[GHC] #4363: openFile sharing permissions are inconsistent across platforms

[GHC]

#4363: openFile sharing permissions are inconsistent across platforms
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    Reporter:  jystic            |       Owner:                             
        Type:  bug               |      Status:  new                        
    Priority:  normal            |   Component:  libraries/base             
     Version:  6.12.3            |    Keywords:                             
    Testcase:                    |   Blockedby:                             
          Os:  Windows           |    Blocking:                             
Architecture:  Unknown/Multiple  |     Failure:  Incorrect result at runtime
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Comment(by jystic):

 I'm not 100% sure, but it looks like openFile ends up calling
 !__hscore_open from libraries\base\include\HsBase.h:

 {{{
 #ifdef __MINGW32__
 INLINE int __hscore_open(wchar_t *file, int how, mode_t mode) {
         if ((how & O_WRONLY) || (how & O_RDWR) || (how & O_APPEND))
           return _wsopen(file,how | _O_NOINHERIT,_SH_DENYRW,mode);
           // _O_NOINHERIT: see #2650
         else
           return _wsopen(file,how | _O_NOINHERIT,_SH_DENYWR,mode);
           // _O_NOINHERIT: see #2650
 }
 #else
 INLINE int __hscore_open(char *file, int how, mode_t mode) {
         return open(file,how,mode);
 }
 #endif
 }}}

 The documentation for [http://msdn.microsoft.com/en-
 us/library/w7sa2b22(VS.80).aspx _wsopen] suggests that there are four
 options that can be passed to it to change the sharing behaviour:

 '''_SH_DENYRW'''
 Denies read and write access to a file.

 '''_SH_DENYWR'''
 Denies write access to a file.

 '''_SH_DENYRD'''
 Denies read access to a file.

 '''_SH_DENYNO'''
 Permits read and write access.

 We pass _SH_DENYRW (deny reads, deny writes) in the case that we are
 writing to the file and _SH_DENYWR (deny writes, allow reads) in the case
 that we are reading from the file but not writing to it.

 If we were to always use _SH_DENYWR then I think it would give the desired
 behaviour.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4363#comment:3>
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