# Tidy segfault on Linux

**URL:** <https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239>\
**Category:** Ruby\
**Created:** [December 5, 2007, 9:00pm UTC](https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239 "2007-12-05T21:00:45Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![lfeistel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ecc23a/32.png) [@lfeistel](https://www.ruby-forum.com/u/lfeistel)\
**Post date:** [December 5, 2007, 9:00pm UTC](https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239/1 "2007-12-05T21:00:45Z")

</div>

Hi–

I’m using the Ruby tidy gem to clean some user-input HTML. It works  
splendidly on my Mac development machine, but seg faults on a CentOS  
linux box.

I’ve tracked through the code, and the crash occurs in Tidybuf.rb’s  
to\_s function. The “struct.bp” method returns a non-nil value (that  
indicates a zero size), but the struct.size is some huge number which  
varies run-to-run.

I’ve googled a ton, and there are a lot of people who have hit  
segfaults using Ruby and tidy. Some of the issue seem to have been a  
namespace conflict between Graphics/ImageMagick and Tidy, but we’ve  
fixed that (by renaming tidy’s GetToken function and recompiling), and  
are still hitting a seg fault.

More detail:

Using a fresh Rails 1.2.5 app, I’ve stepped in console thru the parts  
of Tidyobj.rb’s clean method, like so:

require ‘tidy’  
tidy = Tidyobj.new  
@doc = Tidylib.create  
@outbuf = Tidybuf.new  
str = ‘hi there!’  
rc = -1  
rc = Tidylib.parse\_string(@doc, str)  
rc = Tidylib.clean\_and\_repair(@doc) if rc \>= 0  
rc = (Tidylib.opt\_parse\_value(@doc, :force\_output, true) == 1 ? rc :  
-1) if rc \> 1  
rc = Tidylib.save\_buffer(@doc, @outbuf.struct) if rc \>= 0

At this point:

> > @outbuf.struct.size  
> > =\> 154846656
> 
> > @outbuf.struct.bp  
> > =\> #\<DL::PtrData:0x0x949aa38 ptr=0x0x29c4d0 size=0 free=0x(nil)\>

Then:

> > @outbuf.to\_s  
> > /usr/lib/ruby/site\_ruby/1.8/tidy/tidybuf.rb:39: [BUG] Segmentation  
> > fault  
> > ruby 1.8.4 (2005-12-24) [i386-linux]  
> > Aborted (core dumped)

The shorter way to reproduce this is:

> > tidy=Tidyobj.new  
> > tidy.clean ‘hi’  
> > /usr/lib/ruby/site\_ruby/1.8/tidy/tidybuf.rb:39: [BUG] Segmentation  
> > fault  
> > ruby 1.8.4 (2005-12-24) [i386-linux]  
> > Aborted (core dumped)

If anyone has a clue, please help!

Thanks,  
Lee

---

<div class="post-metadata">

**Author:** ![lfeistel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ecc23a/32.png) [@lfeistel](https://www.ruby-forum.com/u/lfeistel)\
**Post date:** [December 7, 2007, 1:42am UTC](https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239/2 "2007-12-07T01:42:36Z")

</div>

Lee,

Check out this URL for a patch:

[http://rubyforge.org/tracker/index.php?func=detail&aid=10007&group\_id=435&atid=1744](http://rubyforge.org/tracker/index.php?func=detail&aid=10007&group_id=435&atid=1744)

It seems to have fixed the problem for me.

Good luck,

Scott

---

<div class="post-metadata">

**Author:** ![lfeistel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ecc23a/32.png) [@lfeistel](https://www.ruby-forum.com/u/lfeistel)\
**Post date:** [December 14, 2007, 8:13pm UTC](https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239/3 "2007-12-14T20:13:17Z")

</div>

Excellent, thanks, I’ll try it out.

Lee

---

<div class="post-metadata">

**Author:** ![lfeistel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/ecc23a/32.png) [@lfeistel](https://www.ruby-forum.com/u/lfeistel)\
**Post date:** [July 14, 2008, 1:37pm UTC](https://www.ruby-forum.com/t/tidy-segfault-on-linux/122239/4 "2008-07-14T13:37:18Z")

</div>

Hi Lee & Scott,

we ran into the excat same issue Lee described in  
[http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/282246](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/282246)

We tried the patch as suggested by Scott in  
[http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/282454](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/282454)

Unfortunately, no luck… we still segfault.

Just wondering if you were able to solve it… and if so, how?

We have Ruby 1.8.5, Tidy Gem 1.1.2, libtidy 0.99 on CentOS 5.2 (x86\_64).

One thing we found is that Tidy seems to only segfault if one feeds it  
_valid_ HTML. If one feeds it bad HTML, it doesn’t crash (see example  
below).

Thanks!

Bob

—8\<-------------------------------------------------------------------------

require “rubygems”  
require “tidy”

Tidy.path = “/usr/lib64/libtidy.so”

Tidy.open do |t|  
puts “\*\*\* BAD SAMPLE”  
t.clean “I am bad HTML!”  
puts t.errors  
puts t.diagnostics  
end

Tidy.open do |t|  
puts “\*\*\* GOOD SAMPLE”  
t.clean ‘’ +  
‘foo

bar

’  
puts t.errors  
puts t.diagnostics  
end

—8\<-------------------------------------------------------------------------

Outputs the following:

\*\*\* BAD SAMPLE  
line 1 column 1 - Warning: missing \<!DOCTYPE\> declaration  
line 1 column 7 - Warning: plain text isn’t allowed in elements  
line 1 column 7 - Info: previously mentioned  
line 1 column 7 - Warning: inserting implicit   
line 1 column 7 - Warning: inserting missing ‘title’ element  
Info: Document content looks like HTML 3.2  
4 warnings, 0 errors were found!

\*\*\* GOOD SAMPLE  
(eval):5: [BUG] Segmentation fault  
ruby 1.8.5 (2006-08-25) [x86\_64-linux]

Aborted