Re: [Qemu-devel] [PATCH V8 3/8] util: add error_append()

[Wenchao Xia]

于 2014/1/3 23:32, Peter Crosthwaite 写道:
> On Fri, Jan 3, 2014 at 1:08 PM, Wenchao Xia <address@hidden> wrote:
> > Signed-off-by: Wenchao Xia <address@hidden>
> > ---
> >   include/qapi/error.h |    6 ++++++
> >   util/error.c         |   21 +++++++++++++++++++++
> >   2 files changed, 27 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/qapi/error.h b/include/qapi/error.h
> > index 7d4c696..bcfb724 100644
> > --- a/include/qapi/error.h
> > +++ b/include/qapi/error.h
> > @@ -30,6 +30,12 @@ typedef struct Error Error;
> >   void error_set(Error **err, ErrorClass err_class, const char *fmt, ...) 
> > GCC_FMT_ATTR(3, 4);
> >
> >   /**
> > + * Append message to err if err != NULL && *err != NULL. "\n" will be inserted
> > + * after old message.
> > + */
> > +void error_append(Error **err, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
> > +
> > +/**
> >    * Set an indirect pointer to an error given a ErrorClass value and a
> >    * printf-style human message, followed by a strerror() string if
> >    * @os_error is not zero.
> > diff --git a/util/error.c b/util/error.c
> > index 3ee362a..64bbb2d 100644
> > --- a/util/error.c
> > +++ b/util/error.c
> > @@ -46,6 +46,27 @@ void error_set(Error **errp, ErrorClass err_class, const 
> > char *fmt, ...)
> >       errno = saved_errno;
> >   }
> >
> > +void error_append(Error **err, const char *fmt, ...)
>
> errp
>
> > +{
> > +    va_list ap;
> > +    gchar *msg, *msg_old;
> > +
> > +    if (!err || !*err) {
>
> Should appending to an unset error really be a nop? You should just
> set the error as normal in this case (error_set()?).
>
> This avoids callers having to:
>
> if (error_is_set(&err)) {
>     error_append(&err);
> } else {
>     error_set(&err);
> }
>
> so they can just append if they want appending.
>
> Generally speaking, appending to nothing should give you something.
>
> Regards,
> Peter

  Make sense, will fix as above, thanks for review.

> > +        return;
> > +    }
> > +
> > +    va_start(ap, fmt);
> > +    msg = g_strdup_vprintf(fmt, ap);
> > +    va_end(ap);
> > +
> > +    msg_old = (*err)->msg;
> > +    (*err)->msg = g_strdup_printf("%s\n%s", msg_old, msg);
> > +
> > +    g_free(msg);
> > +    g_free(msg_old);
> > +
> > +}
> > +
> >   void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
> >                        const char *fmt, ...)
> >   {
> > --
> > 1.7.1