[pacman-dev] [PATCH] Looping for EINTR on close() is wrong on Linux

[Allan McRae]

On 04/07/13 08:05, Dan McGee wrote:
> On Wed, Jul 3, 2013 at 4:38 PM, Simon Gomizelj <simongmzlj at gmail.com> wrote:
>> That said, the loop is possibly a source of bugs for another reason,
>> apparently its possible for the fd to have been closed and reused by the
>> time EINTR fires, causing an unrelated fd to be closed.
>>
>>> As discussed in this thread, many POSIX implementations, including
>>> Linux, will release the file descriptor immediately, and so if close()
>>> fails with EINTR, it is possible that the file descriptor has already
>>> been reclaimed and in use by some other component. Retrying the close
>>> call, therefore, might close some other component's descriptor.
>>
>>  - https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
>>  - http://linux.derkeiler.com/Mailing-Lists/Kernel/2005-09/3000.html
> 
> Given that we are single-threaded, I don't see how this is possible.
> 

This is not possible now...  but there is code floating around to set
this up and I would like to use it for at least integrity checking.

Also, this appears to be the right thing to do whether we are single- or
multi-threaded.  We should fix the issue whether or not we can expose it.

Allan