From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AC839C433EF for ; Wed, 23 Feb 2022 17:52:23 +0000 (UTC) Received: from localhost ([::1]:55950 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nMvoL-0004HK-FR for qemu-devel@archiver.kernel.org; Wed, 23 Feb 2022 12:52:21 -0500 Received: from eggs.gnu.org ([209.51.188.92]:58618) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nMvmk-0003Mk-VO for qemu-devel@nongnu.org; Wed, 23 Feb 2022 12:50:44 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:45476) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nMvmh-00087b-5t for qemu-devel@nongnu.org; Wed, 23 Feb 2022 12:50:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645638634; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N5jGTYNSXOCq4CE1enF/iv/YJCBaFV9teD3yyV+LOjA=; b=YtTsfuo6ZNE7lEIb/GDXmqO19zMCdUIJbo/oTHGqKngkzgnLiEXe015joW0Im0MuA41cqI aVhaklJPOp4XsnrciiRYhFyfJErtHwPp64ku9GEgG/pQD4sethizwDeOo7Q+UoBoJpNBN0 ftQKKyD6ztlfP/wHZuW3MXFc9ekwC54= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-258-IkjWXgs6MxGjdYyhZQMOXA-1; Wed, 23 Feb 2022 12:50:26 -0500 X-MC-Unique: IkjWXgs6MxGjdYyhZQMOXA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6342F1091DA1; Wed, 23 Feb 2022 17:50:25 +0000 (UTC) Received: from redhat.com (unknown [10.39.195.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E7AB84772; Wed, 23 Feb 2022 17:50:08 +0000 (UTC) Date: Wed, 23 Feb 2022 17:50:05 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: John Snow Subject: Re: [PATCH 4/5] python: qmp_shell: add -e/--exit-on-error option Message-ID: References: <20220221155519.2367-1-damien.hedde@greensocs.com> <20220221155519.2367-5-damien.hedde@greensocs.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Damien Hedde , Eduardo Habkost , qemu-devel , Cleber Rosa Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Feb 23, 2022 at 11:18:26AM -0500, John Snow wrote: > On Wed, Feb 23, 2022 at 10:44 AM Daniel P. Berrangé wrote: > > > > On Wed, Feb 23, 2022 at 10:41:11AM -0500, John Snow wrote: > > > On Wed, Feb 23, 2022 at 10:27 AM Daniel P. Berrangé wrote: > > > > > > > > On Wed, Feb 23, 2022 at 10:22:11AM -0500, John Snow wrote: > > > > > On Mon, Feb 21, 2022 at 10:55 AM Damien Hedde > > > > > wrote: > > > > > > > > > > > > This option makes qmp_shell exit (with error code 1) > > > > > > as soon as one of the following error occurs: > > > > > > + command parsing error > > > > > > + disconnection > > > > > > + command failure (response is an error) > > > > > > > > > > > > _execute_cmd() method now returns None or the response > > > > > > so that read_exec_command() can do the last check. > > > > > > > > > > > > This is meant to be used in combination with an input file > > > > > > redirection. It allows to store a list of commands > > > > > > into a file and try to run them by qmp_shell and easily > > > > > > see if it failed or not. > > > > > > > > > > > > Signed-off-by: Damien Hedde > > > > > > > > > > Based on this patch, it looks like you really want something > > > > > scriptable, so I think the qemu-send idea that Dan has suggested might > > > > > be the best way to go. Are you still hoping to use the interactive > > > > > "short" QMP command format? That might be a bad idea, given how flaky > > > > > the parsing is -- and how we don't actually have a published standard > > > > > for that format. We've *never* liked the bad parsing here, so I have a > > > > > reluctance to use it in more places. > > > > > > > > > > I'm having the naive idea that a script file could be as simple as a > > > > > list of QMP commands to send: > > > > > > > > > > [ > > > > > {"execute": "block-dirty-bitmap-add", "arguments": { ... }}, > > > > > ... > > > > > ] > > > > > > > > I'd really recommend against creating a new format for the script > > > > file, especially one needing opening & closing [] like this, as > > > > that isn't so amenable to dynamic usage/creation. ie you can't > > > > just append an extcra command to an existing file. > > > > > > > > IMHO, the "file" format should be identical to the result of > > > > capturing the socket data off the wire. ie just a concatenation > > > > of QMP commands, with no extra wrapping / change in format. > > > > > > > > > > Eugh. That's just so hard to parse, because there's no off-the-shelf > > > tooling for "load a sequence of JSON documents". Nothing in Python > > > does it. :\ > > > > It isn't that hard if you require each JSON doc to be followed by > > a newline. > > > > Feed one line at a time to the JSON parser, until you get a complete > > JSON doc, process that, then re-init the parser and carry on feeding > > it lines until it emits the next JSON doc, and so on. > > > > There's two interfaces in Python: > > (1) json.load(), which takes a file pointer and either returns a > single, complete JSON document or it raises an Exception. It's not > useful here at all. > (2) json.JSONDecoder().raw_decode(strbuf), which takes a string buffer > and returns a 2-tuple of a JSON Document and the position at which it > stopped decoding. Yes, the latter would do it, but you can also be lazy and just repeatedly call json.loads() until you get a valid parse $ cat demo.py import json cmds = [] bits = [] with open("qmp.txt", "r") as fh: for line in fh: bits.append(line) try: cmdstr = "".join(bits) cmds.append(json.loads(cmdstr)) bits = [] except json.JSONDecodeError: pass for cmd in cmds: print("Command: %s" % cmd) $ cat qmp.txt { "execute": "qmp_capabilities" } { "execute": "blockdev-add", "arguments": { "node-name": "drive0", "driver": "file", "filename": "$TEST_IMG" } } { "execute": "blockdev-add", "arguments": { "driver": "$IMGFMT", "node-name": "drive0-debug", "file": { "driver": "blkdebug", "image": "drive0", "inject-error": [{ "event": "l2_load" }] } } } { "execute": "human-monitor-command", "arguments": { "command-line": "qemu-io drive0-debug \"read 0 512\"" } } { "execute": "quit" } $ python demo.py Command: {'execute': 'qmp_capabilities'} Command: {'execute': 'blockdev-add', 'arguments': {'node-name': 'drive0', 'driver': 'file', 'filename': '$TEST_IMG'}} Command: {'execute': 'blockdev-add', 'arguments': {'driver': '$IMGFMT', 'node-name': 'drive0-debug', 'file': {'driver': 'blkdebug', 'image': 'drive0', 'inject-error': [{'event': 'l2_load'}]}}} Command: {'execute': 'human-monitor-command', 'arguments': {'command-line': 'qemu-io drive0-debug "read 0 512"'}} Command: {'execute': 'quit'} > Wanting to keep the script easy to append to is legitimate. I'm keen > to hear a bit more about the use case here before I press extremely > hard in any given direction, but those are my impulses here. We can see examples of where this could be used in the I/O tests eg in tests/qemu-iotests/071, a frequent pattern is: run_qemu <