X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0647338618E3
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1701424358;
	bh=H8KSXzCQzt+zCm83PvpAgnJVVkr/9hYwPyISFTAc3GU=;
	h=Date:To:Subject:References:In-Reply-To:List-Id:List-Unsubscribe:
	 List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc:
	 From;
	b=LMx/d7YzbcAI3TNrrwUTUdV5wRp2esp9H5HKY06RrtqLUzbtammwisuqCHkKitnxZ
	 RrmJ5tAzNhkY7rHdoCCg1Ek9FkRrm8eH/2JZGPuaSj7QsoT0iYmWBsW4Ju6URgFtoS
	 jTi18JoFCY4JjLxwHt57E+UXw7aCDZhPUjVbERvA=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 754C2385B53B
Date: Fri, 1 Dec 2023 10:51:57 +0100
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin tools to read/write NTFS alternate data streams?
Message-ID: <ZWmsvW0bmko_9Qcc@calimero.vinschen.de>
Mail-Followup-To: cygwin AT cygwin DOT com
References: <CANH4o6N7UONfYy1ir7WZXpOnthSxF=fcqaPe37dPsdU_AoPoLw AT mail DOT gmail DOT com>
MIME-Version: 1.0
Content-Disposition: inline
In-Reply-To: <CANH4o6N7UONfYy1ir7WZXpOnthSxF=fcqaPe37dPsdU_AoPoLw@mail.gmail.com>
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.30
Precedence: list
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Unsubscribe: <https://cygwin.com/mailman/options/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
List-Archive: <https://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <https://cygwin.com/mailman/listinfo/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
Reply-To: cygwin AT cygwin DOT com
Cc: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
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>

On Nov 30 04:55, Martin Wege via Cygwin wrote:
> Hello,
> 
> Does Cygwin have tools (modified /usr/bin/dd ?) to read/write NTFS
> alternate data streams?

No.  As you know, the colon is translated to a normal filename
character, and there's no POSIX-like API to expose ADS raw to user
space.

There is, however, an old function we still expose to user space
for backward compat:

  #include <sys/cygwin.h>

  int cygwin_attach_handle_to_fd (char *name,
				  int fd,
				  HANDLE handle,
				  mode_t bin,
				  DWORD myaccess);

This allows to sneak in a HANDLE into a Cygwin file descriptor
representation, kind of like this:

  HANDLE h;
  int fd;

  h = CreateFile ("foo:bar", GENERIC_READ, FILE_SHARE_VALID_FLAGS,
		  NULL, OPEN_EXISTING, 0, NULL);
  if (h != INVALID_HANDLE_VALUE)
    {
      fd = cygwin_attach_handle_to_fd ("foo", -1, h, 0, GENERIC_READ);
      if (fd < 0)
	bail_out;
    }

For the bin parameter, only 0, O_BINARY or O_TEXT are acceptable,
for myaccess, only GENERIC_READ and/or GENERIC_WRITE are acceptable.


Corinna

-- 
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