[postgis-devel] lwgeom parser robustness and niceness

[Carl Anderson]

strk wrote:
> I've been testing lwgeom stuff.
> I've found it fault on every 'unexpected' format.
> 
> All these queries kill the backend:
> 
>         -- EMPTY geoms
>         SELECT 'POINT()'::lwgeom;
>         SELECT 'MULTIPOINT()'::lwgeom;
>         SELECT 'LINESTRING()'::lwgeom;
>         SELECT 'MULTILINESTRING()'::lwgeom;
>         SELECT 'POLYGON()'::lwgeom;
>         SELECT 'MULTIPOLYGON()'::lwgeom;
>         SELECT 'GEOMETRYCOLLECTION()'::lwgeom;
> 
>         -- NON geoms (a check for first letter is performed)
>         SELECT 'P()'::lwgeom
>         SELECT 'L()'::lwgeom
>         SELECT 'M()'::lwgeom
>         SELECT 'G()'::lwgeom
> 
>         -- INVALID geoms
>         SELECT 'POINT(0 0 0 0 0)'::lwgeom;
>         SELECT 'LINESTRING(0 0)'::lwgeom;
>         SELECT 'POLYGON((0 0, 1 1))'::lwgeom;
>         SELECT 'POLYGON(0 0)'::lwgeom;
>         ... try your own ...
> 
>         -- MIXED dimension geoms
>         SELECT 'MULTIPOINT(0 0 0, 0 0)'::lwgeom;
>         SELECT 'LINESTRING(0 0 0 0, 0 0 0)'::lwgeom;
>         ... try your own ...
> 
> Also, I don't like this error message:
> 
> 	SELECT 'point(0 0)'::lwgeom;
> 	ERROR:  couldnt determine if input lwgeom is WKB or WKT
> 
> I think 1) it's clearly a WKT and 2) we could accept lower or mixed case
> lwgeoms, wouldn't it be acceptable in speed ?
> 
> --strk;

If you edit the bison/lex files to include rules that cover the above 
cases the abends stop.  Not that this is the corrent fix just evidence 
that it is in bison/flex

such as in wktparse.y
from
a_point: point_2d | point_3d | point_4d;

to include a rule for POINT()
a_point: empty | point_2d | point_3d | point_4d;



I am not very good with bison/flex but
I suspect that the parser code is emitting a warning that is tripping
Postgres.  I have poked at the passed in error function But I think I 
would need to RTFM first.


btw
moving Makefile to

	$(YACC) -vd -b wktparse -p lwg_parse_yy wktparse.y

causes it to produce wktparse..tab.c and wktparse.tab.h directly