cmd.pm

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

package IPC::Cmd;

use strict;

BEGIN {

    use constant IS_VMS   => $^O eq 'VMS'                       ? 1 : 0;    
    use constant IS_WIN32 => $^O eq 'MSWin32'                   ? 1 : 0;
    use constant IS_WIN98 => (IS_WIN32 and !Win32::IsWinNT())   ? 1 : 0;

    use Exporter    ();
    use vars        qw[ @ISA $VERSION @EXPORT_OK $VERBOSE $DEBUG
                        $USE_IPC_RUN $USE_IPC_OPEN3 $WARN
                    ];

    $VERSION        = '0.40_1';
    $VERBOSE        = 0;
    $DEBUG          = 0;
    $WARN           = 1;
    $USE_IPC_RUN    = IS_WIN32 && !IS_WIN98;
    $USE_IPC_OPEN3  = not IS_VMS;

    @ISA            = qw[Exporter];
    @EXPORT_OK      = qw[can_run run];
}

require Carp;
use File::Spec;
use Params::Check               qw[check];
use Module::Load::Conditional   qw[can_load];
use Locale::Maketext::Simple    Style => 'gettext';

=pod

=head1 NAME

IPC::Cmd - finding and running system commands made easy

=head1 SYNOPSIS

    use IPC::Cmd qw[can_run run];

    my $full_path = can_run('wget') or warn 'wget is not installed!';

    ### commands can be arrayrefs or strings ###
    my $cmd = "$full_path -b theregister.co.uk";
    my $cmd = [$full_path, '-b', 'theregister.co.uk'];

    ### in scalar context ###
    my $buffer;
    if( scalar run( command => $cmd,
                    verbose => 0,
                    buffer  => \$buffer )
    ) {
        print "fetched webpage successfully: $buffer\n";
    }


    ### in list context ###
    my( $success, $error_code, $full_buf, $stdout_buf, $stderr_buf ) =
            run( command => $cmd, verbose => 0 );

    if( $success ) {
        print "this is what the command printed:\n";
        print join "", @$full_buf;
    }

    ### check for features
    print "IPC::Open3 available: "  . IPC::Cmd->can_use_ipc_open3;      
    print "IPC::Run available: "    . IPC::Cmd->can_use_ipc_run;      
    print "Can capture buffer: "    . IPC::Cmd->can_capture_buffer;     

    ### don't have IPC::Cmd be verbose, ie don't print to stdout or
    ### stderr when running commands -- default is '0'
    $IPC::Cmd::VERBOSE = 0;

=head1 DESCRIPTION

IPC::Cmd allows you to run commands, interactively if desired,
platform independent but have them still work.

The C<can_run> function can tell you if a certain binary is installed
and if so where, whereas the C<run> function can actually execute any
of the commands you give it and give you a clear return value, as well
as adhere to your verbosity settings.

=head1 CLASS METHODS 

=head2 $bool = IPC::Cmd->can_use_ipc_run( [VERBOSE] )

Utility function that tells you if C<IPC::Run> is available. 
If the verbose flag is passed, it will print diagnostic messages
if C<IPC::Run> can not be found or loaded.

=cut


sub can_use_ipc_run     { 
    my $self    = shift;
    my $verbose = shift || 0;
    
    ### ipc::run doesn't run on win98    
    return if IS_WIN98;

    ### if we dont have ipc::run, we obviously can't use it.
    return unless can_load(
                        modules => { 'IPC::Run' => '0.55' },        
                        verbose => ($WARN && $verbose),
                    );
                    
    ### otherwise, we're good to go
    return 1;                    
}

=head2 $bool = IPC::Cmd->can_use_ipc_open3( [VERBOSE] )

Utility function that tells you if C<IPC::Open3> is available. 
If the verbose flag is passed, it will print diagnostic messages
if C<IPC::Open3> can not be found or loaded.

=cut


sub can_use_ipc_open3   { 
    my $self    = shift;
    my $verbose = shift || 0;

    ### ipc::open3 is not working on VMS becasue of a lack of fork.
    ### todo, win32 also does not have fork, so need to do more research.
    return 0 if IS_VMS;

    ### ipc::open3 works on every platform, but it can't capture buffers
    ### on win32 :(
    return unless can_load(
        modules => { map {$_ => '0.0'} qw|IPC::Open3 IO::Select Symbol| },
        verbose => ($WARN && $verbose),
    );
    
    return 1;
}

=head2 $bool = IPC::Cmd->can_capture_buffer

Utility function that tells you if C<IPC::Cmd> is capable of
capturing buffers in it's current configuration.

=cut

sub can_capture_buffer {
    my $self    = shift;

    return 1 if $USE_IPC_RUN    && $self->can_use_ipc_run; 
    return 1 if $USE_IPC_OPEN3  && $self->can_use_ipc_open3 && !IS_WIN32; 
    return;
}


=head1 FUNCTIONS

=head2 $path = can_run( PROGRAM );

C<can_run> takes but a single argument: the name of a binary you wish
to locate. C<can_run> works much like the unix binary C<which> or the bash
command C<type>, which scans through your path, looking for the requested
binary .

Unlike C<which> and C<type>, this function is platform independent and
will also work on, for example, Win32.

It will return the full path to the binary you asked for if it was
found, or C<undef> if it was not.

=cut

sub can_run {
    my $command = shift;

    # a lot of VMS executables have a symbol defined
    # check those first
    if ( $^O eq 'VMS' ) {
        require VMS::DCLsym;
        my $syms = VMS::DCLsym->new;
        return $command if scalar $syms->getsym( uc $command );
    }

    require Config;
    require File::Spec;
    require ExtUtils::MakeMaker;

    if( File::Spec->file_name_is_absolute($command) ) {
        return MM->maybe_command($command);

    } else {
        for my $dir (
            (split /\Q$Config::Config{path_sep}\E/, $ENV{PATH}),
            File::Spec->curdir
        ) {           
            my $abs = File::Spec->catfile($dir, $command);
            return $abs if $abs = MM->maybe_command($abs);
        }
    }
}

=head2 $ok | ($ok, $err, $full_buf, $stdout_buff, $stderr_buff) = run( command => COMMAND, [verbose => BOOL, buffer => \$SCALAR] );

C<run> takes 3 arguments:

=over 4

=item command

This is the command to execute. It may be either a string or an array
reference.
This is a required argument.

See L<CAVEATS> for remarks on how commands are parsed and their
limitations.

=item verbose

This controls whether all output of a command should also be printed
to STDOUT/STDERR or should only be trapped in buffers (NOTE: buffers
require C<IPC::Run> to be installed or your system able to work with
C<IPC::Open3>).

It will default to the global setting of C<$IPC::Cmd::VERBOSE>,
which by default is 0.

=item buffer

This will hold all the output of a command. It needs to be a reference
to a scalar.
Note that this will hold both the STDOUT and STDERR messages, and you
have no way of telling which is which.
If you require this distinction, run the C<run> command in list context
and inspect the individual buffers.

Of course, this requires that the underlying call supports buffers. See
the note on buffers right above.

=back

C<run> will return a simple C<true> or C<false> when called in scalar
context.
In list context, you will be returned a list of the following items:

=over 4

=item success

A simple boolean indicating if the command executed without errors or
not.

=item errorcode

If the first element of the return value (success) was 0, then some
error occurred. This second element is the error code the command
you requested exited with, if available.

=item full_buffer

This is an arrayreference containing all the output the command
generated.
Note that buffers are only available if you have C<IPC::Run> installed,
or if your system is able to work with C<IPC::Open3> -- See below).
This element will be C<undef> if this is not the case.

=item out_buffer

This is an arrayreference containing all the output sent to STDOUT the
command generated.
Note that buffers are only available if you have C<IPC::Run> installed,
or if your system is able to work with C<IPC::Open3> -- See below).
This element will be C<undef> if this is not the case.

=item error_buffer

This is an arrayreference containing all the output sent to STDERR the
command generated.
Note that buffers are only available if you have C<IPC::Run> installed,
or if your system is able to work with C<IPC::Open3> -- See below).
This element will be C<undef> if this is not the case.

=back

See the C<HOW IT WORKS> Section below to see how C<IPC::Cmd> decides
what modules or function calls to use when issuing a command.

=cut

sub run {
    my %hash = @_;
    
    ### if the user didn't provide a buffer, we'll store it here.
    my $def_buf = '';
    
    my($verbose,$cmd,$buffer);
    my $tmpl = {
        verbose => { default  => $VERBOSE,  store => \$verbose },
        buffer  => { default  => \$def_buf, store => \$buffer },
        command => { required => 1,         store => \$cmd,
                     allow    => sub { !ref($_[0]) or ref($_[0]) eq 'ARRAY' } 
        },
    };

    unless( check( $tmpl, \%hash, $VERBOSE ) ) {
        Carp::carp(loc("Could not validate input: %1", Params::Check->last_error));
        return;
    };        

    print loc("Running [%1]...\n", (ref $cmd ? "@$cmd" : $cmd)) if $verbose;

    ### did the user pass us a buffer to fill or not? if so, set this
    ### flag so we know what is expected of us
    ### XXX this is now being ignored. in the future, we could add diagnostic
    ### messages based on this logic
    #my $user_provided_buffer = $buffer == \$def_buf ? 0 : 1;
    
    ### buffers that are to be captured
    my( @buffer, @buff_err, @buff_out );

    ### capture STDOUT
    my $_out_handler = sub {
        my $buf = shift;
        return unless defined $buf;
        
        print STDOUT $buf if $verbose;
        push @buffer,   $buf;
        push @buff_out, $buf;
    };
    
    ### capture STDERR
    my $_err_handler = sub {
        my $buf = shift;
        return unless defined $buf;
        
        print STDERR $buf if $verbose;
        push @buffer,   $buf;
        push @buff_err, $buf;
    };
    

    ### flag to indicate we have a buffer captured
    my $have_buffer = __PACKAGE__->can_capture_buffer ? 1 : 0;
    
    ### flag indicating if the subcall went ok
    my $ok;
    
    ### IPC::Run is first choice if $USE_IPC_RUN is set.
    if( $USE_IPC_RUN and __PACKAGE__->can_use_ipc_run( 1 ) ) {
        ### ipc::run handlers needs the command as a string or an array ref

        __PACKAGE__->_debug( "# Using IPC::Run. Have buffer: $have_buffer" )
            if $DEBUG;
            
        $ok = __PACKAGE__->_ipc_run( $cmd, $_out_handler, $_err_handler );

    ### since IPC::Open3 works on all platforms, and just fails on
    ### win32 for capturing buffers, do that ideally
    } elsif ( $USE_IPC_OPEN3 and __PACKAGE__->can_use_ipc_open3( 1 ) ) {

        __PACKAGE__->_debug( "# Using IPC::Open3. Have buffer: $have_buffer" )
            if $DEBUG;

        ### in case there are pipes in there;
        ### IPC::Open3 will call exec and exec will do the right thing 
        $ok = __PACKAGE__->_open3_run( 
                                ( ref $cmd ? "@$cmd" : $cmd ),
                                $_out_handler, $_err_handler, $verbose 
                            );
        
    ### if we are allowed to run verbose, just dispatch the system command
    } else {
        __PACKAGE__->_debug( "# Using system(). Have buffer: $have_buffer" )
            if $DEBUG;
        $ok = __PACKAGE__->_system_run( (ref $cmd ? "@$cmd" : $cmd), $verbose );
    }
    
    ### fill the buffer;
    $$buffer = join '', @buffer if @buffer;
    
    ### return a list of flags and buffers (if available) in list
    ### context, or just a simple 'ok' in scalar
    return wantarray
                ? $have_buffer
                    ? ($ok, $?, \@buffer, \@buff_out, \@buff_err)
                    : ($ok, $? )
                : $ok
    
    
}

sub _open3_run { 
    my $self            = shift;
    my $cmd             = shift;
    my $_out_handler    = shift;
    my $_err_handler    = shift;
    my $verbose         = shift || 0;

    ### Following code are adapted from Friar 'abstracts' in the