support bigtiff into geotiff reader

src/earthkit/data/readers/geotiff.py

@@ -238,8 +238,9 @@ def _match_magic(magic):
     # https://docs.ogc.org/is/19-008r4/19-008r4.html#_tiff_core_test
     # Bytes 0-1: 'II' (little endian) or 'MM' (big endian)
     # Bytes 2-3: 42 as short in the corresponding byte order
+    #           or 43 for a bigtiff file
     # Bytes 4-7: offset to first image file directory
-    return magic is not None and len(magic) >= 8 and magic[:4] in {b"II*\x00", b"MM\x00*"}
+    return magic is not None and len(magic) >= 8 and magic[:4] in {b"II*\x00", b"II+\x00", b"MM\x00*"}
 
 
 def reader(source, path, *, magic=None, **kwargs):

tests/readers/test_geotiff_reader.py

@@ -20,8 +20,11 @@
 
 @pytest.mark.skipif(NO_RIOXARRAY, reason="rioxarray not available")
 @pytest.mark.with_proj
-def test_geotiff_reader_with_multiband():
-    s = from_source("file", earthkit_test_data_file("dgm50hs_col_32_368_5616_nw.tif"))
+@pytest.mark.parametrize(
+    "fname", [("dgm50hs_col_32_368_5616_nw.tif"), ("dgm50hs_col_32_368_5616_nw_bigtiff.tiff")]
+)
+def test_geotiff_reader_with_multiband(fname):
+    s = from_source("file", earthkit_test_data_file(fname))
     assert len(s) == 3
     assert isinstance(s[0], GeoTIFFField)
     assert isinstance(s[1], GeoTIFFField)