[gdal-dev] Unable to use geom.ExportToWkt() in Python ?

Gregor at HostGIS gregor at hostgis.com
Tue Nov 23 17:43:35 EST 2010

Hey all. I am using the OGR binding for python, to open a SHP and print 
a geometry's WKT. This works until I try to call geom.ExportToWkt() At 
that time I simply get "Premature end of script headers" Running it from 
the command line I get a segmentation fault.

The code snippet:

     driver     = ogr.GetDriverByName('ESRI Shapefile')
     datasource = driver.Open(shapefile,0)
     layer      = datasource.GetLayer()
     spatialRef = layer.GetSpatialRef()
     firstgeom  = layer.GetFeature(0).GetGeometryRef()
     wkt        = firstgeom.ExportToWkt()

GDAL 1.7.1
Python 2.5.1

The strace output is not particularly helpful to me. Maybe it's helpful 
to someone else?

open("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.dbf", O_RDONLY) = 4
open("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.cpg", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.CPG", O_RDONLY) = -1 
ENOENT (No such file or directory)
fstat(4, {st_mode=S_IFREG|0644, st_size=55294, ...}) = 0
= 0x2b8f79cf5000
read(4, "\3i\t\17a\1\0\0\341\0\234\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
4096) = 4096
open("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.prj", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.PRJ", O_RDONLY) = -1 
ENOENT (No such file or directory)
stat("/maps/images.tmp/zipUdUf9L.zip/fedlanl020.idm", 0x7fffd87a7c10) = 
-1 ENOENT (No such file or directory)
0x7fffd87a5da0) = -1 ENOENT (No such file or directory)
O_RDONLY) = -1 ENOENT (No such file or directory)
O_RDONLY) = -1 ENOENT (No such file or directory)
O_RDONLY) = -1 ENOENT (No such file or directory)
O_RDONLY) = -1 ENOENT (No such file or directory)
futex(0x40eceb0, FUTEX_WAKE, 1)         = 0
read(3, "5\364c\300\0\0\0\340v\321P@\0\0\0\0X\364c\300\0\0\0`D\321"..., 
4096) = 4096
--- SIGSEGV (Segmentation fault) @ 0 (0) ---

I do wonder about those "no such file or directory" at the end, where 
it's trying to open something called "types" and trying everything it 
can. True, there are no files named "types" Is that relevant?

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