xref: /linux/scripts/cleanfile (revision 7aacf86b75bc5523d20fd9127104384fce51ce9c) 
1#!/usr/bin/env perl
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
7use warnings;
8use bytes;
9use File::Basename;
10
11# Default options
12$max_width = 79;
13
14# Clean up space-tab sequences, either by removing spaces or
15# replacing them with tabs.
16sub clean_space_tabs($)
17{
18    no bytes;			# Tab alignment depends on characters
19
20    my($li) = @_;
21    my($lo) = '';
22    my $pos = 0;
23    my $nsp = 0;
24    my($i, $c);
25
26    for ($i = 0; $i < length($li); $i++) {
27	$c = substr($li, $i, 1);
28	if ($c eq "\t") {
29	    my $npos = ($pos+$nsp+8) & ~7;
30	    my $ntab = ($npos >> 3) - ($pos >> 3);
31	    $lo .= "\t" x $ntab;
32	    $pos = $npos;
33	    $nsp = 0;
34	} elsif ($c eq "\n" || $c eq "\r") {
35	    $lo .= " " x $nsp;
36	    $pos += $nsp;
37	    $nsp = 0;
38	    $lo .= $c;
39	    $pos = 0;
40	} elsif ($c eq " ") {
41	    $nsp++;
42	} else {
43	    $lo .= " " x $nsp;
44	    $pos += $nsp;
45	    $nsp = 0;
46	    $lo .= $c;
47	    $pos++;
48	}
49    }
50    $lo .= " " x $nsp;
51    return $lo;
52}
53
54# Compute the visual width of a string
55sub strwidth($) {
56    no bytes;			# Tab alignment depends on characters
57
58    my($li) = @_;
59    my($c, $i);
60    my $pos = 0;
61    my $mlen = 0;
62
63    for ($i = 0; $i < length($li); $i++) {
64	$c = substr($li,$i,1);
65	if ($c eq "\t") {
66	    $pos = ($pos+8) & ~7;
67	} elsif ($c eq "\n") {
68	    $mlen = $pos if ($pos > $mlen);
69	    $pos = 0;
70	} else {
71	    $pos++;
72	}
73    }
74
75    $mlen = $pos if ($pos > $mlen);
76    return $mlen;
77}
78
79$name = basename($0);
80
81@files = ();
82
83while (defined($a = shift(@ARGV))) {
84    if ($a =~ /^-/) {
85	if ($a eq '-width' || $a eq '-w') {
86	    $max_width = shift(@ARGV)+0;
87	} else {
88	    print STDERR "Usage: $name [-width #] files...\n";
89	    exit 1;
90	}
91    } else {
92	push(@files, $a);
93    }
94}
95
96foreach $f ( @files ) {
97    print STDERR "$name: $f\n";
98
99    if (! -f $f) {
100	print STDERR "$f: not a file\n";
101	next;
102    }
103
104    if (!open(FILE, '+<', $f)) {
105	print STDERR "$name: Cannot open file: $f: $!\n";
106	next;
107    }
108
109    binmode FILE;
110
111    # First, verify that it is not a binary file; consider any file
112    # with a zero byte to be a binary file.  Is there any better, or
113    # additional, heuristic that should be applied?
114    $is_binary = 0;
115
116    while (read(FILE, $data, 65536) > 0) {
117	if ($data =~ /\0/) {
118	    $is_binary = 1;
119	    last;
120	}
121    }
122
123    if ($is_binary) {
124	print STDERR "$name: $f: binary file\n";
125	next;
126    }
127
128    seek(FILE, 0, 0);
129
130    $in_bytes = 0;
131    $out_bytes = 0;
132    $blank_bytes = 0;
133
134    @blanks = ();
135    @lines  = ();
136    $lineno = 0;
137
138    while ( defined($line = <FILE>) ) {
139	$lineno++;
140	$in_bytes += length($line);
141	$line =~ s/[ \t\r]*$//;		# Remove trailing spaces
142	$line = clean_space_tabs($line);
143
144	if ( $line eq "\n" ) {
145	    push(@blanks, $line);
146	    $blank_bytes += length($line);
147	} else {
148	    push(@lines, @blanks);
149	    $out_bytes += $blank_bytes;
150	    push(@lines, $line);
151	    $out_bytes += length($line);
152	    @blanks = ();
153	    $blank_bytes = 0;
154	}
155
156	$l_width = strwidth($line);
157	if ($max_width && $l_width > $max_width) {
158	    print STDERR
159		"$f:$lineno: line exceeds $max_width characters ($l_width)\n";
160	}
161    }
162
163    # Any blanks at the end of the file are discarded
164
165    if ($in_bytes != $out_bytes) {
166	# Only write to the file if changed
167	seek(FILE, 0, 0);
168	print FILE @lines;
169
170	if ( !defined($where = tell(FILE)) ||
171	     !truncate(FILE, $where) ) {
172	    die "$name: Failed to truncate modified file: $f: $!\n";
173	}
174    }
175
176    close(FILE);
177}
178