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Date: Mon, 28 Apr 2025 22:45:00 -0700 (PDT)
X-X-Sender: jeremyd AT resin DOT csoft DOT net
To: cygwin AT cygwin DOT com
Subject: cygwin_conv_path with size 0
Message-ID: <9c8107b6-a040-d956-2590-ede1517bc2ad@jdrake.com>
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From: Jeremy Drake via Cygwin <cygwin AT cygwin DOT com>
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Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

I was just describing cygwin_conv_path on a rust issue
(https://github.com/rust-lang/backtrace-rs/pull/704).  I was saying that
the pointer `to` is not accessed when `size` is 0, but it turns out on
circa line 4022 in path.cc

to = (void *) wcpcpy ((wchar_t *) to, ro_u_globalroot.Buffer);

This is before `size` is checked and lsiz returned if it was zero, or
ENOSPC set if size is too small, circa line 4060.  This seems like a bug
to me.


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