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inc/inc_IPC-Cmd/IPC/Cmd.pm  view on Meta::CPAN

            ### if it *is* an alarm, propagate
            } elsif( $@ ) {
                die $@;

            ### some error in the sub command
            } else {
                $self->error( $self->_pp_child_error( $cmd, $? ) );
            }

            return;
        }
    }
}

sub _system_run {
    my $self    = shift;
    my $cmd     = shift;
    my $verbose = shift || 0;

    ### pipes have to come in a quoted string, and that clashes with
    ### whitespace. This sub fixes up such commands so they run properly
    $cmd = $self->__fix_cmd_whitespace_and_special_chars( $cmd );

    my @fds_to_dup = $verbose ? () : qw[STDOUT STDERR];
    $self->_fds( \@fds_to_dup );
    $self->__dup_fds( @fds_to_dup );

    ### system returns 'true' on failure -- the exit code of the cmd
    $self->ok( 1 );
    system( ref $cmd ? @$cmd : $cmd ) == 0 or do {
        $self->error( $self->_pp_child_error( $cmd, $? ) );
        $self->ok( 0 );
    };

    ### done in the parent call now
    #$self->__reopen_fds( @fds_to_dup );

    return unless $self->ok;
    return $self->ok;
}

{   my %sc_lookup = map { $_ => $_ } SPECIAL_CHARS;


    sub __fix_cmd_whitespace_and_special_chars {
        my $self = shift;
        my $cmd  = shift;

        ### command has a special char in it
        if( ref $cmd and grep { $sc_lookup{$_} } @$cmd ) {

            ### since we have special chars, we have to quote white space
            ### this *may* conflict with the parsing :(
            my $fixed;
            my @cmd = map { / / ? do { $fixed++; QUOTE.$_.QUOTE } : $_ } @$cmd;

            $self->_debug( "# Quoted $fixed arguments containing whitespace" )
                    if $DEBUG && $fixed;

            ### stringify it, so the special char isn't escaped as argument
            ### to the program
            $cmd = join ' ', @cmd;
        }

        return $cmd;
    }
}

### Command-line arguments (but not the command itself) must be quoted
### to ensure case preservation. Borrowed from Module::Build with adaptations.
### Patch for this supplied by Craig Berry, see RT #46288: [PATCH] Add argument
### quoting for run() on VMS
sub _quote_args_vms {
  ### Returns a command string with proper quoting so that the subprocess
  ### sees this same list of args, or if we get a single arg that is an
  ### array reference, quote the elements of it (except for the first)
  ### and return the reference.
  my @args = @_;
  my $got_arrayref = (scalar(@args) == 1
                      && UNIVERSAL::isa($args[0], 'ARRAY'))
                   ? 1
                   : 0;

  @args = split(/\s+/, $args[0]) unless $got_arrayref || scalar(@args) > 1;

  my $cmd = $got_arrayref ? shift @{$args[0]} : shift @args;

  ### Do not quote qualifiers that begin with '/' or previously quoted args.
  map { if (/^[^\/\"]/) {
          $_ =~ s/\"/""/g;     # escape C<"> by doubling
          $_ = q(").$_.q(");
        }
  }
    ($got_arrayref ? @{$args[0]}
                   : @args
    );

  $got_arrayref ? unshift(@{$args[0]}, $cmd) : unshift(@args, $cmd);

  return $got_arrayref ? $args[0]
                       : join(' ', @args);
}


### XXX this is cribbed STRAIGHT from M::B 0.30 here:
### http://search.cpan.org/src/KWILLIAMS/Module-Build-0.30/lib/Module/Build/Platform/Windows.pm:split_like_shell
### XXX this *should* be integrated into text::parsewords
sub _split_like_shell_win32 {
  # As it turns out, Windows command-parsing is very different from
  # Unix command-parsing.  Double-quotes mean different things,
  # backslashes don't necessarily mean escapes, and so on.  So we
  # can't use Text::ParseWords::shellwords() to break a command string
  # into words.  The algorithm below was bashed out by Randy and Ken
  # (mostly Randy), and there are a lot of regression tests, so we
  # should feel free to adjust if desired.

  local $_ = shift;

  my @argv;
  return @argv unless defined() && length();

  my $arg = '';
  my( $i, $quote_mode ) = ( 0, 0 );

  while ( $i < length() ) {

    my $ch      = substr( $_, $i  , 1 );
    my $next_ch = substr( $_, $i+1, 1 );

    if ( $ch eq '\\' && $next_ch eq '"' ) {
      $arg .= '"';
      $i++;
    } elsif ( $ch eq '\\' && $next_ch eq '\\' ) {
      $arg .= '\\';
      $i++;
    } elsif ( $ch eq '"' && $next_ch eq '"' && $quote_mode ) {
      $quote_mode = !$quote_mode;
      $arg .= '"';
      $i++;
    } elsif ( $ch eq '"' && $next_ch eq '"' && !$quote_mode &&
          ( $i + 2 == length()  ||
        substr( $_, $i + 2, 1 ) eq ' ' )
        ) { # for cases like: a"" => [ 'a' ]
      push( @argv, $arg );
      $arg = '';
      $i += 2;
    } elsif ( $ch eq '"' ) {
      $quote_mode = !$quote_mode;
    } elsif ( $ch eq ' ' && !$quote_mode ) {
      push( @argv, $arg ) if defined( $arg ) && length( $arg );
      $arg = '';
      ++$i while substr( $_, $i + 1, 1 ) eq ' ';
    } else {
      $arg .= $ch;
    }

    $i++;
  }

  push( @argv, $arg ) if defined( $arg ) && length( $arg );
  return @argv;
}



{   use File::Spec;
    use Symbol;

    my %Map = (
        STDOUT => [qw|>&|, \*STDOUT, Symbol::gensym() ],
        STDERR => [qw|>&|, \*STDERR, Symbol::gensym() ],

inc/inc_IPC-Cmd/IPC/Cmd.pm  view on Meta::CPAN

interactive commands will still work.

=item *

Otherwise we will try and temporarily redirect STDERR and STDOUT, do a
C<system()> call with your command and then re-open STDERR and STDOUT.
This is the method of last resort and will still allow you to execute
your commands cleanly. However, no buffers will be available.

=back

=head1 Global Variables

The behaviour of IPC::Cmd can be altered by changing the following
global variables:

=head2 $IPC::Cmd::VERBOSE

This controls whether IPC::Cmd will print any output from the
commands to the screen or not. The default is 0.

=head2 $IPC::Cmd::USE_IPC_RUN

This variable controls whether IPC::Cmd will try to use L<IPC::Run>
when available and suitable.

=head2 $IPC::Cmd::USE_IPC_OPEN3

This variable controls whether IPC::Cmd will try to use L<IPC::Open3>
when available and suitable. Defaults to true.

=head2 $IPC::Cmd::WARN

This variable controls whether run-time warnings should be issued, like
the failure to load an C<IPC::*> module you explicitly requested.

Defaults to true. Turn this off at your own risk.

=head2 $IPC::Cmd::INSTANCES

This variable controls whether C<can_run> will return all instances of
the binary it finds in the C<PATH> when called in a list context.

Defaults to false, set to true to enable the described behaviour.

=head2 $IPC::Cmd::ALLOW_NULL_ARGS

This variable controls whether C<run> will remove any empty/null arguments
it finds in command arguments.

Defaults to false, so it will remove null arguments. Set to true to allow
them.

=head1 Caveats

=over 4

=item Whitespace and IPC::Open3 / system()

When using C<IPC::Open3> or C<system>, if you provide a string as the
C<command> argument, it is assumed to be appropriately escaped. You can
use the C<QUOTE> constant to use as a portable quote character (see above).
However, if you provide an array reference, special rules apply:

If your command contains B<special characters> (< > | &), it will
be internally stringified before executing the command, to avoid that these
special characters are escaped and passed as arguments instead of retaining
their special meaning.

However, if the command contained arguments that contained whitespace,
stringifying the command would loose the significance of the whitespace.
Therefore, C<IPC::Cmd> will quote any arguments containing whitespace in your
command if the command is passed as an arrayref and contains special characters.

=item Whitespace and IPC::Run

When using C<IPC::Run>, if you provide a string as the C<command> argument,
the string will be split on whitespace to determine the individual elements
of your command. Although this will usually just Do What You Mean, it may
break if you have files or commands with whitespace in them.

If you do not wish this to happen, you should provide an array
reference, where all parts of your command are already separated out.
Note however, if there are extra or spurious whitespaces in these parts,
the parser or underlying code may not interpret it correctly, and
cause an error.

Example:
The following code

    gzip -cdf foo.tar.gz | tar -xf -

should either be passed as

    "gzip -cdf foo.tar.gz | tar -xf -"

or as

    ['gzip', '-cdf', 'foo.tar.gz', '|', 'tar', '-xf', '-']

But take care not to pass it as, for example

    ['gzip -cdf foo.tar.gz', '|', 'tar -xf -']

Since this will lead to issues as described above.


=item IO Redirect

Currently it is too complicated to parse your command for IO
redirections. For capturing STDOUT or STDERR there is a work around
however, since you can just inspect your buffers for the contents.

=item Interleaving STDOUT/STDERR

Neither IPC::Run nor IPC::Open3 can interleave STDOUT and STDERR. For short
bursts of output from a program, e.g. this sample,

    for ( 1..4 ) {
        $_ % 2 ? print STDOUT $_ : print STDERR $_;
    }

IPC::[Run|Open3] will first read all of STDOUT, then all of STDERR, meaning
the output looks like '13' on STDOUT and '24' on STDERR, instead of

    1
    2