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Imager::QRCode-ing octet sequences vs. zbarimg(1)

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  Imager::QRCode-ing octet sequences vs. zbarimg(1) Ivan Shmakov <oneingray@gmail.com> - 2013-03-13 11:40 +0000
    Re: Imager::QRCode-ing octet sequences vs. zbarimg(1) Ben Morrow <ben@morrow.me.uk> - 2013-03-13 16:27 +0000
      bytes, English, and prototypes Ivan Shmakov <oneingray@gmail.com> - 2013-03-13 17:28 +0000
      Re: Imager::QRCode-ing octet sequences vs. zbarimg(1) Ivan Shmakov <oneingray@gmail.com> - 2013-03-14 20:25 +0000
      Re: Imager::QRCode-ing octet sequences vs. zbarimg(1) Ivan Shmakov <oneingray@gmail.com> - 2013-03-17 17:57 +0000
        Re: Imager::QRCode-ing octet sequences vs. zbarimg(1) Ben Morrow <ben@morrow.me.uk> - 2013-03-18 23:42 +0000
          [OT] reporting bugs Ivan Shmakov <oneingray@gmail.com> - 2013-03-30 11:02 +0000
            Re: reporting bugs Ben Morrow <ben@morrow.me.uk> - 2013-04-01 22:58 +0100
              Re: reporting bugs Ivan Shmakov <oneingray@gmail.com> - 2013-04-06 13:50 +0000
            configuring CPAN to apply patches (such as #29468, IPv6 in Net::HTTP) Ivan Shmakov <oneingray@gmail.com> - 2013-06-28 19:48 +0000

#203 — Imager::QRCode-ing octet sequences vs. zbarimg(1)

	[AIUI, discussion of Perl modules is more appropriate for
	news:comp.lang.perl.modules.  Yet, it appears to be abandoned,
	thus cross-posting to news:comp.lang.perl.misc.  Cross-posting
	to news:alt.barcodes, too, just in case.]

	I wonder if QR codes are suitable for encoding arbitrary octet
	sequences (AKA 8-bit data)?  I've tried the following Perl code,
	but it appears that the resulting transformations aren't "8-bit
	clean."  Somehow, I suspect a QR::Imager fault, although
	zbarimg(1) may be responsible.  (Unfortunately, the Perl module
	itself doesn't provide a decoder.)

	Any idea what may be going on?

	TIA.

	(The leading 51522d436f64653a and the trailing 0a after
	"Decoded:" are "QR-Code:" and a newline, respectively.  In the
	first example, the first three octets in the output, 621d4f,
	appear to match the input.  Incidentally, the fourth octet has
	its most significant bit set.)

$ perl \
      89br96tnpoogun68sfh1jkj1sb.perl # "use bytes;" commented out
Blob:     621d4f87d3ae92b60932c96b7f81f3a916faff9b03ae54f97d8163987dc8733df1bd8f8b92fb5317657ee2a0a97eed1f12423cdbfa1a73b3166a39cb4b1c0f43
Image:    123 by 123
Decoded:  51522d436f64653a621d4fc287c393c2aec292c2b60932c3896b7fc281c3b3c2a916c3bac3bfc29b03c2ae54c3b97dc28163c2987dc388733dc3b1c2bdc28fc28bc292c3bb5317657ec3a2c2a0c2a97ec3ad1f12423cc39bc3ba1a73c2b3166a39c38b4b1c0f430a
scanned 1 barcode symbols from 1 images in 0.02 seconds

$ perl \
      89br96tnpoogun68sfh1jkj1sb.perl # "use bytes;" in place
Blob:     8abdab3e25ae4e44fbc50d9aedcadfb34b1eb959f78ca306bff1182f00024d1ca9e5d7db8827fdd4ab8169a18130cc3de3b31da82150bff080fe57d591f909cf
Image:    99 by 99
Decoded:  51522d436f64653ac28ac2bdc2ab3e25c2ae4e44c3bbc3850dc29ac3adc38ac39fc2b34b1ec2b959c3b7c28cc2a306c2bfc3b1182f0a
scanned 1 barcode symbols from 1 images in 0.02 seconds

$ LC_ALL=C perl \
      89br96tnpoogun68sfh1jkj1sb.perl # "use bytes;" in place
Blob:     aba7c3b1e7721a22660308e7a7a7f6cfdb48b18fb2143d823021ece0bb2dde2ed0fe2d4b06fb56c4167e867a1f0ef4f495a46a6efb2ce76621fb58b5bd817605
Image:    123 by 123
Decoded:  51522d436f64653ac2abc2a7c383c2b1c3a7721a22660308c3a7c2a7c2a7c3b6c38fc39b48c2b1c28fc2b2143dc2823021c3acc3a0c2bb2dc39e2ec390c3be2d4b06c3bb56c384167ec2867a1f0ec3b4c3b4c295c2a46a6ec3bb2cc3a76621c3bb58c2b5c2bdc28176050a
scanned 1 barcode symbols from 1 images in 0.03 seconds

$ cat < 89br96tnpoogun68sfh1jkj1sb.perl 
use bytes;
use common::sense;
use English;

require Imager::QRCode;
require IPC::Open2;

sub rand_blob (;$) {
    my ($len) = @_;
    $len
	//= 24;
    open (my $f, "<", "/dev/urandom")
	or die ($OS_ERROR);
    binmode ($f);
    my $s;
    die ($OS_ERROR)
	unless (read ($f, $s, $len) == $len);
    ## .
    $s;
}

my $blob
    = rand_blob (64);
print ("Blob:     ", unpack ("H*", $blob), "\n");

my $qr
    = Imager::QRCode->new (qw (mode 8-bit  casesensitive 1));
my $img
    = $qr->plot ($blob);
print ("Image:    ", $img->getwidth (),
       " by ", $img->getheight (), "\n");

my ($in, $out);
my $pid
    = IPC::Open2::open2 ($in, $out, qw (zbarimg -- -))
    or die ($OS_ERROR);
binmode ($in);
binmode ($out);

$img->write ("fh" => $out, "type" => "pnm")
    or die ($img->errstr ());
close ($out);
my $dec
    = <$in>;
print ("Decoded:  ", unpack ("H*", $dec), "\n");
$ 

-- 
FSF associate member #7257

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#204

Quoth Ivan Shmakov <oneingray@gmail.com>:
> 
> 	I wonder if QR codes are suitable for encoding arbitrary octet
> 	sequences (AKA 8-bit data)?  I've tried the following Perl code,
> 	but it appears that the resulting transformations aren't "8-bit
> 	clean."  Somehow, I suspect a QR::Imager fault, although
> 	zbarimg(1) may be responsible.  (Unfortunately, the Perl module
> 	itself doesn't provide a decoder.)

There is a Perl decoder based on zbar (Barcode::ZBar), though presumably
it would behave the same as zbarimg.

[...]
> 
> 	(The leading 51522d436f64653a and the trailing 0a after
> 	"Decoded:" are "QR-Code:" and a newline, respectively.  In the
> 	first example, the first three octets in the output, 621d4f,
> 	appear to match the input.  Incidentally, the fourth octet has
> 	its most significant bit set.)
> 
> $ perl \
>       89br96tnpoogun68sfh1jkj1sb.perl # "use bytes;" commented out
> Blob:    
> 621d4f87d3ae92b60932c96b7f81f3a916faff9b03ae54f97d8163987dc8733df1bd
> 8f8b92fb5317657ee2a0a97eed1f12423cdbfa1a73b3166a39cb4b1c0f43
> Image:    123 by 123
> Decoded: 
> 51522d436f64653a621d4fc287c393c2aec292c2b60932c3896b7fc281c3b3c2a916
> c3bac3bfc29b03c2ae54c3b97dc28163c2987dc388733dc3b1c2bdc28fc28bc292c3
> bb5317657ec3a2c2a0c2a97ec3ad1f12423cc39bc3ba1a73c2b3166a39c38b4b1c0f
> 430a
> scanned 1 barcode symbols from 1 images in 0.02 seconds

    ~% perl -MEncode -E'say unpack "H*", encode "utf8", pack "H*",
        "621d4f87d3ae92b60932c96b7"'
    621d4fc287c393c2aec292c2b60932c3896b70

So you have a UTF-8 problem somewhere. (c2 and c3 (or  and Ã) showing
up unexpectedly is the giveaway here.) Looking at the code, I think it's
zbar which is converting 8859-1 to UTF-8; one way to test this is to
create a QR code containing 17 0xffs at ECC level L; this is the maximum
number of characters that will fit into a 21x21 QR code, so if the code
comes out bigger than that you know there are extra bytes in there
somewhere.

However, it's not unlikely that other QR code readers will do similar
conversions to UTF-8, or other stupid things. Depending on what you're
doing it might be safer to explicitly UTF-8-encode your data (all 8-bit
data can be represented in UTF-8) and then decode it on the other end.
Of course, this will make the codes a little larger than they need to
be.

[...]
> $ cat < 89br96tnpoogun68sfh1jkj1sb.perl 
> use bytes;

You should not use 'bytes'. It doesn't ever do anything useful and
sometimes lets you look at parts of the perl internals you shouldn't be
looking at. In previous versions of perl the documentation was
unfortunately not very clear about that. The current version says

    NOTICE

    This pragma reflects early attempts to incorporate Unicode into perl
    and has since been superseded. It breaks encapsulation (i.e. it
    exposes the innards of how the perl executable currently happens to
    store a string), and use of this module for anything other than
    debugging purposes is strongly discouraged.

> use common::sense;
> use English;

You should not use English, it makes your code harder to read for anyone
who knows Perl, and teaches you bad habits.

> 
> require Imager::QRCode;
> require IPC::Open2;
> 
> sub rand_blob (;$) {

You should not use prototypes unless you need the special parsing
effects they cause.

>     my ($len) = @_;
>     $len
> 	//= 24;
>     open (my $f, "<", "/dev/urandom")
> 	or die ($OS_ERROR);
>     binmode ($f);
>     my $s;
>     die ($OS_ERROR)
> 	unless (read ($f, $s, $len) == $len);
>     ## .
>     $s;
> }

Unless you need cryptographic randomness (and since you're using
urandom, you don't), it would be better to use something like

    sub rand_blob {
        my ($len) = @_;
        $len //= 24;
        return join "", map chr rand 0xff, 0..$len;
    }

Ben

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#205 — bytes, English, and prototypes

>>>>> Ben Morrow <ben@morrow.me.uk> writes:
>>>>> Quoth Ivan Shmakov <oneingray@gmail.com>:

	[Dropping news:comp.lang.perl.modules and news:alt.barcodes from
	Followup-To:.]

[...]

 >> $ cat < 89br96tnpoogun68sfh1jkj1sb.perl 

 >> use bytes;

 > You should not use 'bytes'.  It doesn't ever do anything useful and
 > sometimes lets you look at parts of the perl internals you shouldn't
 > be looking at.

	Indeed, I've read the documentation.  It was my understanding
	that, in the nutshell, the "bytes" pragma makes Perl operate
	strictly on octet sequences for its strings, instead of allowing
	either strings of octets /or/ strings of Unicode characters.

	Frankly, I do not see any harm in using this pragma /provided/
	that the code doesn't switch it on and off at will.

	The question on what setting do the loaded modules use remains
	open, but for the specific example I've given (which uses no
	text-processing modules) I'd expect the chances of running into
	issues to be quite low.

[...]

 >> use English;

 > You should not use English, it makes your code harder to read for
 > anyone who knows Perl, and teaches you bad habits.

	?  I may be having a bit too much Lisp background, but I've
	always considered something_that_one_can_read to be a way better
	identifier for a global than, say, ~.

	Besides, there's a chance that the code I write will be read by
	someone not quite knowing Perl.

[...]

 >> sub rand_blob (;$) {

 > You should not use prototypes unless you need the special parsing
 > effects they cause.

	Is there a practical reason to forgo the compile-time arguments'
	type checking they offer?  For me, code that fails to compile is
	better than code that suddenly dies after running for hours.
	(Which is still better than the code that dies at the wrong
	place; or doesn't die, but silently gives a wrong result.)

[...]

 > Unless you need cryptographic randomness (and since you're using
 > urandom, you don't), it would be better to use something like

 > sub rand_blob {
 >     my ($len) = @_;
 >     $len //= 24;
 >     return join "", map chr rand 0xff, 0..$len;
 > }

	ACK, thanks.  (Although, my guess is that even if urandom(4) is
	worse than random(4), Perl's rand is worse, randomness-wise,
	still.)

-- 
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#206

>>>>> Ben Morrow <ben@morrow.me.uk> writes:

[...]

 > There is a Perl decoder based on zbar (Barcode::ZBar), though
 > presumably it would behave the same as zbarimg.

	... Or it may not.  It definitely worths checking out.

[...]

 > So you have a UTF-8 problem somewhere.  (c2 and c3 (or  and Ã)
 > showing up unexpectedly is the giveaway here.)  Looking at the code,
 > I think it's zbar which is converting 8859-1 to UTF-8; one way to
 > test this is to create a QR code containing 17 0xffs at ECC level L;
 > this is the maximum number of characters that will fit into a 21x21
 > QR code, so if the code comes out bigger than that you know there are
 > extra bytes in there somewhere.

	ACK, thanks!  With qw (level L  margin 0  size 2) being added to
	the parameters, the code now gives (also using $ zbarimg --raw):

Blob:     ffffffffffffffffffffffffffffffffff
Image:    42 by 42
Decoded:  c3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bfc3bf0a
scanned 1 barcode symbols from 1 images in 0.05 seconds

	Thus, unless there's some magic in the resulting QR code saying
	that it's an ISO-8859-1-encoded string (I'm not familiar with QR
	encoding, so can't tell if it's a sensible guess), zbarimg(1),
	is indeed to blame, and perhaps the underlying library, too.

 > However, it's not unlikely that other QR code readers will do similar
 > conversions to UTF-8, or other stupid things.  Depending on what
 > you're doing it might be safer to explicitly UTF-8-encode your data
 > (all 8-bit data can be represented in UTF-8) and then decode it on
 > the other end.  Of course, this will make the codes a little larger
 > than they need to be.

	In this case, there'd indeed be some benefit from using the
	smallest-possible image.  OTOH, I do not expect for the problem
	of interoperability to arise anytime soon.

[...]

-- 
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#207

>>>>> Ben Morrow <ben@morrow.me.uk> writes:
>>>>> Quoth Ivan Shmakov <oneingray@gmail.com>:

 >> I wonder if QR codes are suitable for encoding arbitrary octet
 >> sequences (AKA 8-bit data)?  I've tried the following Perl code, but
 >> it appears that the resulting transformations aren't "8-bit clean."
 >> Somehow, I suspect a QR::Imager fault, although zbarimg(1) may be
 >> responsible.  (Unfortunately, the Perl module itself doesn't provide
 >> a decoder.)

 > There is a Perl decoder based on zbar (Barcode::ZBar), though
 > presumably it would behave the same as zbarimg.

	... Indeed it does, which made me file Debian Bug#703234 [1].

	Now, however, given that the Wikipedia article mentions
	ISO-8859-1 as the default (?) encoding for 8-bit QR codes, the
	issues zbarimg(1) and Barcode::ZBar have may be considered
	separately.

	Taking into account that different symbologies may (and do) use
	different character to code mappings, it may be sensible for
	libzbar to recode the barcode read into an UTF-8 string.  Better
	still is that Perl supports UTF-8 as its native character string
	representation.  What's wrong, however, is that the UTF-8 string
	returned by libzbar to Perl is not properly marked as such, thus
	resulting in the observed (and incorrect) behavior.

	(The obvious workaround is to Encode::decode_utf8 () the
	symbol's data returned by ->get_data ().)

	OTOH, zbarimg(1) should probably respect the current locale's
	encoding, instead of using UTF-8 unconditionally.

[1] http://bugs.debian.org/703234

[...]

-- 
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#208

Quoth Ivan Shmakov <oneingray@gmail.com>:
> >>>>> Ben Morrow <ben@morrow.me.uk> writes:
> >>>>> Quoth Ivan Shmakov <oneingray@gmail.com>:
> 
>  >> I wonder if QR codes are suitable for encoding arbitrary octet
>  >> sequences (AKA 8-bit data)?  I've tried the following Perl code, but
>  >> it appears that the resulting transformations aren't "8-bit clean."
>  >> Somehow, I suspect a QR::Imager fault, although zbarimg(1) may be
>  >> responsible.  (Unfortunately, the Perl module itself doesn't provide
>  >> a decoder.)
> 
>  > There is a Perl decoder based on zbar (Barcode::ZBar), though
>  > presumably it would behave the same as zbarimg.
> 
> 	... Indeed it does, which made me file Debian Bug#703234 [1].

<pet peeve> The correct place to file a bug in a Perl module is in its
CPAN bug tracker, or, in this case, in the zbar Sourceforce tracker.
Filing a bug with some random distro is Not Helpful, since such reports
frequently don't find their way upstream.

> 	Now, however, given that the Wikipedia article mentions
> 	ISO-8859-1 as the default (?) encoding for 8-bit QR codes, the
> 	issues zbarimg(1) and Barcode::ZBar have may be considered
> 	separately.

The zbar source implies that some QR codes contain something called an
ECI which explicitly indicates the charset in use. It's not clear to me
without reading the spec (which apparently isn't freely available, grr)
how 'binary' QR codes with no ECI are supposed to be interpreted.

> 	Taking into account that different symbologies may (and do) use
> 	different character to code mappings, it may be sensible for
> 	libzbar to recode the barcode read into an UTF-8 string.

Well, that's only sensible if the bytes are always supposed to represent
characters. libzbar also does more than just recode 8859-1 -> UTF-8: if
I'm reading it right, it tries to guess the encoding, and if the encoded
data is already valid UTF-8 it will leave it alone.

> Better
> 	still is that Perl supports UTF-8 as its native character string
> 	representation.  What's wrong, however, is that the UTF-8 string
> 	returned by libzbar to Perl is not properly marked as such, thus
> 	resulting in the observed (and incorrect) behavior.

This is a bug, yes.

> 	(The obvious workaround is to Encode::decode_utf8 () the
> 	symbol's data returned by ->get_data ().)
> 
> 	OTOH, zbarimg(1) should probably respect the current locale's
> 	encoding, instead of using UTF-8 unconditionally.

I don't know about that: what if the data can't be represented in that
charset?

Ben

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#209 — [OT] reporting bugs

>>>>> Ben Morrow <ben@morrow.me.uk> writes:
>>>>> Quoth Ivan Shmakov <oneingray@gmail.com>:
>>>>> Ben Morrow <ben@morrow.me.uk> writes:

	(Thanks for the comments regarding ZBar, BTW.  I'm yet to check
	its sources myself, but I've also discovered that it behaves
	strangely not only for the octets having the most significant
	bit set, but for the "plain old" \x0D = \r just as well.)

[...]

 >>> There is a Perl decoder based on zbar (Barcode::ZBar), though
 >>> presumably it would behave the same as zbarimg.

 >> ... Indeed it does, which made me file Debian Bug#703234 [1].

 > <pet peeve> The correct place to file a bug in a Perl module is in
 > its CPAN bug tracker, or, in this case, in the zbar Sourceforce
 > tracker.

	BTW, there's a longstanding bug filed at the CPAN RT [2] (along
	with a patch.)  However, it appears to be filed against
	libwww-perl, while it actually belongs to Net-HTTP.

	The question is: how do I reassign it?

[2] https://rt.cpan.org/Public/Bug/Display.html?id=29468

 > Filing a bug with some random distro is Not Helpful, since such
 > reports frequently don't find their way upstream.

	Yes.  As long as an ideal world is considered, that is.

	There're a few things to note, however.  The general problems
	with upstream may include:

	* there's effectively no upstream;

	* the code in the distribution may be extensively modified, or
	  improperly built, or be alleged to be; the upstream then may
	  discourage the users of "non-authorized" builds to report bugs
	  directly to them; consider, e. g.:

--cut: http://foo2zjs.rkkda.com/ --
    *** DON'T USE the foo2zjs package from:

    Ubuntu, SUSE, Mandrake/Manrivia, Debian, RedHat, Fedora, Gentoo,
    Xandros, EEE PC, Linpus, MacOSX, or BSD!

    *** Download it here and follow the directions below.
--cut: http://foo2zjs.rkkda.com/ --

	  (or the Joerg Schilling, albeit sufficiently different, case);

	* the issue may indeed be specific to the distribution's build;
	  (naturally, building from the upstream sources for every bug
	  being I report just to check that it wasn't introduced by the
	  packagers is hardly an option.)

	Personally, I tend to prefer either the Debian BTS, or the
	CPAN RT, for these make it possible to file bugs via email,
	/and/ are better compatible with Lynx (which happens to be my
	primary browser) than most of the other BTS currently in use.
	(I'm particularly fond of RT, although the version installed at
	CPAN has certain surprising issue when it comes to the
	compatibility with non-ECMAScript-enabled browsers.)

	Alas, even for the Perl modules, the CPAN RT is not always the
	preferred but tracker.  Consider, e. g.:

--cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --
    Please report issues via github at
    https://github.com/gbarr/perl-Convert-ASN1/issues
--cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --

	Lastly, given the developer- and user-base of Debian (especially
	if the derivatives are included), I'd not call it "random."
	That being said, I tend to agree that when the D-M in charge
	fails to forward the request to the upstream, the reporter
	generally should try to do it him- or herself.

	(OTOH, even if D-M forwards the request, it may not have the
	desired effect.  Consider, e. g., Debian Bug#691221 [3].)

[3] http://bugs.debian.org/691221

[...]

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#211 — Re: reporting bugs

[alt.barcodes removed, since this is about Perl process]

Quoth Ivan Shmakov <oneingray@gmail.com>:
> >>>>> Ben Morrow <ben@morrow.me.uk> writes:
> 
>  > <pet peeve> The correct place to file a bug in a Perl module is in
>  > its CPAN bug tracker, or, in this case, in the zbar Sourceforce
>  > tracker.
> 
> 	BTW, there's a longstanding bug filed at the CPAN RT [2] (along
> 	with a patch.)  However, it appears to be filed against
> 	libwww-perl, while it actually belongs to Net-HTTP.
> 
> 	The question is: how do I reassign it?
> 
> [2] https://rt.cpan.org/Public/Bug/Display.html?id=29468

You can't; in fact, it looks like the way rt.cpan.org is set up noone
can move a ticket from one queue to another. The best you could do is
file a separate bug against Net-HTTP, referencing the LWP bug; but since
both dists are maintained by Gisle Aas I'm not sure there'd be much
point.

>  > Filing a bug with some random distro is Not Helpful, since such
>  > reports frequently don't find their way upstream.
[...]
> 	* the issue may indeed be specific to the distribution's build;
> 	  (naturally, building from the upstream sources for every bug
> 	  being I report just to check that it wasn't introduced by the
> 	  packagers is hardly an option.)

Obviously you have a different approach from me. I would consider
building the latest upstream release from source, and probably the
latest upstream equivalent of CVS HEAD, a basic prerequisite for
reporting a bug. After all, it's almost certainly the first thing you'll
be asked to do in any case, and a patch which doesn't apply to HEAD is
probably nearly worthless.

I suppose that in principle 'I'm using a distro; I'm paying them (or
not) to sort out whose bug it is and get it fixed upstream' ought to be
a reasonable argument, but in practice distros tend to be extremely
unreliable about sending bugs upstream, probably because they have had
their own share of flaky upstreams to deal with.

> 	Alas, even for the Perl modules, the CPAN RT is not always the
> 	preferred but tracker.  Consider, e. g.:
> 
> --cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --
>     Please report issues via github at
>     https://github.com/gbarr/perl-Convert-ASN1/issues
> --cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --

There are fields in META.{yml,json} which let a CPAN dist indicate where
its preferred bugtracker is. search.cpan.org will honour these fields if
they are present, so the 'View/Report Bugs' link on the page for
Convert-ASN1 will take you to that github bugtracker. I don't believe
there is currently any support for forwarding the bug-*@rt.cpan.org
emails, though; this is at least in part because modules often outlive
their original authors, and having somewhere to track bugs once the
author has disappeared is useful.

Ben

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#213 — Re: reporting bugs

>>>>> Ben Morrow <ben@morrow.me.uk> writes:
>>>>> Quoth Ivan Shmakov <oneingray@gmail.com>:

 > [alt.barcodes removed, since this is about Perl process]

	(Not necessarily so.)

[...]

 >> BTW, there's a longstanding bug filed at the CPAN RT [2] (along with
 >> a patch.)  However, it appears to be filed against libwww-perl,
 >> while it actually belongs to Net-HTTP.

 >> The question is: how do I reassign it?

 >> [2] https://rt.cpan.org/Public/Bug/Display.html?id=29468

 > You can't; in fact, it looks like the way rt.cpan.org is set up noone
 > can move a ticket from one queue to another.  The best you could do
 > is file a separate bug against Net-HTTP, referencing the LWP bug; but
 > since both dists are maintained by Gisle Aas I'm not sure there'd be
 > much point.

	... Which only makes it more surprising that it wasn't already
	dealt with.  (Especially given the simplicity of the patch.)

[...]

 >> * the issue may indeed be specific to the distribution's build;
 >> (naturally, building from the upstream sources for every bug being I
 >> report just to check that it wasn't introduced by the packagers is
 >> hardly an option.)

 > Obviously you have a different approach from me.  I would consider
 > building the latest upstream release from source, and probably the
 > latest upstream equivalent of CVS HEAD, a basic prerequisite for
 > reporting a bug.  After all, it's almost certainly the first thing
 > you'll be asked to do in any case, and a patch which doesn't apply to
 > HEAD is probably nearly worthless.

	Depending on the goals, it may or may not make sense to ever get
	involved with the latest development version.

	For instance, I'm occasionally employed by a local university,
	to carry over certain computer-related courses (mostly
	short-term.)  Should I discover an issue while preparing for
	them, I'm most likely to report it to the developers.  However,
	distracting myself to write a patch -- which is unlikely to be
	incorporated into the distribution I'll use (and recommend to
	the students) by the time the courses will start -- may bring no
	good to the courses themselves.  In this case, clearly
	documenting the issue and providing a work-around for the
	students to use may constitute a better solution.

	Similarly, while maintaining a few hosts under my
	responsibility, I'd try to stick to the distribution-provided
	software whenever possible, preferably the "stable" branch.
	Given that patches other than security fixes won't generally be
	accepted into Debian "stable," and that there're typically a
	couple of years between releases...

	Yet, indeed, I've made a few contributions to some Git HEADs.
	(Most recently libtasn1, IIRC.)

 > I suppose that in principle 'I'm using a distro; I'm paying them (or
 > not) to sort out whose bug it is and get it fixed upstream' ought to
 > be a reasonable argument, but in practice distros tend to be
 > extremely unreliable about sending bugs upstream, probably because
 > they have had their own share of flaky upstreams to deal with.

	The best thing about Debian is that it's a community-based
	project.  (Which was the reason for me to choose it in the first
	place.)  Basically, the only privileges that the Debian
	Developer status conveys are: to upload, and to vote.

	Essentially, anyone (careful enough not to disrupt the
	established order) is welcome to do this (or any other, for that
	matter) part of the job.  Why, (taking a glance over the latest
	upstream stable releases) I've just forwarded Debian Bug#700617
	and #700618 to CPAN RT#84467 and #84468, respectively.

	(Hopefully, I did the thing right; this time.)

 >> Alas, even for the Perl modules, the CPAN RT is not always the
 >> preferred but tracker.  Consider, e. g.:

 >> --cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --

 >> Please report issues via github at
 >> https://github.com/gbarr/perl-Convert-ASN1/issues

 >> --cut: https://rt.cpan.org/Public/Bug/Display.html?id=79999 --

 > There are fields in META.{yml,json} which let a CPAN dist indicate
 > where its preferred bugtracker is.

	Indeed, these are set correctly in the current META.json.

 > search.cpan.org will honour these fields if they are present, so the
 > 'View/Report Bugs' link on the page for Convert-ASN1 will take you to
 > that github bugtracker.  I don't believe there is currently any
 > support for forwarding the bug-*@rt.cpan.org emails, though; this is
 > at least in part because modules often outlive their original
 > authors, and having somewhere to track bugs once the author has
 > disappeared is useful.

	My point is that GitHubs come and go, but the code remains.
	Certainly, I'd prefer a service that could be easily "cloned,"
	such as a Usenet newsgroup, a Git archive, or similar.

	The Perl-based App::SD was intended to be just such a system.
	Alas, it has seen virtually no development from mid-2011 to
	late-2012.  The situation seem to be slowly improving, though.

-- 
FSF associate member #7257	http://hfday.org/

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#233 — configuring CPAN to apply patches (such as #29468, IPv6 in Net::HTTP)

>>>>> Ivan Shmakov <oneingray@gmail.com> writes:
>>>>> Ben Morrow <ben@morrow.me.uk> writes:

	[The particular example given is relevant to a longstanding bug
	in Net::HTTP, thus cross-posting to news:comp.lang.perl.modules.
	Omitting the latter from Followup-To:, though.]

[...]

 >> <pet peeve> The correct place to file a bug in a Perl module is in
 >> its CPAN bug tracker, or, in this case, in the zbar Sourceforce
 >> tracker.

 > BTW, there's a longstanding bug filed at the CPAN RT [2] (along with
 > a patch.)  However, it appears to be filed against libwww-perl, while
 > it actually belongs to Net-HTTP.

 > The question is: how do I reassign it?

 > [2] https://rt.cpan.org/Public/Bug/Display.html?id=29468

	As there seems to be no progress on this one, I've had to
	finally learn the necessary magic for CPAN to patch that
	(trivial) bug for me on each installation attempt.

	The first part of the incantation is altering $CPAN::Config, to
	which I've added "patches_dir":

--cut: ~/.cpan/CPAN/MyConfig.pm --
my $cpan_home
    = ($ENV{"CPAN"}
       // ($ENV{"HOME"} . "/.cpan"));
...
$CPAN::Config = {
...
    'patches_dir' => $cpan_home . q (/patches),
...
    'prefs_dir' => $cpan_home . q (/prefs),
--cut: ~/.cpan/CPAN/MyConfig.pm --

	The "prefs_dir" value was already there, and it's the directory
	I've added the following YAML data:

### 6yy1cmawx4oqu5kdx7qks77n3n.yml  -*- YAML -*-
## Patch the IPv6 support into Net::HTTP
---
match:
    module: "Net::HTTP"
patches:
  - "cpmz4z7w7toa3mk6bi4rmp66n8.patch"
### 6yy1cmawx4oqu5kdx7qks77n3n.yml ends here

	The patch itself goes to the "patches_dir" as specified above
	(it's the same as the one given at [2], yet with an earlier
	$VERSION within the context section of the diff):

--- lib/Net/HTTP.pm.~1~	2011-11-21 20:23:21.000000000 +0000
+++ lib/Net/HTTP.pm	2012-01-08 18:13:21.000000000 +0000
@@ -5,8 +5,13 @@
 
 $VERSION = "6.02";
 unless ($SOCKET_CLASS) {
-    eval { require IO::Socket::INET } || require IO::Socket;
-    $SOCKET_CLASS = "IO::Socket::INET";
+    if (eval { require IO::Socket::INET6 }) {
+        $SOCKET_CLASS = "IO::Socket::INET6";
+    } else {
+        eval { require IO::Socket::INET }
+            || require IO::Socket;
+        $SOCKET_CLASS = "IO::Socket::INET";
+    }
 }
 require Net::HTTP::Methods;
 require Carp;

	Voil`a!  The $ cpan Net::HTTP command that followed resulted in
	the fixed version of the module being installed.  (Even though
	there was an expected "fuzz" warning from patch(1).)

[...]

-- 
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