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From: Eric Blake <eblake@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	"Peter Maydell" <peter.maydell@linaro.org>,
	"open list:Block layer core" <qemu-block@nongnu.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Jason Wang" <jasowang@redhat.com>,
	qemu-devel@nongnu.org, "Michael Roth" <mdroth@linux.vnet.ibm.com>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	"Amit Shah" <amit.shah@redhat.com>,
	"Luiz Capitulino" <lcapitulino@redhat.com>,
	"Andreas Färber" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [PATCH v11 19/28] qapi: Change munging of CamelCase enum values
Date: Fri, 13 Nov 2015 14:37:10 -0700	[thread overview]
Message-ID: <56465806.8030103@redhat.com> (raw)
In-Reply-To: <87wptlu5sg.fsf@blackfin.pond.sub.org>

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On 11/13/2015 11:13 AM, Markus Armbruster wrote:

> We need c_name() to protect ticklish identifiers only when its result is
> used as identifier.  Not when it's *part* of an identifier,
> e.g. prefixed with qapi_, or camel_to_upper(type_name) + '_'.
> 
> We can protect even when we don't need to, if that helps keeping things
> simple.

As far as I can tell, as soon as we reserve Q_ in addition to q_, and
fix the bug in c_name() applying munging backwards, then we are safe to
state that any comparison between two names for collisions will be
accurate as long as both sides of the comparison picked the same value
of c_name(name, protect), whether or not our later use of that name is
done with protect=True or protect=False.

> 
> The obvious simple way to check for collisions works like this:
> 
> 1. Every QAPI name is mangled in exactly one way, modulo case: always
>    with c_name(), and always with the same value of protect.

That part is easy.  Maybe I could even reuse guardname(name) instead of
c_name(name).upper(), although I don't know that it buys any clarity.

> 
> 2. We require the mangled name to be case-insensitively unique in its
>    name space.

That part is a bit harder: we unfortunately have the existing clash
between the command 'stop' and the event 'STOP'.  I didn't find any
other clashes in existing clients, though (phew), so we can either
whitelist just that one, or more likely, set up separate namespaces for
commands vs. events when doing the case collision tests.

But it's a bummer that it won't be quite as easy as I had hoped (using a
single dictionary for both lookups and case collisions is easier than
having two dictionaries to separate namespaces, while still searching
both dictionaries for lookups).

At any rate, I'm playing with patches along these lines.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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  reply	other threads:[~2015-11-13 21:37 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-11  6:51 [Qemu-devel] [PATCH v11 00/28] qapi member collision, alternate layout (post-introspection cleanups, subset D) Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 01/28] qapi: Track simple union tag in object.local_members Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 02/28] qapi-types: Consolidate gen_struct() and gen_union() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 03/28] qapi-types: Simplify gen_struct_field[s] Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 04/28] qapi: Drop obsolete tag value collision assertions Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 05/28] qapi: Simplify QAPISchemaObjectTypeMember.check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 06/28] qapi: Clean up after previous commit Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 07/28] qapi: Fix up commit 7618b91's clash sanity checking change Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 08/28] qapi: Eliminate QAPISchemaObjectType.check() variable members Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 09/28] qapi: Factor out QAPISchemaObjectTypeMember.check_clash() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 10/28] qapi: Simplify QAPISchemaObjectTypeVariants.check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 11/28] qapi: Check for qapi collisions of flat union branches Eric Blake
2015-11-11 13:42   ` Markus Armbruster
2015-11-11 15:49     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 12/28] qapi: Factor out QAPISchemaObjectType.check_clash() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 13/28] qapi: Hoist tag collision check to Variants.check() Eric Blake
2015-11-11 13:56   ` Markus Armbruster
2015-11-11 16:11     ` Eric Blake
2015-11-11 17:03       ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 14/28] qapi: Remove outdated tests related to QMP/branch collisions Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 15/28] qapi: Track owner of each object member Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 16/28] qapi: Detect collisions in C member names Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 17/28] cpu: Convert CpuInfo into flat union Eric Blake
2015-11-11 14:13   ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 18/28] qerror: more error_setg() usage Eric Blake
2015-11-11 13:26   ` Andreas Färber
2015-11-11 14:21   ` Markus Armbruster
2015-11-11 14:23     ` Andreas Färber
2015-11-11 15:51       ` Eric Blake
2015-11-11 16:19     ` Eric Blake
2015-11-11 17:31       ` Markus Armbruster
2015-11-11 17:44         ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 19/28] qapi: Change munging of CamelCase enum values Eric Blake
2015-11-11 13:29   ` Andreas Färber
2015-11-11 14:50   ` Markus Armbruster
2015-11-11 16:03     ` Eric Blake
2015-11-11 17:11       ` Markus Armbruster
2015-11-12  8:34         ` Gerd Hoffmann
2015-11-12 11:16           ` Markus Armbruster
2015-11-12  8:29       ` Gerd Hoffmann
2015-11-11 16:06     ` Eric Blake
2015-11-13 17:46   ` Eric Blake
2015-11-13 18:13     ` Markus Armbruster
2015-11-13 21:37       ` Eric Blake [this message]
2015-11-16 14:30         ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 20/28] qapi: Forbid case-insensitive clashes Eric Blake
2015-11-11 14:53   ` Markus Armbruster
2015-11-13  5:32     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 21/28] qapi: Convert qtype_code into qapi enum type Eric Blake
2015-11-11 16:42   ` Markus Armbruster
2015-11-11 17:03     ` Eric Blake
2015-11-12 13:16       ` Markus Armbruster
2015-11-18  6:27         ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 22/28] qapi: Simplify visiting of alternate types Eric Blake
2015-11-12 14:21   ` Markus Armbruster
2015-11-12 15:54   ` Markus Armbruster
2015-11-13 23:54   ` Eric Blake
2015-11-16 14:31     ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 23/28] qapi: Fix alternates that accept 'number' but not 'int' Eric Blake
2015-11-12 15:01   ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 24/28] qapi: Add positive tests to qapi-schema-test Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 25/28] qapi: Simplify visits of optional fields Eric Blake
2015-11-12 15:11   ` Markus Armbruster
2015-11-12 15:30     ` Eric Blake
2015-11-12 16:20       ` Markus Armbruster
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 26/28] qapi: Move duplicate member checks to schema check() Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 27/28] qapi: Move duplicate enum value " Eric Blake
2015-11-12 15:46   ` Markus Armbruster
2015-11-12 16:08     ` Eric Blake
2015-11-18  6:48     ` Eric Blake
2015-11-11  6:51 ` [Qemu-devel] [PATCH v11 28/28] qapi: Detect base class loops Eric Blake
2015-11-12 16:06   ` Markus Armbruster

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