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Date: Wed, 8 Oct 2025 21:02:08 +0300
Message-ID: <CAFNJpnjAnoKgKtCCoajeEoustA6SCQ213eboZ9dq1L3-tdQF0g@mail.gmail.com>
Subject: MAX_PATH issue, 256 long file names are not visible to Cygwin
To: cygwin@cygwin.com
Cc: Oleksandr Gavenko <gavenkoa@gmail.com>
From: Oleksandr Gavenko via Cygwin <cygwin@cygwin.com>
Reply-To: Oleksandr Gavenko <gavenkoa@gmail.com>
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Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie.com@cygwin.com>
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During rsync in WSL 2 via p9 I've got few read errors.

I investigated paths with Cygwin tools, ls.exe fails with error:

/usr/bin/ls: cannot access
'/users/user/net/tmp/test/124'$'\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211\\321\\211''.t':
No such file or directory

To reproduce:

mkdir test
cd test
n='щ'; for ((i=1; i<150; i+=1)); do echo $i >$(printf "%03s"
$i)"$n.txt"; n="$nщ"; done

It start fails with:

bash: 125щщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщщ.txt:
File name too long

I edited 124...txt file manually, adding another extra symbol to the
name in Explorer. Far manager and Explorer see file correctly,
Cygwin's ls.exe fails (see the first error at the top of email).

If we count the length of the last non-failing file name in UTF-8
coding, the length is 3 + 124*2 + 4 = 255.

Flipping through cygwin-ug-net-nochunks.html didn't enlightened me, like:

> What's new and what changed from 1.5 to 1.7
> PATH_MAX is now 4096. Internally, path names can be as long as the underlying OS can handle (32K).

I had to shorten names to keep WSL2 to ext4 fs backup working ( wmic
diskdrive list brief + wsl --mount \\.\PHYSICALDRIVE2 --partition 1
--type ext4 + rsync ) anyway.

Still, I manage files via Emacs-W32 Dired (utilizing ls.exe with
ls-lisp.el), wondering if the situation is OK for Cygwin failing on
256 long file names.

Please CC me gavenkoa@gmail.com in a reply, I'm not subscribed.

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