Re: [PATCH -next] tools build: Check return value of fwrite_unlocked in jvmti_agent.c

[Wangshaobo (bobo)]

å 2020/7/30 18:03, Arnaldo Carvalho de Melo åé:
> Em Wed, Jul 29, 2020 at 04:47:36PM -0700, Ian Rogers escreveu:
> > On Fri, Jul 24, 2020 at 3:07 AM Wang ShaoBo <bobo.shaobowang@xxxxxxxxxx> wrote:
> > > Function jvmti_write_code called by compiled_method_load_cb may return
> > > error in using fwrite_unlocked, this failure should be captured and
> > > warned.
> > >
> > > Signed-off-by: Wang ShaoBo <bobo.shaobowang@xxxxxxxxxx>
> > > ---
> > >   tools/perf/jvmti/jvmti_agent.c | 23 +++++++++++++++--------
> > >   1 file changed, 15 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/tools/perf/jvmti/jvmti_agent.c b/tools/perf/jvmti/jvmti_agent.c
> > > index 88108598d6e9..a1fe6aa16b6d 100644
> > > --- a/tools/perf/jvmti/jvmti_agent.c
> > > +++ b/tools/perf/jvmti/jvmti_agent.c
> > > @@ -363,7 +363,7 @@ jvmti_write_code(void *agent, char const *sym,
> > >          struct jr_code_load rec;
> > >          size_t sym_len;
> > >          FILE *fp = agent;
> > > -       int ret = -1;
> > > +       int ret;
> > >
> > >          /* don't care about 0 length function, no samples */
> > >          if (size == 0)
> > > @@ -401,16 +401,23 @@ jvmti_write_code(void *agent, char const *sym,
> > >          rec.code_index = code_generation++;
> > >
> > >          ret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
> > > -       fwrite_unlocked(sym, sym_len, 1, fp);
> > > +       if (ret)
> > > +               goto error;
> > Sorry, it seems I lost a reply to this. Won't ret here be the number
> > of items written and not an error code? Consequently all writes will
> > immediately goto error?
> Yeah, I removed it from tmp.perf/core.
>
> Wang, please address Ian review, and consider having just one out exit
> label.
>
> - Arnaldo
>   

I am sorry I forgot what does fwrite_unlocked return, as same as fwrite 
error happens,

the return val is a short item count (or zero)Â but not equals the items 
written. I have fixed

it and already sent v2 and address Ian review, thanks a lot.

... and i refer to the writing of function jvmti_write_debug_info() for 
giving out exit label,

thanks again,

- Wang ShaoBo

> > Thanks,
> > Ian
> >
> > > +       ret = fwrite_unlocked(sym, sym_len, 1, fp);
> > > +       if (ret)
> > > +               goto error;
> > >
> > > -       if (code)
> > > -               fwrite_unlocked(code, size, 1, fp);
> > > +       if (code) {
> > > +               ret = fwrite_unlocked(code, size, 1, fp);
> > > +               if (ret)
> > > +                       goto error;
> > > +       }
> > >
> > >          funlockfile(fp);
> > > -
> > > -       ret = 0;
> > > -
> > > -       return ret;
> > > +       return 0;
> > > +error:
> > > +       funlockfile(fp);
> > > +       return -1;
> > >   }
> > >
> > >   int
> > > --
> > > 2.17.1