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#!/usr/bin/perl
# Copyright (C) 2016-2024 Ole Tange, http://ole.tange.dk and Free
# Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see <https://www.gnu.org/licenses/>
# or write to the Free Software Foundation, Inc., 51 Franklin St,
# Fifth Floor, Boston, MA 02110-1301 USA
#
# SPDX-FileCopyrightText: 2021-2024 Ole Tange, http://ole.tange.dk and Free Software and Foundation, Inc.
# SPDX-License-Identifier: GPL-3.0-or-later
use Symbol qw(gensym);
use IPC::Open3;
use POSIX qw(:errno_h);
use IO::Select;
use strict;
use threads;
use threads::shared;
use Thread::Queue;
my $opened :shared;
my $q = Thread::Queue->new();
my $okq = Thread::Queue->new();
my @producers;
if(not @ARGV) {
if(-t *STDIN) {
print "Usage:\n";
print " parcat file(s)\n";
print " cat argfile | parcat\n";
} else {
# Read arguments from stdin
chomp(@ARGV = <STDIN>);
}
}
my $files_to_open = 0;
# Default: fd = stdout
my $fd = 1;
for (@ARGV) {
# --rm = remove file when opened
/^--rm$/ and do { $opt::rm = 1; next; };
# -1 = output to fd 1, -2 = output to fd 2
/^-(\d+)$/ and do { $fd = $1; next; };
push @producers, threads->create('producer', $_, $fd);
$files_to_open++;
}
sub producer {
# Open a file/fifo, set non blocking, enqueue fileno of the file handle
my $file = shift;
my $output_fd = shift;
open(my $fh, "<", $file) || do {
print STDERR "parcat: Cannot open $file\n";
exit(1);
};
# Remove file when it has been opened
if($opt::rm) {
unlink $file;
}
set_fh_non_blocking($fh);
$opened++;
# Pass the fileno to parent
$q->enqueue(fileno($fh),$output_fd);
# Get an OK that the $fh is opened and we can release the $fh
while(1) {
my $ok = $okq->dequeue();
if($ok == fileno($fh)) { last; }
# Not ours - very unlikely to happen
$okq->enqueue($ok);
}
return;
}
my $s = IO::Select->new();
my %buffer;
sub add_file {
my $infd = shift;
my $outfd = shift;
open(my $infh, "<&=", $infd) || die;
open(my $outfh, ">&=", $outfd) || die;
$s->add($infh);
# Tell the producer now opened here and can be released
$okq->enqueue($infd);
# Initialize the buffer
@{$buffer{$infh}{$outfd}} = ();
$Global::fh{$outfd} = $outfh;
}
sub add_files {
# Non-blocking dequeue
my ($infd,$outfd);
do {
($infd,$outfd) = $q->dequeue_nb(2);
if(defined($outfd)) {
add_file($infd,$outfd);
}
} while(defined($outfd));
}
sub add_files_block {
# Blocking dequeue
my ($infd,$outfd) = $q->dequeue(2);
add_file($infd,$outfd);
}
my $fd;
my (@ready,$infh,$rv,$buf);
do {
# Wait until at least one file is opened
add_files_block();
while($q->pending or keys %buffer) {
add_files();
while(keys %buffer) {
@ready = $s->can_read(0.01);
if(not @ready) {
add_files();
}
for $infh (@ready) {
# There is only one key, namely the output file descriptor
for my $outfd (keys %{$buffer{$infh}}) {
$rv = sysread($infh, $buf, 65536);
if (!$rv) {
if($! == EAGAIN) {
# Would block: Nothing read
next;
} else {
# Nothing read, but would not block:
# This file is done
$s->remove($infh);
for(@{$buffer{$infh}{$outfd}}) {
syswrite($Global::fh{$outfd},$_);
}
delete $buffer{$infh};
# Closing the $infh causes it to block
# close $infh;
add_files();
next;
}
}
# Something read.
# Find \n or \r for full line
my $i = (rindex($buf,"\n")+1);
if($i) {
# Print full line
for(@{$buffer{$infh}{$outfd}}, substr($buf,0,$i)) {
syswrite($Global::fh{$outfd},$_);
}
# @buffer = remaining half line
$buffer{$infh}{$outfd} = [substr($buf,$i,$rv-$i)];
} else {
# Something read, but not a full line
push @{$buffer{$infh}{$outfd}}, $buf;
}
redo;
}
}
}
}
} while($opened < $files_to_open);
for (@producers) {
$_->join();
}
sub set_fh_non_blocking {
# Set filehandle as non-blocking
# Inputs:
# $fh = filehandle to be blocking
# Returns:
# N/A
my $fh = shift;
$Global::use{"Fcntl"} ||= eval "use Fcntl qw(:DEFAULT :flock); 1;";
my $flags;
fcntl($fh, &F_GETFL, $flags) || die $!; # Get the current flags on the filehandle
$flags |= &O_NONBLOCK; # Add non-blocking to the flags
fcntl($fh, &F_SETFL, $flags) || die $!; # Set the flags on the filehandle
}
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