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:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=woLSfSn5tmgb0MyW 1F1sSazHxu3mrXI/w2Tkaa5wr2FUz4R8yx2WsDIOVEwxQSo58wsgcpRLyv4jyDEW GAQGP/96mjWHDV5Q70+nHPvcJKH5bGQ8fodKrkmE+rL8w9Tv8N7kMMgy+uWK9jju X85XsHFX75KelwqFXqrR/4fImBk= 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:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=YbGO9KvkyxDvsLhkUO3G1P shJSQ=; b=lvFkVqXouPE0rl8NRsj4Xqx6jF6lSXNjmZAqO28+6ttr6VZAC9oGdj nJXVaJ3t8lgG7oH0tkNL8zNyMXVwZDKMeq/liHp9+L5NBuNQaB7Ys62UcvWeni5/ RI8r0u3lIjH/MJIs6XXXOpsGwRjrfNt2ylqbhGwvaBTXQ2/1ljpoU= 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-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 spammy=wake, H*i:sk:CAOTD34, H*r:ip*192.168.0.6, highly X-HELO: mail-io0-f170.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=5RsXaufsKkL19q6MagPtUZVwQqoMSJSCYgN1BVIDTnY=; b=V7VXMJzgOqA2d++c/K9unLuC9rl/Q73Z2ZN3v/GQM+PlfGNj9CTrVMA4S3NQwiORHs l6k4JTJgGIS+JICBTikgfXCqOpyg5gX6JyLQMRJDIPQkq+Z0KnKH35YT5yA9ht+KyhnE iRqsYZLpX00YziUnzz04u3cQZaNrHfszsq7j9m5sayWbC9fjUOtivd6kkuGD7gvnFp4l 6dlIpM+ClDM1OBCghDoSKDbJ+BA0ZoIZ+u5BWMyipbeb1OwsIVr017gLX3PUsYBazxx5 9LgLtEZbOglpYD5043QGGwGpNt2WyMr64T4Os+hB2/CPaZaz5Ezgk3eEcF5Ly36RCvvn perg== X-Gm-Message-State: AKaTC01dv7ZCG0+7DJKexMGxydVlcmkMdmGh75DQjZuD+iV0mSFL2frKNSckyistGyr5iw== X-Received: by 10.36.200.10 with SMTP id w10mr23358192itf.21.1480428718209; Tue, 29 Nov 2016 06:11:58 -0800 (PST) Subject: Re: Retrieving per-process environment block? To: cygwin AT cygwin DOT com References: <20161117140012 DOT GA23664 AT calimero DOT vinschen DOT de> From: cyg Simple Message-ID: <084579a5-19c0-8475-56bb-c0836ef7088f@gmail.com> Date: Tue, 29 Nov 2016 09:11:38 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-IsSubscribed: yes On 11/29/2016 8:26 AM, Erik Bray wrote: > On Thu, Nov 17, 2016 at 3:00 PM, Corinna Vinschen > wrote: >> On Nov 17 14:30, Erik Bray wrote: >>> Hi all, >>> >>> For a quick bit of background, I'm working on porting the highly >>> useful psutil [1] Python library to Cygwin. This has proved an >>> interesting exercise, as much of the functionality of psutil works on >>> Cygwin through existing POSIX interfaces, and a handful of >>> Linux-specific interfaces as well. But there are some bits that >>> simply don't map at all. >>> >>> The one I'm struggling with right now is retrieving Cygwin environment >>> variables for a process (under inspection--i.e. not listing a >>> process's environment from within that process which is obviously >>> trivial). >>> >>> I've looked at every route I could conceive of but as far as I can >>> tell this is currently impossible. That's fine for now--I simply >>> disable that functionality in psutil. But it is unfortunate, though, >>> since the information is there. >>> >>> There are a couple avenues I could see to this. The most "obvious" >>> (to me) being to implement /proc//environ. >>> >>> I would be willing to provide a patch for this if it would be >>> accepted. Is there some particular non-obvious hurdle to this that it >>> hasn't been implemented? Obviously there are security >>> implications--the /proc//environ should only be readable to the >>> process's owner, but that is already within Cygwin's capabilities, and >>> works for other /proc files. >> >> Patch welcome. Implementing this should be fairly straightforward. >> The only hurdle is winsup/CONTRIBUTORS ;) > > Thanks--I went to go work on this finally but it turns out not to be > straightforward after all, as the process's environment is not shared > in any way between processes. > > I could do this, if each process kept a copy of its environment block > in shared memory, which would in turn have to be updated every time > the process's environment is updated. But I don't know what the > impact of that would be performance-wise. > > Any advice? > Sounds like a job for a thread that wakes every X time units to check the contents of the environment. Or is there a notification API that could be used to wake the thread? I know there is a disk change notification API for this; maybe one for environment changes as well. -- cyg Simple -- 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