shp2pgsql may be parsing shp's multipolygon incorrectly

[qtxie]

I find shp2pgsql may be parsing shp's multipolygon incorrectly, which will generate two overlapped innter rings. Please see the picture in attachment.

The algorithm to put the inner rings into the list of the outer rings may be wrong. In function:

file: shp2pgsql-core.c
int
FindPolygons(SHPObject *obj, Ring ***Out);
{
    ...
    /* Put the inner rings into the list of the outer rings */
    /* of which they are within */
    for (pi = 0; pi < in_index; pi++)
    {
        // May be wrong to do those.
        // Some inner rings insert to the wrong outer ring
        ....
    }

According 'ESRI_shapefile_technical_description.pdf', the rings along with a outer ring is the inner rings belong with it, so we don't need to find the inner ring manually.

[qtxie]

Correct split the multipolygon

[qtxie]

Incorrect split the multipolygon

[robe]

sounds complicated -- too much so for a micro release

[pramsey]

Confirmed, this polygon

MULTIPOLYGON(
 ((0 0,100 0,100 100,0 100,0 0),(10 10,90 10,90 90,10 90,10 10)),
 ((20 20,20 80,80 80,80 20,20 20),(30 30,30 70,70 70,70 30,30 30))
)

when exported to shape and then reimported, turns into this one

MULTIPOLYGON(
 ((0 0,0 100,100 100,100 0,0 0),(10 10,90 10,90 90,10 90,10 10),(30 30,70 30,70 70,30 70,30 30)),
 ((20 20,20 80,80 80,80 20,20 20))
)

[pramsey]

Fixed in 2.1 at r13932

[pramsey]

Fixed in trunk at r13933