Luiz Capitulino <lcapitul...@redhat.com> writes:
> On Thu, 09 Feb 2012 17:19:00 +0100
> Markus Armbruster <arm...@redhat.com> wrote:
>
>> Kevin Wolf <kw...@redhat.com> writes:
>>
>> > Am 09.02.2012 16:16, schrieb Markus Armbruster:
>> >> Kevin Wolf <kw...@redhat.com> writes:
>> >>
>> >>> Am 07.02.2012 15:09, schrieb Markus Armbruster:
>> >>>> This part takes care of backends "file", "pipe", "pty" and "stdio".
>> >>>> Unlike many other backends, these leave open error reporting to their
>> >>>> caller. Because the caller doesn't know what went wrong, this results
>> >>>> in a pretty useless error message.
>> >>>>
>> >>>> Change them to report their errors. Improves comically user-hostile
>> >>>> messages like this one for "-chardev file,id=foo,path=/x"
>> >>>>
>> >>>> chardev: opening backend "file" failed
>> >>>>
>> >>>> to
>> >>>>
>> >>>> qemu-system-x86_64: -chardev file,id=foo,path=/x: Can't create file
>> >>>> '/x': Permission denied
>> >>>> chardev: opening backend "file" failed
>> >>>>
>> >>>> The useless "opening backend failed" message will be cleaned up
>> >>>> shortly.
>> >>>>
>> >>>> Signed-off-by: Markus Armbruster <arm...@redhat.com>
>> >>>> ---
>> >>>> qemu-char.c | 19 +++++++++++++++----
>> >>>> 1 files changed, 15 insertions(+), 4 deletions(-)
>> >>>
>> >>>> @@ -1002,7 +1013,7 @@ static CharDriverState
>> >>>> *qemu_chr_open_pty(QemuOpts *opts)
>> >>>> chr->filename = g_malloc(len);
>> >>>> snprintf(chr->filename, len, "pty:%s", q_ptsname(master_fd));
>> >>>> qemu_opt_set(opts, "path", q_ptsname(master_fd));
>> >>>> - fprintf(stderr, "char device redirected to %s\n",
>> >>>> q_ptsname(master_fd));
>> >>>> + error_printf("char device redirected to %s\n",
>> >>>> q_ptsname(master_fd));
>> >>>>
>> >>>> s = g_malloc0(sizeof(PtyCharDriver));
>> >>>> chr->opaque = s;
>> >>>
>> >>> Not really an error message. Does it make any sense at all to have this
>> >>> message?
>> >>
>> >> error_printf() prints to the error channel (monitor or stderr), but not
>> >> necessarily an error message. See for instance drive_init()'s use of it
>> >> to print format help.
>> >
>> > Ah, right. I confused it with error_report() which includes an error
>> > location. That would be rather unexpected.
>>
>> Indeed.
>>
>> >> Not sure whether it makes sense to have this message. I guess it exists
>> >> because the pty is chosen automatically, but the user might still want
>> >> to know which one was chosen.
>> >
>> > Does "the user" include management tools?
>> >
>> > If we had a chardev_add monitor command, its output would be moved from
>> > stderr to the monitor. We don't have that,
>>
>> Yet! One of the reasons for doing this series was preparing the ground
>> for chardev_add.
>
> I haven't taken a look in detail in this series, but if your end goal is to
> add chardev_add, then you should probably be using error_set() all around.
The goal is to improve the atrocious error reporting, no more, no less.
Nice side effect: it gets us one little step closer to chardev_add.
Converting to error_set() will be much easier after this series than
before.
