vl: Fix bogus error message for implied mon ID clashing
monitor_parse() desugars --monitor, --qmp and -qmp-pretty to --mon.
The ID it picks can clash with a user-specified ID. When it happens,
the error message is misleading.
Reproducer:
$ qemu --mon id=compat_monitor0 --monitor stdio
Message before the patch:
duplicate chardev: compat_monitor0
There's no "duplicate chardev" here. The problem is a duplicate
monitor ID. Moreover, the message provides no clue which option
caused the problem. The patch changes the message to:
qemu: --monitor stdio: Duplicate ID 'compat_monitor0' for mon
monitor_parse() is also used for creating a default monitor, but
that's not done when the user specifies a monitor, so an ID clash is
impossible then.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/vl.c b/vl.c
index 983259b..2573afd 100644
--- a/vl.c
+++ b/vl.c
@@ -2195,6 +2195,7 @@
static void monitor_parse(const char *optarg, const char *mode, bool pretty)
{
static int monitor_device_index = 0;
+ Error *local_err = NULL;
QemuOpts *opts;
const char *p;
char label[32];
@@ -2215,9 +2216,10 @@
}
}
- opts = qemu_opts_create(qemu_find_opts("mon"), label, 1, NULL);
+ opts = qemu_opts_create(qemu_find_opts("mon"), label, 1, &local_err);
if (!opts) {
- fprintf(stderr, "duplicate chardev: %s\n", label);
+ error_report("%s", error_get_pretty(local_err));
+ error_free(local_err);
exit(1);
}
qemu_opt_set(opts, "mode", mode);
