[racket-dev] [plt] Push #29680: master branch updated

I'll adjust the docs to clarify that the permission change followed by
delete is a non-atomic sequence, with no attempt to revert a permission
change if the delete fails.

Ending up with just the permission change is one possible outcome, and
I hope the clarification will also make other outcomes more apparent.
For example, it could happen that X's permission is changed, then X is
concurrently replaced by a new file again without write permission, and
the still-in-progress delete fails due to a permission failure after
all.

At Wed, 14 Jan 2015 09:31:37 -0600, Robby Findler wrote:
> Is it perhaps worth being more explicit about this possibility in the
> docs? I'm thinking of a sentence that says "when <the parameter> is
> set, delete-file may have only the effect of changing the permissions
> on the file" or similar.
> 
> Robby
> 
> On Wed, Jan 14, 2015 at 8:29 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> > At Wed, 14 Jan 2015 09:07:08 -0500, Neil Toronto wrote:
> >> On 01/13/2015 02:00 PM, mflatt at racket-lang.org wrote:
> >> > 9f3c82c Matthew Flatt <mflatt at racket-lang.org> 2015-01-13 08:47
> >> > :
> >> > | Windows: change `delete-{file,directory}` to attempt permission 
> correction
> >> > |
> >> > | If a file or directory delete fails, try adjusting the file or directory
> >> > | permissions to allow writes, then try deleting again. This process 
> should
> >> > | provide a more Unix-like experience and make programs behave more
> >> > | consistently.
> >> > |
> >> > | A new `current-force-delete-permissions` parameter provides access to
> >> > | the raw native behavior.
> >>
> >> If I'm understand the new behavior correctly, it's possible for a
> >> failing `delete-file` to raise an exception, having changed the file to
> >> be writable. Do I have that right, and is that OK?
> >
> > That is correct. I'm not too happy about it, but I think it's a good
> > trade-off relative to the old behavior (as a default).
> >
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