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Perl::CriticPerl::CritUserPContributedtPerluDocumentationodingWithUTF8Layer(3)

NAME
       Perl::Critic::Policy::InputOutput::RequireEncodingWithUTF8Layer - Write
       "open $fh, q{<:encoding(UTF-8)},	$filename;" instead of "open $fh,
       q{<:utf8}, $filename;".

AFFILIATION
       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION
       Use of the ":utf8" I/O layer (as	opposed	to ":encoding(UTF8)" or
       ":encoding(UTF-8)") was suggested in the	Perl documentation up to
       version 5.8.8. This may be OK for output, but on	input ":utf8" does not
       validate	the input, leading to unexpected results.

       An exploit based	on this	behavior of ":utf8" is exhibited on PerlMonks
       at <http://www.perlmonks.org/?node_id=644786>. The exploit involves a
       string read from	an external file and sanitized with "m/^(\w+)$/",
       where $1	nonetheless ends up containing shell meta-characters.

       To summarize:

	open $fh, '<:utf8', 'foo.txt';		   # BAD
	open $fh, '<:encoding(UTF8)', 'foo.txt';   # GOOD
	open $fh, '<:encoding(UTF-8)', 'foo.txt';  # BETTER

       See the Encode documentation for	the difference between "UTF8" and
       "UTF-8".	The short version is that "UTF-8" implements the Unicode
       standard, and "UTF8" is liberalized.

       For consistency's sake, this policy checks files	opened for output as
       well as input. For complete coverage it also checks "binmode()" calls,
       where the direction of operation	can not	be determined.

CONFIGURATION
       This Policy is not configurable except for the standard options.

NOTES
       Because "Perl::Critic" does a static analysis, this policy can not
       detect cases like

	my $encoding = ':utf8';
	binmode	$fh, $encoding;

       where the encoding is computed.

SEE ALSO
       PerlIO

       Encode

       "perldoc	-f binmode"

       <http://www.socialtext.net/perl5/index.cgi?the_utf8_perlio_layer>

       <http://www.perlmonks.org/?node_id=644786>

AUTHOR
       Thomas R. Wyant,	III wyant at cpan dot org

COPYRIGHT
       Copyright (c) 2010-2011 Thomas R. Wyant,	III

       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

perl v5.24.1Perl::Critic::Policy::InputOutput::RequireEncodingWithUTF8Layer(3)

NAME | AFFILIATION | DESCRIPTION | CONFIGURATION | NOTES | SEE ALSO | AUTHOR | COPYRIGHT

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