FreeBSD/Linux Kernel Cross Reference
sys/scripts/cleanfile

     #!/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 string
    sub 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);
   }

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