| Colbourn, Charles 2006-05-19, 8:13 am |
| Hi,
I'm working on some code that needs to be able to s in an LDIF file based
on DN. The idea is to iterate through the file, finding each entry in turn
and using tell($ldif->handle) to get the position in the file. That provides
an index to allow something like random read access to the file. I knocked
up this test case to make sure it was feasible:
# ldif fpos test
use strict;
use warnings;
use Net::LDAP::LDIF;
my $ldif = Net::LDAP::LDIF->new("dump.ldif","r",onerror=>'die');
my $entry = $ldif->read_entry;
my $fpos = tell($ldif->handle);
print "Fpos =$fpos\n";
$entry = $ldif->read_entry;
print "DN = ".$entry->dn()."\nfpos = ",tell($ldif->handle)."\n\n";
for (1..100)
{
$entry = $ldif->read_entry;
}
print "Current position = ".tell($ldif->handle)."\n";
print "DN way down in file = ".$entry->dn."\n";
s($ldif->handle,$fpos,0);
print "fps = ".tell($ldif->handle)."\n";
$entry = $ldif->read_entry;
print "Sought dn = ".$entry->dn."\n";
print "fps = ".tell($ldif->handle)."\n";
Unfortunately, although sing the filehandle back to the chosen DN works
to the extent that the filehandle pointer is in the right place,
$ldif->read_entry returns the entry after the last one read in the 1..100
loop - i.e. as if the s hadn't happened. Digging around, it appears that
Net::LDAP::LDIF is caching the next entry in the file as it reads each
entry, in Net::LDAP::LDIF::_read_lines. Each time _read_lines is called, if
the cached next entry exists it returns that, otherwise it reads the file.
If the second do{}until block in this sub is commented out as follows the
test case works:
sub _read_lines {
my $self = shift;
my @ldif;
{
local $/ = "";
my $fh = $self->{'fh'};
my $ln;
do { # allow comments separated by blank lines
$ln = $self->{_next_lines} || scalar <$fh>;
unless ($ln) {
$self->{_next_lines} = '';
$self->{_current_lines} = '';
$self->eof(1);
return;
}
$ln =~ s/\n //sg;
$ln =~ s/^#.*\n//mg;
chomp($ln);
$self->{_current_lines} = $ln;
} until ($self->{_current_lines} || $self->eof());
chomp(@ldif = split(/^/, $ln));
#do {
# $ln = scalar <$fh> || '';
# $self->eof(1) unless $ln;
# $ln =~ s/\n //sg;
# $ln =~ s/^#.*\n//mg;
# chomp($ln);
# $self->{_next_lines} = $ln;
#} until ($self->{_next_lines} || $self->eof());
}
@ldif;
}
but I'm not sure why the code is caching the next entry, and what commenting
out this block might break; plus of course I don' t really want to have a
customised version of the module on my installation. The alternative would
be to directly remove the private attrib _next_lines, or to recreate the
object before each s - neither of which strike me as a good idea. Anyone
care to comment?
cheers,
Charles Colbourn.
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