[ZODB-Dev] [FileStorage] "description too long" error

[Jim Fulton]

On Jan 12, 2008, at 9:59 AM, Alan Runyan wrote:
...
> ZODB's error handling of transaction header length may be incorrect  
> as well:
>
> the code in FileStorage.py:
>
> def _begin(self, tid, u, d, e):
>     self._nextpos = 0
>     self._thl = TRANS_HDR_LEN + len(u) + len(d) + len(e)
>     if self._thl > 65535:
>         # one of u, d, or e may be > 65535
>        # We have to check lengths here because struct.pack
>        # doesn't raise an exception on overflow
>        if len(u) > 65535:
>            raise FileStorageError('user name too long')
>        if len(d) > 65535:
>             raise FileStorageError('description too long')
>        if len(e) > 65535:
>            raise FileStorageError('too much extension data')
>
> 1. What if each u, d, e were each 32k?  this exception would
> not be triggered.

And it shouldn't be. Each has their own 2-byte length field in the  
transaction header,

If I ever do FileStorage2 (don't hold your breath) I'd combine the  
user and description with the extension data into a single field with  
a 4-byte length.

Jim

--
Jim Fulton
Zope Corporation