JezK
Edit File: SharedMem.pm
################################################################################ # # Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz <mhx@cpan.org>. # Version 1.x, Copyright (C) 1997, Graham Barr <gbarr@pobox.com>. # # This program is free software; you can redistribute it and/or # modify it under the same terms as Perl itself. # ################################################################################ package IPC::SharedMem; use IPC::SysV qw(IPC_STAT IPC_RMID shmat shmdt memread memwrite); use strict; use vars qw($VERSION); use Carp; $VERSION = '2.07'; # Figure out if we have support for native sized types my $N = do { my $foo = eval { pack "L!", 0 }; $@ ? '' : '!' }; { package IPC::SharedMem::stat; use Class::Struct qw(struct); struct 'IPC::SharedMem::stat' => [ uid => '$', gid => '$', cuid => '$', cgid => '$', mode => '$', segsz => '$', lpid => '$', cpid => '$', nattch => '$', atime => '$', dtime => '$', ctime => '$', ]; } sub new { @_ == 4 or croak 'IPC::SharedMem->new(KEY, SIZE, FLAGS)'; my($class, $key, $size, $flags) = @_; my $id = shmget $key, $size, $flags; return undef unless defined $id; bless { _id => $id, _addr => undef, _isrm => 0 }, $class } sub id { my $self = shift; $self->{_id}; } sub addr { my $self = shift; $self->{_addr}; } sub stat { my $self = shift; my $data = ''; shmctl $self->id, IPC_STAT, $data or return undef; IPC::SharedMem::stat->new->unpack($data); } sub attach { @_ >= 1 && @_ <= 2 or croak '$shm->attach([FLAG])'; my($self, $flag) = @_; defined $self->addr and return undef; $self->{_addr} = shmat($self->id, undef, $flag || 0); defined $self->addr; } sub detach { my $self = shift; defined $self->addr or return undef; my $rv = defined shmdt($self->addr); undef $self->{_addr} if $rv; $rv; } sub remove { my $self = shift; return undef if $self->is_removed; my $rv = shmctl $self->id, IPC_RMID, 0; $self->{_isrm} = 1 if $rv; return $rv; } sub is_removed { my $self = shift; $self->{_isrm}; } sub read { @_ == 3 or croak '$shm->read(POS, SIZE)'; my($self, $pos, $size) = @_; my $buf = ''; if (defined $self->addr) { memread($self->addr, $buf, $pos, $size) or return undef; } else { shmread($self->id, $buf, $pos, $size) or return undef; } $buf; } sub write { @_ == 4 or croak '$shm->write(STRING, POS, SIZE)'; my($self, $str, $pos, $size) = @_; if (defined $self->addr) { return memwrite($self->addr, $str, $pos, $size); } else { return shmwrite($self->id, $str, $pos, $size); } } 1; __END__ =head1 NAME IPC::SharedMem - SysV Shared Memory IPC object class =head1 SYNOPSIS use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR); use IPC::SharedMem; $shm = IPC::SharedMem->new(IPC_PRIVATE, 8, S_IRWXU); $shm->write(pack("S", 4711), 2, 2); $data = $shm->read(0, 2); $ds = $shm->stat; $shm->remove; =head1 DESCRIPTION A class providing an object based interface to SysV IPC shared memory. =head1 METHODS =over 4 =item new ( KEY , SIZE , FLAGS ) Creates a new shared memory segment of C<SIZE> bytes size associated with C<KEY>. A new segment is created if =over 4 =item * C<KEY> is equal to C<IPC_PRIVATE> =item * C<KEY> does not already have a shared memory segment associated with it, and C<I<FLAGS> & IPC_CREAT> is true. =back On creation of a new shared memory segment C<FLAGS> is used to set the permissions. Be careful not to set any flags that the Sys V IPC implementation does not allow: in some systems setting execute bits makes the operations fail. =item id Returns the shared memory identifier. =item read ( POS, SIZE ) Read C<SIZE> bytes from the shared memory segment at C<POS>. Returns the string read, or C<undef> if there was an error. The return value becomes tainted. See L<shmread>. =item write ( STRING, POS, SIZE ) Write C<SIZE> bytes to the shared memory segment at C<POS>. Returns true if successful, or false if there is an error. See L<shmwrite>. =item remove Remove the shared memory segment from the system or mark it as removed as long as any processes are still attached to it. =item is_removed Returns true if the shared memory segment has been removed or marked for removal. =item stat Returns an object of type C<IPC::SharedMem::stat> which is a sub-class of C<Class::Struct>. It provides the following fields. For a description of these fields see you system documentation. uid gid cuid cgid mode segsz lpid cpid nattch atime dtime ctime =item attach ( [FLAG] ) Permanently attach to the shared memory segment. When a C<IPC::SharedMem> object is attached, it will use L<memread> and L<memwrite> instead of L<shmread> and L<shmwrite> for accessing the shared memory segment. Returns true if successful, or false on error. See L<shmat(2)>. =item detach Detach from the shared memory segment that previously has been attached to. Returns true if successful, or false on error. See L<shmdt(2)>. =item addr Returns the address of the shared memory that has been attached to in a format suitable for use with C<pack('P')>. Returns C<undef> if the shared memory has not been attached. =back =head1 SEE ALSO L<IPC::SysV>, L<Class::Struct> =head1 AUTHORS Marcus Holland-Moritz <mhx@cpan.org> =head1 COPYRIGHT Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz. Version 1.x, Copyright (c) 1997, Graham Barr. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut