def check_string(result, func, cargs, offset=-1, str_result=False):
"""
Checks the string output returned from the given function, and frees
the string pointer allocated by OGR. The `str_result` keyword
may be used when the result is the string pointer, otherwise
the OGR error code is assumed. The `offset` keyword may be used
to extract the string pointer passed in by-reference at the given
slice offset in the function arguments.
"""
if str_result:
# For routines that return a string.
ptr = result
if not ptr:
s = None
else:
s = string_at(result)
else:
# Error-code return specified.
check_err(result)
ptr = ptr_byref(cargs, offset)
# Getting the string value
s = ptr.value
# Correctly freeing the allocated memory beind GDAL pointer
# w/the VSIFree routine.
if ptr:
lgdal.VSIFree(ptr)
return s
def check_arg_errcode(result, func, cargs):
"""
The error code is returned in the last argument, by reference.
Check its value with `check_err` before returning the result.
"""
check_err(arg_byref(cargs))
return result
def check_const_string(result, func, cargs, offset=None):
"""
Similar functionality to `check_string`, but does not free the pointer.
"""
if offset:
check_err(result)
ptr = ptr_byref(cargs, offset)
return ptr.value
else:
return result
def check_geom_offset(result, func, cargs, offset=-1):
"Chcks the geometry at the given offset in the C parameter list."
check_err(result)
geom = ptr_byref(cargs, offset=offset)
return check_geom(geom, func, cargs)
def check_errcode(result, func, cargs):
"""
Check the error code returned (c_int).
"""
check_err(result)
return
