Prevent a crash when accessing block shapes of an HDF5 file (#2859)

Resolves #2855

CHANGES.txt

@@ -1,9 +1,10 @@
 Changes
 =======
 
-1.3.8 (TBD)
------------
+1.3.8 (2023-06-26)
+------------------
 
+- Prevent a crash when accessing the block shapes of a multidataset HDF5 file (#).
 - Add a workaround for a GDAL multithreading bug introduced in 3.6.0 (#2851).
 
 1.3.7 (2023-05-22)

rasterio/_base.pyx

@@ -518,8 +518,8 @@ cdef class DatasetBase:
         list
         """
         cdef GDALRasterBandH band = NULL
-        cdef int xsize
-        cdef int ysize
+        cdef int xsize = 0
+        cdef int ysize = 0
 
         if self._block_shapes is None:
             self._block_shapes = []
@@ -1031,8 +1031,11 @@ cdef class DatasetBase:
                 blockxsize=self.block_shapes[0][1],
                 blockysize=self.block_shapes[0][0],
                 tiled=True)
-        else:
+        elif len(self.block_shapes) > 0:
             m.update(blockysize=self.block_shapes[0][0], tiled=False)
+        else:
+            m.update(tiled=False)
+
         if self.compression:
             m['compress'] = self.compression.name
         if self.interleaving:

tests/test_subdatasets.py

@@ -3,15 +3,24 @@
 import rasterio
 
 with rasterio.Env() as env:
-    HAVE_NETCDF = 'NetCDF' in env.drivers().keys()
+    HAVE_NETCDF = "NetCDF" in env.drivers().keys()
+    HAVE_HDF5 = "HDF5" in env.drivers().keys()
 
 
-@pytest.mark.skipif(not HAVE_NETCDF,
-                    reason="GDAL not compiled with NetCDF driver.")
+@pytest.mark.skipif(not HAVE_NETCDF, reason="GDAL not compiled with NetCDF driver.")
 def test_subdatasets():
     """Get subdataset names and descriptions"""
-    with rasterio.open('netcdf:tests/data/RGB.nc') as src:
+    with rasterio.open("netcdf:tests/data/RGB.nc") as src:
         subs = src.subdatasets
         assert len(subs) == 3
         for name in subs:
-            assert name.startswith('netcdf')
+            assert name.startswith("netcdf")
+
+
+@pytest.mark.skipif(not HAVE_HDF5, reason="GDAL not compiled with HDF5 driver.")
+def test_subdatasets_h5():
+    """Get subdataset names and descriptions"""
+    with rasterio.open("tests/data/two-subs.h5") as src:
+        subs = src.subdatasets
+        assert len(subs) == 2
+        assert src.profile["count"] == 0