Plack::Util − Utility subroutines for Plack server and framework developers
TRUE, FALSE
my $true = Plack::Util::TRUE;
my $false = Plack::Util::FALSE;
Utility constants to include when you specify boolean variables in $env hash (e.g. "psgi.multithread").
load_class
my $class = Plack::Util::load_class($class [, $prefix ]);
Constructs a class name and "require" the class. Throws an exception if the .pm file for the class is not found, just with the built-in "require".
If $prefix is set, the class name is prepended to the $class unless $class begins with "+" sign, which means the class name is already fully qualified.
my $class =
Plack::Util::load_class("Foo"); # Foo
my $class = Plack::Util::load_class("Baz",
"Foo::Bar"); # Foo::Bar::Baz
my $class = Plack::Util::load_class("+XYZ::ZZZ",
"Foo::Bar"); # XYZ::ZZZ
Note that this function doesn’t validate (or "sanitize") the passed string, hence if you pass a user input to this function (which is an insecure thing to do in the first place) it might lead to unexpected behavior of loading files outside your @INC path. If you want a generic module loading function, you should check out CPAN modules such as Module::Runtime.
is_real_fh
if ( Plack::Util::is_real_fh($fh) ) { }
returns true if a given $fh is a real file handle that has a file descriptor. It returns false if $fh is PerlIO handle that is not really related to the underlying file etc.
content_length
my $cl = Plack::Util::content_length($body);
Returns the length of content from body if it can be calculated. If $body is an array ref it’s a sum of length of each chunk, if $body is a real filehandle it’s a remaining size of the filehandle, otherwise returns undef.
set_io_path
Plack::Util::set_io_path($fh, "/path/to/foobar.txt");
Sets the (absolute) file path to $fh filehandle object, so you can call "$fh−>path" on it. As a side effect $fh is blessed to an internal package but it can still be treated as a normal file handle.
This module doesn’t normalize or absolutize the given path, and is intended to be used from Server or Middleware implementations. See also IO::File::WithPath.
foreach
Plack::Util::foreach($body, $cb);
Iterate through $body which is an array reference or IO::Handle−like object and pass each line (which is NOT really guaranteed to be a line) to the callback function.
It internally sets the buffer length $/ to 65536 in case it reads the binary file, unless otherwise set in the caller’s code.
load_psgi
my $app = Plack::Util::load_psgi $psgi_file_or_class;
Load "app.psgi" file or a class name (like "MyApp::PSGI") and require the file to get PSGI application handler. If the file can’t be loaded (e.g. file doesn’t exist or has a perl syntax error), it will throw an exception.
Since version 1.0006, this function would not load PSGI files from include paths (@INC) unless it looks like a class name that only consists of "[A−Za−z0−9_:]". For example:
Plack::Util::load_psgi("app.psgi");
# ./app.psgi
Plack::Util::load_psgi("/path/to/app.psgi"); #
/path/to/app.psgi
Plack::Util::load_psgi("MyApp::PSGI"); #
MyApp/PSGI.pm from @INC
Security: If you give this function a class name or module name that is loadable from your system, it will load the module. This could lead to a security hole:
my $psgi = ...;
# user−input: consider "Moose"
$app = Plack::Util::load_psgi($psgi); # this would lead to
'require "Moose.pm"'!
Generally speaking, passing an external input to this function is considered very insecure. If you really want to do that, validate that a given file name contains dots (like "foo.psgi") and also turn it into a full path in your caller’s code.
run_app
my $res = Plack::Util::run_app $app, $env;
Runs the $app by wrapping errors with eval and if an error is found, logs it to "$env−>{'psgi.errors'}" and returns the template 500 Error response.
header_get, header_exists, header_set, header_push, header_remove
my $hdrs = [
'Content−Type' => 'text/plain' ];
my $v = Plack::Util::header_get($hdrs, $key); # First found
only
my @v = Plack::Util::header_get($hdrs, $key);
my $bool = Plack::Util::header_exists($hdrs, $key);
Plack::Util::header_set($hdrs, $key, $val); # overwrites
existent header
Plack::Util::header_push($hdrs, $key, $val);
Plack::Util::header_remove($hdrs, $key);
Utility functions to manipulate PSGI response headers array reference. The methods that read existent header value handles header name as case insensitive.
my $hdrs = [
'Content−Type' => 'text/plain' ];
my $v = Plack::Util::header_get($hdrs,
'content−type'); # 'text/plain'
headers
my $headers = [
'Content−Type' => 'text/plain' ];
my $h = Plack::Util::headers($headers);
$h−>get($key);
if ($h−>exists($key)) { ... }
$h−>set($key => $val);
$h−>push($key => $val);
$h−>remove($key);
$h−>headers; # same reference as $headers
Given a header array reference, returns a convenient object that has an instance methods to access "header_*" functions with an OO interface. The object holds a reference to the original given $headers argument and updates the reference accordingly when called write methods like "set", "push" or "remove". It also has "headers" method that would return the same reference.
status_with_no_entity_body
if (status_with_no_entity_body($res−>[0])) { }
Returns true if the given status code doesn’t have any Entity body in HTTP response, i.e. it’s 100, 101, 204 or 304.
inline_object
my $o =
Plack::Util::inline_object(
write => sub { $h−>push_write(@_) },
close => sub { $h−>push_shutdown },
);
$o−>write(@stuff);
$o−>close;
Creates an instant object that can react to methods passed in the constructor. Handy to create when you need to create an IO stream object for input or errors.
encode_html
my $encoded_string = Plack::Util::encode_html( $string );
Entity encodes "<", ">", "&", """ and "'" in the input string and returns it.
response_cb
See "RESPONSE CALLBACK" in Plack::Middleware for details.