[GHC] #8935: Obscure linker bug leads to crash in GHCi

[GHC]

#8935: Obscure linker bug leads to crash in GHCi
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        Reporter:  simonmar          |            Owner:  simonmar
            Type:  bug               |           Status:  infoneeded
        Priority:  high              |        Milestone:  7.8.3
       Component:  Runtime System    |          Version:  7.8.1-rc2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  GHCi crash        |       Difficulty:  Rocket Science
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by trommler):

 And another question:
 From `internal_dlopen()`:
 {{{
    if (hdl == NULL) {
       /* dlopen failed; return a ptr to the error msg. */
       errmsg = dlerror();
       if (errmsg == NULL) errmsg = "addDLL: unknown error";
       errmsg_copy = stgMallocBytes(strlen(errmsg)+1, "addDLL");
       strcpy(errmsg_copy, errmsg);
       errmsg = errmsg_copy;
    }
    o_so = stgMallocBytes(sizeof(OpenedSO), "addDLL");
    o_so->handle = hdl;
    o_so->next   = openedSOs;
    openedSOs    = o_so;
 }}}
 If dlopen() fails we are adding a `NULL` handle to `openedSOs`. Which on
 my system means `RTLD_DEFAULT`. Is that what we want?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8935#comment:28>
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