[GHC] #8058: If .ghci is a symlink, permissions aren't read correctly

[GHC]

#8058: If .ghci is a symlink, permissions aren't read correctly
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        Reporter:  berdario    |            Owner:
            Type:  bug         |           Status:  closed
        Priority:  low         |        Milestone:
       Component:  GHCi        |          Version:  7.6.2
      Resolution:  invalid     |         Keywords:
Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple             |       Difficulty:  Easy (less than 1 hour)
 Type of failure:  Other       |       Blocked By:
       Test Case:              |  Related Tickets:
        Blocking:              |
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Comment (by berdario):

 Uhm, "writable by someone else" seems to include the group, even if the
 group "dario" doesn't include any user other than "dario" himself.

 Why does ghci care about the permissions of the parent directory by the
 way? I just tried and it seems that on linux, having writing permissions
 for a directory isn't enough to move it away (and substitute it with a
 malicious one)
 (fwiw: this is a linux box with hostname "macbook", not macosx... sorry
 for the confusion)

 So, if for some reason (other unices?) we really need to check the
 permissions of the parent directory, the error message may mention it

 Also, "someone else" is quite a fuzzy concept... "has to have write
 permission for only your user" might be better?

 {{{
 dario at macbook ~> ls -ld (dirname (readlink .ghci))
 drwxrwxr-x 7 dario dario 4096 Sep 12 22:19 /home/dario/.dotfiles/dotfiles/

 dario at macbook ~> ghci
 GHCi, version 7.6.2: http://www.haskell.org/ghc/  :? for help
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 *** WARNING: /home/dario/.dotfiles/dotfiles is writable by someone else,
 IGNORING!
 Prelude>
 Leaving GHCi.

 dario at macbook ~> chmod g-w (dirname (readlink .ghci))

 dario at macbook ~> ghci
 GHCi, version 7.6.2: http://www.haskell.org/ghc/  :? for help
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 Prelude>
 Leaving GHCi.

 }}}

 Thank you

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8058#comment:7>
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