-# $Id: Storable.pm,v 1.0.1.13 2001/12/01 13:34:49 ram Exp $
#
# Copyright (c) 1995-2000, Raphael Manfredi
#
use AutoLoader;
use vars qw($canonical $forgive_me $VERSION);
-$VERSION = '2.02';
+$VERSION = '2.04';
*AUTOLOAD = \&AutoLoader::AUTOLOAD; # Grrr...
#
return B<all> strings as utf8 sequences, or to attempt to convert utf8
data back to 8 bit and C<croak()> if the conversion fails.
+Prior to Storable 2.01, no distinction was made between signed and
+unsigned integers on storing. By default Storable prefers to store a
+scalars string representation (if it has one) so this would only cause
+problems when storing large unsigned integers that had never been coverted
+to string or floating point. In other words values that had been generated
+by integer operations such as logic ops and then not used in any string or
+arithmetic context before storing.
+
+=head2 64 bit data in perl 5.6.0 and 5.6.1
+
+This section only applies to you if you have existing data written out
+by Storable 2.02 or earlier on perl 5.6.0 or 5.6.1 on Unix or Linux which
+has been configured with 64 bit integer support (not the default)
+If you got a precompiled perl, rather than running Configure to build
+your own perl from source, then it almost certainly does not affect you,
+and you can stop reading now (unless you're curious). If you're using perl
+on Windows it does not affect you.
+
+Storable writes a file header which contains the sizes of various C
+language types for the C compiler that built Storable (when not writing in
+network order), and will refuse to load files written by a Storable not
+on the same (or compatible) architecture. This check and a check on
+machine byteorder is needed because the size of various fields in the file
+are given by the sizes of the C language types, and so files written on
+different architectures are incompatible. This is done for increased speed.
+(When writing in network order, all fields are written out as standard
+lengths, which allows full interworking, but takes longer to read and write)
+
+Perl 5.6.x introduced the ability to optional configure the perl interpreter
+to use C's C<long long> type to allow scalars to store 64 bit integers on 32
+bit systems. However, due to the way the Perl configuration system
+generated the C configuration files on non-Windows platforms, and the way
+Storable generates its header, nothing in the Storable file header reflected
+whether the perl writing was using 32 or 64 bit integers, despite the fact
+that Storable was storing some data differently in the file. Hence Storable
+running on perl with 64 bit integers will read the header from a file
+written by a 32 bit perl, not realise that the data is actually in a subtly
+incompatible format, and then go horribly wrong (possibly crashing) if it
+encountered a stored integer. This is a design failure.
+
+Storable has now been changed to write out and read in a file header with
+information about the size of integers. It's impossible to detect whether
+an old file being read in was written with 32 or 64 bit integers (they have
+the same header) so it's impossible to automatically switch to a correct
+backwards compatibility mode. Hence this Storable defaults to the new,
+correct behaviour.
+
+What this means is that if you have data written by Storable 1.x running
+on perl 5.6.0 or 5.6.1 configured with 64 bit integers on Unix or Linux
+then by default this Storable will refuse to read it, giving the error
+I<Byte order is not compatible>. If you have such data then you you
+should set C<$Storable::interwork_56_64bit> to a true value to make this
+Storable read and write files with the old header. You should also
+migrate your data, or any older perl you are communicating with, to this
+current version of Storable.
+
+If you don't have data written with specific configuration of perl described
+above, then you do not and should not do anything. Don't set the flag -
+not only will Storable on an identically configured perl refuse to load them,
+but Storable a differently configured perl will load them believing them
+to be correct for it, and then may well fail or crash part way through
+reading them.
+
=head1 CREDITS
Thank you to (in chronological order):
projects / p5sagit/p5-mst-13.2.git / blobdiff