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#!/usr/bin/perl -w## Clean a text file -- or directory of text files -- of stealth whitespace.# WARNING: this can be a highly destructive operation.  Use with caution.# use bytes;use File::Basename; # Default options$max_width = 79; # Clean up space-tab sequences, either by removing spaces or# replacing them with tabs.sub clean_space_tabs($){    no bytes;			# Tab alignment depends on characters     my($li) = @_;    my($lo) = '';    my $pos = 0;    my $nsp = 0;    my($i, $c);     for ($i = 0; $i < length($li); $i++) {	$c = substr($li, $i, 1);	if ($c eq "\t") {	    my $npos = ($pos+$nsp+8) & ~7;	    my $ntab = ($npos >> 3) - ($pos >> 3);	    $lo .= "\t" x $ntab;	    $pos = $npos;	    $nsp = 0;	} elsif ($c eq "\n" || $c eq "\r") {	    $lo .= " " x $nsp;	    $pos += $nsp;	    $nsp = 0;	    $lo .= $c;	    $pos = 0;	} elsif ($c eq " ") {	    $nsp++;	} else {	    $lo .= " " x $nsp;	    $pos += $nsp;	    $nsp = 0;	    $lo .= $c;	    $pos++;	}    }    $lo .= " " x $nsp;    return $lo;} # Compute the visual width of a stringsub strwidth($) {    no bytes;			# Tab alignment depends on characters     my($li) = @_;    my($c, $i);    my $pos = 0;    my $mlen = 0;     for ($i = 0; $i < length($li); $i++) {	$c = substr($li,$i,1);	if ($c eq "\t") {	    $pos = ($pos+8) & ~7;	} elsif ($c eq "\n") {	    $mlen = $pos if ($pos > $mlen);	    $pos = 0;	} else {	    $pos++;	}    }     $mlen = $pos if ($pos > $mlen);    return $mlen;} $name = basename($0); @files = (); while (defined($a = shift(@ARGV))) {    if ($a =~ /^-/) {	if ($a eq '-width' || $a eq '-w') {	    $max_width = shift(@ARGV)+0;	} else {	    print STDERR "Usage: $name [-width #] files...\n";	    exit 1;	}    } else {	push(@files, $a);    }} foreach $f ( @files ) {    print STDERR "$name: $f\n";     if (! -f $f) {	print STDERR "$f: not a file\n";	next;    }     if (!open(FILE, '+<', $f)) {	print STDERR "$name: Cannot open file: $f: $!\n";	next;    }     binmode FILE;     # First, verify that it is not a binary file; consider any file    # with a zero byte to be a binary file.  Is there any better, or    # additional, heuristic that should be applied?    $is_binary = 0;     while (read(FILE, $data, 65536) > 0) {	if ($data =~ /\0/) {	    $is_binary = 1;	    last;	}    }     if ($is_binary) {	print STDERR "$name: $f: binary file\n";	next;    }     seek(FILE, 0, 0);     $in_bytes = 0;    $out_bytes = 0;    $blank_bytes = 0;     @blanks = ();    @lines  = ();    $lineno = 0;     while ( defined($line = <FILE>) ) {	$lineno++;	$in_bytes += length($line);	$line =~ s/[ \t\r]*$//;		# Remove trailing spaces	$line = clean_space_tabs($line); 	if ( $line eq "\n" ) {	    push(@blanks, $line);	    $blank_bytes += length($line);	} else {	    push(@lines, @blanks);	    $out_bytes += $blank_bytes;	    push(@lines, $line);	    $out_bytes += length($line);	    @blanks = ();	    $blank_bytes = 0;	} 	$l_width = strwidth($line);	if ($max_width && $l_width > $max_width) {	    print STDERR		"$f:$lineno: line exceeds $max_width characters ($l_width)\n";	}    }     # Any blanks at the end of the file are discarded     if ($in_bytes != $out_bytes) {	# Only write to the file if changed	seek(FILE, 0, 0);	print FILE @lines; 	if ( !defined($where = tell(FILE)) ||	     !truncate(FILE, $where) ) {	    die "$name: Failed to truncate modified file: $f: $!\n";	}    }     close(FILE);}