[ViewVC] Diff of: cvs/CBOR-XS/XS.pm

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC vs.
Revision 1.50 by root, Sun Apr 24 09:11:14 2016 UTC

 Regarding compactness, C<CBOR::XS>-encoded data structures are usually
 about 20% smaller than the same data encoded as (compact) JSON or
 L<Storable>.
 In addition to the core CBOR data format, this module implements a
-number of extensions, to support cyclic and shared data structures (see
+number of extensions, to support cyclic and shared data structures
-C<allow_sharing>), string deduplication (see C<pack_strings>) and scalar
+(see C<allow_sharing> and C<allow_cycles>), string deduplication (see
-references (always enabled).
+C<pack_strings>) and scalar references (always enabled).
 The primary goal of this module is to be I<correct> and the secondary goal
 is to be I<fast>. To reach the latter goal it was written in C.
 See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and
 package CBOR::XS;
 use common::sense;
-our $VERSION = '1.0';
+our $VERSION = 1.41;
 our @ISA = qw(Exporter);
 our @EXPORT = qw(encode_cbor decode_cbor);
 use Exporter;
 reference to the earlier value.
 This means that such values will only be encoded once, and will not result
 in a deep cloning of the value on decode, in decoders supporting the value
 sharing extension. This also makes it possible to encode cyclic data
-structures.
+structures (which need C<allow_cycles> to ne enabled to be decoded by this
+module).
 It is recommended to leave it off unless you know your
 communication partner supports the value sharing extensions to CBOR
 (L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the
 resulting data structure might be unusable.
 Detecting shared values incurs a runtime overhead when values are encoded
 that have a reference counter large than one, and might unnecessarily
 increase the encoded size, as potentially shared values are encode as
-sharable whether or not they are actually shared.
+shareable whether or not they are actually shared.
 At the moment, only targets of references can be shared (e.g. scalars,
 arrays or hashes pointed to by a reference). Weirder constructs, such as
 an array with multiple "copies" of the I<same> string, which are hard but
 not impossible to create in Perl, are not supported (this is the same as
 structures cannot be encoded in this mode.
 This option does not affect C<decode> in any way - shared values and
 references will always be decoded properly if present.
+=item $cbor = $cbor->allow_cycles ([$enable])
+=item $enabled = $cbor->get_allow_cycles
+If C<$enable> is true (or missing), then C<decode> will happily decode
+self-referential (cyclic) data structures. By default these will not be
+decoded, as they need manual cleanup to avoid memory leaks, so code that
+isn't prepared for this will not leak memory.
+If C<$enable> is false (the default), then C<decode> will throw an error
+when it encounters a self-referential/cyclic data structure.
+FUTURE DIRECTION: the motivation behind this option is to avoid I<real>
+cycles - future versions of this module might chose to decode cyclic data
+structures using weak references when this option is off, instead of
+throwing an error.
+This option does not affect C<encode> in any way - shared values and
+references will always be encoded properly if present.
 =item $cbor = $cbor->pack_strings ([$enable])
 =item $enabled = $cbor->get_pack_strings
 If C<$enable> is true (or missing), then C<encode> will try not to encode
 the standard CBOR way.
 This option does not affect C<decode> in any way - string references will
 always be decoded properly if present.
+=item $cbor = $cbor->validate_utf8 ([$enable])
+=item $enabled = $cbor->get_validate_utf8
+If C<$enable> is true (or missing), then C<decode> will validate that
+elements (text strings) containing UTF-8 data in fact contain valid UTF-8
+data (instead of blindly accepting it). This validation obviously takes
+extra time during decoding.
+The concept of "valid UTF-8" used is perl's concept, which is a superset
+of the official UTF-8.
+If C<$enable> is false (the default), then C<decode> will blindly accept
+UTF-8 data, marking them as valid UTF-8 in the resulting data structure
+regardless of whether thats true or not.
+Perl isn't too happy about corrupted UTF-8 in strings, but should
+generally not crash or do similarly evil things. Extensions might be not
+so forgiving, so it's recommended to turn on this setting if you receive
+untrusted CBOR.
+This option does not affect C<encode> in any way - strings that are
+supposedly valid UTF-8 will simply be dumped into the resulting CBOR
+string without checking whether that is, in fact, true or not.
 =item $cbor = $cbor->filter ([$cb->($tag, $value)])
 =item $cb_or_undef = $cbor->get_filter
 Sets or replaces the tagged value decoding filter (when C<$cb> is
    CBOR::XS->new->decode_prefix ("......")
    => ("...", 3)
 =back
+=head2 INCREMENTAL PARSING
+In some cases, there is the need for incremental parsing of JSON
+texts. While this module always has to keep both CBOR text and resulting
+Perl data structure in memory at one time, it does allow you to parse a
+CBOR stream incrementally, using a similar to using "decode_prefix" to see
+if a full CBOR object is available, but is much more efficient.
+It basically works by parsing as much of a CBOR string as possible - if
+the CBOR data is not complete yet, the pasrer will remember where it was,
+to be able to restart when more data has been accumulated. Once enough
+data is available to either decode a complete CBOR value or raise an
+error, a real decode will be attempted.
+A typical use case would be a network protocol that consists of sending
+and receiving CBOR-encoded messages. The solution that works with CBOR and
+about anything else is by prepending a length to every CBOR value, so the
+receiver knows how many octets to read. More compact (and slightly slower)
+would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where
+a CBOR value ends, and doesn't need an explicit length.
+The following methods help with this:
+=over 4
+=item @decoded = $cbor->incr_parse ($buffer)
+This method attempts to decode exactly one CBOR value from the beginning
+of the given C<$buffer>. The value is removed from the C<$buffer> on
+success. When C<$buffer> doesn't contain a complete value yet, it returns
+nothing. Finally, when the C<$buffer> doesn't start with something
+that could ever be a valid CBOR value, it raises an exception, just as
+C<decode> would. In the latter case the decoder state is undefined and
+must be reset before being able to parse further.
+This method modifies the C<$buffer> in place. When no CBOR value can be
+decoded, the decoder stores the current string offset. On the next call,
+continues decoding at the place where it stopped before. For this to make
+sense, the C<$buffer> must begin with the same octets as on previous
+unsuccessful calls.
+You can call this method in scalar context, in which case it either
+returns a decoded value or C<undef>. This makes it impossible to
+distinguish between CBOR null values (which decode to C<undef>) and an
+unsuccessful decode, which is often acceptable.
+=item @decoded = $cbor->incr_parse_multiple ($buffer)
+Same as C<incr_parse>, but attempts to decode as many CBOR values as
+possible in one go, instead of at most one. Calls to C<incr_parse> and
+C<incr_parse_multiple> can be interleaved.
+=item $cbor->incr_reset
+Resets the incremental decoder. This throws away any saved state, so that
+subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse
+a new CBOR value from the beginning of the C<$buffer> again.
+This method can be caled at any time, but it I<must> be called if you want
+to change your C<$buffer> or there was a decoding error and you want to
+reuse the C<$cbor> object for future incremental parsings.
+=back
 =head1 MAPPING
 This section describes how CBOR::XS maps Perl values to CBOR values and
 vice versa. These mappings are designed to "do the right thing" in most
 =item hash references
 Perl hash references become CBOR maps. As there is no inherent ordering in
 hash keys (or CBOR maps), they will usually be encoded in a pseudo-random
-order. This order can be different each time a hahs is encoded.
+order. This order can be different each time a hash is encoded.
 Currently, tied hashes will use the indefinite-length format, while normal
 hashes will use the fixed-length format.
 =item array references
 =back
 =head2 OBJECT SERIALISATION
+This module implements both a CBOR-specific and the generic
+L<Types::Serialier> object serialisation protocol. The following
+subsections explain both methods.
+=head3 ENCODING
 This module knows two way to serialise a Perl object: The CBOR-specific
 way, and the generic way.
-Whenever the encoder encounters a Perl object that it cnanot serialise
+Whenever the encoder encounters a Perl object that it cannot serialise
 directly (most of them), it will first look up the C<TO_CBOR> method on
 it.
 If it has a C<TO_CBOR> method, it will call it with the object as only
 argument, and expects exactly one return value, which it will then
 The C<FREEZE> method can return any number of values (i.e. zero or
 more). These will be encoded as CBOR perl object, together with the
 classname.
+These methods I<MUST NOT> change the data structure that is being
+serialised. Failure to comply to this can result in memory corruption -
+and worse.
 If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail
 with an error.
+=head3 DECODING
-Objects encoded via C<TO_CBOR> cannot be automatically decoded, but
+Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded,
-objects encoded via C<FREEZE> can be decoded using the following protocol:
+but objects encoded via C<FREEZE> can be decoded using the following
+protocol:
 When an encoded CBOR perl object is encountered by the decoder, it will
 look up the C<THAW> method, by using the stored classname, and will fail
 if the method cannot be found.
 After the lookup it will call the C<THAW> method with the stored classname
 as first argument, the constant string C<CBOR> as second argument, and all
 values returned by C<FREEZE> as remaining arguments.
-=head4 EXAMPLES
+=head3 EXAMPLES
 Here is an example C<TO_CBOR> method:
    sub My::Object::TO_CBOR {
       my ($obj) = @_;
 These tags are automatically created (and decoded) for serialisable
 objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object
 serialisation protocol). See L<OBJECT SERIALISATION> for details.
-=item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>)
+=item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>)
-These tags are automatically decoded when encountered, resulting in
+These tags are automatically decoded when encountered (and they do not
+result in a cyclic data structure, see C<allow_cycles>), resulting in
 shared values in the decoded object. They are only encoded, however, when
-C<allow_sharable> is enabled.
+C<allow_sharing> is enabled.
+Not all shared values can be successfully decoded: values that reference
+themselves will I<currently> decode as C<undef> (this is not the same
+as a reference pointing to itself, which will be represented as a value
+that contains an indirect reference to itself - these will be decoded
+properly).
+Note that considerably more shared value data structures can be decoded
+than will be encoded - currently, only values pointed to by references
+will be shared, others will not. While non-reference shared values can be
+generated in Perl with some effort, they were considered too unimportant
+to be supported in the encoder. The decoder, however, will decode these
+values as shared values.
-=item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>)
+=item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>)
 These tags are automatically decoded when encountered. They are only
 encoded, however, when C<pack_strings> is enabled.
 =item 22098 (indirection, L<http://cbor.schmorp.de/indirection>)
 provide these modules. The decoding usually fails with an exception if the
 required module cannot be loaded.
 =over 4
+=item 0, 1 (date/time string, seconds since the epoch)
+These tags are decoded into L<Time::Piece> objects. The corresponding
+C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently.
+The L<Time::Piece> API is generally surprisingly bad, and fractional
+seconds are only accidentally kept intact, so watch out. On the plus side,
+the module comes with perl since 5.10, which has to count for something.
 =item 2, 3 (positive/negative bignum)
 These tags are decoded into L<Math::BigInt> objects. The corresponding
 C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR
 integers, and others into positive/negative CBOR bignums.
 C<URI::TO_CBOR> method again results in a CBOR URI value.
 =back
 =cut
-our %FILTER = (
-   # 0 # rfc4287 datetime, utf-8
-   # 1 # unix timestamp, any
-   2 => sub { # pos bigint
-      require Math::BigInt;
-      Math::BigInt->new ("0x" . unpack "H*", pop)
-   },
-   3 => sub { # neg bigint
-      require Math::BigInt;
-      -Math::BigInt->new ("0x" . unpack "H*", pop)
-   },
-   4 => sub { # decimal fraction, array
-      require Math::BigFloat;
-      Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
-   },
-   5 => sub { # bigfloat, array
-      require Math::BigFloat;
-      scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
-   },
-   21 => sub { pop }, # expected conversion to base64url encoding
-   22 => sub { pop }, # expected conversion to base64 encoding
-   23 => sub { pop }, # expected conversion to base16 encoding
-   # 24 # embedded cbor, byte string
-   32 => sub {
-      require URI;
-      URI->new (pop)
-   },
-   # 33 # base64url rfc4648, utf-8
-   # 34 # base64 rfc46484, utf-8
-   # 35 # regex pcre/ecma262, utf-8
-   # 36 # mime message rfc2045, utf-8
-);
 =head1 CBOR and JSON
 CBOR is supposed to implement a superset of the JSON data model, and is,
 with some coercion, able to represent all JSON texts (something that other
 properly. Half precision types are accepted, but not encoded.
 Strict mode and canonical mode are not implemented.
+=head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT
+On perls that were built without 64 bit integer support (these are rare
+nowadays, even on 32 bit architectures, as all major Perl distributions
+are built with 64 bit integer support), support for any kind of 64 bit
+integer in CBOR is very limited - most likely, these 64 bit values will
+be truncated, corrupted, or otherwise not decoded correctly. This also
+includes string, array and map sizes that are stored as 64 bit integers.
 =head1 THREADS
 This module is I<not> guaranteed to be thread safe and there are no
 plans to change this until Perl gets thread support (as opposed to the
 horribly slow so-called "threads" which are simply slow and bloated
 service. I put the contact address into my modules for a reason.
 =cut
 our %FILTER = (
-   # 0 # rfc4287 datetime, utf-8
+   0 => sub { # rfc4287 datetime, utf-8
-   # 1 # unix timestamp, any
+      require Time::Piece;
+      # Time::Piece::Strptime uses the "incredibly flexible date parsing routine"
+      # from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything
+      # else either. Whats incredibe over standard strptime totally escapes me.
+      # doesn't do fractional times, either. sigh.
+      # In fact, it's all a lie, it uses whatever strptime it wants, and of course,
+      # they are all incompatible. The openbsd one simply ignores %z (but according to the
+      # docs, it would be much more incredibly flexible indeed. If it worked, that is.).
+      scalar eval {
+         my $s = $_[1];
+         $s =~ s/Z$/+00:00/;
+         $s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$//
+            or die;
+         my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully
+         my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S");
+         Time::Piece::gmtime ($d->epoch + $b)
+      } || die "corrupted CBOR date/time string ($_[0])";
+   },
+   1 => sub { # seconds since the epoch, possibly fractional
+      require Time::Piece;
+      scalar Time::Piece::gmtime (pop)
+   },
    2 => sub { # pos bigint
       require Math::BigInt;
       Math::BigInt->new ("0x" . unpack "H*", pop)
    },
       Math::BigFloat->new ($_[1][1] . "E" . $_[1][0])
    },
    5 => sub { # bigfloat, array
       require Math::BigFloat;
-      scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2)
+      scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0])
    },
    21 => sub { pop }, # expected conversion to base64url encoding
    22 => sub { pop }, # expected conversion to base64 encoding
    23 => sub { pop }, # expected conversion to base16 encoding
 }
 sub URI::TO_CBOR {
    my $uri = $_[0]->as_string;
    utf8::upgrade $uri;
-   CBOR::XS::tag 32, $uri
+   tag 32, $uri
 }
 sub Math::BigInt::TO_CBOR {
    if ($_[0] >= -2147483648 && $_[0] <= 2147483647) {
       $_[0]->numify
    } else {
       my $hex = substr $_[0]->as_hex, 2;
       $hex = "0$hex" if 1 & length $hex; # sigh
-      CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
+      tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex
    }
 }
 sub Math::BigFloat::TO_CBOR {
    my ($m, $e) = $_[0]->parts;
-   CBOR::XS::tag 4, [$e->numify, $m]
+   tag 4, [$e->numify, $m]
+}
+sub Time::Piece::TO_CBOR {
+   tag 1, 0 + $_[0]->epoch
 }
 XSLoader::load "CBOR::XS", $VERSION;
 =head1 SEE ALSO

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Comparing CBOR-XS/XS.pm (file contents): Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC vs. Revision 1.50 by root, Sun Apr 24 09:11:14 2016 UTC

Diff Legend

Comparing CBOR-XS/XS.pm (file contents):
Revision 1.28 by root, Thu Nov 28 16:09:04 2013 UTC vs.
Revision 1.50 by root, Sun Apr 24 09:11:14 2016 UTC