Re: DBD::Oracle - is ora_lob_read mangling BLOB data?

 That does indeed make the problem go away.  Blob data is no longer
marked as utf-8.  Thank you.Because we may not be able to upgrade to
DBD::Oracle 1.23 right away, I would still like to know if there are any
problems with "binary" data being marked as utf-8 that "use bytes" can't
fix.  However, I'll find a better place to ask that question.

  ----- Original Message -----
  From: [email protected]
  To: "Milo van der Leij"
  Cc: [email protected]
  Subject: Re: DBD::Oracle - is ora_lob_read mangling BLOB data?
  Date: Fri, 27 Mar 2009 09:02:41 -0400 (EDT)


  Ok I think I found the problem

  use this version of oracle.xs

  http://svn.perl.org/modules/dbd-oracle/trunk/Oracle.xs

  and see if it solves you problems

  cheers
  john scoles

  > Thank you.Just to share everything I know: It looks like in
  ora_lob_read
  > in Oracle.xs, OCILobCharSetForm_log_stat is called to populate
  csform.
  > The value of csform is what is used to determine whether to turn
  utf-8
  > on. However, OCILobCharSetForm returns 0 for BLOBs and BFILEs
  (since
  > they have no characterset) and a returned value of 0 is never
  checked
  > for. Instead, the code assumes that csform is either SQLCS_IMPLICIT
  or
  > SQLCS_NCHAR.
  >
  > ----- Original Message -----
  > From: "John Scoles"
  > To: "Milo van der Leij"
  > Cc: [email protected]
  > Subject: Re: DBD::Oracle - is ora_lob_read mangling BLOB data?
  > Date: Thu, 26 Mar 2009 10:02:57 -0400
  >
  >
  > I will have a look at it tomorrow as you gave me a good example.
  >
  > The latest version is ready to go out the door but I can delay it a
  > little more as I look into it.
  >
  > Cheers
  > John Scoles
  >
  > Milo van der Leij wrote:
  > > My apologies. I am seeing this behavior with DBD::Oracle
  > > versions 1.17 and 1.22
  > >
  > > ----- Original Message -----
  > > From: "John Scoles"
  > > To: "Milo van der Leij"
  > > Cc: [email protected]
  > > Subject: Re: DBD::Oracle - is ora_lob_read mangling BLOB data?
  > > Date: Thu, 26 Mar 2009 06:43:32 -0400
  > >
  > > Can you tell us which version of DBD::Oracle you are using. There
  > > is quite a differance between versions when it comes to UTF8
  > > handling.
  > >
  > > Milo van der Leij wrote:
  > > > I am in the progress of changing some code that uses
  DBD::Oracle
  > > > to use the documented ora_lob_read function instead of the
  > > > undocumented blob_read, and I suddenly hit the error "Malformed
  > > > UTF-8 character (unexpected end of string) in length".
  > > >
  > > > As it turns out, Perl's length function returns the number of
  > > > characters in the string. If Perl thinks the string contains
  > > > text and the text is in utf-8, then this can be different from
  > > > the number of bytes in the string. I regret to say that I am
  > > > very unfamiliar with how Perl handles utf-8, but I am familiar
  > > > enough with Oracle to see that treating BLOB data as character
  > > > data is incorrect.
  > > >
  > > > I see the call to SvUTF8_on in ora_lob_read in Oracle.xs, I see
  > > > how the value of NLS_LANG plays in, and I see how it affects
  both
  > > > CLOB and BLOB data, so I understand why I am getting the result
  I
  > > > am getting. But I have some questions:
  > > >
  > > > (For someone who understands utf-8 in Perl:) Is there danger in
  > > > binary data being treated as utf-8, other than the length
  > > > function crashing? Is there a workaround? (I see "use bytes",
  > > > but Perl 5.10 doc for the length function says "the internal
  > > > encoding is variable, and the number of bytes usually
  > > > meaningless" which scares me.)
  > > >
  > > > (For someone who understands the stuff in Oracle.xs:) Is it
  even
  > > > possible to change ora_lob_read to only call SvUTF8_on for CLOB
  > > > data and not for BLOB data?
  > > >
  > > > My test case is included below. Connection info will need to be
  > > > altered before it runs. Commenting out the line with AL32UTF8
  > > > makes the problem go away.
  > > >
  > > > use strict;
  > > > use DBI;
  > > > use DBD::Oracle qw(:ora_types);
  > > >
  > > > $ENV{'NLS_LANG'} = '_.AL32UTF8';
  > > > my $hDB = DBI->connect('dbi:Oracle:TEST', 'SCOTT', 'TIGER');
  > > >
  > > > my $hSQL = $hDB->prepare(qq{
  > > > DECLARE
  > > > b blob;
  > > > BEGIN
  > > > dbms_lob.createtemporary(b,true);
  > > > dbms_lob.writeappend(b,256,utl_raw.xrange('00','FF'));
  > > > :b := b;
  > > > END;
  > > > }, { ora_auto_lob => 0 });
  > > >
  > > > my $b;
  > > > $hSQL->bind_param_inout( ':b', \$b, 0, { ora_type => ORA_BLOB }
  > );
  > > > $hSQL->execute;
  > > >
  > > > my $data = $hDB->ora_lob_read( $b, 1, 1024 );
  > > > print "Read ", length($data), " bytes.\n";
  > > >
  > > >
  > > >
  > >
  > >
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