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Revision 1.155 by root, Mon Nov 24 18:42:51 2014 UTC vs.
Revision 1.163 by root, Thu Aug 17 01:42:19 2017 UTC

40Beginning with version 2.0 of the JSON module, when both JSON and 40Beginning with version 2.0 of the JSON module, when both JSON and
41JSON::XS are installed, then JSON will fall back on JSON::XS (this can be 41JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
42overridden) with no overhead due to emulation (by inheriting constructor 42overridden) with no overhead due to emulation (by inheriting constructor
43and methods). If JSON::XS is not available, it will fall back to the 43and methods). If JSON::XS is not available, it will fall back to the
44compatible JSON::PP module as backend, so using JSON instead of JSON::XS 44compatible JSON::PP module as backend, so using JSON instead of JSON::XS
45gives you a portable JSON API that can be fast when you need and doesn't 45gives you a portable JSON API that can be fast when you need it and
46require a C compiler when that is a problem. 46doesn't require a C compiler when that is a problem.
47 47
48As this is the n-th-something JSON module on CPAN, what was the reason 48As this is the n-th-something JSON module on CPAN, what was the reason
49to write yet another JSON module? While it seems there are many JSON 49to write yet another JSON module? While it seems there are many JSON
50modules, none of them correctly handle all corner cases, and in most cases 50modules, none of them correctly handle all corner cases, and in most cases
51their maintainers are unresponsive, gone missing, or not listening to bug 51their maintainers are unresponsive, gone missing, or not listening to bug
101 101
102package JSON::XS; 102package JSON::XS;
103 103
104use common::sense; 104use common::sense;
105 105
106our $VERSION = 3.01; 106our $VERSION = 3.03;
107our @ISA = qw(Exporter); 107our @ISA = qw(Exporter);
108 108
109our @EXPORT = qw(encode_json decode_json); 109our @EXPORT = qw(encode_json decode_json);
110 110
111use Exporter; 111use Exporter;
697 697
698This is useful if your JSON texts are not delimited by an outer protocol 698This is useful if your JSON texts are not delimited by an outer protocol
699and you need to know where the JSON text ends. 699and you need to know where the JSON text ends.
700 700
701 JSON::XS->new->decode_prefix ("[1] the tail") 701 JSON::XS->new->decode_prefix ("[1] the tail")
702 => ([], 3) 702 => ([1], 3)
703 703
704=back 704=back
705 705
706 706
707=head1 INCREMENTAL PARSING 707=head1 INCREMENTAL PARSING
748C<incr_skip> to skip the erroneous part). This is the most common way of 748C<incr_skip> to skip the erroneous part). This is the most common way of
749using the method. 749using the method.
750 750
751And finally, in list context, it will try to extract as many objects 751And finally, in list context, it will try to extract as many objects
752from the stream as it can find and return them, or the empty list 752from the stream as it can find and return them, or the empty list
753otherwise. For this to work, there must be no separators between the JSON 753otherwise. For this to work, there must be no separators (other than
754objects or arrays, instead they must be concatenated back-to-back. If 754whitespace) between the JSON objects or arrays, instead they must be
755an error occurs, an exception will be raised as in the scalar context 755concatenated back-to-back. If an error occurs, an exception will be
756case. Note that in this case, any previously-parsed JSON texts will be 756raised as in the scalar context case. Note that in this case, any
757lost. 757previously-parsed JSON texts will be lost.
758 758
759Example: Parse some JSON arrays/objects in a given string and return 759Example: Parse some JSON arrays/objects in a given string and return
760them. 760them.
761 761
762 my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]"); 762 my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]");
768C<incr_parse> in I<scalar context> successfully returned an object. Under 768C<incr_parse> in I<scalar context> successfully returned an object. Under
769all other circumstances you must not call this function (I mean it. 769all other circumstances you must not call this function (I mean it.
770although in simple tests it might actually work, it I<will> fail under 770although in simple tests it might actually work, it I<will> fail under
771real world conditions). As a special exception, you can also call this 771real world conditions). As a special exception, you can also call this
772method before having parsed anything. 772method before having parsed anything.
773
774That means you can only use this function to look at or manipulate text
775before or after complete JSON objects, not while the parser is in the
776middle of parsing a JSON object.
773 777
774This function is useful in two cases: a) finding the trailing text after a 778This function is useful in two cases: a) finding the trailing text after a
775JSON object or b) parsing multiple JSON objects separated by non-JSON text 779JSON object or b) parsing multiple JSON objects separated by non-JSON text
776(such as commas). 780(such as commas).
777 781
1563are browser design bugs, but it is still you who will have to deal with 1567are browser design bugs, but it is still you who will have to deal with
1564it, as major browser developers care only for features, not about getting 1568it, as major browser developers care only for features, not about getting
1565security right). 1569security right).
1566 1570
1567 1571
1572=head1 "OLD" VS. "NEW" JSON (RFC 4627 VS. RFC 7159)
1573
1574TL;DR: Due to security concerns, JSON::XS will not allow scalar data in
1575JSON texts by default - you need to create your own JSON::XS object and
1576enable C<allow_nonref>:
1577
1578
1579 my $json = JSON::XS->new->allow_nonref;
1580
1581 $text = $json->encode ($data);
1582 $data = $json->decode ($text);
1583
1584The long version: JSON being an important and supposedly stable format,
1585the IETF standardised it as RFC 4627 in 2006. Unfortunately, the inventor
1586of JSON, Dougles Crockford, unilaterally changed the definition of JSON in
1587javascript. Rather than create a fork, the IETF decided to standardise the
1588new syntax (apparently, so Iw as told, without finding it very amusing).
1589
1590The biggest difference between thed original JSON and the new JSON is that
1591the new JSON supports scalars (anything other than arrays and objects) at
1592the toplevel of a JSON text. While this is strictly backwards compatible
1593to older versions, it breaks a number of protocols that relied on sending
1594JSON back-to-back, and is a minor security concern.
1595
1596For example, imagine you have two banks communicating, and on one side,
1597trhe JSON coder gets upgraded. Two messages, such as C<10> and C<1000>
1598might then be confused to mean C<101000>, something that couldn't happen
1599in the original JSON, because niether of these messages would be valid
1600JSON.
1601
1602If one side accepts these messages, then an upgrade in the coder on either
1603side could result in this becoming exploitable.
1604
1605This module has always allowed these messages as an optional extension, by
1606default disabled. The security concerns are the reason why the default is
1607still disabled, but future versions might/will likely upgrade to the newer
1608RFC as default format, so you are advised to check your implementation
1609and/or override the default with C<< ->allow_nonref (0) >> to ensure that
1610future versions are safe.
1611
1612
1568=head1 INTEROPERABILITY WITH OTHER MODULES 1613=head1 INTEROPERABILITY WITH OTHER MODULES
1569 1614
1570C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean 1615C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
1571constants. That means that the JSON true and false values will be 1616constants. That means that the JSON true and false values will be
1572comaptible to true and false values of iother modules that do the same, 1617comaptible to true and false values of other modules that do the same,
1573such as L<JSON::PP> and L<CBOR::XS>. 1618such as L<JSON::PP> and L<CBOR::XS>.
1574 1619
1575 1620
1576=head1 INTEROPERABILITY WITH OTHER JSON DECODERS 1621=head1 INTEROPERABILITY WITH OTHER JSON DECODERS
1577 1622
1594 1639
1595When you use C<allow_tags> to use the extended (and also nonstandard and 1640When you use C<allow_tags> to use the extended (and also nonstandard and
1596invalid) JSON syntax for serialised objects, and you still want to decode 1641invalid) JSON syntax for serialised objects, and you still want to decode
1597the generated When you want to serialise objects, you can run a regex 1642the generated When you want to serialise objects, you can run a regex
1598to replace the tagged syntax by standard JSON arrays (it only works for 1643to replace the tagged syntax by standard JSON arrays (it only works for
1599"normal" packagesnames without comma, newlines or single colons). First, 1644"normal" package names without comma, newlines or single colons). First,
1600the readable Perl version: 1645the readable Perl version:
1601 1646
1602 # if your FREEZE methods return no values, you need this replace first: 1647 # if your FREEZE methods return no values, you need this replace first:
1603 $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[\s*\]/[$1]/gx; 1648 $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[\s*\]/[$1]/gx;
1604 1649
1640Since this module was written, Google has written a new JSON RFC, RFC 7159 1685Since this module was written, Google has written a new JSON RFC, RFC 7159
1641(and RFC7158). Unfortunately, this RFC breaks compatibility with both the 1686(and RFC7158). Unfortunately, this RFC breaks compatibility with both the
1642original JSON specification on www.json.org and RFC4627. 1687original JSON specification on www.json.org and RFC4627.
1643 1688
1644As far as I can see, you can get partial compatibility when parsing by 1689As far as I can see, you can get partial compatibility when parsing by
1645using C<< ->allow_nonref >>. However, consider thew security implications 1690using C<< ->allow_nonref >>. However, consider the security implications
1646of doing so. 1691of doing so.
1647 1692
1648I haven't decided yet when to break compatibility with RFC4627 by default 1693I haven't decided yet when to break compatibility with RFC4627 by default
1649(and potentially leave applications insecure) and change the default to 1694(and potentially leave applications insecure) and change the default to
1650follow RFC7159, but application authors are well advised to call C<< 1695follow RFC7159, but application authors are well advised to call C<<
1651->allow_nonref(0) >> even if this is the current default, if they cannot 1696->allow_nonref(0) >> even if this is the current default, if they cannot
1652handle non-reference values, in preparation for the day when the4 default 1697handle non-reference values, in preparation for the day when the default
1653will change. 1698will change.
1654 1699
1655 1700
1656=head1 THREADS 1701=head1 (I-)THREADS
1657 1702
1658This module is I<not> guaranteed to be thread safe and there are no 1703This module is I<not> guaranteed to be ithread (or MULTIPLICITY-) safe
1659plans to change this until Perl gets thread support (as opposed to the 1704and there are no plans to change this. Note that perl's builtin so-called
1660horribly slow so-called "threads" which are simply slow and bloated 1705theeads/ithreads are officially deprecated and should not be used.
1661process simulations - use fork, it's I<much> faster, cheaper, better).
1662
1663(It might actually work, but you have been warned).
1664 1706
1665 1707
1666=head1 THE PERILS OF SETLOCALE 1708=head1 THE PERILS OF SETLOCALE
1667 1709
1668Sometimes people avoid the Perl locale support and directly call the 1710Sometimes people avoid the Perl locale support and directly call the

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