Fix GFile downloads (#1666)

Previous version seemed to be broken

- Used a local variable that was never set.
- Used a utility from Keras that did not exist.
- Did not handle not found errors properly.

keras_nlp/src/utils/preset_utils.py

@@ -23,7 +23,6 @@
 from packaging.version import parse
 
 from keras_nlp.src.api_export import keras_nlp_export
-from keras_nlp.src.backend import config
 from keras_nlp.src.backend import config as backend_config
 from keras_nlp.src.backend import keras
 from keras_nlp.src.utils.keras_utils import print_msg
@@ -155,14 +154,19 @@ def get_file(preset, path):
 
     elif scheme in tf.io.gfile.get_registered_schemes():
         url = os.path.join(preset, path)
-        subdir = preset.replace("://", "_").replace("-", "_")
+        subdir = preset.replace("://", "_").replace("-", "_").replace("/", "_")
         filename = os.path.basename(path)
         subdir = os.path.join(subdir, os.path.dirname(path))
-        return copy_gfile_to_cache(
-            filename,
-            url,
-            cache_subdir=os.path.join("models", subdir),
-        )
+        try:
+            return copy_gfile_to_cache(
+                filename,
+                url,
+                cache_subdir=os.path.join("models", subdir),
+            )
+        except tf.errors.NotFoundError as e:
+            raise FileNotFoundError(
+                f"`{path}` doesn't exist in preset directory `{preset}`.",
+            ) from e
     elif scheme == HF_SCHEME:
         if huggingface_hub is None:
             raise ImportError(
@@ -211,16 +215,16 @@ def get_file(preset, path):
 
 def copy_gfile_to_cache(filename, url, cache_subdir):
     """Much of this is adapted from get_file of keras core."""
-    if cache_subdir is None:
-        cache_dir = config.keras_home()
-
-    datadir_base = os.path.expanduser(cache_dir)
-    if not os.access(datadir_base, os.W_OK):
-        datadir_base = os.path.join("/tmp", ".keras")
-    datadir = os.path.join(datadir_base, cache_subdir)
-    os.makedirs(datadir, exist_ok=True)
+    if "KERAS_HOME" in os.environ:
+        cachdir_base = os.environ.get("KERAS_HOME")
+    else:
+        cachdir_base = os.path.expanduser(os.path.join("~", ".keras"))
+    if not os.access(cachdir_base, os.W_OK):
+        cachdir_base = os.path.join("/tmp", ".keras")
+    cachedir = os.path.join(cachdir_base, cache_subdir)
+    os.makedirs(cachedir, exist_ok=True)
 
-    fpath = os.path.join(datadir, filename)
+    fpath = os.path.join(cachedir, filename)
     if not os.path.exists(fpath):
         print_msg(f"Downloading data from {url}")
         tf.io.gfile.copy(url, fpath)