Re: [Qemu-devel] [PATCH v2 27/35] vnc: Clean up error reporting in vnc_init_func()

[Markus Armbruster]

Fei Li <address@hidden> writes:

> On 10/15/2018 07:53 PM, Markus Armbruster wrote:
>> Calling error_report() in a function that takes an Error ** argument
>> is suspicious.  vnc_init_func() does that, and then fails without
>> setting an error.  Its caller main(), via qemu_opts_foreach(), is fine
>> with it, but clean it up anyway.
>>
>> Cc: Gerd Hoffmann <address@hidden>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>   ui/vnc.c | 9 +++++----
>>   vl.c     | 2 +-
>>   2 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/ui/vnc.c b/ui/vnc.c
>> index 98e3d3b1d8..fcd2744d52 100644
>> --- a/ui/vnc.c
>> +++ b/ui/vnc.c
>> @@ -4082,13 +4082,14 @@ int vnc_init_func(void *opaque, QemuOpts *opts, 
>> Error **errp)
>>       assert(id);
>>       vnc_display_init(id, &local_err);
>>       if (local_err) {
>> -        error_report_err(local_err);
>> -        exit(1);
>> +        error_propagate(errp, local_err);
> Shall we use error_propagate(errp, local_err, ("Failed to init VNC
> server: ");
> like vnc_display_open does?

I don't know.  

The error reporting is somewhat poor around here.  Consider:

    $ qemu-system-x86_64 -display vnc=:0,share=nope
    qemu-system-x86_64: -display vnc=:0,share=nope: Failed to start VNC server: 
unknown vnc share= option

The "Failed to start VNC server: " prefix doesn't really add value.

    $ qemu-system-x86_64 -display vnc=:0 -k bad
    qemu-system-x86_64: -display vnc=:0: could not read keymap file: 'bad'

The error message refers to -display instead of -k.  I doubt adding the
prefix would improve it.

Gerd, what do you think?

> If yes, I guess this error message should be added from last patch [26/35].

Yes.

> If not, please omit. :)
>
> Have a nice day
> Fei
>> +        return -1;
>>       }
>>       vnc_display_open(id, &local_err);
>>       if (local_err != NULL) {
>> -        error_reportf_err(local_err, "Failed to start VNC server: ");
>> -        exit(1);
>> +        error_propagate_prepend(errp, local_err,
>> +                                "Failed to start VNC server: ");
>> +        return -1;
>>       }
>>       return 0;
>>   }
>> diff --git a/vl.c b/vl.c
>> index c053117028..8e0006d49c 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -4526,7 +4526,7 @@ int main(int argc, char **argv, char **envp)
>>       /* init remote displays */
>>   #ifdef CONFIG_VNC
>>       qemu_opts_foreach(qemu_find_opts("vnc"),
>> -                      vnc_init_func, NULL, NULL);
>> +                      vnc_init_func, NULL, &error_fatal);
>>   #endif
>>         if (using_spice) {