Re: [Qemu-devel] [PATCH v2] qtest: Don't segfault with invalid -qtest option

["Andreas Färber" <afaerber@suse.de>]

Am 10.02.2014 15:29, schrieb Markus Armbruster:
> Andreas Färber <afaerber@suse.de> writes:
> 
>> Am 10.02.2014 09:48, schrieb Markus Armbruster:
>>> Fam Zheng <famz@redhat.com> writes:
>>>
>>>> This prints an error message, instead of core dump, when "-qtest"
>>>> option value is invalid, e.g.:
>>>>
>>>>     $ ./x86_64-softmmu/qemu-system-x86_64 -qtest unknown
>>>>         qemu-system-x86_64: Failed to initialize device for qtest:
>>>>         "unknown"
>>>>
>>>> Signed-off-by: Fam Zheng <famz@redhat.com>
>>>> ---
>>>>  include/sysemu/qtest.h | 3 ++-
>>>>  qtest.c                | 8 +++++++-
>>>>  vl.c                   | 8 +++++++-
>>>>  3 files changed, 16 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/include/sysemu/qtest.h b/include/sysemu/qtest.h
>>>> index 112a661..2de61c6 100644
>>>> --- a/include/sysemu/qtest.h
>>>> +++ b/include/sysemu/qtest.h
>>>> @@ -15,6 +15,7 @@
>>>>  #define QTEST_H
>>>>  
>>>>  #include "qemu-common.h"
>>>> +#include "qapi/error.h"
>>>>  
>>>>  extern bool qtest_allowed;
>>>>  
>>>> @@ -24,7 +25,7 @@ static inline bool qtest_enabled(void)
>>>>  }
>>>>  
>>>>  int qtest_init_accel(void);
>>>> -void qtest_init(const char *qtest_chrdev, const char *qtest_log);
>>>> +void qtest_init(const char *qtest_chrdev, const char *qtest_log, Error **errp);
>>>>  
>>>>  static inline int qtest_available(void)
>>>>  {
>>>> diff --git a/qtest.c b/qtest.c
>>>> index dcf1301..a4ad407 100644
>>>> --- a/qtest.c
>>>> +++ b/qtest.c
>>>> @@ -507,12 +507,18 @@ int qtest_init_accel(void)
>>>>      return 0;
>>>>  }
>>>>  
>>>> -void qtest_init(const char *qtest_chrdev, const char *qtest_log)
>>>> +void qtest_init(const char *qtest_chrdev, const char *qtest_log, Error **errp)
>>>>  {
>>>>      CharDriverState *chr;
>>>>  
>>>>      chr = qemu_chr_new("qtest", qtest_chrdev, NULL);
>>>>  
>>>> +    if (chr == NULL) {
>>>> +        error_setg(errp, "Failed to initialize device for qtest: \"%s\"",
>>>> +                   qtest_chrdev);
>>>> +        return;
>>>> +    }
>>>> +
>>>>      qemu_chr_add_handlers(chr, qtest_can_read, qtest_read, qtest_event, chr);
>>>>      qemu_chr_fe_set_echo(chr, true);
>>>>  
>>>> diff --git a/vl.c b/vl.c
>>>> index e2e576c..bee455d 100644
>>>> --- a/vl.c
>>>> +++ b/vl.c
>>>> @@ -4079,7 +4079,13 @@ int main(int argc, char **argv, char **envp)
>>>>      configure_accelerator();
>>>>  
>>>>      if (qtest_chrdev) {
>>>> -        qtest_init(qtest_chrdev, qtest_log);
>>>> +        Error *local_err = NULL;
>>>> +        qtest_init(qtest_chrdev, qtest_log, &local_err);
>>>> +        if (error_is_set(&local_err)) {
>>>> +            error_report("%s", error_get_pretty(local_err));
>>>> +            error_free(local_err);
>>>> +            exit(1);
>>>> +        }
>>>>      }
>>>>  
>>>>      machine_opts = qemu_get_machine_opts();
>>>
>>> No objections, although I would've gone for simple & stupid instead:
>>> Make qtest_init() return success / failure, and error_report() either in
>>> qtest_init() or its caller, without the detour through an Error object.
>>
>> error_report() had been in the function in v1 and I suggested to either
>> move the exit() there too (avoids signature changes and keeps them
>> together, avoiding multiple error messages for the same failure) or to
> 
> Yes, that's even simpler.
> 
>> do it via Error** here.
>>
>> Since he decided for this route, I would propose to apply v2 to qom-next
>> with error_is_set(&local_err) replaced with just local_err, honoring
>> your cleanup patch.
> 
> Again, no objections :)

Thanks, applied to qom-next with the following change:

diff --git a/vl.c b/vl.c
index 1bcd083..0f7d31f 100644
--- a/vl.c
+++ b/vl.c
@@ -4080,7 +4080,7 @@ int main(int argc, char **argv, char **envp)
     if (qtest_chrdev) {
         Error *local_err = NULL;
         qtest_init(qtest_chrdev, qtest_log, &local_err);
-        if (error_is_set(&local_err)) {
+        if (local_err) {
             error_report("%s", error_get_pretty(local_err));
             error_free(local_err);
             exit(1);

https://github.com/afaerber/qemu-cpu/commits/qom-next

Regards,
Andreas

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