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Re: Fun with cp -R error when both foo and foo.exe exist




On 10/9/18 1:22 AM, Marco Atzeri wrote:
Am 08.10.2018 um 23:24 schrieb Dan Kegel:


A nice workaround might be for the cygwin version of cp could arrange
to wait to create .exe files until after any potential non-suffixed
file has been processed... not sure how easy that would be.

Apologies if this has already been discussed.
- Dan

it is not cp handling the magic, but the cygwin dll.

Mostly the cygwin dll, but cp itself DOES have some cygwin-specific downstream patches to try and behave smarter. At any rate, POSIX requires cp to handle command line arguments in the order given, but does not require recursion to copy in any specific order for files within a directory. But the order that makes the most sense is the order that readdir() returns things, because any other order requires sorting the files (and thus the memory to track the files) and a longer window for races to occur with anything else changing directory contents in parallel. Perhaps you could even argue that readdir() should visit 'foo' and 'foo.exe' in a particular order, no matter whether the native ordering would display them in the opposite order. But in general, whether someone patches the cygwin dll or cp, it seems like some rather hairy code for what is normally a rare corner case, so it probably won't happen unless someone actually contributes a patch.

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Eric Blake, Principal Software Engineer
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