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Date: Mon, 7 Nov 2022 10:33:25 +0100
From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: Accessing long filesystem paths using Python
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List-Id: <cygwin.cygwin.com>

Hi Fridjof,

Please don't top-post.

On Nov  4 13:30, Fritjof Bornebusch wrote:
> On Nov  4 13:57, marco atzeri wrote:
>> On Fri, Nov 4, 2022 at 1:16 PM Fritjof Bornebusch wrote:
>> >
>> > Hi,
>> >
>> > I need to write files whose path exceed the maximum value of 260 characters.
>> > Using Windows paths, you can add \\?\ as prefix, e.g., \\?\C:\Users\foo\bar\<file://%3f/C:/Users/foo/bar/>....
>> >
>> > However, it seems like this is not the case in Cygwin. When I use \\?\/home/foo/bar<file://%3f/home/foo/bar>, I get no file pointer back.
>> >
>> > Does someone have a clue how I can bypass this?
>> >
>> > Best,
>> > Fritjof
>> >
>> 
>> Have you tried POSIX style ?
>> /cygdrive/C/Users/foo/bar..
> 
> Jep,
> 
> No success.

Works for me:

======================================================================
$ cat > longp.sh <<EOF
#!/bin/bash

POSIX_MAX=4096
# 240 chars per path component
DIRNAM="123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890"

LPATH=/tmp
cd /tmp

while [ $(echo -n "$LPATH" | wc -c) -lt $POSIX_MAX ]
do
  mkdir "$DIRNAM" || exit 1
  LPATH="$LPATH/$DIRNAM"
  ls -d "$LPATH" || exit 2
  cd "$LPATH" || exit 3
  echo "Current length: $(echo -n $LPATH | wc -c)"
  sleep 1
done
EOF
$ chmod +x longp.sh
$ ./longp.sh
/tmp/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
Current length: 245
[...]
12345678901234567890/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
Current length: 4101
$
======================================================================

If you have specific trouble, please provide a specific, simple testcase,
preferredly in plain C or as shell script.


Thanks,
Corinna