package IO::Handle;
=head1 NAME
IO::Handle - supply object methods for I/O handles
=head1 SYNOPSIS
use IO::Handle;
$io = new IO::Handle;
if ($io->fdopen(fileno(STDIN),"r")) {
print $io->getline;
$io->close;
}
$io = new IO::Handle;
if ($io->fdopen(fileno(STDOUT),"w")) {
$io->print("Some text\n");
}
use IO::Handle '_IOLBF';
$io->setvbuf($buffer_var, _IOLBF, 1024);
undef $io; # automatically closes the file if it's open
autoflush STDOUT 1;
=head1 DESCRIPTION
C<IO::Handle> is the base class for all other IO handle classes. It is
not intended that objects of C<IO::Handle> would be created directly,
but instead C<IO::Handle> is inherited from by several other classes
in the IO hierarchy.
If you are reading this documentation, looking for a replacement for
the C<FileHandle> package, then I suggest you read the documentation
for C<IO::File>
A C<IO::Handle> object is a reference to a symbol (see the C<Symbol> package)
=head1 CONSTRUCTOR
=over 4
=item new ()
Creates a new C<IO::Handle> object.
=item new_from_fd ( FD, MODE )
Creates a C<IO::Handle> like C<new> does.
It requires two parameters, which are passed to the method C<fdopen>;
if the fdopen fails, the object is destroyed. Otherwise, it is returned
to the caller.
=back
=head1 METHODS
See L<perlfunc> for complete descriptions of each of the following
supported C<IO::Handle> methods, which are just front ends for the
corresponding built-in functions:
close
fileno
getc
eof
read
truncate
stat
print
printf
sysread
syswrite
See L<perlvar> for complete descriptions of each of the following
supported C<IO::Handle> methods:
autoflush
output_field_separator
output_record_separator
input_record_separator
input_line_number
format_page_number
format_lines_per_page
format_lines_left
format_name
format_top_name
format_line_break_characters
format_formfeed
format_write
Furthermore, for doing normal I/O you might need these:
=over
=item $io->fdopen ( FD, MODE )
C<fdopen> is like an ordinary C<open> except that its first parameter
is not a filename but rather a file handle name, a IO::Handle object,
or a file descriptor number.
=item $io->opened
Returns true if the object is currently a valid file descriptor.
=item $io->getline
This works like <$io> described in L<perlop/"I/O Operators">
except that it's more readable and can be safely called in an
array context but still returns just one line.
=item $io->getlines
This works like <$io> when called in an array context to
read all the remaining lines in a file, except that it's more readable.
It will also croak() if accidentally called in a scalar context.
=item $io->ungetc ( ORD )
Pushes a character with the given ordinal value back onto the given
handle's input stream.
=item $io->write ( BUF, LEN [, OFFSET }\] )
This C<write> is like C<write> found in C, that is it is the
opposite of read. The wrapper for the perl C<write> function is
called C<format_write>.
=item $io->flush
Flush the given handle's buffer.
=item $io->error
Returns a true value if the given handle has experienced any errors
since it was opened or since the last call to C<clearerr>.
=item $io->clearerr
Clear the given handle's error indicator.
=item $io->sync
C<sync> synchronizes a file's in-memory state with that on the
physical medium. C<sync> does not operate at the perlio api level, but
operates on the file descriptor, this means that any data held at the
perlio api level will not be synchronized. To synchronize data that is
buffered at the perlio api level you must use the flush method. C<sync>
is not implemented on all platforms. See L<fsync(3c)>.
=item $io->flush
C<flush> causes perl to flush any buffered data at the perlio api level.
Any unread data in the buffer will be discarded, and any unwritten data
will be written to the underlying file descriptor.
=item $io->blocking ( [ BOOL ] )
If called with an argument C<blocking> will turn on non-blocking IO if
C<BOOL> is false, and turn it off if C<BOOL> is true.
C<blocking> will return the value of the previous setting, or the
current setting if C<BOOL> is not given.
If an error occurs C<blocking> will return undef and C<$!> will be set.
=back
If the C functions setbuf() and/or setvbuf() are available, then
C<IO::Handle::setbuf> and C<IO::Handle::setvbuf> set the buffering
policy for an IO::Handle. The calling sequences for the Perl functions
are the same as their C counterparts--including the constants C<_IOFBF>,
C<_IOLBF>, and C<_IONBF> for setvbuf()--except that the buffer parameter
specifies a scalar variable to use as a buffer. WARNING: A variable
used as a buffer by C<setbuf> or C<setvbuf> must not be modified in any
way until the IO::Handle is closed or C<setbuf> or C<setvbuf> is called
again, or memory corruption may result! Note that you need to import
the constants C<_IOFBF>, C<_IOLBF>, and C<_IONBF> explicitly.
Lastly, there is a special method for working under B<-T> and setuid/gid
scripts:
=over
=item $io->untaint
Marks the object as taint-clean, and as such data read from it will also
be considered taint-clean. Note that this is a very trusting action to
take, and appropriate consideration for the data source and potential
vulnerability should be kept in mind.
=back
=head1 NOTE
A C<IO::Handle> object is a GLOB reference. Some modules that
inherit from C<IO::Handle> may want to keep object related variables
in the hash table part of the GLOB. In an attempt to prevent modules
trampling on each other I propose the that any such module should prefix
its variables with its own name separated by _'s. For example the IO::Socket
module keeps a C<timeout> variable in 'io_socket_timeout'.
=head1 SEE ALSO
L<perlfunc>,
L<perlop/"I/O Operators">,
L<IO::File>
=head1 BUGS
Due to backwards compatibility, all filehandles resemble objects
of class C<IO::Handle>, or actually classes derived from that class.
They actually aren't. Which means you can't derive your own
class from C<IO::Handle> and inherit those methods.
=head1 HISTORY
Derived from FileHandle.pm by Graham Barr E<lt>F<gbarr@pobox.com>E<gt>
=cut
require 5.000;
use strict;
use vars qw($VERSION @EXPORT_OK @ISA);
use Carp;
use Symbol;
use SelectSaver;
use IO (); # Load the XS module
require Exporter;
@ISA = qw(Exporter);
$VERSION = "1.18";
@EXPORT_OK = qw(
autoflush
output_field_separator
output_record_separator
input_record_separator
input_line_number
format_page_number
format_lines_per_page
format_lines_left
format_name
format_top_name
format_line_break_characters
format_formfeed
format_write
print
printf
getline
getlines
SEEK_SET
SEEK_CUR
SEEK_END
_IOFBF
_IOLBF
_IONBF
);
################################################
## Constructors, destructors.
##
sub new {
my $class = ref($_[0]) || $_[0] || "IO::Handle";
@_ == 1 or croak "usage: new $class";
my $io = gensym;
bless $io, $class;
}
sub new_from_fd {
my $class = ref($_[0]) || $_[0] || "IO::Handle";
@_ == 3 or croak "usage: new_from_fd $class FD, MODE";
my $io = gensym;
shift;
IO::Handle::fdopen($io, @_)
or return undef;
bless $io, $class;
}
#
# There is no need for DESTROY to do anything, because when the
# last reference to an IO object is gone, Perl automatically
# closes its associated files (if any). However, to avoid any
# attempts to autoload DESTROY, we here define it to do nothing.
#
sub DESTROY {}
################################################
## Open and close.
##
sub _open_mode_string {
my ($mode) = @_;
$mode =~ /^\+?(<|>>?)$/
or $mode =~ s/^r(\+?)$/$1</
or $mode =~ s/^w(\+?)$/$1>/
or $mode =~ s/^a(\+?)$/$1>>/
or croak "IO::Handle: bad open mode: $mode";
$mode;
}
sub fdopen {
@_ == 3 or croak 'usage: $io->fdopen(FD, MODE)';
my ($io, $fd, $mode) = @_;
local(*GLOB);
if (ref($fd) && "".$fd =~ /GLOB\(/o) {
# It's a glob reference; Alias it as we cannot get name of anon GLOBs
my $n = qualify(*GLOB);
*GLOB = *{*$fd};
$fd = $n;
} elsif ($fd =~ m#^\d+$#) {
# It's an FD number; prefix with "=".
$fd = "=$fd";
}
open($io, _open_mode_string($mode) . '&' . $fd)
? $io : undef;
}
sub close {
@_ == 1 or croak 'usage: $io->close()';
my($io) = @_;
close($io);
}
################################################
## Normal I/O functions.
##
# flock
# select
sub opened {
@_ == 1 or croak 'usage: $io->opened()';
defined fileno($_[0]);
}
sub fileno {
@_ == 1 or croak 'usage: $io->fileno()';
fileno($_[0]);
}
sub getc {
@_ == 1 or croak 'usage: $io->getc()';
getc($_[0]);
}
sub eof {
@_ == 1 or croak 'usage: $io->eof()';
eof($_[0]);
}
sub print {
@_ or croak 'usage: $io->print([ARGS])';
my $this = shift;
print $this @_;
}
sub printf {
@_ >= 2 or croak 'usage: $io->printf(FMT,[ARGS])';
my $this = shift;
printf $this @_;
}
sub getline {
@_ == 1 or croak 'usage: $io->getline()';
my $this = shift;
return scalar <$this>;
}
*gets = \&getline; # deprecated
sub getlines {
@_ == 1 or croak 'usage: $io->getlines()';
wantarray or
croak 'Can\'t call $io->getlines in a scalar context, use $io->getline';
my $this = shift;
return <$this>;
}
sub truncate {
@_ == 2 or croak 'usage: $io->truncate(LEN)';
truncate($_[0], $_[1]);
}
sub read {
@_ == 3 || @_ == 4 or croak 'usage: $io->read(BUF, LEN [, OFFSET])';
read($_[0], $_[1], $_[2], $_[3] || 0);
}
sub sysread {
@_ == 3 || @_ == 4 or croak 'usage: $io->sysread(BUF, LEN [, OFFSET])';
sysread($_[0], $_[1], $_[2], $_[3] || 0);
}
sub write {
@_ == 3 || @_ == 4 or croak 'usage: $io->write(BUF, LEN [, OFFSET])';
local($\) = "";
print { $_[0] } substr($_[1], $_[3] || 0, $_[2]);
}
sub syswrite {
@_ == 3 || @_ == 4 or croak 'usage: $io->syswrite(BUF, LEN [, OFFSET])';
syswrite($_[0], $_[1], $_[2], $_[3] || 0);
}
sub stat {
@_ == 1 or croak 'usage: $io->stat()';
stat($_[0]);
}
################################################
## State modification functions.
##
sub autoflush {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $|;
$| = @_ > 1 ? $_[1] : 1;
$prev;
}
sub output_field_separator {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $,;
$, = $_[1] if @_ > 1;
$prev;
}
sub output_record_separator {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $\;
$\ = $_[1] if @_ > 1;
$prev;
}
sub input_record_separator {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $/;
carp "input_record_separator is not supported on a per-handle basis"
if ref($_[0]);
$/ = $_[1] if @_ > 1;
$prev;
}
sub input_line_number {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $.;
carp "input_line_number is not supported on a per-handle basis"
if ref($_[0]);
$. = $_[1] if @_ > 1;
$prev;
}
sub format_page_number {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $%;
$% = $_[1] if @_ > 1;
$prev;
}
sub format_lines_per_page {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $=;
$= = $_[1] if @_ > 1;
$prev;
}
sub format_lines_left {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $-;
$- = $_[1] if @_ > 1;
$prev;
}
sub format_name {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $~;
$~ = qualify($_[1], caller) if @_ > 1;
$prev;
}
sub format_top_name {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $^;
$^ = qualify($_[1], caller) if @_ > 1;
$prev;
}
sub format_line_break_characters {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $:;
$: = $_[1] if @_ > 1;
$prev;
}
sub format_formfeed {
my $old = new SelectSaver qualify($_[0], caller);
my $prev = $^L;
$^L = $_[1] if @_ > 1;
$prev;
}
sub formline {
my $io = shift;
my $picture = shift;
local($^A) = $^A;
local($\) = "";
formline($picture, @_);
print $io $^A;
}
sub format_write {
@_ < 3 || croak 'usage: $io->write( [FORMAT_NAME] )';
if (@_ == 2) {
my ($io, $fmt) = @_;
my $oldfmt = $io->format_name($fmt);
write($io);
$io->format_name($oldfmt);
} else {
write($_[0]);
}
}
sub fcntl {
@_ == 3 || croak 'usage: $io->fcntl( OP, VALUE );';
my ($io, $op, $val) = @_;
my $r = fcntl($io, $op, $val);
defined $r && $r eq "0 but true" ? 0 : $r;
}
sub ioctl {
@_ == 3 || croak 'usage: $io->ioctl( OP, VALUE );';
my ($io, $op, $val) = @_;
my $r = ioctl($io, $op, $val);
defined $r && $r eq "0 but true" ? 0 : $r;
}
# this sub is for compatability with older releases of IO that used
# a sub called constant to detemine if a constant existed -- GMB
#
# The SEEK_* and _IO?BF constants were the only constants at that time
# any new code should just chech defined(&CONSTANT_NAME)
sub constant {
no strict 'refs';
my $name = shift;
(($name =~ /^(SEEK_(SET|CUR|END)|_IO[FLN]BF)$/) && defined &{$name})
? &{$name}() : undef;
}
1;