DMARC-Filter: OpenDMARC Filter v1.4.2 delorie.com 51CHQfM2849045
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org A48FA3858C53
Message-ID: <39ada7f0-3ce7-4380-8fed-5b90d863ac19@SystematicSW.ab.ca>
Date: Wed, 12 Feb 2025 10:26:09 -0700
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: /bin/cp of sparse files broken in
 3.6.0-0.362.g68c13dc92f65.x86_64?
Content-Language: en-CA
To: cygwin AT cygwin DOT com
References: <CALXu0UdYOUeFSF0GXtqccbA=ZeQQEn62y5MBdEdJPVCkHHXgrw AT mail DOT gmail DOT com>
Autocrypt: addr=Brian DOT Inglis AT SystematicSW DOT ab DOT ca; keydata=
 xjMEXopx8xYJKwYBBAHaRw8BAQdAnCK0qv/xwUCCZQoA9BHRYpstERrspfT0NkUWQVuoePbN
 LkJyaWFuIEluZ2xpcyA8QnJpYW4uSW5nbGlzQFN5c3RlbWF0aWNTdy5hYi5jYT7ClgQTFggA
 PhYhBMM5/lbU970GBS2bZB62lxu92I8YBQJeinHzAhsDBQkJZgGABQsJCAcCBhUKCQgLAgQW
 AgMBAh4BAheAAAoJEB62lxu92I8Y0ioBAI8xrggNxziAVmr+Xm6nnyjoujMqWcq3oEhlYGAO
 WacZAQDFtdDx2koSVSoOmfaOyRTbIWSf9/Cjai29060fsmdsDM44BF6KcfMSCisGAQQBl1UB
 BQEBB0Awv8kHI2PaEgViDqzbnoe8B9KMHoBZLS92HdC7ZPh8HQMBCAfCfgQYFggAJhYhBMM5
 /lbU970GBS2bZB62lxu92I8YBQJeinHzAhsMBQkJZgGAAAoJEB62lxu92I8YZwUBAJw/74rF
 IyaSsGI7ewCdCy88Lce/kdwX7zGwid+f8NZ3AQC/ezTFFi5obXnyMxZJN464nPXiggtT9gN5
 RSyTY8X+AQ==
Organization: Systematic Software
In-Reply-To: <CALXu0UdYOUeFSF0GXtqccbA=ZeQQEn62y5MBdEdJPVCkHHXgrw@mail.gmail.com>
Precedence: list
From: Brian Inglis via Cygwin <cygwin AT cygwin DOT com>
Reply-To: cygwin AT cygwin DOT com
Cc: Brian Inglis <Brian DOT Inglis AT SystematicSW DOT ab DOT ca>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
Errors-To: cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com
Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>
Content-Transfer-Encoding: 8bit

On 2025-02-12 09:32, Cedric Blancher via Cygwin wrote:
> Is copying sparse files broken in 3.6.0-0.362.g68c13dc92f65.x86_64?
> cp --version
> cp (GNU coreutils) 9.5
> Packaged by Cygwin (9.5-1
> Checklist:
> - Volume has FILE_SUPPORTS_SPARSE_FILES
> - Cygwin mount has "sparse" option (mount Y: -o sparse,exec /cygdrive/y)
> - source file has FILE_ATTRIBUTE_SPARSE_FILE set
> 
> But  cp --sparse=auto ... or any other combination of --sparse does
> copy holes, i.e. turns 500GB of hole into 500GB of data (zero bytes).
> 
> echo "hello sparse file\n" >testcase17_sparse_begins_with_data && dd
> if=/dev/null of=testcase17_sparse_begins_with_data oflag=append bs=1
> count=1 seek=$((65536*512)) && echo "endoffile"
>>> testcase17_sparse_begins_with_data

Does that include --sparse=always not creating holes, and how are you checking 
whether the file is stored as sparse with holes or not - should this be visible 
in dir/ls file sizes?

It may be unsupported in Cygwin cp (coreutils) - build tests detect 
insufficient? SEEK_DATA support, inability to create large sparse files, and the 
(NTFS) file system as not supporting sparse files.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher  but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple