[Xastir-dev] Core dump due to indexing array with char

[Magne Mæhre]

While I was playing with converting OpenStreetMap[1] data to shape files
for Xastir tonight, I stumbled across a problem where xastir
consistently core dumped.

The problem was that a string read from the dbf file contained a
character (tex:  /Oslash ) that was mapped to a negative value.

When the character was used as an index to the label_hash array
in draw_shapefile_map (map_shp.c:2914)
     ptr2 = label_hash[-40]
a core dump resulted.

A quick fix was to change to type of 'temp' to unsigned char * to
force it to be positive:

   map_shp.c:
     l:1923     changed to "const unsigned char *temp;"

...but I guess a better solution would be to have a more explicit
type conversion instead of relying on the implicit (and
implementation defined) conversion?


--Magne / LA1BFA

[1] http://www.openstreetmap.org/   http://wiki.openstreetmap.org/