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Date: Fri, 13 Sep 2024 13:45:48 +0400
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To: cygwin AT cygwin DOT com
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Subject: Writing to '\\.\X:' that has no backing PhysicalDrive?
From: Ilya Basin via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Ilya Basin <basinilya AT gmail DOT com>
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Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

Hi.
I was trying to write an .img file to a VeraCrypt drive.
VeraCrypt doesn't create a virtual PhysicalDrive so tools like Rufus don't see it.
I hoped that with cygwin I would be able to do that, but Cygwin only creates /dev/sd?? nodes for PhysicalDrive partitions.
I tried `dd` with '\\.\X:', but it can't open for writing because it treats it as a directory (reading succeeds).

$ dd count=1 if='\\.\E:' | xxd
1+0 records in
1+0 records out
512 bytes copied, 0.0213007 s, 24.0 kB/s
00000000: eb52 904e 5446 5320 2020 2000 0208 0000  .R.NTFS    .....
...

$ dd if=/dev/null count=0 of='\\.\E:'
dd: failed to open '\\.\E:': Is a directory

Same error in MSYS2.

Does cygwin provide some (hidden) /dev/ nodes for drive letters or volumes like "\\?\Volume{GUID}"? Can I create one with mknod?


My current workaround is a PowerShell/.NET script that calls CreateFile/WriteFile with proper flags.
Rufus doesn't show any hard drives, Win32DiskImager crashes on launch. Surprisingly, I couldn't find a decent GUI program for this task.

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