#12164 NORM 13.1.0: XO-4 os5 yum Invalid GPG Key

Zarro Boogs per Child bugtracker at laptop.org
Fri Nov 9 19:27:10 EST 2012

#12164: XO-4 os5 yum Invalid GPG Key
           Reporter:  Quozl      |       Owner:  dsd          
               Type:  defect     |      Status:  new          
           Priority:  normal     |   Milestone:  13.1.0       
          Component:  distro     |     Version:  not specified
         Resolution:             |    Keywords:               
        Next_action:  never set  |    Verified:  0            
Deployment_affected:             |   Blockedby:               
           Blocking:             |  

Comment(by wmb at firmworks.com):

 I've done a fair amount of exploration of this program too, and have seen
 some bizarre results.  For example, if you insert the line

      foo = crc & 0x1000000

 before the if statement, the answer changes.  Worse yet, the answer
 sometimes changes from run to run of the same program text!

 I have looked at the implementation of the Python interpreter to see what
 happens when you say  "if crc & 0x1000000 :".  It turns out to be
 surprisingly complex, due to the fact that Python internally represents
 long integer values in sign-magnitude format, converting to twos-
 complement for bitwise operations, and then back to sign-magnitude for the
 result.  Furthermore, the interpretation of an integer value as a boolean
 (i.e. for "if") depends on a size optimization where a zero-valued integer
 is represented as an object of size 0.  All of this results in allocation
 of new temporary objects, so there are many opportunities for memory or
 cache corruption to change values.

 This one has me worried...

Ticket URL: <http://dev.laptop.org/ticket/12164#comment:10>
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