xref: /linux/scripts/cleanfile (revision bf80eef2212a1e8451df13b52533f4bc31bb4f8e) 
1#!/usr/bin/env perl
2# SPDX-License-Identifier: GPL-2.0
3#
4# Clean a text file -- or directory of text files -- of stealth whitespace.
5# WARNING: this can be a highly destructive operation.  Use with caution.
6#
7
8use warnings;
9use bytes;
10use File::Basename;
11
12# Default options
13$max_width = 79;
14
15# Clean up space-tab sequences, either by removing spaces or
16# replacing them with tabs.
17sub clean_space_tabs($)
18{
19    no bytes;			# Tab alignment depends on characters
20
21    my($li) = @_;
22    my($lo) = '';
23    my $pos = 0;
24    my $nsp = 0;
25    my($i, $c);
26
27    for ($i = 0; $i < length($li); $i++) {
28	$c = substr($li, $i, 1);
29	if ($c eq "\t") {
30	    my $npos = ($pos+$nsp+8) & ~7;
31	    my $ntab = ($npos >> 3) - ($pos >> 3);
32	    $lo .= "\t" x $ntab;
33	    $pos = $npos;
34	    $nsp = 0;
35	} elsif ($c eq "\n" || $c eq "\r") {
36	    $lo .= " " x $nsp;
37	    $pos += $nsp;
38	    $nsp = 0;
39	    $lo .= $c;
40	    $pos = 0;
41	} elsif ($c eq " ") {
42	    $nsp++;
43	} else {
44	    $lo .= " " x $nsp;
45	    $pos += $nsp;
46	    $nsp = 0;
47	    $lo .= $c;
48	    $pos++;
49	}
50    }
51    $lo .= " " x $nsp;
52    return $lo;
53}
54
55# Compute the visual width of a string
56sub strwidth($) {
57    no bytes;			# Tab alignment depends on characters
58
59    my($li) = @_;
60    my($c, $i);
61    my $pos = 0;
62    my $mlen = 0;
63
64    for ($i = 0; $i < length($li); $i++) {
65	$c = substr($li,$i,1);
66	if ($c eq "\t") {
67	    $pos = ($pos+8) & ~7;
68	} elsif ($c eq "\n") {
69	    $mlen = $pos if ($pos > $mlen);
70	    $pos = 0;
71	} else {
72	    $pos++;
73	}
74    }
75
76    $mlen = $pos if ($pos > $mlen);
77    return $mlen;
78}
79
80$name = basename($0);
81
82@files = ();
83
84while (defined($a = shift(@ARGV))) {
85    if ($a =~ /^-/) {
86	if ($a eq '-width' || $a eq '-w') {
87	    $max_width = shift(@ARGV)+0;
88	} else {
89	    print STDERR "Usage: $name [-width #] files...\n";
90	    exit 1;
91	}
92    } else {
93	push(@files, $a);
94    }
95}
96
97foreach $f ( @files ) {
98    print STDERR "$name: $f\n";
99
100    if (! -f $f) {
101	print STDERR "$f: not a file\n";
102	next;
103    }
104
105    if (!open(FILE, '+<', $f)) {
106	print STDERR "$name: Cannot open file: $f: $!\n";
107	next;
108    }
109
110    binmode FILE;
111
112    # First, verify that it is not a binary file; consider any file
113    # with a zero byte to be a binary file.  Is there any better, or
114    # additional, heuristic that should be applied?
115    $is_binary = 0;
116
117    while (read(FILE, $data, 65536) > 0) {
118	if ($data =~ /\0/) {
119	    $is_binary = 1;
120	    last;
121	}
122    }
123
124    if ($is_binary) {
125	print STDERR "$name: $f: binary file\n";
126	next;
127    }
128
129    seek(FILE, 0, 0);
130
131    $in_bytes = 0;
132    $out_bytes = 0;
133    $blank_bytes = 0;
134
135    @blanks = ();
136    @lines  = ();
137    $lineno = 0;
138
139    while ( defined($line = <FILE>) ) {
140	$lineno++;
141	$in_bytes += length($line);
142	$line =~ s/[ \t\r]*$//;		# Remove trailing spaces
143	$line = clean_space_tabs($line);
144
145	if ( $line eq "\n" ) {
146	    push(@blanks, $line);
147	    $blank_bytes += length($line);
148	} else {
149	    push(@lines, @blanks);
150	    $out_bytes += $blank_bytes;
151	    push(@lines, $line);
152	    $out_bytes += length($line);
153	    @blanks = ();
154	    $blank_bytes = 0;
155	}
156
157	$l_width = strwidth($line);
158	if ($max_width && $l_width > $max_width) {
159	    print STDERR
160		"$f:$lineno: line exceeds $max_width characters ($l_width)\n";
161	}
162    }
163
164    # Any blanks at the end of the file are discarded
165
166    if ($in_bytes != $out_bytes) {
167	# Only write to the file if changed
168	seek(FILE, 0, 0);
169	print FILE @lines;
170
171	if ( !defined($where = tell(FILE)) ||
172	     !truncate(FILE, $where) ) {
173	    die "$name: Failed to truncate modified file: $f: $!\n";
174	}
175    }
176
177    close(FILE);
178}
179