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From: Mingye Wang <arthur200126 AT gmail DOT com>
Date: Tue, 8 Oct 2019 17:05:16 +0800
Message-ID: <CAD66C+b4uBtV=DUZ1n7Nk+KEoac0G9rkGYLVE7eEeKEuCKZmVA@mail.gmail.com>
Subject: [bug] globify dospath reacts poorly with escaped double quotes
To: cygwin AT cygwin DOT com
Content-Type: text/plain; charset="UTF-8"

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?)

--
Regards,
Mingye Wang

--
Mingye Wang (Artoria2e5)

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