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SubjectRe: [PATCH v4 07/53] tools api fs: Avoid reading whole file for a 1 byte bool
On Sun, Nov 5, 2023 at 7:56 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Thu, Nov 2, 2023 at 10:58 AM Ian Rogers <irogers@google.com> 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@google.com>
> > ---
> > 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
> >

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