Re: [PATCH v4 07/53] tools api fs: Avoid reading whole file for a 1 byte bool

[Ian Rogers]

On Sun, Nov 5, 2023 at 7:56 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> On Thu, Nov 2, 2023 at 10:58 AM Ian Rogers <irogers@xxxxxxxxxx> wrote:
> >
> > sysfs__read_bool used the first byte from a fully read file into a
> > string. It then looked at the first byte's value. Avoid doing this and
> > just read the first byte.
> >
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > ---
> >  tools/lib/api/fs/fs.c | 18 +++++++++---------
> >  1 file changed, 9 insertions(+), 9 deletions(-)
> >
> > diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
> > index 496812b5f1d2..4c35a689d1fc 100644
> > --- a/tools/lib/api/fs/fs.c
> > +++ b/tools/lib/api/fs/fs.c
> > @@ -447,15 +447,16 @@ int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
> >
> >  int sysfs__read_bool(const char *entry, bool *value)
> >  {
> > -       char *buf;
> > -       size_t size;
> > -       int ret;
> > +       struct io io;
> > +       char bf[16];
> > +       int ret = 0;
> >
> > -       ret = sysfs__read_str(entry, &buf, &size);
> > -       if (ret < 0)
> > -               return ret;
> > +       io.fd = open(entry, O_RDONLY);
>
> The entry is a name in sysfs, so you need to get the full name.
>
> Thanks,
> Namhyung

Thanks, added in v5.

Ian

>
> > +       if (io.fd < 0)
> > +               return -errno;
> >
> > -       switch (buf[0]) {
> > +       io__init(&io, io.fd, bf, sizeof(bf));
> > +       switch (io__get_char(&io)) {
> >         case '1':
> >         case 'y':
> >         case 'Y':
> > @@ -469,8 +470,7 @@ int sysfs__read_bool(const char *entry, bool *value)
> >         default:
> >                 ret = -1;
> >         }
> > -
> > -       free(buf);
> > +       close(io.fd);
> >
> >         return ret;
> >  }
> > --
> > 2.42.0.869.gea05f2083d-goog
> >