First stab at 5.003 -> 5.004 integration.

p4raw-id: //depot/perl@18

4 files changed, 1574 insertions, 391 deletions

diff --git a/ext/DB_File/DB_File.pm b/ext/DB_File/DB_File.pm
index 61ac26aafe..2d5e744671 100644
--- a/ext/DB_File/DB_File.pm
+++ b/ext/DB_File/DB_File.pm
@@ -1,181 +1,144 @@
 # DB_File.pm -- Perl 5 interface to Berkeley DB 
 #
 # written by Paul Marquess (pmarquess@bfsec.bt.co.uk)
-# last modified 14th November 1995
-# version 1.01
+# last modified 30th Apr 1997
+# version 1.14
+#
+#     Copyright (c) 1995, 1996, 1997 Paul Marquess. All rights reserved.
+#     This program is free software; you can redistribute it and/or
+#     modify it under the same terms as Perl itself.
+
 
 package DB_File::HASHINFO ;
 
+require 5.003 ;
+
 use strict;
-use vars qw(%elements);
 use Carp;
+require Tie::Hash;
+@DB_File::HASHINFO::ISA = qw(Tie::Hash);
+
+sub new
+{
+    my $pkg = shift ;
+    my %x ;
+    tie %x, $pkg ;
+    bless \%x, $pkg ;
+}
+
 
 sub TIEHASH
 {
-    bless {} ;
+    my $pkg = shift ;
+
+    bless { VALID => { map {$_, 1} 
+		       qw( bsize ffactor nelem cachesize hash lorder)
+		     }, 
+	    GOT   => {}
+          }, $pkg ;
 }
 
-%elements = ( 'bsize'     => 0,
-              'ffactor'   => 0,
-              'nelem'     => 0,
-              'cachesize' => 0,
-              'hash'      => 0,
-              'lorder'    => 0
-            ) ;
 
 sub FETCH 
 {  
-    return $_[0]{$_[1]} if defined $elements{$_[1]}  ;
+    my $self  = shift ;
+    my $key   = shift ;
 
-    croak "DB_File::HASHINFO::FETCH - Unknown element '$_[1]'" ;
+    return $self->{GOT}{$key} if exists $self->{VALID}{$key}  ;
+
+    my $pkg = ref $self ;
+    croak "${pkg}::FETCH - Unknown element '$key'" ;
 }
 
 
 sub STORE 
 {
-    if ( defined $elements{$_[1]} )
+    my $self  = shift ;
+    my $key   = shift ;
+    my $value = shift ;
+
+    if ( exists $self->{VALID}{$key} )
     {
-        $_[0]{$_[1]} = $_[2] ;
+        $self->{GOT}{$key} = $value ;
         return ;
     }
     
-    croak "DB_File::HASHINFO::STORE - Unknown element '$_[1]'" ;
+    my $pkg = ref $self ;
+    croak "${pkg}::STORE - Unknown element '$key'" ;
 }
 
 sub DELETE 
 {
-    if ( defined $elements{$_[1]} )
+    my $self = shift ;
+    my $key  = shift ;
+
+    if ( exists $self->{VALID}{$key} )
     {
-        delete ${$_[0]}{$_[1]} ;
+        delete $self->{GOT}{$key} ;
         return ;
     }
     
-    croak "DB_File::HASHINFO::DELETE - Unknown element '$_[1]'" ;
+    my $pkg = ref $self ;
+    croak "DB_File::HASHINFO::DELETE - Unknown element '$key'" ;
 }
 
-
-sub DESTROY {undef %{$_[0]} }
-sub FIRSTKEY { croak "DB_File::HASHINFO::FIRSTKEY is not implemented" }
-sub NEXTKEY { croak "DB_File::HASHINFO::NEXTKEY is not implemented" }
-sub EXISTS { croak "DB_File::HASHINFO::EXISTS is not implemented" }
-sub CLEAR { croak "DB_File::HASHINFO::CLEAR is not implemented" }
-
-package DB_File::BTREEINFO ;
-
-use strict;
-use vars qw(%elements);
-use Carp;
-
-sub TIEHASH
+sub EXISTS
 {
-    bless {} ;
-}
-
-%elements = ( 'flags'	=> 0,
-              'cachesize'  => 0,
-              'maxkeypage' => 0,
-              'minkeypage' => 0,
-              'psize'      => 0,
-              'compare'    => 0,
-              'prefix'     => 0,
-              'lorder'     => 0
-            ) ;
-
-sub FETCH 
-{  
-    return $_[0]{$_[1]} if defined $elements{$_[1]}  ;
+    my $self = shift ;
+    my $key  = shift ;
 
-    croak "DB_File::BTREEINFO::FETCH - Unknown element '$_[1]'" ;
+    exists $self->{VALID}{$key} ;
 }
 
-
-sub STORE 
+sub NotHere
 {
-    if ( defined $elements{$_[1]} )
-    {
-        $_[0]{$_[1]} = $_[2] ;
-        return ;
-    }
-    
-    croak "DB_File::BTREEINFO::STORE - Unknown element '$_[1]'" ;
-}
+    my $self = shift ;
+    my $method = shift ;
 
-sub DELETE 
-{
-    if ( defined $elements{$_[1]} )
-    {
-        delete ${$_[0]}{$_[1]} ;
-        return ;
-    }
-    
-    croak "DB_File::BTREEINFO::DELETE - Unknown element '$_[1]'" ;
+    croak ref($self) . " does not define the method ${method}" ;
 }
 
-
-sub DESTROY {undef %{$_[0]} }
-sub FIRSTKEY { croak "DB_File::BTREEINFO::FIRSTKEY is not implemented" }
-sub NEXTKEY { croak "DB_File::BTREEINFO::NEXTKEY is not implemented" }
-sub EXISTS { croak "DB_File::BTREEINFO::EXISTS is not implemented" }
-sub CLEAR { croak "DB_File::BTREEINFO::CLEAR is not implemented" }
+sub DESTROY  { undef %{$_[0]} }
+sub FIRSTKEY { my $self = shift ; $self->NotHere("FIRSTKEY") }
+sub NEXTKEY  { my $self = shift ; $self->NotHere("NEXTKEY") }
+sub CLEAR    { my $self = shift ; $self->NotHere("CLEAR") }
 
 package DB_File::RECNOINFO ;
 
-use strict;
-use vars qw(%elements);
-use Carp;
+use strict ;
+
+@DB_File::RECNOINFO::ISA = qw(DB_File::HASHINFO) ;
 
 sub TIEHASH
 {
-    bless {} ;
-}
-
-%elements = ( 'bval'      => 0,
-              'cachesize' => 0,
-              'psize'     => 0,
-              'flags'     => 0,
-              'lorder'    => 0,
-              'reclen'    => 0,
-              'bfname'    => 0
-            ) ;
-sub FETCH 
-{  
-    return $_[0]{$_[1]} if defined $elements{$_[1]}  ;
+    my $pkg = shift ;
 
-    croak "DB_File::RECNOINFO::FETCH - Unknown element '$_[1]'" ;
+    bless { VALID => { map {$_, 1} 
+		       qw( bval cachesize psize flags lorder reclen bfname )
+		     },
+	    GOT   => {},
+          }, $pkg ;
 }
 
+package DB_File::BTREEINFO ;
 
-sub STORE 
-{
-    if ( defined $elements{$_[1]} )
-    {
-        $_[0]{$_[1]} = $_[2] ;
-        return ;
-    }
-    
-    croak "DB_File::RECNOINFO::STORE - Unknown element '$_[1]'" ;
-}
+use strict ;
 
-sub DELETE 
+@DB_File::BTREEINFO::ISA = qw(DB_File::HASHINFO) ;
+
+sub TIEHASH
 {
-    if ( defined $elements{$_[1]} )
-    {
-        delete ${$_[0]}{$_[1]} ;
-        return ;
-    }
-    
-    croak "DB_File::RECNOINFO::DELETE - Unknown element '$_[1]'" ;
+    my $pkg = shift ;
+
+    bless { VALID => { map {$_, 1} 
+		       qw( flags cachesize maxkeypage minkeypage psize 
+			   compare prefix lorder )
+	    	     },
+	    GOT   => {},
+          }, $pkg ;
 }
 
 
-sub DESTROY {undef %{$_[0]} }
-sub FIRSTKEY { croak "DB_File::RECNOINFO::FIRSTKEY is not implemented" }
-sub NEXTKEY { croak "DB_File::RECNOINFO::NEXTKEY is not implemented" }
-sub EXISTS { croak "DB_File::BTREEINFO::EXISTS is not implemented" }
-sub CLEAR { croak "DB_File::BTREEINFO::CLEAR is not implemented" }
-
-
-
 package DB_File ;
 
 use strict;
@@ -183,12 +146,12 @@ use vars qw($VERSION @ISA @EXPORT $AUTOLOAD $DB_BTREE $DB_HASH $DB_RECNO) ;
 use Carp;
 
 
-$VERSION = "1.01" ;
+$VERSION = "1.14" ;
 
 #typedef enum { DB_BTREE, DB_HASH, DB_RECNO } DBTYPE;
-$DB_BTREE = TIEHASH DB_File::BTREEINFO ;
-$DB_HASH  = TIEHASH DB_File::HASHINFO ;
-$DB_RECNO = TIEHASH DB_File::RECNOINFO ;
+$DB_BTREE = new DB_File::BTREEINFO ;
+$DB_HASH  = new DB_File::HASHINFO ;
+$DB_RECNO = new DB_File::RECNOINFO ;
 
 require Tie::Hash;
 require Exporter;
@@ -197,6 +160,7 @@ require DynaLoader;
 @ISA = qw(Tie::Hash Exporter DynaLoader);
 @EXPORT = qw(
         $DB_BTREE $DB_HASH $DB_RECNO 
+
 	BTREEMAGIC
 	BTREEVERSION
 	DB_LOCK
@@ -225,6 +189,7 @@ require DynaLoader;
 	R_SETCURSOR
 	R_SNAPSHOT
 	__R_UNUSED
+
 );
 
 sub AUTOLOAD {
@@ -246,16 +211,86 @@ sub AUTOLOAD {
     goto &$AUTOLOAD;
 }
 
+
+# import borrowed from IO::File
+#   exports Fcntl constants if available.
+sub import {
+    my $pkg = shift;
+    my $callpkg = caller;
+    Exporter::export $pkg, $callpkg, @_;
+    eval {
+        require Fcntl;
+        Exporter::export 'Fcntl', $callpkg, '/^O_/';
+    };
+}
+
 bootstrap DB_File $VERSION;
 
 # Preloaded methods go here.  Autoload methods go after __END__, and are
 # processed by the autosplit program.
 
+sub tie_hash_or_array
+{
+    my (@arg) = @_ ;
+    my $tieHASH = ( (caller(1))[3] =~ /TIEHASH/ ) ;
+
+    $arg[4] = tied %{ $arg[4] } 
+	if @arg >= 5 && ref $arg[4] && $arg[4] =~ /=HASH/ && tied %{ $arg[4] } ;
+
+    DoTie_($tieHASH, @arg) ;
+}
+
+sub TIEHASH
+{
+    tie_hash_or_array(@_) ;
+}
+
+sub TIEARRAY
+{
+    tie_hash_or_array(@_) ;
+}
+
+sub get_dup
+{
+    croak "Usage: \$db->get_dup(key [,flag])\n"
+        unless @_ == 2 or @_ == 3 ;
+ 
+    my $db        = shift ;
+    my $key       = shift ;
+    my $flag	  = shift ;
+    my $value 	  = 0 ;
+    my $origkey   = $key ;
+    my $wantarray = wantarray ;
+    my %values	  = () ;
+    my @values    = () ;
+    my $counter   = 0 ;
+    my $status    = 0 ;
+ 
+    # iterate through the database until either EOF ($status == 0)
+    # or a different key is encountered ($key ne $origkey).
+    for ($status = $db->seq($key, $value, R_CURSOR()) ;
+	 $status == 0 and $key eq $origkey ;
+         $status = $db->seq($key, $value, R_NEXT()) ) {
+ 
+        # save the value or count number of matches
+        if ($wantarray) {
+	    if ($flag)
+                { ++ $values{$value} }
+	    else
+                { push (@values, $value) }
+	}
+        else
+            { ++ $counter }
+     
+    }
+ 
+    return ($wantarray ? ($flag ? %values : @values) : $counter) ;
+}
+
+
 1;
 __END__
 
-=cut
-
 =head1 NAME
 
 DB_File - Perl5 access to Berkeley DB
@@ -263,18 +298,30 @@ DB_File - Perl5 access to Berkeley DB
 =head1 SYNOPSIS
 
  use DB_File ;
-  
- [$X =] tie %hash,  DB_File, $filename [, $flags, $mode, $DB_HASH] ;
- [$X =] tie %hash,  DB_File, $filename, $flags, $mode, $DB_BTREE ;
- [$X =] tie @array, DB_File, $filename, $flags, $mode, $DB_RECNO ;
-   
+ 
+ [$X =] tie %hash,  'DB_File', [$filename, $flags, $mode, $DB_HASH] ;
+ [$X =] tie %hash,  'DB_File', $filename, $flags, $mode, $DB_BTREE ;
+ [$X =] tie @array, 'DB_File', $filename, $flags, $mode, $DB_RECNO ;
+
  $status = $X->del($key [, $flags]) ;
  $status = $X->put($key, $value [, $flags]) ;
  $status = $X->get($key, $value [, $flags]) ;
- $status = $X->seq($key, $value [, $flags]) ;
+ $status = $X->seq($key, $value, $flags) ;
  $status = $X->sync([$flags]) ;
  $status = $X->fd ;
-    
+
+ # BTREE only
+ $count = $X->get_dup($key) ;
+ @list  = $X->get_dup($key) ;
+ %list  = $X->get_dup($key, 1) ;
+
+ # RECNO only
+ $a = $X->length;
+ $a = $X->pop ;
+ $X->push(list);
+ $a = $X->shift;
+ $X->unshift(list);
+
  untie %hash ;
  untie @array ;
 
@@ -282,10 +329,14 @@ DB_File - Perl5 access to Berkeley DB
 
 B<DB_File> is a module which allows Perl programs to make use of the
 facilities provided by Berkeley DB.  If you intend to use this
-module you should really have a copy of the Berkeley DB manualpage at
+module you should really have a copy of the Berkeley DB manual pages at
 hand. The interface defined here mirrors the Berkeley DB interface
 closely.
 
+Please note that this module will only work with version 1.x of
+Berkeley DB. Once Berkeley DB version 2 is released, B<DB_File> will be
+upgraded to work with it.
+
 Berkeley DB is a C library which provides a consistent interface to a
 number of database formats.  B<DB_File> provides an interface to all
 three of the database types currently supported by Berkeley DB.
@@ -294,9 +345,9 @@ The file types are:
 
 =over 5
 
-=item DB_HASH
+=item B<DB_HASH>
 
-This database type allows arbitrary key/data pairs to be stored in data
+This database type allows arbitrary key/value pairs to be stored in data
 files. This is equivalent to the functionality provided by other
 hashing packages like DBM, NDBM, ODBM, GDBM, and SDBM. Remember though,
 the files created using DB_HASH are not compatible with any of the
@@ -307,16 +358,16 @@ applications, is built into Berkeley DB. If you do need to use your own
 hashing algorithm it is possible to write your own in Perl and have
 B<DB_File> use it instead.
 
-=item DB_BTREE
+=item B<DB_BTREE>
 
-The btree format allows arbitrary key/data pairs to be stored in a
+The btree format allows arbitrary key/value pairs to be stored in a
 sorted, balanced binary tree.
 
 As with the DB_HASH format, it is possible to provide a user defined
 Perl routine to perform the comparison of keys. By default, though, the
 keys are stored in lexical order.
 
-=item DB_RECNO
+=item B<DB_RECNO>
 
 DB_RECNO allows both fixed-length and variable-length flat text files
 to be manipulated using the same key/value pair interface as in DB_HASH
@@ -325,7 +376,7 @@ number.
 
 =back
 
-=head2 How does DB_File interface to Berkeley DB?
+=head2 Interface to Berkeley DB
 
 B<DB_File> allows access to Berkeley DB files using the tie() mechanism
 in Perl 5 (for full details, see L<perlfunc/tie()>). This facility
@@ -333,13 +384,14 @@ allows B<DB_File> to access Berkeley DB files using either an
 associative array (for DB_HASH & DB_BTREE file types) or an ordinary
 array (for the DB_RECNO file type).
 
-In addition to the tie() interface, it is also possible to use most of
-the functions provided in the Berkeley DB API.
+In addition to the tie() interface, it is also possible to access most
+of the functions provided in the Berkeley DB API directly.
+See L<THE API INTERFACE>.
 
-=head2 Differences with Berkeley DB
+=head2 Opening a Berkeley DB Database File
 
 Berkeley DB uses the function dbopen() to open or create a database.
-Below is the C prototype for dbopen().
+Here is the C prototype for dbopen():
 
       DB*
       dbopen (const char * file, int flags, int mode, 
@@ -352,35 +404,133 @@ I<openinfo> points to a data structure which allows tailoring of the
 specific interface method.
 
 This interface is handled slightly differently in B<DB_File>. Here is
-an equivalent call using B<DB_File>.
+an equivalent call using B<DB_File>:
 
-        tie %array, DB_File, $filename, $flags, $mode, $DB_HASH ;
+        tie %array, 'DB_File', $filename, $flags, $mode, $DB_HASH ;
 
 The C<filename>, C<flags> and C<mode> parameters are the direct
 equivalent of their dbopen() counterparts. The final parameter $DB_HASH
 performs the function of both the C<type> and C<openinfo> parameters in
 dbopen().
 
-In the example above $DB_HASH is actually a reference to a hash
-object. B<DB_File> has three of these pre-defined references. Apart
-from $DB_HASH, there is also $DB_BTREE and $DB_RECNO.
+In the example above $DB_HASH is actually a pre-defined reference to a
+hash object. B<DB_File> has three of these pre-defined references.
+Apart from $DB_HASH, there is also $DB_BTREE and $DB_RECNO.
 
 The keys allowed in each of these pre-defined references is limited to
 the names used in the equivalent C structure. So, for example, the
 $DB_HASH reference will only allow keys called C<bsize>, C<cachesize>,
-C<ffactor>, C<hash>, C<lorder> and C<nelem>.
+C<ffactor>, C<hash>, C<lorder> and C<nelem>. 
+
+To change one of these elements, just assign to it like this:
+
+	$DB_HASH->{'cachesize'} = 10000 ;
+
+The three predefined variables $DB_HASH, $DB_BTREE and $DB_RECNO are
+usually adequate for most applications.  If you do need to create extra
+instances of these objects, constructors are available for each file
+type.
+
+Here are examples of the constructors and the valid options available
+for DB_HASH, DB_BTREE and DB_RECNO respectively.
+
+     $a = new DB_File::HASHINFO ;
+     $a->{'bsize'} ;
+     $a->{'cachesize'} ;
+     $a->{'ffactor'};
+     $a->{'hash'} ;
+     $a->{'lorder'} ;
+     $a->{'nelem'} ;
+
+     $b = new DB_File::BTREEINFO ;
+     $b->{'flags'} ;
+     $b->{'cachesize'} ;
+     $b->{'maxkeypage'} ;
+     $b->{'minkeypage'} ;
+     $b->{'psize'} ;
+     $b->{'compare'} ;
+     $b->{'prefix'} ;
+     $b->{'lorder'} ;
+
+     $c = new DB_File::RECNOINFO ;
+     $c->{'bval'} ;
+     $c->{'cachesize'} ;
+     $c->{'psize'} ;
+     $c->{'flags'} ;
+     $c->{'lorder'} ;
+     $c->{'reclen'} ;
+     $c->{'bfname'} ;
+
+The values stored in the hashes above are mostly the direct equivalent
+of their C counterpart. Like their C counterparts, all are set to a
+default values - that means you don't have to set I<all> of the
+values when you only want to change one. Here is an example:
+
+     $a = new DB_File::HASHINFO ;
+     $a->{'cachesize'} =  12345 ;
+     tie %y, 'DB_File', "filename", $flags, 0777, $a ;
+
+A few of the options need extra discussion here. When used, the C
+equivalent of the keys C<hash>, C<compare> and C<prefix> store pointers
+to C functions. In B<DB_File> these keys are used to store references
+to Perl subs. Below are templates for each of the subs:
+
+    sub hash
+    {
+        my ($data) = @_ ;
+        ...
+        # return the hash value for $data
+	return $hash ;
+    }
+
+    sub compare
+    {
+	my ($key, $key2) = @_ ;
+        ...
+        # return  0 if $key1 eq $key2
+        #        -1 if $key1 lt $key2
+        #         1 if $key1 gt $key2
+        return (-1 , 0 or 1) ;
+    }
+
+    sub prefix
+    {
+	my ($key, $key2) = @_ ;
+        ...
+        # return number of bytes of $key2 which are 
+        # necessary to determine that it is greater than $key1
+        return $bytes ;
+    }
+
+See L<Changing the BTREE sort order> for an example of using the
+C<compare> template.
 
-To change one of these elements, just assign to it like this
+If you are using the DB_RECNO interface and you intend making use of
+C<bval>, you should check out L<The 'bval' Option>.
 
-	$DB_HASH->{cachesize} = 10000 ;
+=head2 Default Parameters
 
+It is possible to omit some or all of the final 4 parameters in the
+call to C<tie> and let them take default values. As DB_HASH is the most
+common file format used, the call:
 
-=head2 RECNO
+    tie %A, "DB_File", "filename" ;
 
+is equivalent to:
 
-In order to make RECNO more compatible with Perl the array offset for all
-RECNO arrays begins at 0 rather than 1 as in Berkeley DB.
+    tie %A, "DB_File", "filename", O_CREAT|O_RDWR, 0666, $DB_HASH ;
 
+It is also possible to omit the filename parameter as well, so the
+call:
+
+    tie %A, "DB_File" ;
+
+is equivalent to:
+
+    tie %A, "DB_File", undef, O_CREAT|O_RDWR, 0666, $DB_HASH ;
+
+See L<In Memory Databases> for a discussion on the use of C<undef>
+in place of a filename.
 
 =head2 In Memory Databases
 
@@ -388,153 +538,751 @@ Berkeley DB allows the creation of in-memory databases by using NULL
 (that is, a C<(char *)0> in C) in place of the filename.  B<DB_File>
 uses C<undef> instead of NULL to provide this functionality.
 
+=head1 DB_HASH
+
+The DB_HASH file format is probably the most commonly used of the three
+file formats that B<DB_File> supports. It is also very straightforward
+to use.
+
+=head2 A Simple Example
+
+This example shows how to create a database, add key/value pairs to the
+database, delete keys/value pairs and finally how to enumerate the
+contents of the database.
+
+    use strict ;
+    use DB_File ;
+    use vars qw( %h $k $v ) ;
+
+    tie %h, "DB_File", "fruit", O_RDWR|O_CREAT, 0640, $DB_HASH 
+        or die "Cannot open file 'fruit': $!\n";
+
+    # Add a few key/value pairs to the file
+    $h{"apple"} = "red" ;
+    $h{"orange"} = "orange" ;
+    $h{"banana"} = "yellow" ;
+    $h{"tomato"} = "red" ;
+
+    # Check for existence of a key
+    print "Banana Exists\n\n" if $h{"banana"} ;
+
+    # Delete a key/value pair.
+    delete $h{"apple"} ;
+
+    # print the contents of the file
+    while (($k, $v) = each %h)
+      { print "$k -> $v\n" }
+
+    untie %h ;
+
+here is the output:
+
+    Banana Exists
+ 
+    orange -> orange
+    tomato -> red
+    banana -> yellow
+
+Note that the like ordinary associative arrays, the order of the keys
+retrieved is in an apparently random order.
+
+=head1 DB_BTREE
+
+The DB_BTREE format is useful when you want to store data in a given
+order. By default the keys will be stored in lexical order, but as you
+will see from the example shown in the next section, it is very easy to
+define your own sorting function.
+
+=head2 Changing the BTREE sort order
+
+This script shows how to override the default sorting algorithm that
+BTREE uses. Instead of using the normal lexical ordering, a case
+insensitive compare function will be used.
+
+    use strict ;
+    use DB_File ;
+
+    my %h ;
+
+    sub Compare
+    {
+        my ($key1, $key2) = @_ ;
+        "\L$key1" cmp "\L$key2" ;
+    }
+
+    # specify the Perl sub that will do the comparison
+    $DB_BTREE->{'compare'} = \&Compare ;
+
+    tie %h, "DB_File", "tree", O_RDWR|O_CREAT, 0640, $DB_BTREE 
+        or die "Cannot open file 'tree': $!\n" ;
+
+    # Add a key/value pair to the file
+    $h{'Wall'} = 'Larry' ;
+    $h{'Smith'} = 'John' ;
+    $h{'mouse'} = 'mickey' ;
+    $h{'duck'}  = 'donald' ;
+
+    # Delete
+    delete $h{"duck"} ;
+
+    # Cycle through the keys printing them in order.
+    # Note it is not necessary to sort the keys as
+    # the btree will have kept them in order automatically.
+    foreach (keys %h)
+      { print "$_\n" }
+
+    untie %h ;
+
+Here is the output from the code above.
+
+    mouse
+    Smith
+    Wall
+
+There are a few point to bear in mind if you want to change the
+ordering in a BTREE database:
+
+=over 5
+
+=item 1.
+
+The new compare function must be specified when you create the database.
+
+=item 2.
+
+You cannot change the ordering once the database has been created. Thus
+you must use the same compare function every time you access the
+database.
+
+=back 
+
+=head2 Handling Duplicate Keys 
+
+The BTREE file type optionally allows a single key to be associated
+with an arbitrary number of values. This option is enabled by setting
+the flags element of C<$DB_BTREE> to R_DUP when creating the database.
+
+There are some difficulties in using the tied hash interface if you
+want to manipulate a BTREE database with duplicate keys. Consider this
+code:
+
+    use strict ;
+    use DB_File ;
+
+    use vars qw($filename %h ) ;
+
+    $filename = "tree" ;
+    unlink $filename ;
+ 
+    # Enable duplicate records
+    $DB_BTREE->{'flags'} = R_DUP ;
+ 
+    tie %h, "DB_File", $filename, O_RDWR|O_CREAT, 0640, $DB_BTREE 
+	or die "Cannot open $filename: $!\n";
+ 
+    # Add some key/value pairs to the file
+    $h{'Wall'} = 'Larry' ;
+    $h{'Wall'} = 'Brick' ; # Note the duplicate key
+    $h{'Wall'} = 'Brick' ; # Note the duplicate key and value
+    $h{'Smith'} = 'John' ;
+    $h{'mouse'} = 'mickey' ;
+
+    # iterate through the associative array
+    # and print each key/value pair.
+    foreach (keys %h)
+      { print "$_  -> $h{$_}\n" }
+
+    untie %h ;
+
+Here is the output:
+
+    Smith   -> John
+    Wall    -> Larry
+    Wall    -> Larry
+    Wall    -> Larry
+    mouse   -> mickey
+
+As you can see 3 records have been successfully created with key C<Wall>
+- the only thing is, when they are retrieved from the database they
+I<seem> to have the same value, namely C<Larry>. The problem is caused
+by the way that the associative array interface works. Basically, when
+the associative array interface is used to fetch the value associated
+with a given key, it will only ever retrieve the first value.
+
+Although it may not be immediately obvious from the code above, the
+associative array interface can be used to write values with duplicate
+keys, but it cannot be used to read them back from the database.
+
+The way to get around this problem is to use the Berkeley DB API method
+called C<seq>.  This method allows sequential access to key/value
+pairs. See L<THE API INTERFACE> for details of both the C<seq> method
+and the API in general.
+
+Here is the script above rewritten using the C<seq> API method.
+
+    use strict ;
+    use DB_File ;
+ 
+    use vars qw($filename $x %h $status $key $value) ;
+
+    $filename = "tree" ;
+    unlink $filename ;
+ 
+    # Enable duplicate records
+    $DB_BTREE->{'flags'} = R_DUP ;
+ 
+    $x = tie %h, "DB_File", $filename, O_RDWR|O_CREAT, 0640, $DB_BTREE 
+	or die "Cannot open $filename: $!\n";
+ 
+    # Add some key/value pairs to the file
+    $h{'Wall'} = 'Larry' ;
+    $h{'Wall'} = 'Brick' ; # Note the duplicate key
+    $h{'Wall'} = 'Brick' ; # Note the duplicate key and value
+    $h{'Smith'} = 'John' ;
+    $h{'mouse'} = 'mickey' ;
+ 
+    # iterate through the btree using seq
+    # and print each key/value pair.
+    $key = $value = 0 ;
+    for ($status = $x->seq($key, $value, R_FIRST) ;
+         $status == 0 ;
+         $status = $x->seq($key, $value, R_NEXT) )
+      {  print "$key -> $value\n" }
+ 
+    undef $x ;
+    untie %h ;
+
+that prints:
+
+    Smith   -> John
+    Wall    -> Brick
+    Wall    -> Brick
+    Wall    -> Larry
+    mouse   -> mickey
+
+This time we have got all the key/value pairs, including the multiple
+values associated with the key C<Wall>.
+
+=head2 The get_dup() Method
+
+B<DB_File> comes with a utility method, called C<get_dup>, to assist in
+reading duplicate values from BTREE databases. The method can take the
+following forms:
+
+    $count = $x->get_dup($key) ;
+    @list  = $x->get_dup($key) ;
+    %list  = $x->get_dup($key, 1) ;
+
+In a scalar context the method returns the number of values associated
+with the key, C<$key>.
+
+In list context, it returns all the values which match C<$key>. Note
+that the values will be returned in an apparently random order.
+
+In list context, if the second parameter is present and evaluates
+TRUE, the method returns an associative array. The keys of the
+associative array correspond to the values that matched in the BTREE
+and the values of the array are a count of the number of times that
+particular value occurred in the BTREE.
+
+So assuming the database created above, we can use C<get_dup> like
+this:
+
+    my $cnt  = $x->get_dup("Wall") ;
+    print "Wall occurred $cnt times\n" ;
+
+    my %hash = $x->get_dup("Wall", 1) ;
+    print "Larry is there\n" if $hash{'Larry'} ;
+    print "There are $hash{'Brick'} Brick Walls\n" ;
+
+    my @list = $x->get_dup("Wall") ;
+    print "Wall =>	[@list]\n" ;
+
+    @list = $x->get_dup("Smith") ;
+    print "Smith =>	[@list]\n" ;
+ 
+    @list = $x->get_dup("Dog") ;
+    print "Dog =>	[@list]\n" ;
+
+
+and it will print:
+
+    Wall occurred 3 times
+    Larry is there
+    There are 2 Brick Walls
+    Wall =>	[Brick Brick Larry]
+    Smith =>	[John]
+    Dog =>	[]
+
+=head2 Matching Partial Keys 
+
+The BTREE interface has a feature which allows partial keys to be
+matched. This functionality is I<only> available when the C<seq> method
+is used along with the R_CURSOR flag.
+
+    $x->seq($key, $value, R_CURSOR) ;
+
+Here is the relevant quote from the dbopen man page where it defines
+the use of the R_CURSOR flag with seq:
+
+    Note, for the DB_BTREE access method, the returned key is not
+    necessarily an exact match for the specified key. The returned key
+    is the smallest key greater than or equal to the specified key,
+    permitting partial key matches and range searches.
+
+In the example script below, the C<match> sub uses this feature to find
+and print the first matching key/value pair given a partial key.
+
+    use strict ;
+    use DB_File ;
+    use Fcntl ;
+
+    use vars qw($filename $x %h $st $key $value) ;
+
+    sub match
+    {
+        my $key = shift ;
+        my $value = 0;
+        my $orig_key = $key ;
+        $x->seq($key, $value, R_CURSOR) ;
+        print "$orig_key\t-> $key\t-> $value\n" ;
+    }
+
+    $filename = "tree" ;
+    unlink $filename ;
+
+    $x = tie %h, "DB_File", $filename, O_RDWR|O_CREAT, 0640, $DB_BTREE
+        or die "Cannot open $filename: $!\n";
+ 
+    # Add some key/value pairs to the file
+    $h{'mouse'} = 'mickey' ;
+    $h{'Wall'} = 'Larry' ;
+    $h{'Walls'} = 'Brick' ; 
+    $h{'Smith'} = 'John' ;
+ 
+
+    $key = $value = 0 ;
+    print "IN ORDER\n" ;
+    for ($st = $x->seq($key, $value, R_FIRST) ;
+	 $st == 0 ;
+         $st = $x->seq($key, $value, R_NEXT) )
+	
+      {  print "$key -> $value\n" }
+ 
+    print "\nPARTIAL MATCH\n" ;
+
+    match "Wa" ;
+    match "A" ;
+    match "a" ;
+
+    undef $x ;
+    untie %h ;
+
+Here is the output:
+
+    IN ORDER
+    Smith -> John
+    Wall  -> Larry
+    Walls -> Brick
+    mouse -> mickey
+
+    PARTIAL MATCH
+    Wa -> Wall  -> Larry
+    A  -> Smith -> John
+    a  -> mouse -> mickey
+
+=head1 DB_RECNO
+
+DB_RECNO provides an interface to flat text files. Both variable and
+fixed length records are supported.
+
+In order to make RECNO more compatible with Perl the array offset for
+all RECNO arrays begins at 0 rather than 1 as in Berkeley DB.
+
+As with normal Perl arrays, a RECNO array can be accessed using
+negative indexes. The index -1 refers to the last element of the array,
+-2 the second last, and so on. Attempting to access an element before
+the start of the array will raise a fatal run-time error.
+
+=head2 The 'bval' Option
+
+The operation of the bval option warrants some discussion. Here is the
+definition of bval from the Berkeley DB 1.85 recno manual page:
+
+    The delimiting byte to be used to mark  the  end  of  a
+    record for variable-length records, and the pad charac-
+    ter for fixed-length records.  If no  value  is  speci-
+    fied,  newlines  (``\n'')  are  used to mark the end of
+    variable-length records and  fixed-length  records  are
+    padded with spaces.
+
+The second sentence is wrong. In actual fact bval will only default to
+C<"\n"> when the openinfo parameter in dbopen is NULL. If a non-NULL
+openinfo parameter is used at all, the value that happens to be in bval
+will be used. That means you always have to specify bval when making
+use of any of the options in the openinfo parameter. This documentation
+error will be fixed in the next release of Berkeley DB.
+
+That clarifies the situation with regards Berkeley DB itself. What
+about B<DB_File>? Well, the behavior defined in the quote above is
+quite useful, so B<DB_File> conforms it.
+
+That means that you can specify other options (e.g. cachesize) and
+still have bval default to C<"\n"> for variable length records, and
+space for fixed length records.
+
+=head2 A Simple Example
+
+Here is a simple example that uses RECNO.
+
+    use strict ;
+    use DB_File ;
+
+    my @h ;
+    tie @h, "DB_File", "text", O_RDWR|O_CREAT, 0640, $DB_RECNO 
+        or die "Cannot open file 'text': $!\n" ;
+
+    # Add a few key/value pairs to the file
+    $h[0] = "orange" ;
+    $h[1] = "blue" ;
+    $h[2] = "yellow" ;
+
+    # Check for existence of a key
+    print "Element 1 Exists with value $h[1]\n" if $h[1] ;
+
+    # use a negative index
+    print "The last element is $h[-1]\n" ;
+    print "The 2nd last element is $h[-2]\n" ;
+
+    untie @h ;
+
+Here is the output from the script:
+
+
+    Element 1 Exists with value blue
+    The last element is yellow
+    The 2nd last element is blue
+
+=head2 Extra Methods
+
+As you can see from the example above, the tied array interface is
+quite limited. To make the interface more useful, a number of methods
+are supplied with B<DB_File> to simulate the standard array operations
+that are not currently implemented in Perl's tied array interface. All
+these methods are accessed via the object returned from the tie call.
+
+Here are the methods:
+
+=over 5
+
+=item B<$X-E<gt>push(list) ;>
+
+Pushes the elements of C<list> to the end of the array.
+
+=item B<$value = $X-E<gt>pop ;>
+
+Removes and returns the last element of the array.
 
-=head2 Using the Berkeley DB Interface Directly
+=item B<$X-E<gt>shift>
+
+Removes and returns the first element of the array.
+
+=item B<$X-E<gt>unshift(list) ;>
+
+Pushes the elements of C<list> to the start of the array.
+
+=item B<$X-E<gt>length>
+
+Returns the number of elements in the array.
+
+=back
+
+=head2 Another Example
+
+Here is a more complete example that makes use of some of the methods
+described above. It also makes use of the API interface directly (see 
+L<THE API INTERFACE>).
+
+    use strict ;
+    use vars qw(@h $H $file $i) ;
+    use DB_File ;
+    use Fcntl ;
+    
+    $file = "text" ;
+
+    unlink $file ;
+
+    $H = tie @h, "DB_File", $file, O_RDWR|O_CREAT, 0640, $DB_RECNO 
+        or die "Cannot open file $file: $!\n" ;
+    
+    # first create a text file to play with
+    $h[0] = "zero" ;
+    $h[1] = "one" ;
+    $h[2] = "two" ;
+    $h[3] = "three" ;
+    $h[4] = "four" ;
+
+    
+    # Print the records in order.
+    #
+    # The length method is needed here because evaluating a tied
+    # array in a scalar context does not return the number of
+    # elements in the array.  
+
+    print "\nORIGINAL\n" ;
+    foreach $i (0 .. $H->length - 1) {
+        print "$i: $h[$i]\n" ;
+    }
+
+    # use the push & pop methods
+    $a = $H->pop ;
+    $H->push("last") ;
+    print "\nThe last record was [$a]\n" ;
+
+    # and the shift & unshift methods
+    $a = $H->shift ;
+    $H->unshift("first") ;
+    print "The first record was [$a]\n" ;
+
+    # Use the API to add a new record after record 2.
+    $i = 2 ;
+    $H->put($i, "Newbie", R_IAFTER) ;
+
+    # and a new record before record 1.
+    $i = 1 ;
+    $H->put($i, "New One", R_IBEFORE) ;
+
+    # delete record 3
+    $H->del(3) ;
+
+    # now print the records in reverse order
+    print "\nREVERSE\n" ;
+    for ($i = $H->length - 1 ; $i >= 0 ; -- $i)
+      { print "$i: $h[$i]\n" }
+
+    # same again, but use the API functions instead
+    print "\nREVERSE again\n" ;
+    my ($s, $k, $v)  = (0, 0, 0) ;
+    for ($s = $H->seq($k, $v, R_LAST) ; 
+             $s == 0 ; 
+             $s = $H->seq($k, $v, R_PREV))
+      { print "$k: $v\n" }
+
+    undef $H ;
+    untie @h ;
+
+and this is what it outputs:
+
+    ORIGINAL
+    0: zero
+    1: one
+    2: two
+    3: three
+    4: four
+
+    The last record was [four]
+    The first record was [zero]
+
+    REVERSE
+    5: last
+    4: three
+    3: Newbie
+    2: one
+    1: New One
+    0: first
+
+    REVERSE again
+    5: last
+    4: three
+    3: Newbie
+    2: one
+    1: New One
+    0: first
+
+Notes:
+
+=over 5
+
+=item 1.
+
+Rather than iterating through the array, C<@h> like this:
+
+    foreach $i (@h)
+
+it is necessary to use either this:
+
+    foreach $i (0 .. $H->length - 1) 
+
+or this:
+
+    for ($a = $H->get($k, $v, R_FIRST) ;
+         $a == 0 ;
+         $a = $H->get($k, $v, R_NEXT) )
+
+=item 2.
+
+Notice that both times the C<put> method was used the record index was
+specified using a variable, C<$i>, rather than the literal value
+itself. This is because C<put> will return the record number of the
+inserted line via that parameter.
+
+=back
+
+=head1 THE API INTERFACE
 
 As well as accessing Berkeley DB using a tied hash or array, it is also
-possible to make direct use of most of the functions defined in the
+possible to make direct use of most of the API functions defined in the
 Berkeley DB documentation.
 
+To do this you need to store a copy of the object returned from the tie.
 
-To do this you need to remember the return value from the tie.
-
-	$db = tie %hash, DB_File, "filename"
+	$db = tie %hash, "DB_File", "filename" ;
 
 Once you have done that, you can access the Berkeley DB API functions
-directly.
+as B<DB_File> methods directly like this:
 
 	$db->put($key, $value, R_NOOVERWRITE) ;
 
-All the functions defined in L<dbx(3X)> are available except for
-close() and dbopen() itself. The B<DB_File> interface to these
-functions have been implemented to mirror the the way Berkeley DB
-works. In particular note that all the functions return only a status
-value. Whenever a Berkeley DB function returns data via one of its
-parameters, the B<DB_File> equivalent does exactly the same.
+B<Important:> If you have saved a copy of the object returned from
+C<tie>, the underlying database file will I<not> be closed until both
+the tied variable is untied and all copies of the saved object are
+destroyed. 
+
+    use DB_File ;
+    $db = tie %hash, "DB_File", "filename" 
+        or die "Cannot tie filename: $!" ;
+    ...
+    undef $db ;
+    untie %hash ;
 
-All the constants defined in L<dbopen> are also available.
+See L<The untie() Gotcha> for more details.
 
-Below is a list of the functions available.
+All the functions defined in L<dbopen> are available except for
+close() and dbopen() itself. The B<DB_File> method interface to the
+supported functions have been implemented to mirror the way Berkeley DB
+works whenever possible. In particular note that:
 
 =over 5
 
-=item get
+=item *
 
-Same as in C<recno> except that the flags parameter is optional.
-Remember the value associated with the key you request is returned in
-the $value parameter.
+The methods return a status value. All return 0 on success.
+All return -1 to signify an error and set C<$!> to the exact
+error code. The return code 1 generally (but not always) means that the
+key specified did not exist in the database.
 
-=item put
+Other return codes are defined. See below and in the Berkeley DB
+documentation for details. The Berkeley DB documentation should be used
+as the definitive source.
 
-As usual the flags parameter is optional. 
+=item *
 
-If you use either the R_IAFTER or R_IBEFORE flags, the key parameter
-will have the record number of the inserted key/value pair set.
+Whenever a Berkeley DB function returns data via one of its parameters,
+the equivalent B<DB_File> method does exactly the same.
 
-=item del
+=item *
 
-The flags parameter is optional.
+If you are careful, it is possible to mix API calls with the tied
+hash/array interface in the same piece of code. Although only a few of
+the methods used to implement the tied interface currently make use of
+the cursor, you should always assume that the cursor has been changed
+any time the tied hash/array interface is used. As an example, this
+code will probably not do what you expect:
 
-=item fd
+    $X = tie %x, 'DB_File', $filename, O_RDWR|O_CREAT, 0777, $DB_BTREE
+        or die "Cannot tie $filename: $!" ;
 
-As in I<recno>.
+    # Get the first key/value pair and set  the cursor
+    $X->seq($key, $value, R_FIRST) ;
 
-=item seq
+    # this line will modify the cursor
+    $count = scalar keys %x ; 
 
-The flags parameter is optional.
+    # Get the second key/value pair.
+    # oops, it didn't, it got the last key/value pair!
+    $X->seq($key, $value, R_NEXT) ;
 
-Both the key and value parameters will be set.
+The code above can be rearranged to get around the problem, like this:
 
-=item sync
+    $X = tie %x, 'DB_File', $filename, O_RDWR|O_CREAT, 0777, $DB_BTREE
+        or die "Cannot tie $filename: $!" ;
 
-The flags parameter is optional.
+    # this line will modify the cursor
+    $count = scalar keys %x ; 
+
+    # Get the first key/value pair and set  the cursor
+    $X->seq($key, $value, R_FIRST) ;
+
+    # Get the second key/value pair.
+    # worked this time.
+    $X->seq($key, $value, R_NEXT) ;
 
 =back
 
-=head1 EXAMPLES
+All the constants defined in L<dbopen> for use in the flags parameters
+in the methods defined below are also available. Refer to the Berkeley
+DB documentation for the precise meaning of the flags values.
 
-It is always a lot easier to understand something when you see a real
-example. So here are a few.
+Below is a list of the methods available.
 
-=head2 Using HASH
+=over 5
 
-	use DB_File ;
-	use Fcntl ;
-	
-	tie %h,  "DB_File", "hashed", O_RDWR|O_CREAT, 0640, $DB_HASH ;
-	
-	# Add a key/value pair to the file
-	$h{"apple"} = "orange" ;
-	
-	# Check for existence of a key
-	print "Exists\n" if $h{"banana"} ;
-	
-	# Delete 
-	delete $h{"apple"} ;
-	
-	untie %h ;
+=item B<$status = $X-E<gt>get($key, $value [, $flags]) ;>
 
-=head2 Using BTREE
+Given a key (C<$key>) this method reads the value associated with it
+from the database. The value read from the database is returned in the
+C<$value> parameter.
 
-Here is sample of code which used BTREE. Just to make life more
-interesting the default comparision function will not be used. Instead
-a Perl sub, C<Compare()>, will be used to do a case insensitive
-comparison.
+If the key does not exist the method returns 1.
 
-        use DB_File ;
-        use Fcntl ;
-	 
-	sub Compare
-        {
-	    my ($key1, $key2) = @_ ;
-	
-	    "\L$key1" cmp "\L$key2" ;
-	}
-	
-        $DB_BTREE->{compare} = 'Compare' ;
-	 
-        tie %h,  'DB_File', "tree", O_RDWR|O_CREAT, 0640, $DB_BTREE ;
-	 
-        # Add a key/value pair to the file
-        $h{'Wall'} = 'Larry' ;
-        $h{'Smith'} = 'John' ;
-	$h{'mouse'} = 'mickey' ;
-	$h{'duck'}   = 'donald' ;
-	 
-        # Delete
-        delete $h{"duck"} ;
-	 
-	# Cycle through the keys printing them in order.
-	# Note it is not necessary to sort the keys as
-	# the btree will have kept them in order automatically.
-	foreach (keys %h)
-	  { print "$_\n" }
-	
-        untie %h ;
+No flags are currently defined for this method.
 
-Here is the output from the code above.
+=item B<$status = $X-E<gt>put($key, $value [, $flags]) ;>
 
-	mouse
-	Smith
-	Wall
+Stores the key/value pair in the database.
 
+If you use either the R_IAFTER or R_IBEFORE flags, the C<$key> parameter
+will have the record number of the inserted key/value pair set.
 
-=head2 Using RECNO
+Valid flags are R_CURSOR, R_IAFTER, R_IBEFORE, R_NOOVERWRITE and
+R_SETCURSOR.
 
-	use DB_File ;
-	use Fcntl ;
-	
-	$DB_RECNO->{psize} = 3000 ;
-	
-	tie @h,  DB_File, "text", O_RDWR|O_CREAT, 0640, $DB_RECNO ;
-	
-	# Add a key/value pair to the file
-	$h[0] = "orange" ;
-	
-	# Check for existence of a key
-	print "Exists\n" if $h[1] ;
-	
-	untie @h ;
+=item B<$status = $X-E<gt>del($key [, $flags]) ;>
+
+Removes all key/value pairs with key C<$key> from the database.
+
+A return code of 1 means that the requested key was not in the
+database.
+
+R_CURSOR is the only valid flag at present.
+
+=item B<$status = $X-E<gt>fd ;>
+
+Returns the file descriptor for the underlying database.
+
+See L<Locking Databases> for an example of how to make use of the
+C<fd> method to lock your database.
+
+=item B<$status = $X-E<gt>seq($key, $value, $flags) ;>
+
+This interface allows sequential retrieval from the database. See
+L<dbopen> for full details.
+
+Both the C<$key> and C<$value> parameters will be set to the key/value
+pair read from the database.
+
+The flags parameter is mandatory. The valid flag values are R_CURSOR,
+R_FIRST, R_LAST, R_NEXT and R_PREV.
+
+=item B<$status = $X-E<gt>sync([$flags]) ;>
+
+Flushes any cached buffers to disk.
+
+R_RECNOSYNC is the only valid flag at present.
+
+=back
+
+=head1 HINTS AND TIPS 
 
 
 =head2 Locking Databases
@@ -545,7 +1293,6 @@ uses the I<fd> method to get the file descriptor, and then a careful
 open() to give something Perl will flock() for you.  Run this repeatedly
 in the background to watch the locks granted in proper order.
 
-    use Fcntl;
     use DB_File;
 
     use strict;
@@ -588,13 +1335,211 @@ in the background to watch the locks granted in proper order.
 
     print "$$: Write lock granted\n";
     $db{$key} = $value;
+    $db->sync;	# to flush
     sleep 10;
 
     flock(DB_FH, LOCK_UN);
+    undef $db;
     untie %db;
     close(DB_FH);
     print "$$: Updated db to $key=$value\n";
 
+=head2 Sharing Databases With C Applications
+
+There is no technical reason why a Berkeley DB database cannot be
+shared by both a Perl and a C application.
+
+The vast majority of problems that are reported in this area boil down
+to the fact that C strings are NULL terminated, whilst Perl strings are
+not. 
+
+Here is a real example. Netscape 2.0 keeps a record of the locations you
+visit along with the time you last visited them in a DB_HASH database.
+This is usually stored in the file F<~/.netscape/history.db>. The key
+field in the database is the location string and the value field is the
+time the location was last visited stored as a 4 byte binary value.
+
+If you haven't already guessed, the location string is stored with a
+terminating NULL. This means you need to be careful when accessing the
+database.
+
+Here is a snippet of code that is loosely based on Tom Christiansen's
+I<ggh> script (available from your nearest CPAN archive in
+F<authors/id/TOMC/scripts/nshist.gz>).
+
+    use strict ;
+    use DB_File ;
+    use Fcntl ;
+
+    use vars qw( $dotdir $HISTORY %hist_db $href $binary_time $date ) ;
+    $dotdir = $ENV{HOME} || $ENV{LOGNAME};
+
+    $HISTORY = "$dotdir/.netscape/history.db";
+
+    tie %hist_db, 'DB_File', $HISTORY
+        or die "Cannot open $HISTORY: $!\n" ;;
+
+    # Dump the complete database
+    while ( ($href, $binary_time) = each %hist_db ) {
+
+        # remove the terminating NULL
+        $href =~ s/\x00$// ;
+
+        # convert the binary time into a user friendly string
+        $date = localtime unpack("V", $binary_time);
+        print "$date $href\n" ;
+    }
+
+    # check for the existence of a specific key
+    # remember to add the NULL
+    if ( $binary_time = $hist_db{"http://mox.perl.com/\x00"} ) {
+        $date = localtime unpack("V", $binary_time) ;
+        print "Last visited mox.perl.com on $date\n" ;
+    }
+    else {
+        print "Never visited mox.perl.com\n"
+    }
+
+    untie %hist_db ;
+
+=head2 The untie() Gotcha
+
+If you make use of the Berkeley DB API, it is I<very> strongly
+recommended that you read L<perltie/The untie Gotcha>. 
+
+Even if you don't currently make use of the API interface, it is still
+worth reading it.
+
+Here is an example which illustrates the problem from a B<DB_File>
+perspective:
+
+    use DB_File ;
+    use Fcntl ;
+
+    my %x ;
+    my $X ;
+
+    $X = tie %x, 'DB_File', 'tst.fil' , O_RDWR|O_TRUNC
+        or die "Cannot tie first time: $!" ;
+
+    $x{123} = 456 ;
+
+    untie %x ;
+
+    tie %x, 'DB_File', 'tst.fil' , O_RDWR|O_CREAT
+        or die "Cannot tie second time: $!" ;
+
+    untie %x ;
+
+When run, the script will produce this error message:
+
+    Cannot tie second time: Invalid argument at bad.file line 14.
+
+Although the error message above refers to the second tie() statement
+in the script, the source of the problem is really with the untie()
+statement that precedes it.
+
+Having read L<perltie> you will probably have already guessed that the
+error is caused by the extra copy of the tied object stored in C<$X>.
+If you haven't, then the problem boils down to the fact that the
+B<DB_File> destructor, DESTROY, will not be called until I<all>
+references to the tied object are destroyed. Both the tied variable,
+C<%x>, and C<$X> above hold a reference to the object. The call to
+untie() will destroy the first, but C<$X> still holds a valid
+reference, so the destructor will not get called and the database file
+F<tst.fil> will remain open. The fact that Berkeley DB then reports the
+attempt to open a database that is alreday open via the catch-all
+"Invalid argument" doesn't help.
+
+If you run the script with the C<-w> flag the error message becomes:
+
+    untie attempted while 1 inner references still exist at bad.file line 12.
+    Cannot tie second time: Invalid argument at bad.file line 14.
+
+which pinpoints the real problem. Finally the script can now be
+modified to fix the original problem by destroying the API object
+before the untie:
+
+    ...
+    $x{123} = 456 ;
+
+    undef $X ;
+    untie %x ;
+
+    $X = tie %x, 'DB_File', 'tst.fil' , O_RDWR|O_CREAT
+    ...
+
+
+=head1 COMMON QUESTIONS
+
+=head2 Why is there Perl source in my database?
+
+If you look at the contents of a database file created by DB_File,
+there can sometimes be part of a Perl script included in it.
+
+This happens because Berkeley DB uses dynamic memory to allocate
+buffers which will subsequently be written to the database file. Being
+dynamic, the memory could have been used for anything before DB
+malloced it. As Berkeley DB doesn't clear the memory once it has been
+allocated, the unused portions will contain random junk. In the case
+where a Perl script gets written to the database, the random junk will
+correspond to an area of dynamic memory that happened to be used during
+the compilation of the script.
+
+Unless you don't like the possibility of there being part of your Perl
+scripts embedded in a database file, this is nothing to worry about.
+
+=head2 How do I store complex data structures with DB_File?
+
+Although B<DB_File> cannot do this directly, there is a module which
+can layer transparently over B<DB_File> to accomplish this feat.
+
+Check out the MLDBM module, available on CPAN in the directory
+F<modules/by-module/MLDBM>.
+
+=head2 What does "Invalid Argument" mean?
+
+You will get this error message when one of the parameters in the
+C<tie> call is wrong. Unfortunately there are quite a few parameters to
+get wrong, so it can be difficult to figure out which one it is.
+
+Here are a couple of possibilities:
+
+=over 5
+
+=item 1.
+
+Attempting to reopen a database without closing it. 
+
+=item 2.
+
+Using the O_WRONLY flag.
+
+=back
+
+=head2 What does "Bareword 'DB_File' not allowed" mean? 
+
+You will encounter this particular error message when you have the
+C<strict 'subs'> pragma (or the full strict pragma) in your script.
+Consider this script:
+
+    use strict ;
+    use DB_File ;
+    use vars qw(%x) ;
+    tie %x, DB_File, "filename" ;
+
+Running it produces the error in question:
+
+    Bareword "DB_File" not allowed while "strict subs" in use 
+
+To get around the error, place the word C<DB_File> in either single or
+double quotes, like this:
+
+    tie %x, "DB_File", "filename" ;
+
+Although it might seem like a real pain, it is really worth the effort
+of having a C<use strict> in all your scripts.
+
 =head1 HISTORY
 
 =over
@@ -631,14 +1576,97 @@ Fixed a core dump problem with SunOS.
 The return value from TIEHASH wasn't set to NULL when dbopen returned
 an error.
 
-=head1 WARNINGS
+=item 1.02
+
+Merged OS/2 specific code into DB_File.xs
 
-If you happen find any other functions defined in the source for this
-module that have not been mentioned in this document -- beware.  I may
-drop them at a moments notice.
+Removed some redundant code in DB_File.xs.
 
-If you cannot find any, then either you didn't look very hard or the
-moment has passed and I have dropped them.
+Documentation update.
+
+Allow negative subscripts with RECNO interface.
+
+Changed the default flags from O_RDWR to O_CREAT|O_RDWR.
+
+The example code which showed how to lock a database needed a call to
+C<sync> added. Without it the resultant database file was empty.
+
+Added get_dup method.
+
+=item 1.03
+
+Documentation update.
+
+B<DB_File> now imports the constants (O_RDWR, O_CREAT etc.) from Fcntl
+automatically.
+
+The standard hash function C<exists> is now supported.
+
+Modified the behavior of get_dup. When it returns an associative
+array, the value is the count of the number of matching BTREE values.
+
+=item 1.04
+
+Minor documentation changes.
+
+Fixed a bug in hash_cb. Patches supplied by Dave Hammen,
+E<lt>hammen@gothamcity.jsc.nasa.govE<gt>.
+
+Fixed a bug with the constructors for DB_File::HASHINFO,
+DB_File::BTREEINFO and DB_File::RECNOINFO. Also tidied up the
+constructors to make them C<-w> clean.
+
+Reworked part of the test harness to be more locale friendly.
+
+=item 1.05
+
+Made all scripts in the documentation C<strict> and C<-w> clean.
+
+Added logic to F<DB_File.xs> to allow the module to be built after Perl
+is installed.
+
+=item 1.06
+
+Minor namespace cleanup: Localized C<PrintBtree>.
+
+=item 1.07
+
+Fixed bug with RECNO, where bval wasn't defaulting to "\n".
+
+=item 1.08
+
+Documented operation of bval.
+
+=item 1.09
+
+Minor bug fix in DB_File::HASHINFO, DB_File::RECNOINFO and
+DB_File::BTREEINFO.
+
+Changed default mode to 0666.
+
+=item 1.10
+
+Fixed fd method so that it still returns -1 for in-memory files when db
+1.86 is used.
+
+=item 1.11
+
+Documented the untie gotcha.
+
+=item 1.12
+
+Documented the incompatibility with version 2 of Berkeley DB.
+
+=item 1.13
+
+Minor changes to DB_FIle.xs and DB_File.pm
+
+=item 1.14
+
+Made it illegal to tie an associative array to a RECNO database and an
+ordinary array to a HASH or BTREE database.
+
+=back
 
 =head1 BUGS
 
@@ -651,23 +1679,50 @@ suggest any enhancements, I would welcome your comments.
 
 =head1 AVAILABILITY
 
-Berkeley DB is available at your nearest CPAN archive (see
+B<DB_File> comes with the standard Perl source distribution. Look in
+the directory F<ext/DB_File>.
+
+This version of B<DB_File> will only work with version 1.x of Berkeley
+DB. It is I<not> yet compatible with version 2.
+
+Version 1 of Berkeley DB is available at your nearest CPAN archive (see
 L<perlmod/"CPAN"> for a list) in F<src/misc/db.1.85.tar.gz>, or via the
-host F<ftp.cs.berkeley.edu> in F</ucb/4bsd/db.tar.gz>.  It is I<not> under
-the GPL.
+host F<ftp.cs.berkeley.edu> in F</ucb/4bsd/db.tar.gz>.  Alternatively,
+check out the Berkeley DB home page at F<http://www.bostic.com/db>. It
+is I<not> under the GPL.
+
+If you are running IRIX, then get Berkeley DB from
+F<http://reality.sgi.com/ariel>. It has the patches necessary to
+compile properly on IRIX 5.3.
+
+As of January 1997, version 1.86 of Berkeley DB is available from the
+Berkeley DB home page. Although this release does fix a number of bugs
+that were present in 1.85 you should be aware of the following
+information (taken from the Berkeley DB home page) before you consider
+using it:
+
+    DB version 1.86 includes a new implementation of the hash access
+    method that fixes a variety of hashing problems found in DB version
+    1.85. We are making it available as an interim solution until DB
+    2.0 is available.
+
+    PLEASE NOTE: the underlying file format for the hash access method
+    changed between version 1.85 and version 1.86, so you will have to
+    dump and reload all of your databases to convert from version 1.85
+    to version 1.86. If you do not absolutely require the fixes from
+    version 1.86, we strongly urge you to wait until DB 2.0 is released
+    before upgrading from 1.85.  
+
 
 =head1 SEE ALSO
 
 L<perl(1)>, L<dbopen(3)>, L<hash(3)>, L<recno(3)>, L<btree(3)> 
 
-Berkeley DB is available from F<ftp.cs.berkeley.edu> in the directory
-F</ucb/4bsd>.
-
 =head1 AUTHOR
 
 The DB_File interface was written by Paul Marquess
-<pmarquess@bfsec.bt.co.uk>.
-Questions about the DB system itself may be addressed to Keith Bostic
-<bostic@cs.berkeley.edu>.
+E<lt>pmarquess@bfsec.bt.co.ukE<gt>.
+Questions about the DB system itself may be addressed to
+E<lt>db@sleepycat.com<gt>.
 
 =cut
diff --git a/ext/DB_File/DB_File.xs b/ext/DB_File/DB_File.xs
index fe967e6279..b76c53e8a5 100644
--- a/ext/DB_File/DB_File.xs
+++ b/ext/DB_File/DB_File.xs
@@ -3,11 +3,15 @@
  DB_File.xs -- Perl 5 interface to Berkeley DB 
 
  written by Paul Marquess (pmarquess@bfsec.bt.co.uk)
- last modified 14th November 1995
- version 1.01
+ last modified 30th Apr 1997
+ version 1.14
 
  All comments/suggestions/problems are welcome
 
+     Copyright (c) 1995, 1996, 1997 Paul Marquess. All rights reserved.
+     This program is free software; you can redistribute it and/or
+     modify it under the same terms as Perl itself.
+
  Changes:
 	0.1 - 	Initial Release
 	0.2 - 	No longer bombs out if dbopen returns an error.
@@ -17,6 +21,28 @@
 	1.01 - 	Fixed a SunOS core dump problem.
 		The return value from TIEHASH wasn't set to NULL when
 		dbopen returned an error.
+	1.02 - 	Use ALIAS to define TIEARRAY.
+		Removed some redundant commented code.
+		Merged OS2 code into the main distribution.
+		Allow negative subscripts with RECNO interface.
+		Changed the default flags to O_CREAT|O_RDWR
+	1.03 - 	Added EXISTS
+	1.04 -  fixed a couple of bugs in hash_cb. Patches supplied by
+		Dave Hammen, hammen@gothamcity.jsc.nasa.gov
+	1.05 -  Added logic to allow prefix & hash types to be specified via
+		Makefile.PL
+	1.06 -  Minor namespace cleanup: Localized PrintBtree.
+	1.07 -  Fixed bug with RECNO, where bval wasn't defaulting to "\n". 
+	1.08 -  No change to DB_File.xs
+	1.09 -  Default mode for dbopen changed to 0666
+	1.10 -  Fixed fd method so that it still returns -1 for
+		in-memory files when db 1.86 is used.
+	1.11 -  No change to DB_File.xs
+	1.12 -  No change to DB_File.xs
+	1.13 -  Tidied up a few casts.
+	1.14 -  Made it illegal to tie an associative array to a RECNO
+	        database and an ordinary array to a HASH or BTREE database.
+
 */
 
 #include "EXTERN.h"  
@@ -27,25 +53,41 @@
 
 #include <fcntl.h> 
 
+#ifdef mDB_Prefix_t 
+#ifdef DB_Prefix_t
+#undef DB_Prefix_t
+#endif
+#define DB_Prefix_t	mDB_Prefix_t 
+#endif
+
+#ifdef mDB_Hash_t
+#ifdef DB_Hash_t
+#undef DB_Hash_t
+#endif
+#define DB_Hash_t	mDB_Hash_t
+#endif
+
+union INFO {
+        HASHINFO 	hash ;
+        RECNOINFO 	recno ;
+        BTREEINFO 	btree ;
+      } ;
+
 typedef struct {
 	DBTYPE	type ;
 	DB * 	dbp ;
 	SV *	compare ;
 	SV *	prefix ;
 	SV *	hash ;
+	int	in_memory ;
+	union INFO info ;
 	} DB_File_type;
 
 typedef DB_File_type * DB_File ;
 typedef DBT DBTKEY ;
 
-union INFO {
-        HASHINFO 	hash ;
-        RECNOINFO 	recno ;
-        BTREEINFO 	btree ;
-      } ;
 
-
-/* #define TRACE  */
+/* #define TRACE    */
 
 #define db_DESTROY(db)                  ((db->dbp)->close)(db->dbp)
 #define db_DELETE(db, key, flags)       ((db->dbp)->del)(db->dbp, &key, flags)
@@ -54,21 +96,27 @@ union INFO {
 
 #define db_close(db)			((db->dbp)->close)(db->dbp)
 #define db_del(db, key, flags)          ((db->dbp)->del)(db->dbp, &key, flags)
-#define db_fd(db)                       ((db->dbp)->fd)(db->dbp) 
+#define db_fd(db)                       (db->in_memory	\
+						? -1 	\
+						: ((db->dbp)->fd)(db->dbp) )
 #define db_put(db, key, value, flags)   ((db->dbp)->put)(db->dbp, &key, &value, flags)
 #define db_get(db, key, value, flags)   ((db->dbp)->get)(db->dbp, &key, &value, flags)
 #define db_seq(db, key, value, flags)   ((db->dbp)->seq)(db->dbp, &key, &value, flags)
 #define db_sync(db, flags)              ((db->dbp)->sync)(db->dbp, flags)
 
 
-#define OutputValue(arg, name)  \
-	{ if (RETVAL == 0) sv_setpvn(arg, name.data, name.size) ; }
+#define OutputValue(arg, name)  				\
+	{ if (RETVAL == 0) {					\
+	      sv_setpvn(arg, name.data, name.size) ;		\
+	  }							\
+	}
 
 #define OutputKey(arg, name)	 				\
 	{ if (RETVAL == 0) \
 	  { 							\
-		if (db->type != DB_RECNO) 			\
+		if (db->type != DB_RECNO) {			\
 		    sv_setpvn(arg, name.data, name.size); 	\
+		}						\
 		else 						\
 		    sv_setiv(arg, (I32)*(I32*)name.data - 1); 	\
 	  } 							\
@@ -117,7 +165,7 @@ const DBT * key2 ;
     SPAGAIN ;
 
     if (count != 1)
-        croak ("DB_File btree_compare: expected 1 return value from %s, got %d\n", count) ;
+        croak ("DB_File btree_compare: expected 1 return value from compare sub, got %d\n", count) ;
 
     retval = POPi ;
 
@@ -164,7 +212,7 @@ const DBT * key2 ;
     SPAGAIN ;
 
     if (count != 1)
-        croak ("DB_File btree_prefix: expected 1 return value from %s, got %d\n", count) ;
+        croak ("DB_File btree_prefix: expected 1 return value from prefix sub, got %d\n", count) ;
  
     retval = POPi ;
  
@@ -187,7 +235,12 @@ size_t size ;
     if (size == 0)
         data = "" ;
 
+     /* DGH - Next two lines added to fix corrupted stack problem */
+    ENTER ;
+    SAVETMPS;
+
     PUSHMARK(sp) ;
+
     XPUSHs(sv_2mortal(newSVpv((char*)data,size)));
     PUTBACK ;
 
@@ -196,7 +249,7 @@ size_t size ;
     SPAGAIN ;
 
     if (count != 1)
-        croak ("DB_File hash_cb: expected 1 return value from %s, got %d\n", count) ;
+        croak ("DB_File hash_cb: expected 1 return value from hash sub, got %d\n", count) ;
 
     retval = POPi ;
 
@@ -212,44 +265,45 @@ size_t size ;
 
 static void
 PrintHash(hash)
-HASHINFO hash ;
+HASHINFO * hash ;
 {
     printf ("HASH Info\n") ;
-    printf ("  hash      = %s\n", (hash.hash != NULL ? "redefined" : "default")) ;
-    printf ("  bsize     = %d\n", hash.bsize) ;
-    printf ("  ffactor   = %d\n", hash.ffactor) ;
-    printf ("  nelem     = %d\n", hash.nelem) ;
-    printf ("  cachesize = %d\n", hash.cachesize) ;
-    printf ("  lorder    = %d\n", hash.lorder) ;
+    printf ("  hash      = %s\n", (hash->hash != NULL ? "redefined" : "default")) ;
+    printf ("  bsize     = %d\n", hash->bsize) ;
+    printf ("  ffactor   = %d\n", hash->ffactor) ;
+    printf ("  nelem     = %d\n", hash->nelem) ;
+    printf ("  cachesize = %d\n", hash->cachesize) ;
+    printf ("  lorder    = %d\n", hash->lorder) ;
 
 }
 
 static void
 PrintRecno(recno)
-RECNOINFO recno ;
+RECNOINFO * recno ;
 {
     printf ("RECNO Info\n") ;
-    printf ("  flags     = %d\n", recno.flags) ;
-    printf ("  cachesize = %d\n", recno.cachesize) ;
-    printf ("  psize     = %d\n", recno.psize) ;
-    printf ("  lorder    = %d\n", recno.lorder) ;
-    printf ("  reclen    = %d\n", recno.reclen) ;
-    printf ("  bval      = %d\n", recno.bval) ;
-    printf ("  bfname    = %s\n", recno.bfname) ;
+    printf ("  flags     = %d\n", recno->flags) ;
+    printf ("  cachesize = %d\n", recno->cachesize) ;
+    printf ("  psize     = %d\n", recno->psize) ;
+    printf ("  lorder    = %d\n", recno->lorder) ;
+    printf ("  reclen    = %lu\n", (unsigned long)recno->reclen) ;
+    printf ("  bval      = %d 0x%x\n", recno->bval, recno->bval) ;
+    printf ("  bfname    = %d [%s]\n", recno->bfname, recno->bfname) ;
 }
 
+static void
 PrintBtree(btree)
-BTREEINFO btree ;
+BTREEINFO * btree ;
 {
     printf ("BTREE Info\n") ;
-    printf ("  compare    = %s\n", (btree.compare ? "redefined" : "default")) ;
-    printf ("  prefix     = %s\n", (btree.prefix ? "redefined" : "default")) ;
-    printf ("  flags      = %d\n", btree.flags) ;
-    printf ("  cachesize  = %d\n", btree.cachesize) ;
-    printf ("  psize      = %d\n", btree.psize) ;
-    printf ("  maxkeypage = %d\n", btree.maxkeypage) ;
-    printf ("  minkeypage = %d\n", btree.minkeypage) ;
-    printf ("  lorder     = %d\n", btree.lorder) ;
+    printf ("  compare    = %s\n", (btree->compare ? "redefined" : "default")) ;
+    printf ("  prefix     = %s\n", (btree->prefix ? "redefined" : "default")) ;
+    printf ("  flags      = %d\n", btree->flags) ;
+    printf ("  cachesize  = %d\n", btree->cachesize) ;
+    printf ("  psize      = %d\n", btree->psize) ;
+    printf ("  maxkeypage = %d\n", btree->maxkeypage) ;
+    printf ("  minkeypage = %d\n", btree->minkeypage) ;
+    printf ("  lorder     = %d\n", btree->lorder) ;
 }
 
 #else
@@ -275,147 +329,194 @@ DB * db ;
     else if (RETVAL == 1) /* No key means empty file */
         RETVAL = 0 ;
 
-    return (RETVAL) ;
+    return ((I32)RETVAL) ;
+}
+
+static recno_t
+GetRecnoKey(db, value)
+DB_File  db ;
+I32      value ;
+{
+    if (value < 0) {
+	/* Get the length of the array */
+	I32 length = GetArrayLength(db->dbp) ;
+
+	/* check for attempt to write before start of array */
+	if (length + value + 1 <= 0)
+	    croak("Modification of non-creatable array value attempted, subscript %ld", (long)value) ;
+
+	value = length + value + 1 ;
+    }
+    else
+        ++ value ;
+
+    return value ;
 }
 
 static DB_File
-ParseOpenInfo(name, flags, mode, sv, string)
+ParseOpenInfo(isHASH, name, flags, mode, sv)
+int    isHASH ;
 char * name ;
 int    flags ;
 int    mode ;
 SV *   sv ;
-char * string ;
 {
     SV **	svp;
     HV *	action ;
-    union INFO	info ;
     DB_File	RETVAL = (DB_File)safemalloc(sizeof(DB_File_type)) ;
     void *	openinfo = NULL ;
-    /* DBTYPE	type = DB_HASH ; */
+    union INFO	* info  = &RETVAL->info ;
 
+    /* Default to HASH */
     RETVAL->hash = RETVAL->compare = RETVAL->prefix = NULL ;
     RETVAL->type = DB_HASH ;
 
+     /* DGH - Next line added to avoid SEGV on existing hash DB */
+    CurrentDB = RETVAL; 
+
+    /* fd for 1.86 hash in memory files doesn't return -1 like 1.85 */
+    RETVAL->in_memory = (name == NULL) ;
+
     if (sv)
     {
         if (! SvROK(sv) )
             croak ("type parameter is not a reference") ;
 
-        action = (HV*)SvRV(sv);
+        svp  = hv_fetch( (HV*)SvRV(sv), "GOT", 3, FALSE) ;
+        if (svp && SvOK(*svp))
+            action  = (HV*) SvRV(*svp) ;
+	else
+	    croak("internal error") ;
+
         if (sv_isa(sv, "DB_File::HASHINFO"))
         {
+
+	    if (!isHASH)
+	        croak("DB_File can only tie an associative array to a DB_HASH database") ;
+
             RETVAL->type = DB_HASH ;
-            openinfo = (void*)&info ;
+            openinfo = (void*)info ;
   
             svp = hv_fetch(action, "hash", 4, FALSE); 
 
             if (svp && SvOK(*svp))
             {
-                info.hash.hash = hash_cb ;
+                info->hash.hash = hash_cb ;
 		RETVAL->hash = newSVsv(*svp) ;
             }
             else
-	        info.hash.hash = NULL ;
+	        info->hash.hash = NULL ;
 
            svp = hv_fetch(action, "bsize", 5, FALSE);
-           info.hash.bsize = svp ? SvIV(*svp) : 0;
+           info->hash.bsize = svp ? SvIV(*svp) : 0;
            
            svp = hv_fetch(action, "ffactor", 7, FALSE);
-           info.hash.ffactor = svp ? SvIV(*svp) : 0;
+           info->hash.ffactor = svp ? SvIV(*svp) : 0;
          
            svp = hv_fetch(action, "nelem", 5, FALSE);
-           info.hash.nelem = svp ? SvIV(*svp) : 0;
+           info->hash.nelem = svp ? SvIV(*svp) : 0;
          
            svp = hv_fetch(action, "cachesize", 9, FALSE);
-           info.hash.cachesize = svp ? SvIV(*svp) : 0;
+           info->hash.cachesize = svp ? SvIV(*svp) : 0;
          
            svp = hv_fetch(action, "lorder", 6, FALSE);
-           info.hash.lorder = svp ? SvIV(*svp) : 0;
+           info->hash.lorder = svp ? SvIV(*svp) : 0;
 
            PrintHash(info) ; 
         }
         else if (sv_isa(sv, "DB_File::BTREEINFO"))
         {
+	    if (!isHASH)
+	        croak("DB_File can only tie an associative array to a DB_BTREE database");
+
             RETVAL->type = DB_BTREE ;
-            openinfo = (void*)&info ;
+            openinfo = (void*)info ;
    
             svp = hv_fetch(action, "compare", 7, FALSE);
             if (svp && SvOK(*svp))
             {
-                info.btree.compare = btree_compare ;
+                info->btree.compare = btree_compare ;
 		RETVAL->compare = newSVsv(*svp) ;
             }
             else
-                info.btree.compare = NULL ;
+                info->btree.compare = NULL ;
 
             svp = hv_fetch(action, "prefix", 6, FALSE);
             if (svp && SvOK(*svp))
             {
-                info.btree.prefix = btree_prefix ;
+                info->btree.prefix = btree_prefix ;
 		RETVAL->prefix = newSVsv(*svp) ;
             }
             else
-                info.btree.prefix = NULL ;
+                info->btree.prefix = NULL ;
 
             svp = hv_fetch(action, "flags", 5, FALSE);
-            info.btree.flags = svp ? SvIV(*svp) : 0;
+            info->btree.flags = svp ? SvIV(*svp) : 0;
    
             svp = hv_fetch(action, "cachesize", 9, FALSE);
-            info.btree.cachesize = svp ? SvIV(*svp) : 0;
+            info->btree.cachesize = svp ? SvIV(*svp) : 0;
          
             svp = hv_fetch(action, "minkeypage", 10, FALSE);
-            info.btree.minkeypage = svp ? SvIV(*svp) : 0;
+            info->btree.minkeypage = svp ? SvIV(*svp) : 0;
         
             svp = hv_fetch(action, "maxkeypage", 10, FALSE);
-            info.btree.maxkeypage = svp ? SvIV(*svp) : 0;
+            info->btree.maxkeypage = svp ? SvIV(*svp) : 0;
 
             svp = hv_fetch(action, "psize", 5, FALSE);
-            info.btree.psize = svp ? SvIV(*svp) : 0;
+            info->btree.psize = svp ? SvIV(*svp) : 0;
          
             svp = hv_fetch(action, "lorder", 6, FALSE);
-            info.btree.lorder = svp ? SvIV(*svp) : 0;
+            info->btree.lorder = svp ? SvIV(*svp) : 0;
 
             PrintBtree(info) ;
          
         }
         else if (sv_isa(sv, "DB_File::RECNOINFO"))
         {
+	    if (isHASH)
+	        croak("DB_File can only tie an array to a DB_RECNO database");
+
             RETVAL->type = DB_RECNO ;
-            openinfo = (void *)&info ;
+            openinfo = (void *)info ;
 
             svp = hv_fetch(action, "flags", 5, FALSE);
-            info.recno.flags = (u_long) svp ? SvIV(*svp) : 0;
+            info->recno.flags = (u_long) (svp ? SvIV(*svp) : 0);
          
             svp = hv_fetch(action, "cachesize", 9, FALSE);
-            info.recno.cachesize = (u_int) svp ? SvIV(*svp) : 0;
+            info->recno.cachesize = (u_int) (svp ? SvIV(*svp) : 0);
          
             svp = hv_fetch(action, "psize", 5, FALSE);
-            info.recno.psize = (int) svp ? SvIV(*svp) : 0;
+            info->recno.psize = (u_int) (svp ? SvIV(*svp) : 0);
          
             svp = hv_fetch(action, "lorder", 6, FALSE);
-            info.recno.lorder = (int) svp ? SvIV(*svp) : 0;
+            info->recno.lorder = (int) (svp ? SvIV(*svp) : 0);
          
             svp = hv_fetch(action, "reclen", 6, FALSE);
-            info.recno.reclen = (size_t) svp ? SvIV(*svp) : 0;
+            info->recno.reclen = (size_t) (svp ? SvIV(*svp) : 0);
          
 	    svp = hv_fetch(action, "bval", 4, FALSE);
             if (svp && SvOK(*svp))
             {
                 if (SvPOK(*svp))
-		    info.recno.bval = (u_char)*SvPV(*svp, na) ;
+		    info->recno.bval = (u_char)*SvPV(*svp, na) ;
 		else
-		    info.recno.bval = (u_char)(unsigned long) SvIV(*svp) ;
+		    info->recno.bval = (u_char)(unsigned long) SvIV(*svp) ;
             }
             else
  	    {
-		if (info.recno.flags & R_FIXEDLEN)
-                    info.recno.bval = (u_char) ' ' ;
+		if (info->recno.flags & R_FIXEDLEN)
+                    info->recno.bval = (u_char) ' ' ;
 		else
-                    info.recno.bval = (u_char) '\n' ;
+                    info->recno.bval = (u_char) '\n' ;
 	    }
          
             svp = hv_fetch(action, "bfname", 6, FALSE); 
-            info.recno.bfname = (char *) svp ? SvPV(*svp,na) : 0;
+            if (svp && SvOK(*svp)) {
+		char * ptr = SvPV(*svp,na) ;
+                info->recno.bfname = (char*) (na ? ptr : NULL) ;
+	    }
+	    else
+		info->recno.bfname = NULL ;
 
             PrintRecno(info) ;
         }
@@ -424,17 +525,14 @@ char * string ;
     }
 
 
-    RETVAL->dbp = dbopen(name, flags, mode, RETVAL->type, openinfo) ; 
-
-#if 0
-    /* kludge mode on: RETVAL->type for DB_RECNO is set to DB_BTREE
-		       so remember a DB_RECNO by saving the address
-		       of one of it's internal routines
-    */
-    if (RETVAL->dbp && type == DB_RECNO)
-        DB_recno_close = RETVAL->dbp->close ;
-#endif
+    /* OS2 Specific Code */
+#ifdef OS2
+#ifdef __EMX__
+    flags |= O_BINARY;
+#endif /* __EMX__ */
+#endif /* OS2 */
 
+    RETVAL->dbp = dbopen(name, flags, mode, RETVAL->type, openinfo) ; 
 
     return (RETVAL) ;
 }
@@ -695,7 +793,8 @@ constant(name,arg)
 
 
 DB_File
-db_TIEHASH(dbtype, name=undef, flags=O_RDWR, mode=0640, type=DB_HASH)
+db_DoTie_(isHASH, dbtype, name=undef, flags=O_CREAT|O_RDWR, mode=0666, type=DB_HASH)
+	int		isHASH
 	char *		dbtype
 	int		flags
 	int		mode
@@ -704,22 +803,29 @@ db_TIEHASH(dbtype, name=undef, flags=O_RDWR, mode=0640, type=DB_HASH)
 	    char *	name = (char *) NULL ; 
 	    SV *	sv = (SV *) NULL ; 
 
-	    if (items >= 2 && SvOK(ST(1))) 
-	        name = (char*) SvPV(ST(1), na) ; 
+	    if (items >= 3 && SvOK(ST(2))) 
+	        name = (char*) SvPV(ST(2), na) ; 
 
-            if (items == 5)
-	        sv = ST(4) ;
+            if (items == 6)
+	        sv = ST(5) ;
 
-	    RETVAL = ParseOpenInfo(name, flags, mode, sv, "new") ;
+	    RETVAL = ParseOpenInfo(isHASH, name, flags, mode, sv) ;
 	    if (RETVAL->dbp == NULL)
 	        RETVAL = NULL ;
 	}
 	OUTPUT:	
 	    RETVAL
 
+>>>> ORIGINAL VERSION
+BOOT:
+    newXS("DB_File::TIEARRAY", XS_DB_File_db_TIEHASH, file);
+
+==== THEIR VERSION
+==== YOUR VERSION
 BOOT:
     newXS("DB_File::TIEARRAY", XS_DB_File_TIEHASH, file);
 
+<<<<
 int
 db_DESTROY(db)
 	DB_File		db
@@ -743,6 +849,21 @@ db_DELETE(db, key, flags=0)
 	INIT:
 	  CurrentDB = db ;
 
+
+int
+db_EXISTS(db, key)
+	DB_File		db
+	DBTKEY		key
+	CODE:
+	{
+          DBT		value ;
+	
+	  CurrentDB = db ;
+	  RETVAL = (((db->dbp)->get)(db->dbp, &key, &value, 0) == 0) ;
+	}
+	OUTPUT:
+	  RETVAL
+
 int
 db_FETCH(db, key, flags=0)
 	DB_File		db
@@ -783,7 +904,7 @@ db_FIRSTKEY(db)
 	    ST(0) = sv_newmortal();
 	    if (RETVAL == 0)
 	    {
-	        if (Db->type != DB_RECNO)
+	        if (db->type != DB_RECNO)
 	            sv_setpvn(ST(0), key.data, key.size);
 	        else
 	            sv_setiv(ST(0), (I32)*(I32*)key.data - 1);
@@ -804,7 +925,7 @@ db_NEXTKEY(db, key)
 	    ST(0) = sv_newmortal();
 	    if (RETVAL == 0)
 	    {
-	        if (Db->type != DB_RECNO)
+	        if (db->type != DB_RECNO)
 	            sv_setpvn(ST(0), key.data, key.size);
 	        else
 	            sv_setiv(ST(0), (I32)*(I32*)key.data - 1);
@@ -859,9 +980,11 @@ pop(db)
 	    /* Now delete it */
 	    if (RETVAL == 0)
 	    {
+		/* the call to del will trash value, so take a copy now */
+	        sv_setpvn(ST(0), value.data, value.size);
 	        RETVAL = (Db->del)(Db, &key, R_CURSOR) ;
-	        if (RETVAL == 0)
-	            sv_setpvn(ST(0), value.data, value.size);
+	        if (RETVAL != 0) 
+	            sv_setsv(ST(0), &sv_undef); 
 	    }
 	}
 
@@ -870,20 +993,22 @@ shift(db)
 	DB_File		db
 	CODE:
 	{
-	    DBTKEY	key ;
 	    DBT		value ;
+	    DBTKEY	key ;
 	    DB *	Db = db->dbp ;
 
 	    CurrentDB = db ;
 	    /* get the first value */
-	    RETVAL = (Db->seq)(Db, &key, &value, R_FIRST) ;	
+	    RETVAL = (Db->seq)(Db, &key, &value, R_FIRST) ;	 
 	    ST(0) = sv_newmortal();
 	    /* Now delete it */
 	    if (RETVAL == 0)
 	    {
-	        RETVAL = (Db->del)(Db, &key, R_CURSOR) ;
-	        if (RETVAL == 0)
-	            sv_setpvn(ST(0), value.data, value.size);
+		/* the call to del will trash value, so take a copy now */
+	        sv_setpvn(ST(0), value.data, value.size);
+	        RETVAL = (Db->del)(Db, &key, R_CURSOR) ; 
+	        if (RETVAL != 0)
+	            sv_setsv (ST(0), &sv_undef) ;
 	    }
 	}
 
@@ -990,3 +1115,4 @@ db_seq(db, key, value, flags)
 	OUTPUT:
 	  key
 	  value
+
diff --git a/ext/DB_File/Makefile.PL b/ext/DB_File/Makefile.PL
index 4cda63507d..39b8bc7030 100644
--- a/ext/DB_File/Makefile.PL
+++ b/ext/DB_File/Makefile.PL
@@ -1,11 +1,16 @@
-use ExtUtils::MakeMaker;
+use ExtUtils::MakeMaker 5.16 ;
+use Config ;
+
+# OS2 is a special case, so check for it now.
+my $OS2 = "-DOS2" if $Config{'osname'} eq 'os2' ;
 
 WriteMakefile(
-	NAME 	=> 'DB_File',
-	LIBS 	=> ["-L/usr/local/lib -ldb"],
-	MAN3PODS 	=> ' ', 	# Pods will be built by installman.
-	#INC	=> '-I/usr/local/include',
+	NAME 		=> 'DB_File',
+	LIBS 		=> ["-L/usr/local/lib -ldb"],
+        MAN3PODS        => ' ',         # Pods will be built by installman.
+	#INC		=> '-I/usr/local/include',
 	VERSION_FROM	=> 'DB_File.pm',
-	XSPROTOARG => '-noprototypes', 		# XXX remove later?
-);
+	XSPROTOARG	=> '-noprototypes',
+	DEFINE		=> "$OS2",
+	);
 
diff --git a/ext/DB_File/typemap b/ext/DB_File/typemap
index 4acc65e078..5ca9c54f72 100644
--- a/ext/DB_File/typemap
+++ b/ext/DB_File/typemap
@@ -1,8 +1,8 @@
 # typemap for Perl 5 interface to Berkeley DB
 #
 # written by Paul Marquess (pmarquess@bfsec.bt.co.uk)
-# last modified 23rd June 1994
-# version 0.1
+# last modified 28th June 1996
+# version 0.2
 #
 #################################### DB SECTION
 #
@@ -15,15 +15,12 @@ DBTKEY			T_dbtkeydatum
 
 INPUT
 T_dbtkeydatum
-	if (db->type != DB_RECNO)
-	{
+	if (db->type != DB_RECNO) {
 	    $var.data = SvPV($arg, na);
 	    $var.size = (int)na;
 	}
-	else
-	{
-	    Value =  SvIV($arg) ; 
-	    ++ Value ; 
+	else {
+	    Value =  GetRecnoKey(db, SvIV($arg)) ; 
 	    $var.data = & Value; 
 	    $var.size = (int)sizeof(recno_t);
 	}