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Re^4: sysread() is deprecated on :utf8 handles

by mje (Curate)
on Jul 20, 2017 at 15:56 UTC ( #1195630=note: print w/replies, xml ) Need Help??


in reply to Re^3: sysread() is deprecated on :utf8 handles
in thread sysread() is deprecated on :utf8 handles

I did not try File::Slurper because I am not slurping a file, I'm reading data from a socket.

I don't want to suppress the warning since it is warning of a deprecation which implies it will break in the future.

There is a parent and a forked child process. The child creates a socket and starts listening for connections using IO::Select to see when the socket is read ready. The parent connects to the child's socket, sets encoding(UTF-8) and sends UTF-8 encoded XML down the socket to the child. The child sees the parents connect, accepts it enables encoding(UTF-8) on the new socket. When the child sees data, it reads it with sysread. There is a bit more to it than that but that is the essence of it.

The code is like (but not exactly) this

use 5.016; use strict; use warnings; use Socket; use IO::Socket; use IO::Socket::INET; use Data::Dumper; use IO::Select; use Errno qw(EPIPE); my $port = '11111'; my $pid = fork; if ($pid) { # server sleep 10; my $sock1; my $attempts = 100; while ($attempts--) { $sock1 = IO::Socket::INET->new ( PeerHost => 'localhost', PeerPort => '9001', Proto => 'tcp'); if (!$sock1) { say "Cannot connect to child socket - $!"; sleep 2; } else { last; } } if (!$sock1) { say "Failed to connect after 100 attempts"; say "Killing child"; kill 'TERM', $pid; say "waiting on child"; waitpid($pid, 0); } binmode($sock1, ':encoding(UTF-8)'); $sock1->send("<element>Hello</element>\r\n"); sleep 10; my $sock2 = IO::Socket::INET->new ( PeerHost => 'localhost', PeerPort => '9001', Proto => 'tcp'); $sock2->send("<element>Hello2</element>\r\n"); sleep 10; say "shutdown 1"; shutdown($sock1, 1); # stopped writing shutdown($sock2, 1); # stopped writing sleep 5; say "shutdown 2"; shutdown($sock1, 2); # stopped using this socket shutdown($sock2, 2); # stopped using this socket sleep 5; say "closing socket"; close($sock1); close($sock2); say "Killing child"; kill 'TERM', $pid; say "waiting on child"; waitpid($pid, 0); say "parent exiting"; exit; } elsif (!defined $pid) { die "fork failed with $!"; } else { # child say "child started"; sleep 15; my $sock = IO::Socket::INET->new(Listen => 50, LocalAddr => 'localhost', LocalPort => 9001, Proto => 'tcp', ReuseAddr => 1); my $select = IO::Select->new(); $select->add($sock); my $buf = ''; while (1) { #exit 0; uncomment to test SIGPIPE my @ready = $select->can_read(5); foreach my $ready (@ready) { if ($ready == $sock) { my $s = $sock->accept(); my $client_address = $s->peerhost(); my $client_port = $s->peerport(); say "connection from $client_address:$client_port\n"; $select->add($s); binmode($s, ':encoding(UTF-8)'); } else { say "Child reading socket"; my $read = sysread($ready, $buf, 1024, length($buf)); if (!defined($read)) { say "Child sysread error - $!"; last; } elsif ($read == 0) { say "Child EOF"; $select->remove($ready); close $ready; sleep 1; last; } else { while ($buf =~ s/^(.*)\r\n//) { say "Child got /$1/"; # child does something with this }; } } } } exit; }

Results in

child started Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused connection from 127.0.0.1:39310 Child reading socket Child got /<element>Hello</element>/ connection from 127.0.0.1:39318 Child reading socket Child got /<element>Hello2</element>/ shutdown 1 Child reading socket Child EOF Child reading socket Child EOF shutdown 2 closing socket Killing child waiting on child parent exiting

Replies are listed 'Best First'.
Re^5: sysread() is deprecated on :utf8 handles
by thanos1983 (Parson) on Jul 20, 2017 at 19:57 UTC

    Hello mje,

    You can use read as a temporary solution it does not give the warning, but it is not the same as sysread.

    From the read documentation:

    The call is implemented in terms of either Perl's or your system's native fread(3) library function. To get a true read(2) system call, see sysread.

    I just tested with your code and the output looks ok:

    $ perl test.pl child started Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused connection from 127.0.0.1:33980 Child reading socket shutdown 1 Child got /<element>Hello</element>/ connection from 127.0.0.1:33982 Child reading socket Child EOF Child reading socket Child got /<element>Hello2</element>/ Child reading socket Child EOF shutdown 2 closing socket Killing child waiting on child parent exiting

    In comparison with sysread:

    $ perl test.pl child started Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused Cannot connect to child socket - Connection refused connection from 127.0.0.1:33788 Child reading socket sysread() is deprecated on :utf8 handles at test.pl line 108. Child got /<element>Hello</element>/ connection from 127.0.0.1:33792 Child reading socket sysread() is deprecated on :utf8 handles at test.pl line 108. Child got /<element>Hello2</element>/ shutdown 1 Child reading socket sysread() is deprecated on :utf8 handles at test.pl line 108. Child EOF Child reading socket sysread() is deprecated on :utf8 handles at test.pl line 108. Child EOF shutdown 2 closing socket Killing child waiting on child parent exiting

    Give it a try if it meets your criteria.

    I tested on:

    $ perl -v This is perl 5, version 24, subversion 1 (v5.24.1) built for x86_64-li +nux-gnu-thread-multi (with 67 registered patches, see perl -V for more detail) Copyright 1987-2017, Larry Wall Perl may be copied only under the terms of either the Artistic License + or the GNU General Public License, which may be found in the Perl 5 source ki +t. Complete documentation for Perl, including FAQ lists, should be found +on this system using "man perl" or "perldoc perl". If you have access to + the Internet, point your browser at http://www.perl.org/, the Perl Home Pa +ge.

    Hope this helps, BR.

    Seeking for Perl wisdom...on the process of learning...not there...yet!

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