    },
        { "atomic4k",              SQLITE_IOCAP_ATOMIC4K    },
        { "atomic8k",              SQLITE_IOCAP_ATOMIC8K    },
        { "atomic16k",             SQLITE_IOCAP_ATOMIC16K   },
        { "atomic32k",             SQLITE_IOCAP_ATOMIC32K   },
        { "atomic64k",             SQLITE_IOCAP_ATOMIC64K   },
        { "sequential",            SQLITE_IOCAP_SEQUENTIAL  },
        { "safe_append",           SQLITE_IOCAP_SAFE_APPEND },
        { "undeletable_when_open", SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN },
        { 0, 0 }
      };
      Tcl_Obj *pRet;
      int iFlag;

      if( objc>3 ){
        Tcl_WrongNumArgs(interp, 2, objv, "?ATTR-LIST?");

  string range [string repeat "${a_string_counter}." $n] 1 $n
}

# Create a [testvfs] and install it as the default VFS. Set the device
# characteristics flags to "SAFE_DELETE".
#
testvfs tvfs -default 1
tvfs devchar undeletable_when_open

# Set up a hook so that each time a journal file is opened, closed or
# deleted, the method name ("xOpen", "xClose" or "xDelete") and the final
# segment of the journal file-name (i.e. "test.db-journal") are appended to
# global list variable $::oplog.
#
tvfs filter {xOpen xClose xDelete}