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Subject: Re: Fun with cp -R error when both foo and foo.exe exist
To: cygwin AT cygwin DOT com
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From: Eric Blake <eblake AT redhat DOT com>
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Date: Tue, 9 Oct 2018 11:52:52 -0500
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On 10/9/18 11:21 AM, Dan Kegel wrote:
> On Tue, Oct 9, 2018 at 5:03 AM Eric Blake <eblake AT redhat DOT com> wrote:
>> 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.
> 
> Right.  Here's a completely untested guess patch:
> 
> --- a/winsup/cygwin/syscalls.cc
> +++ b/winsup/cygwin/syscalls.cc
> @@ -1363,7 +1363,15 @@ open (const char *unix_path, int flags, ...)
>            opt |= PC_CTTY;
>          }
> 
> -      if (!(fh = build_fh_name (unix_path, opt, stat_suffixes)))
> +      suffix_info *suffices = stat_suffixes;

suffices is a completely different word; did you mean suffixes?

> +      if ((opt & (O_WRONLY|O_BINARY)) == (O_WRONLY|O_BINARY))

O_WRONLY need not be a bitmask; it's better to use O_ACCMODE for the 
bitmask, as in
  opt & (O_ACCMODE|O_BINARY) == O_WRONLY|O_BINARY

> +        {
> +         /* Hack so 'cp foo bar' doesn't abort with
> +             'cp: cannot create regular file bar: File exists'
> +            if bar.exe already exists  */
> +       suffices = NULL;
> +       }
> +      if (!(fh = build_fh_name (unix_path, opt, suffices)))

So, with mistakes corrected, your hack is that cygwin doing auto-suffix 
probing should be suppressed in the case of opening a file O_WRONLY? Why 
does O_BINARY have to fit in the equation?

>          __leave;                /* errno already set */
>         if ((flags & O_NOFOLLOW) && fh->issymlink ())
>          {
> 
> Feel free to throw rotten fruit :-)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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