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

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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