NAME

Net::UNIX - UNIX-domain sockets interface module

SYNOPSIS

    use Net::Gen;               # optional
    use Net::UNIX;

DESCRIPTION

The "Net::UNIX" module provides services for UNIX-domain socket communication. It is layered atop the "Net::Gen" module, which is part of the same distribution.

Public Methods

The following methods are provided by the "Net::UNIX" module itself, rather than just being inherited from "Net::Gen".

new

Usage:

    $obj = new Net::UNIX;
    $obj = new Net::UNIX $pathname;
    $obj = new Net::UNIX \%parameters;
    $obj = new Net::UNIX $pathname, \%parameters;
    $obj = 'Net::UNIX'->new();
    $obj = 'Net::UNIX'->new($pathname);
    $obj = 'Net::UNIX'->new(\%parameters);
    $obj = 'Net::UNIX'->new($pathname, \%parameters);

Returns a newly-initialised object of the given class. If called for a derived class, no validation of the supplied parameters will be performed. (This is so that the derived class can add the parameter validation it needs to the object before allowing the validation.) Otherwise, it will cause the parameters to be validated by calling its "init" method. In particular, this means that if a pathname is given, an object will be returned only if a connect() call was successful.

The examples above show the indirect object syntax which many prefer, as well as the guaranteed-to-be-safe static method call. There are occasional problems with the indirect object syntax, which tend to be rather obscure when encountered. See http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-01/msg01674.html for details.

init

Usage:

    return undef unless $self = $self->init;
    return undef unless $self = $self->init(\%parameters);
    return undef unless $self = $self->init($pathname);
    return undef unless $self = $self->init($pathname, \%parameters);

Verifies that all previous parameter assignments are valid (via "checkparams"). Returns the incoming object on success, and "undef" on failure. Usually called only via a derived class's "init" method or its own "new" call.

bind

Usage:

    $ok = $obj->bind;
    $ok = $obj->bind($pathname);
    $ok = $obj->bind($pathname,\%newparameters);

Updates the object with the supplied new parameters (if supplied), then sets up the "srcaddrlist" object parameter with the specified $pathname argument (if supplied), and then returns the value from the inherited "bind" method.

Example:

    $ok = $obj->bind('/tmp/.fnord'); # start a service on /tmp/.fnord

connect

Usage:

    $ok = $obj->connect;
    $ok = $obj->connect($pathname);
    $ok = $obj->connect($pathname,\%newparameters);

Attempts to establish a connection for the object. If the "newparams" argument is specified, it will be used to update the object parameters. Then, if the $pathname argument is specified, it will be used to set the "dstaddrlist" object parameter. Finally, the result of a call to the inherited "connect" method will be returned.

format_addr

Usage:

    $string = $obj->format_addr($sockaddr);
    $string = format_addr Module $sockaddr;

Returns a formatted representation of the socket address. This is normally just a pathname, or the constant string ''.

PRINT

Usage:

    $ok = $obj->PRINT(@args);
    $ok = print $tied_fh @args;

This method, intended to be used with tied filehandles, behaves like one of two inherited methods from the "Net::Gen" class, depending on the setting of the object parameter "unbuffered_output" and whether the socket is a SOCK_STREAM (stream) socket or a datagram socket (the default). If that parameter is false (the default) or the socket is a stream socket, then the normal print() builtin is used. If the "unbuffered_output" parameter is true for a datagram socket, then each print() operation will actually result in a call to the "send" method. The value of the $\ variable is ignored in that case, but the $, variable is still used if the @args array has multiple elements.

READLINE

Usage:

    $line_or_datagram = $obj->READLINE;
    $line_or_datagram = <TIED_FH>;
    $line_or_datagram = readline(TIED_FH);
    @lines_or_datagrams = $obj->READLINE;
    @lines_or_datagrams = <TIED_FH>;
    @lines_or_datagrams = readline(TIED_FH);

This method, intended to be used with tied filehandles, behaves like one of two inherited methods from the "Net::Gen" class, depending on the setting of the object parameter "unbuffered_input" and whether the socket is a SOCK_STREAM (stream) socket or a datagram socket (the default). If that parameter is false (the default) or the socket is a stream socket, then this method does line-buffering of its input as defined by the current setting of the $/ variable. If the "unbuffered_input" parameter is true for a datagram socket, then the input records will be exact recv() datagrams, disregarding the setting of the $/ variable.

Protected Methods

[See the description in "Protected Methods" in Net::Gen for my definition of protected methods in Perl.]

None.

Known Socket Options

There are no socket options known to the "Net::UNIX" module itself.

Known Object Parameters

The following object parameters are registered by the "Net::UNIX" module (as distinct from being inherited from "Net::Gen"):

unbuffered_input: If true, the "READLINE" operation on tied filehandles which are datagram sockets will return each recv() buffer as though it were a single separate line, independently of the setting of the $/ variable. The default is false, which causes the "READLINE" interface to return lines split at boundaries as appropriate for $/. (The "READLINE" method for tied filehandles is the "<FH>" operation.)

unbuffered_output: If true, the "PRINT" operation on tied filehandles which are datagram sockets will result in calls to the send() builtin rather than the print() builtin, as described in "PRINT" above. The default is false, which causes the "PRINT" method to use the print() builtin.

unbuffered_IO: This object parameter's value is unreliable on "getparam" or "getparams" method calls. It is provided as a handy way to set both the "unbuffered_output" and "unbuffered_input" object parameters to the same value at the same time during "new" calls.

TIESCALAR

Tieing of scalars to a UNIX-domain handle is supported by inheritance from the "TIESCALAR" method of "Net::Gen". That method only succeeds if a call to a "new" method results in an object for which the "isconnected" method returns a true result. Thus, for "Net::UNIX", "TIESCALAR" will not succeed unless the "pathname" argument is given.

Each assignment to the tied scalar is really a call to the "put" method (via the "STORE" method), and each read from the tied scalar is really a call to the "READLINE" method (via the "FETCH" method).

TIEHANDLE support

As inherited from "Net::Gen", with the addition of unbuffered datagram I/O options for the "FETCH", "READLINE", and "PRINT" methods.

Non-Method Subroutines

pack_sockaddr_un

Usage:

    $connect_address = pack_sockaddr_un($family, $pathname);
    $connect_address = pack_sockaddr_un($pathname);

Returns the packed "struct sockaddr_un" corresponding to the provided $family and $pathname arguments. The $family argument as assumed to be "AF_UNIX" if it is missing. This is otherwise the same as the pack_sockaddr_un() routine in the "Socket" module.

unpack_sockaddr_un

Usage:

    ($family, $pathname) = unpack_sockaddr_un($connected_address);
    $pathname = unpack_sockaddr_un($connected_address);

Returns the address family and pathname (if known) from the supplied packed "struct sockaddr_un". This is the inverse of pack_sockaddr_un(). It differs from the implementation in the "Socket" module in its return of the $family value, and in that it trims the returned pathname at the first null character.

Exports

default: None.

exportable: "pack_sockaddr_un" "unpack_sockaddr_un"

tags: The following :tags are available for grouping exportable items:

:routines: "pack_sockaddr_un" "unpack_sockaddr_un"

:ALL: All of the above exportable items.

THREADING STATUS

This module has been tested with threaded perls, and should be as thread-safe as perl itself. (As of 5.005_03 and 5.005_57, that's not all that safe just yet.) It also works with interpreter-based threads ('ithreads') in more recent perl releases.

AUTHOR

Spider Boardman <spidb@cpan.org>