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From: Ken Brown <kbrown AT cornell DOT edu>
To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject: Re: [bug] globify dospath reacts poorly with escaped double quotes
Date: Thu, 10 Oct 2019 13:13:18 +0000
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On 10/8/2019 5:05 AM, Mingye Wang wrote:
> Hi,
> 
> This bug is inherited from early versions of Cygwin. It's so old that
> MSYS2 has this problem too.
> 
> There is no way of conveying a double quote in an argument once
> globify() decides it has seen a dospath. Neither the `\"` nor `""`
> work, because they are both unified to `\"` in quoted() and turned
> into a `\\` pattern in globify().
> 
> This is problematic for programmers trying to write a routine to
> reliably escape an argument for the Cygwin command-line.
> 
> A way to patch the problem is with a lookahead in globify():
> 
> if (dos_spec && *s == '\\') {
> /**/p++ = '\\';
> /**/if (s[1] == '"' && s[2]) {
> /****/*p = *++s;
> /****/continue;
> /**/}
> }
> *p = *s;
> 
> [Apologies for the formatting; the gmail web editor hates leading spaces.]
> 
> (Note: The backslash thing has always been different from the MSCRT
> handling, which only transforms backslashes followed by a double
> quote. But this is fine as long as we are internally consistent.
> Well... is it documented anywhere?)

I don't know enough about Windows command-line quoting to comment on the 
substance of this.  But it would help those who do if you would send your patch 
to the cygwin-patches mailing list using git format-patch and git send-email. 
And please use the formatting conventions of the surrounding code.  For example,

if (dos_spec && *s == '\\')
   {
     [...]
   }

Thanks.

Ken

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