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Re: symlinks to unlinked but open files should work

Am 03.07.2016, 13:14 Uhr, schrieb Corinna Vinschen:

You don't even need a symlink.  This will show the same result:

  exec >out1
  rm out1
  [[ -w /dev/fd/1 ]] || echo /dev/fd/1 not writable 1>&2

I noticed that too meanwhile, but I thought you would not need that information ;) It's only about the /dev/fd-symlinks, otherwise cygwin seems to be correct: they don't work anywhere on an open but deleted file:

ln -sf out1 lout1
exec >out1
[[ -w lout1 ]] || echo lout1 not writable-1 1>&2
rm out1
[[ -w lout1 ]] || echo lout1 not writable-2 1>&2
rm lout1

correctly prints the second message.

In Cygwin we move a deleted but still open file out of the way (into
the trash) so the path is incorrect afterwards but even if we wouldn't
do that, the underlying problem can't be solved:

The problem is that a deleted file in Windows can't be opened anymore.
If you translate the above -w <file> into a libc call access
("/dev/fd/1", W_OK) or its Windows equivalent, that call will always
fail on a deleted file.  Same for open/CreateFile, etc.

Sorry, but off the top of my head I don't see a feasible workaround for
this problem.

Not a big issue - I don't know any situation this would break except the above /dev/fd-test.


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