vsimem: Implicitly create parent directories when creating a file

MIGRATION_GUIDE.TXT

@@ -6,6 +6,16 @@ MIGRATION GUIDE FROM GDAL 3.7 to GDAL 3.8
     of a OGRSpatialReference*. Drivers should clone the passed SRS if they need
     to keep it.
 
+- The /vsimem virtual file system is modified to automatically create parent
+  directories when a file is created. (e.g., creating /vsimem/parent/child.txt
+  would cause the directory /vsimem/parent to be created.) If the parent
+  directory cannot be created because the file /vsimem/parent exists, file
+  creation will now fail.
+
+- In SWIG bindings, the function FileFromMemBuffer now returns an error code
+  if the file could not be created.
+
+
 MIGRATION GUIDE FROM GDAL 3.6 to GDAL 3.7
 -----------------------------------------
 

autotest/gcore/vsifile.py

@@ -378,6 +378,39 @@ def test_vsifile_8():
     gdal.Rmdir("/vsimem/newdir")
 
 
+###############################################################################
+# Test implicit directory creation in /vsimem
+
+
+def test_vsifile_implicit_dir_creation_1(tmp_vsimem):
+
+    assert gdal.VSIStatL(str(tmp_vsimem)) is not None
+    assert gdal.VSIStatL(str(tmp_vsimem)).IsDirectory()
+
+    fpath = str(tmp_vsimem / "subdir1" / "subdir2" / "subdir3" / "myfile.txt")
+    fp = gdal.VSIFOpenL(str(fpath), "wb")
+    assert fp is not None
+    gdal.VSIFCloseL(fp)
+
+    assert gdal.VSIStatL(str(tmp_vsimem / "subdir1")).IsDirectory()
+    assert gdal.VSIStatL(str(tmp_vsimem / "subdir1" / "subdir2")).IsDirectory()
+    assert gdal.VSIStatL(
+        str(tmp_vsimem / "subdir1" / "subdir2" / "subdir3")
+    ).IsDirectory()
+
+
+def test_vsifile_implicit_dir_creation_2(tmp_vsimem):
+
+    fpath = str(tmp_vsimem / "afile")
+    fp = gdal.VSIFOpenL(str(fpath), "wb")
+    assert fp is not None
+    gdal.VSIFCloseL(fp)
+
+    fpath = str(tmp_vsimem / "afile" / "anotherfile")
+    fp = gdal.VSIFOpenL(str(fpath), "wb")
+    assert fp is None
+
+
 ###############################################################################
 # Test ReadDir()
 

autotest/gdrivers/daas.py

@@ -1520,11 +1520,26 @@ def test_daas_getbuffer_raw():
 ###############################################################################
 
 
-def _daas_getbuffer(pixel_encoding, drv_name, drv_options, mime_type):
+@pytest.mark.parametrize(
+    "pixel_encoding,drv_name,drv_options,mime_type",
+    [
+        (
+            "JPEG2000",
+            "JP2OPENJPEG",
+            ["QUALITY=100", "REVERSIBLE=YES", "RESOLUTIONS=1", "CODEC=JP2"],
+            "image/jp2",
+        ),
+        ("JPEG2000", "JP2KAK", ["QUALITY=100", "CODEC=JP2"], "image/jp2"),
+        ("JPEG", "JPEG", ["QUALITY=100"], "image/jpeg"),
+        ("PNG", "PNG", [], "image/png"),
+    ],
+    ids=("jpeg2000_jp2openjpeg", "jpeg2000_jp2kak", "jpeg", "png"),
+)
+def test_daas_getbuffer(tmp_vsimem, pixel_encoding, drv_name, drv_options, mime_type):
 
     drv = gdal.GetDriverByName(drv_name)
     if drv is None:
-        pytest.skip()
+        pytest.skip(f"Driver {drv_name} not available")
 
     handler = webserver.SequentialHandler()
     handler.add(
@@ -1580,7 +1595,7 @@ def _daas_getbuffer(pixel_encoding, drv_name, drv_options, mime_type):
     src_ds.GetRasterBand(1).WriteRaster(0, 0, 100, 100, "A", buf_xsize=1, buf_ysize=1)
     src_ds.GetRasterBand(2).WriteRaster(0, 0, 100, 100, "B", buf_xsize=1, buf_ysize=1)
     src_ds.GetRasterBand(3).WriteRaster(0, 0, 100, 100, "C", buf_xsize=1, buf_ysize=1)
-    tmpfile = "/vsimem/tmp"
+    tmpfile = tmp_vsimem / "tmp"
     drv.CreateCopy(tmpfile, src_ds, options=drv_options)
     f = gdal.VSIFOpenL(tmpfile, "rb")
     content = gdal.VSIFReadL(1, 10000, f)
@@ -1634,41 +1649,6 @@ def _daas_getbuffer(pixel_encoding, drv_name, drv_options, mime_type):
 ###############################################################################
 
 
-def test_daas_getbuffer_png():
-    _daas_getbuffer("PNG", "PNG", [], "image/png")
-
-
-###############################################################################
-
-
-def test_daas_getbuffer_jpeg():
-    _daas_getbuffer("JPEG", "JPEG", ["QUALITY=100"], "image/jpeg")
-
-
-###############################################################################
-
-
-def test_daas_getbuffer_jpeg2000_jp2kak():
-
-    _daas_getbuffer("JPEG2000", "JP2KAK", ["QUALITY=100", "CODEC=JP2"], "image/jp2")
-
-
-###############################################################################
-
-
-def test_daas_getbuffer_jpeg2000_jp2openjpeg():
-
-    _daas_getbuffer(
-        "JPEG2000",
-        "JP2OPENJPEG",
-        ["QUALITY=100", "REVERSIBLE=YES", "RESOLUTIONS=1", "CODEC=JP2"],
-        "image/jp2",
-    )
-
-
-###############################################################################
-
-
 def test_daas_getbuffer_overview():
 
     handler = webserver.SequentialHandler()
@@ -2169,7 +2149,7 @@ def test_daas_mask():
 ###############################################################################
 
 
-def test_daas_png_response_4_bands_for_a_one_band_request():
+def test_daas_png_response_4_bands_for_a_one_band_request(tmp_vsimem):
 
     # Valid JSon but invalid height (string)
     handler = webserver.SequentialHandler()
@@ -2228,7 +2208,7 @@ def test_daas_png_response_4_bands_for_a_one_band_request():
     src_ds.GetRasterBand(2).WriteRaster(0, 0, 2, 3, "B", buf_xsize=1, buf_ysize=1)
     src_ds.GetRasterBand(3).WriteRaster(0, 0, 2, 3, "C", buf_xsize=1, buf_ysize=1)
     src_ds.GetRasterBand(4).WriteRaster(0, 0, 2, 3, "D", buf_xsize=1, buf_ysize=1)
-    tmpfile = "/vsimem/out.png"
+    tmpfile = tmp_vsimem / "out.png"
     gdal.GetDriverByName("PNG").CreateCopy(tmpfile, src_ds)
     f = gdal.VSIFOpenL(tmpfile, "rb")
     png_content = gdal.VSIFReadL(1, 10000, f)

autotest/gdrivers/jp2openjpeg.py

@@ -2575,8 +2575,10 @@ def test_jp2openjpeg_45():
     del out_ds
 
     # Now do the checks
-    dircontent = gdal.ReadDir("/vsimem/gmljp2")
-    assert dircontent is None
+    dircontent = gdal.ReadDir("/vsimem/")
+    if dircontent:
+        for filename in dircontent:
+            assert not filename.startswith("gmljp2")
 
     ds = gdal.Open("/vsimem/jp2openjpeg_45.jp2")
     gmljp2 = ds.GetMetadata_List("xml:gml.root-instance")[0]
@@ -2741,8 +2743,10 @@ def test_jp2openjpeg_45():
     )
     del out_ds
 
-    dircontent = gdal.ReadDir("/vsimem/gmljp2")
-    assert dircontent is None
+    dircontent = gdal.ReadDir("/vsimem/")
+    if dircontent:
+        for filename in dircontent:
+            assert not filename.startswith("gmljp2")
 
     ds = ogr.Open("/vsimem/jp2openjpeg_45.jp2")
     assert ds.GetLayerCount() == 1