printf() & friends return the number of characters written on success,
negative value on error.
monitor_printf(), monitor_vfprintf(), monitor_vprintf(),
error_printf(), error_printf_unless_qmp(), error_vprintf(), and
error_vprintf_unless_qmp() return void. Some of them carry a TODO
comment asking for int instead.
Improve them to return int like printf() does.
This makes our use of monitor_printf() as fprintf_function slightly
less dirty: the function cast no longer adds a return value that isn't
there. It still changes a parameter's pointer type. That will be
addressed in a future commit.
monitor_vfprintf() always returns zero. Improve it to return the
proper value.
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417190641.26814-11-armbru@redhat.com>
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