Hi Sakari,
On Wed, Feb 20, 2019 at 11:26:52PM +0200, Sakari Ailus wrote:
> On Wed, Feb 20, 2019 at 02:51:22PM +0200, Laurent Pinchart wrote:
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > ---
> > yavta.c | 25 +++++++++++++++++++++++++
> > 1 file changed, 25 insertions(+)
> >
> > diff --git a/yavta.c b/yavta.c
> > index 1490878c6f7e..2d49131a4271 100644
> > --- a/yavta.c
> > +++ b/yavta.c
> > @@ -1334,6 +1334,31 @@ static int video_parse_control_array(const struct v4l2_query_ext_ctrl *query,
> > __u32 value;
> >
> > for ( ; isspace(*val); ++val) { };
> > +
> > + if (*val == '<') {
> > + /* Read the control value from the given file. */
> > + ssize_t size;
> > + int fd;
> > +
> > + val++;
> > + fd = open(val, O_RDONLY);
> > + if (fd < 0) {
> > + printf("unable to open control file `%s'\n", val);
> > + return -EINVAL;
> > + }
> > +
> > + size = read(fd, ctrl->ptr, ctrl->size);
>
> Note that a read of count reads *up to* count number of bytes from the file
> descriptor. In other words, it's perfectly correct for it to read less than
> requested.
>
> How about using fread(3) instead? Or changing this into a loop?
Do you expect this to cause issues in practice ? When does read() return
less data than requested for regular files ?
> > + if (size != (ssize_t)ctrl->size) {
> > + printf("error reading control file `%s' (%s)\n", val,
> > + strerror(errno));
> > + close(fd);
> > + return -EINVAL;
> > + }
> > +
> > + close(fd);
> > + return 0;
> > + }
> > +
> > if (*val++ != '{')
> > return -EINVAL;
> >
--
Regards,
Laurent Pinchart
