# "stack level too deep" when getting SHA-1 hash

**URL:** <https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590>\
**Category:** Ruby\
**Created:** [July 27, 2007, 9:16pm UTC](https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590 "2007-07-27T21:16:41Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [July 27, 2007, 9:16pm UTC](https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590/1 "2007-07-27T21:16:41Z")

</div>

Here is a session I had with irb:

[200]~% irb  
irb(main):001:0\> require ‘digest/sha1’  
=\> true  
irb(main):002:0\> Digest::Sha1.new.hexdigest(‘fdjslk’)  
SystemStackError: stack level too deep  
from d:/ruby/lib/ruby/1.8/digest.rb:9:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
… 22338 levels…  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const_missing' from d:/ruby/lib/ruby/1.8/digest.rb:18:in`const\_get’  
from d:/ruby/lib/ruby/1.8/digest.rb:18:in `const\_missing’  
from (irb):2irb(main):003:0\>  
irb(main):004:0\* exit  
[201]~% ruby -v  
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]

I tried this from two computers and got the same results. What am I  
doing wrong?

Thanks!

Tim

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<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [July 27, 2007, 10:18pm UTC](https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590/2 "2007-07-27T22:18:51Z")

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On Jul 27, 2007, at 14:15 , removed\_email\_address@domain.invalid wrote:

> Here is a session I had with irb:
> 
> [200]~% irb  
> irb(main):001:0\> require ‘digest/sha1’  
> =\> true  
> irb(main):002:0\> Digest::Sha1.new.hexdigest(‘fdjslk’)

Spelling (capitalization) and calling error? I don’t think you [need|  
should use] new.

$ ruby --version  
ruby 1.8.6 (2007-03-13 patchlevel 0) [powerpc-darwin8.9.0]  
$ irb  
irb(main):001:0\> require ‘digest/sha1’  
=\> true  
irb(main):002:0\> Digest::SHA1.hexdigest(‘fdjslk’)  
=\> “df3d3f2922e369f348a90a5f65aef87f80e03fa7”

Michael G.  
grzm seespotcode net

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [July 27, 2007, 11:21pm UTC](https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590/3 "2007-07-27T23:21:00Z")

</div>

Thank you Michael! That works.

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [July 27, 2007, 11:54pm UTC](https://www.ruby-forum.com/t/stack-level-too-deep-when-getting-sha-1-hash/110590/4 "2007-07-27T23:54:07Z")

</div>

On Jul 27, 2:18 pm, Michael G. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> should use] new.
> 
> $ ruby --version  
> ruby 1.8.6 (2007-03-13 patchlevel 0) [powerpc-darwin8.9.0]  
> $ irb  
> irb(main):001:0\> require ‘digest/sha1’  
> =\> true  
> irb(main):002:0\> Digest::SHA1.hexdigest(‘fdjslk’)  
> =\> “df3d3f2922e369f348a90a5f65aef87f80e03fa7”

Yep, it’s caused by this misguided piece of code from digest.rb:

def self.const\_missing(name)  
case name  
when :SHA256, :SHA384, :SHA512  
lib = ‘digest/sha2.so’  
else  
lib = File.join(‘digest’, name.to\_s.downcase)  
end

```
begin
  require lib
rescue LoadError => e
  raise LoadError, "library not found for class Digest::#{name} --

```

#{lib}"  
end

```
Digest.const_get(name)

```

end

I’d call this a bug, personally.

Regards,

Dan