fix segfaults with NA crs

Author: paleolimbot

src/gdal_read_stream.cpp

@@ -98,10 +98,14 @@ Rcpp::List CPL_read_gdal_stream(
         R_ExternalPtrAddr(stream_xptr));
 
     OGRSpatialReference* crs = poLayer->GetSpatialRef();
-    char* wkt_out;
-    crs->exportToWkt(&wkt_out);
-    std::string wkt_str(wkt_out);
-    CPLFree(wkt_out);
+
+    Rcpp::String wkt_str = NA_STRING;
+    if (crs != nullptr) {
+        char* wkt_out;
+        crs->exportToWkt(&wkt_out);
+        wkt_str = wkt_out;
+        CPLFree(wkt_out);
+    }
 
     struct ArrowArrayStream stream_temp;
     if (!poLayer->GetArrowStream(&stream_temp, array_stream_options)) {

tests/testthat/test_read.R

@@ -174,8 +174,6 @@ test_that("we get a warning when not specifying one of multiple layers", {
 
 test_that("reading non-spatial table works", {
     skip_if_not(sf_extSoftVersion()[["GDAL"]] >= "2.2.0") # error on OSX for 2.1.3
-    # currently segfaults using the stream interface
-    skip_if(default_st_read_use_stream())
 
     expect_warning(st_read(system.file("gpkg/nospatial.gpkg", package = "sf")),
                    "no simple feature geometries present")

tests/testthat/test_sp.R

@@ -104,8 +104,6 @@ test_that("Can convert `XY` objects to sp", {
 })
 
 test_that("Can't convert `M` dimension to sp", {
-  # Segfaults using the stream interface
-  skip_if(default_st_read_use_stream())
   skip_if_not_installed("sp")
   skip_if_not(sf_extSoftVersion()[["GDAL"]] >= "2.1.0")
   x <- read_sf(system.file("shape/storms_xyzm_feature.shp", package = "sf"), quiet = TRUE)

tests/testthat/test_write.R

@@ -148,9 +148,6 @@ test_that("append errors work", {
 })
 
 test_that("non-spatial tables can be written to GPKG; #1345", {
-  # currently segfaults using the stream interface
-  skip_if(default_st_read_use_stream())
-  
   nc = system.file("gpkg/nc.gpkg", package = "sf")
   tf = tempfile(fileext = ".gpkg")
   file.copy(nc, tf)

tests/testthat/test_zm_range.R

@@ -144,9 +144,6 @@ test_that("transform includes zm in output", {
 
 
 test_that("XYM-only objects correctly calculate M (and not Z)", {
-	# currently segfaults using the stream interface
-    skip_if(default_st_read_use_stream())
-
 	skip_if_not(sf_extSoftVersion()["GDAL"] > "2.1.0")
 
 	sf_m <- sf::st_read(system.file("/shape/storms_xyzm.shp", package = "sf"), quiet = TRUE)