X-Recipient: archive-cygwin AT delorie DOT com DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:references:in-reply-to:from:date :message-id:subject:to:content-type; q=dns; s=default; b=e9mn8HB 484SY9YbeB6OszL6ILxMhImcxQr+YP+4UAcvX8xyoi1ppYtpy8zVmqrbpnM6HLea /A0v2rg2nj9fgBWdgNc4oNcChu5Wgh8FT9ESgzlb7l4JaN29tc0tb3MVuIARStk5 jE/W31+g7JsZpK+VPGCPodVvMGn8SrC4fVJg= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:references:in-reply-to:from:date :message-id:subject:to:content-type; s=default; bh=3lUTrwolEkPIu GfnQoG5ycRhYlI=; b=qnd/0s8+VK/hehDo8NQ9RvWr2GWiVh/U1hWpMimZEwDQE xa4TTgxDCHPSLiDkwzhZn4CHIRtyzwfR9Gmc+ObpzN3wTD7n7ZtHgXw0WfQ4Vz2F pNIijMNJ8IXdvJq+NYeBTHVjDsjJXRS0qWS3EMmUhI6JeVEqz92CONB8EgftPw= Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 spammy=Hx-spam-relays-external:ESMTPA X-HELO: bird.maple.relay.mailchannels.net X-Sender-Id: dreamhost|x-authsender|dropbox AT opencoder DOT net X-Sender-Id: dreamhost|x-authsender|dropbox AT opencoder DOT net X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|dropbox AT opencoder DOT net X-MailChannels-Auth-Id: dreamhost X-Abaft-Imminent: 59ee3ac36116fec8_1544996183589_3431043853 X-MC-Loop-Signature: 1544996183589:2133734616 X-MC-Ingress-Time: 1544996183589 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=opencoder.net; h= mime-version:references:in-reply-to:from:date:message-id:subject :to:content-type; s=opencoder.net; bh=tOn4MwbGY7sxxdGrEOnkwas0rA k=; b=IQ0wLsE/R/0ScmFnR6+Vk5vCG9XL+NEckgVC127uR2LJ8HAYT7qln68Jmc XgmhJ6bWo20zPwlIuSVCb3daOYFMtO5f3iV5ZQ/ahkoilZ/sE723/pYWYwKZq6ul PeqKfHyYQAXZYym0MbpPXA1cdSTwB7zcSOhzPmGLQA2LKfaEM= MIME-Version: 1.0 References: <0f030e809f063f5a5e64ff7a7a0c3227 AT xs4all DOT nl> <20181216202847 DOT GK28727 AT calimero DOT vinschen DOT de> In-Reply-To: <20181216202847.GK28727@calimero.vinschen.de> X-DH-BACKEND: pdx1-sub0-mail-a27 From: Wayne Davison Date: Sun, 16 Dec 2018 13:36:10 -0800 Message-ID: Subject: Re: /dev/fd/N not synonymous with file descriptor N; it is on Linux To: cygwin Content-Type: text/plain; charset="UTF-8" X-VR-OUT-STATUS: OK X-VR-OUT-SCORE: 0 X-VR-OUT-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedtkedrudehledgudehvdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucggtfgfnhhsuhgsshgtrhhisggvpdfftffgtefojffquffvnecuuegrihhlohhuthemuceftddtnecunecujfgurhepgghfjgfhfffkuffvtgesthdtredttddtjeenucfhrhhomhephggrhihnvgcuffgrvhhishhonhcuoeifrgihnhgvsehophgvnhgtohguvghrrdhnvghtqeenucfkphepvddtledrkeehrddvuddtrdehudenucfrrghrrghmpehmohguvgepshhmthhppdhhvghlohepmhgrihhlqdhothduqdhfhedurdhgohhoghhlvgdrtghomhdpihhnvghtpedvtdelrdekhedrvddutddrhedupdhrvghtuhhrnhdqphgrthhhpeghrgihnhgvucffrghvihhsohhnuceofigrhihnvgesohhpvghntghouggvrhdrnhgvtheqpdhmrghilhhfrhhomhepfigrhihnvgesohhpvghntghouggvrhdrnhgvthdpnhhrtghpthhtoheptgihghifihhnsegthihgfihinhdrtghomhenucevlhhushhtvghrufhiiigvpedt X-IsSubscribed: yes On Sun, Dec 16, 2018 at 12:29 PM Corinna Vinschen wrote: > In contrast to Linux the symlinks are not just faked symlinks with the underlying OS having direct access to the file descriptors. Yeah, Linux is more like a fuse where the open filehandles are used directly on open, and the stat calls return pretend symlinks with the lsof info. > The way it's implemented in Cygwin uses the actual file path resolution and then either works or fails as above. If Cygwin can't be changed into a fuse idiom, perhaps a hard-link idiom could be used? For instance, when the /proc/$PID/fd/0 symlink is being created, the code could try to hard-link the file to /proc/$PID/.fd/0 first (note the dot-fd) before creating the normal fd/0 symlink. Then, when a request came in to read /proc/$PID/fd/0, it could check if the associated hard-link exists and read from that instead. Or perhaps the "symlink" info could be stored elsewhere and the fd/0 file could be the hard-link, requiring the stat code to be tweaked to look up the pretend-symlink info? ..wayne.. -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple