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SubjectRe: [SCRIPT] chomp: trim trailing whitespace
Jeff Garzik wrote:
> H. Peter Anvin wrote:
>> Jeff Garzik wrote:
>>>
>>> Attached to this email is chomp.pl, a Perl script which removes
>>> trailing whitespace from several files. I've had this for years, as
>>> trailing whitespace is one of my pet peeves.
>>>
>>> Now that git-applymbox complains loudly whenever a patch adds
>>> trailing whitespace, I figured this script may be useful to others.
>>>
>>
>> This is the script I use for the same purpose. It's a bit more
>> sophisticated, in that it detects and avoids binary files, and doesn't
>> throw an error if it encounters a directory (which can happen if you
>> give it a wildcard.)
>
> Chewing the EOF blanks is nice. The only nit I have is that your script
> rewrites the file even if nothing was changed.
>

Ah, good point. Attached version fixes that. It still doesn't break
hard links, which may be a desirable feature.

-hpa
#!/usr/bin/perl
#
# Clean a text file of stealth whitespace
#

use bytes;

$name = 'cleanfile';

foreach $f ( @ARGV ) {
print STDERR "$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
$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 = ();

while ( defined($line = <FILE>) ) {
$in_bytes += length($line);
$line =~ s/[ \t\r\n]*$/\n/;

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;
}
}

# 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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