[sane-devel] [patch] fix SANE_Device

[Oliver Rauch]

Am Mit, 2004-11-17 um 06.04 schrieb Frank Zago:
> Frank Zago wrote:
> >=20
> >>
> >> The SANE standard defines the comunication between frontend and back=
end.
> >> It does not define any structs that shall be internally used by the
> >> frontend or backend.
> >>
> >> I think the clean appoach is that the backend handles the texts inte=
rnal
> >> as non const strings and only creats the SANE_Device struct to retur=
n
> >> the data to the frontend. The SANE_Device struct is defined for the
> >> purpose to transfer the data from the backend to the frontend as con=
st
> >> chars. When the backend has to use non const definitions then it is =
not
> >> allowed to use the SANE_Device struct so it has to use it=C2=B4s own=
 data
> >> types and not the one of the SANE standard.
> >>
> >> Oliver
> >=20
> >=20
> > So, in that case what about the patch in attachment.
> >=20
> > I've also changed the internal definition of SANE_Option_Descriptor f=
or=20
> > the same  reason. It breaks about 5 backends, but they can all be eas=
ily=20
> > fixed by hand by removing a few const. I'd say that the current=20
> > definition of SANE_Device and SANE_Option_Descriptor and created an u=
gly=20
> > cascade of unnecessary casts and consts in all the backends.
> >=20
> > Frank.
> >=20
> >=20
> >=20
> > ---------------------------------------------------------------------=
---
> >=20
> > Index: include/sane/sane.h
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > RCS file: /cvsroot/sane/sane-backends/include/sane/sane.h,v
> > retrieving revision 1.6
> > diff -u -3 -p -B -b -u -r1.6 sane.h
> > --- include/sane/sane.h	13 Nov 2004 20:29:14 -0000	1.6
> > +++ include/sane/sane.h	14 Nov 2004 18:59:03 -0000
> > @@ -92,6 +92,16 @@ typedef enum
> >    }
> >  SANE_Unit;
> > =20
> > +#ifdef BACKEND_NAME
> > +typedef struct
> > +  {
> > +    SANE_String name;	/* unique device name */
> > +    SANE_String vendor;	/* device vendor string */
> > +    SANE_String model;	/* device model name */
> > +    SANE_String type;	/* device type (e.g., "flatbed scanner") */
> > +  }
> > +SANE_Device;
> > +#else
> >  typedef struct
> >    {
> >      SANE_String_Const name;	/* unique device name */
> > @@ -100,6 +110,7 @@ typedef struct
> >      SANE_String_Const type;	/* device type (e.g., "flatbed scanner")=
 */
> >    }
> >  SANE_Device;
> > +#endif
> > =20
> >  #define SANE_CAP_SOFT_SELECT		(1 << 0)
> >  #define SANE_CAP_HARD_SELECT		(1 << 1)
> > @@ -134,6 +145,28 @@ typedef struct
> >    }
> >  SANE_Range;
> > =20
> > +#ifdef BACKEND_NAME
> > +typedef struct
> > +  {
> > +    SANE_String name;	/* name of this option (command-line name) */
> > +    SANE_String title;	/* title of this option (single-line) */
> > +    SANE_String desc;	/* description of this option (multi-line) */
> > +    SANE_Value_Type type;	/* how are values interpreted? */
> > +    SANE_Unit unit;		/* what is the (physical) unit? */
> > +    SANE_Int size;
> > +    SANE_Int cap;		/* capabilities */
> > +
> > +    SANE_Constraint_Type constraint_type;
> > +    union
> > +      {
> > +	SANE_String *string_list;	/* NULL-terminated list */
> > +	SANE_Word *word_list;	/* first element is list-length */
> > +	SANE_Range *range;
> > +      }
> > +    constraint;
> > +  }
> > +SANE_Option_Descriptor;
> > +#else
> >  typedef struct
> >    {
> >      SANE_String_Const name;	/* name of this option (command-line nam=
e) */
> > @@ -154,6 +187,7 @@ typedef struct
> >      constraint;
> >    }
> >  SANE_Option_Descriptor;
> > +#endif
> > =20
> >  typedef enum
> >    {
>=20
>=20
>=20
> SO? Is anyone for or against this patch?
>=20
Hello Frank.

I am not a fan of this patch.
I think it will work but I think it is a hack.

It seems that only a few backends have problems with this.
Why not fix it in a proper way:

create the strings as non const and then set the
sane_device structur to point to these strings?!

But when I am the only one who is against this patch
then I will be quiet and it will be ok for me. It is nothing
that will steal my sleep :)


Oliver