Re: [SCRIPT] chomp: trim trailing whitespace

["H. Peter Anvin" <hpa@zytor.com>]

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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

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#!/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);
}