From: Eric Blake <eblake@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org
Cc: lvivier@redhat.com, thuth@redhat.com, pkrempa@redhat.com,
ehabkost@redhat.com, qemu-block@nongnu.org,
libvir-list@redhat.com, jasowang@redhat.com, dgilbert@redhat.com,
mreitz@redhat.com, kraxel@redhat.com, pbonzini@redhat.com
Subject: Re: [PATCH v2 25/31] qemu-img: Use user_creatable_process_cmdline() for --object
Date: Fri, 26 Feb 2021 16:17:25 -0600 [thread overview]
Message-ID: <d0bec2d3-ee92-a3c8-d39a-c2569ac433b6@redhat.com> (raw)
In-Reply-To: <d4b18317-89e0-cfb1-d9a2-046e94f5d8f7@redhat.com>
On 2/26/21 3:56 PM, Eric Blake wrote:
> On 2/24/21 7:52 AM, Kevin Wolf wrote:
>> This switches qemu-img from a QemuOpts-based parser for --object to
>> user_creatable_process_cmdline() which uses a keyval parser and enforces
>> the QAPI schema.
>>
>> Apart from being a cleanup, this makes non-scalar properties accessible.
>>
>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>> ---
>> qemu-img.c | 239 ++++++++---------------------------------------------
>> 1 file changed, 33 insertions(+), 206 deletions(-)
>>
>
>> @@ -1423,15 +1373,9 @@ static int img_compare(int argc, char **argv)
>> case 'U':
>> force_share = true;
>> break;
>> - case OPTION_OBJECT: {
>> - QemuOpts *opts;
>> - opts = qemu_opts_parse_noisily(&qemu_object_opts,
>> - optarg, true);
>> - if (!opts) {
>> - ret = 2;
>> - goto out4;
>
> Our exit status here of 2 on failure appears to be intentional (since we
> reserve 0 for identical, 1 for mismatch, >1 for error)...
>
>> - }
>> - } break;
>> + case OPTION_OBJECT:
>> + user_creatable_process_cmdline(optarg);
>> + break;
>
> ...but becomes 1 here. Does that matter?
>
> /me goes and tests...
>
> Ouch: with current qemu.git master and none of this series applied:
>
> $ ./qemu-img compare --object foo,id=x /dev/null /dev/null
> qemu-img: invalid object type: foo
> $ echo $?
> 1
Okay, that didn't do what I expected, but this does:
$ ./qemu-img compare --object foo,id=1 /dev/null /dev/null
qemu-img: Parameter 'id' expects an identifier
Identifiers consist of letters, digits, '-', '.', '_', starting with a
letter.
$ echo $?
2
> $ gdb --args ./qemu-img compare --object foo,id=x /dev/null /dev/null
> (gdb) b qemu_opts_pars
> (gdb) r
> (gdb) fin
> Run till exit from #0 qemu_opts_parse_noisily (
> list=0x55555578f020 <qemu_object_opts>, params=0x7fffffffd8a8
> "foo,id=x",
> permit_abbrev=true) at ../util/qemu-option.c:948
> 0x00005555555805f9 in img_compare (argc=5, argv=0x7fffffffd480)
> at ../qemu-img.c:1428
> 1428 opts = qemu_opts_parse_noisily(&qemu_object_opts,
> Value returned is $1 = (QemuOpts *) 0x55555583b4b0
> (gdb) p *opts
> $3 = {id = 0x5555557a0d58 <qemu_trace_opts+24> "`\264\203UUU", list = 0x51,
and this may be my confusion with gdb. Right after 'fin', *opts is not
the same as *$1 (apparently gdb has stopped at a point where the 'opts'
currently in scope is not the opts set by qemu_opts_parse_noisily, but
before the opts in scope has actually been assigned the returned value).
>
> That looks buggy. qemu_opts_parse_noisily() is NOT returning NULL, but
> rather a pointer to something garbage (that id pointing to a garbage
> string in the middle of qemu_trace_opts is fishy), and so we've been
> exiting with status 1 in spite of the code.
>
> Looks like we'll want a separate patch fixing that first.
So I was wrong on when qemu_opts_parse_noisily() returns NULL - it does
NOT reject unknown object names (that was the job of the
qemu_opts_foreach call later), but merely rejects bad/duplicate ids.
Thus this code was indeed giving an exit status of 2 when actually
triggered correctly,
>
>> case OPTION_IMAGE_OPTS:
>> image_opts = true;
>> break;
>> @@ -1450,13 +1394,6 @@ static int img_compare(int argc, char **argv)
>> filename1 = argv[optind++];
>> filename2 = argv[optind++];
>>
>> - if (qemu_opts_foreach(&qemu_object_opts,
>> - user_creatable_add_opts_foreach,
>> - qemu_img_object_print_help, &error_fatal)) {
>> - ret = 2;
>> - goto out4;
>
> Same deal with return value. Except here we used &error_fatal (which
> forces an exit status of 1 rather than returning), and so never even
> reach the ret=2 code. Looks like we broke that in commit 334c43e2c3,
> where we used to pass NULL instead of &error_fatal (although that commit
> was in turn fixing another problem).
...and THIS spot is why my original attempt to prove that your code was
causing a regression was seeing an exit status of 1, where I instead
ended up proving that we already regressed.
>
> The rest of this patch looks fine, although maybe
> user_creatable_process_cmdline() should be given an 'int status'
> parameter for specifying 1 vs. 2 (or any other non-zero value) if we
> intend to fix the status of qemu-img compare failures. (Thankfully,
> even though qemu-img check also has a variety of documented return
> values other than 1, at least it documented 1 as internal errors and was
> already using 1 for --object failures).
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
next prev parent reply other threads:[~2021-02-26 22:19 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-24 13:52 [PATCH v2 00/31] qapi/qom: QAPIfy --object and object-add Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 01/31] tests: Drop 'props' from object-add calls Kevin Wolf
2021-02-25 22:40 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 02/31] qapi/qom: Drop deprecated 'props' from object-add Kevin Wolf
2021-02-25 22:42 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 03/31] qapi/qom: Add ObjectOptions for iothread Kevin Wolf
2021-02-25 22:55 ` Eric Blake
2021-03-02 17:27 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 04/31] qapi/qom: Add ObjectOptions for authz-* Kevin Wolf
2021-02-26 14:02 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 05/31] qapi/qom: Add ObjectOptions for cryptodev-* Kevin Wolf
2021-02-26 14:36 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 06/31] qapi/qom: Add ObjectOptions for dbus-vmstate Kevin Wolf
2021-02-26 15:58 ` Eric Blake
2021-03-02 17:36 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 07/31] qapi/qom: Add ObjectOptions for memory-backend-* Kevin Wolf
2021-02-26 16:23 ` Eric Blake
2021-03-02 18:11 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 08/31] qapi/qom: Add ObjectOptions for rng-*, deprecate 'opened' Kevin Wolf
2021-02-26 16:54 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 09/31] qapi/qom: Add ObjectOptions for throttle-group Kevin Wolf
2021-02-26 17:26 ` Eric Blake
2021-03-02 18:18 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 10/31] qapi/qom: Add ObjectOptions for secret*, deprecate 'loaded' Kevin Wolf
2021-02-26 19:17 ` Eric Blake
2021-03-02 18:23 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 11/31] qapi/qom: Add ObjectOptions for tls-*, " Kevin Wolf
2021-02-26 19:33 ` Eric Blake
2021-03-02 18:27 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 12/31] qapi/qom: Add ObjectOptions for can-* Kevin Wolf
2021-02-26 19:42 ` Eric Blake
2021-03-02 18:32 ` Kevin Wolf
2021-03-02 20:03 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 13/31] qapi/qom: Add ObjectOptions for colo-compare Kevin Wolf
2021-02-26 19:46 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 14/31] qapi/qom: Add ObjectOptions for filter-* Kevin Wolf
2021-02-26 20:03 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 15/31] qapi/qom: Add ObjectOptions for pr-manager-helper Kevin Wolf
2021-02-26 20:04 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 16/31] qapi/qom: Add ObjectOptions for confidential-guest-support Kevin Wolf
2021-02-24 15:21 ` Dr. David Alan Gilbert
2021-02-24 16:25 ` Kevin Wolf
2021-02-26 20:27 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 17/31] qapi/qom: Add ObjectOptions for input-* Kevin Wolf
2021-02-26 20:55 ` Eric Blake
2021-03-02 18:42 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 18/31] qapi/qom: Add ObjectOptions for x-remote-object Kevin Wolf
2021-02-26 21:01 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 19/31] qapi/qom: QAPIfy object-add Kevin Wolf
2021-02-26 11:30 ` Paolo Bonzini
2021-03-01 11:54 ` Kevin Wolf
2021-03-01 12:03 ` Paolo Bonzini
2021-02-26 21:18 ` Eric Blake
2021-03-02 18:54 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 20/31] qom: Make "object" QemuOptsList optional Kevin Wolf
2021-02-26 21:20 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 21/31] qemu-storage-daemon: Implement --object with qmp_object_add() Kevin Wolf
2021-02-26 21:22 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 22/31] qom: Remove user_creatable_add_dict() Kevin Wolf
2021-02-26 21:23 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 23/31] qom: Factor out user_creatable_process_cmdline() Kevin Wolf
2021-02-26 21:26 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 24/31] qemu-io: Use user_creatable_process_cmdline() for --object Kevin Wolf
2021-02-26 21:27 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 25/31] qemu-img: " Kevin Wolf
2021-02-26 21:56 ` Eric Blake
2021-02-26 22:17 ` Eric Blake [this message]
2021-02-24 13:52 ` [PATCH v2 26/31] qemu-nbd: " Kevin Wolf
2021-02-26 22:18 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 27/31] qom: Add user_creatable_add_from_str() Kevin Wolf
2021-02-26 22:21 ` Eric Blake
2021-03-02 19:39 ` Kevin Wolf
2021-02-24 13:52 ` [PATCH v2 28/31] hmp: QAPIfy object_add Kevin Wolf
2021-02-24 15:31 ` Dr. David Alan Gilbert
2021-02-26 22:23 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 29/31] qom: Add user_creatable_parse_str() Kevin Wolf
2021-02-26 22:24 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 30/31] vl: QAPIfy -object Kevin Wolf
2021-02-26 22:40 ` Eric Blake
2021-02-24 13:52 ` [PATCH v2 31/31] qom: Drop QemuOpts based interfaces Kevin Wolf
2021-02-26 22:42 ` Eric Blake
2021-02-24 16:01 ` [PATCH v2 00/31] qapi/qom: QAPIfy --object and object-add Peter Krempa
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