scripts/cleanfile

   1 #!/usr/bin/perl -w
   2 #
   3 # Clean a text file -- or directory of text files -- of stealth whitespace.
   4 # WARNING: this can be a highly destructive operation.  Use with caution.
   5 #
   6
   7 use bytes;
   8 use File::Basename;
   9
  10 #
  11 # Clean up space-tab sequences, either by removing spaces or
  12 # replacing them with tabs.
  13 sub clean_space_tabs($)
  14 {
  15     no bytes;                   # Tab alignment depends on characters
  16
  17     my($li) = @_;
  18     my($lo) = '';
  19     my $pos = 0;
  20     my $nsp = 0;
  21     my($i, $c);
  22
  23     for ($i = 0; $i < length($li); $i++) {
  24         $c = substr($li, $i, 1);
  25         if ($c eq "\t") {
  26             my $npos = ($pos+$nsp+8) & ~7;
  27             my $ntab = ($npos >> 3) - ($pos >> 3);
  28             $lo .= "\t" x $ntab;
  29             $pos = $npos;
  30             $nsp = 0;
  31         } elsif ($c eq "\n" || $c eq "\r") {
  32             $lo .= " " x $nsp;
  33             $pos += $nsp;
  34             $nsp = 0;
  35             $lo .= $c;
  36             $pos = 0;
  37         } elsif ($c eq " ") {
  38             $nsp++;
  39         } else {
  40             $lo .= " " x $nsp;
  41             $pos += $nsp;
  42             $nsp = 0;
  43             $lo .= $c;
  44             $pos++;
  45         }
  46     }
  47     $lo .= " " x $nsp;
  48     return $lo;
  49 }
  50
  51 $name = basename($0);
  52
  53 foreach $f ( @ARGV ) {
  54     print STDERR "$name: $f\n";
  55
  56     if (! -f $f) {
  57         print STDERR "$f: not a file\n";
  58         next;
  59     }
  60
  61     if (!open(FILE, '+<', $f)) {
  62         print STDERR "$name: Cannot open file: $f: $!\n";
  63         next;
  64     }
  65
  66     binmode FILE;
  67
  68     # First, verify that it is not a binary file; consider any file
  69     # with a zero byte to be a binary file.  Is there any better, or
  70     # additional, heuristic that should be applied?
  71     $is_binary = 0;
  72
  73     while (read(FILE, $data, 65536) > 0) {
  74         if ($data =~ /\0/) {
  75             $is_binary = 1;
  76             last;
  77         }
  78     }
  79
  80     if ($is_binary) {
  81         print STDERR "$name: $f: binary file\n";
  82         next;
  83     }
  84
  85     seek(FILE, 0, 0);
  86
  87     $in_bytes = 0;
  88     $out_bytes = 0;
  89     $blank_bytes = 0;
  90
  91     @blanks = ();
  92     @lines  = ();
  93
  94     while ( defined($line = <FILE>) ) {
  95         $in_bytes += length($line);
  96         $line =~ s/[ \t\r]*$//;         # Remove trailing spaces
  97         $line = clean_space_tabs($line);
  98
  99         if ( $line eq "\n" ) {
 100             push(@blanks, $line);
 101             $blank_bytes += length($line);
 102         } else {
 103             push(@lines, @blanks);
 104             $out_bytes += $blank_bytes;
 105             push(@lines, $line);
 106             $out_bytes += length($line);
 107             @blanks = ();
 108             $blank_bytes = 0;
 109         }
 110     }
 111
 112     # Any blanks at the end of the file are discarded
 113
 114     if ($in_bytes != $out_bytes) {
 115         # Only write to the file if changed
 116         seek(FILE, 0, 0);
 117         print FILE @lines;
 118
 119         if ( !defined($where = tell(FILE)) ||
 120              !truncate(FILE, $where) ) {
 121             die "$name: Failed to truncate modified file: $f: $!\n";
 122         }
 123     }
 124
 125     close(FILE);
 126 }