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@xxxxxxxxxx>
> ---
> 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
$ 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,
loc = {kind = (unknown: 0x557f08f0), num = 21845,
ptr = 0x55555578f020 <qemu_object_opts>, prev = 0x0}, head = {
tqh_first = 0x0, tqh_circ = {tql_next = 0x0, tql_prev = 0x0}}, next = {
tqe_next = 0x55555583b500, tqe_circ = {tql_next = 0x55555583b500,
tql_prev = 0x55555583b528}}}
(gdb)
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.
> 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).
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
