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: dbi-dev@perl.org
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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