[GHC] #10298: Infinite loop when shared libraries are unavailable

[GHC]

#10298: Infinite loop when shared libraries are unavailable
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        Reporter:  snoyberg          |                   Owner:  simonmar
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Runtime System    |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Runtime crash     |  (amd64)
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by rwbarton):

 I was able to reproduce the loop, but rather than copying `/usr/lib/x86_64
 -linux-gnu/gconv/` into the chroot, I tried copying in `/usr/lib/locale/`
 instead, and that was also sufficient to let the program run normally.
 It's to be expected that a program built with GHC needs those locale
 files, since String IO is locale-aware. Of course an infinite loop is not
 so easy to debug, and it'd be nice to have an error message.

 In fact the error status from `iconv_open` is being correctly checked, and
 converted to an exception, which is then caught and displayed by the
 default exception handler. The trouble is that the display of exceptions
 is also locale-aware...

 Curiously even an empty `main = return ()` triggers this behavior with
 7.8.4, but it runs successfully on 7.10.1. I couldn't figure out why,
 perhaps some change in the IO manager?

 I don't have any good ideas about how to improve this situation. Maybe try
 to set up the locale for IO at some point, catch the exception if it fails
 and `barf()` rather than using regular IO to display the exception. But
 when exactly?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10298#comment:1>
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