Geometry Nodes: implement file path callback for import nodes

Add geometry file import nodes support to the for-each-path logic.
This will make `bpy.data.file_path_map()` report the input files for
OBJ, PLY, etc. import nodes (and any other node that has a string
property of subtype `PROP_FILEPATH`).

Currently this only supports static file paths, so where the file path
is set as the input socket's default value. When the path is
determined via any noodle, this is ignored and the default value is
reported anyway.

This is necessary for the new version of Blender Asset Tracer, which
in turn is needed to resolve studio/flamenco#104423.

Pull Request: https://projects.blender.org/blender/blender/pulls/144874

source/blender/blenkernel/intern/node.cc

@@ -434,6 +434,26 @@ static void node_foreach_path(ID *id, BPathForeachPathData *bpath_data)
       }
       break;
     }
+    case NTREE_GEOMETRY: {
+      for (bNode *node : ntree->all_nodes()) {
+        for (bNodeSocket *socket : node->input_sockets()) {
+          /* Find file path input sockets. */
+          if (socket->type != SOCK_STRING) {
+            continue;
+          }
+          bNodeSocketValueString *socket_value = static_cast<bNodeSocketValueString *>(
+              socket->default_value);
+          if (socket_value->value[0] == '\0' || socket_value->subtype != PROP_FILEPATH) {
+            continue;
+          }
+
+          /* Process the file path. */
+          BKE_bpath_foreach_path_fixed_process(
+              bpath_data, socket_value->value, sizeof(socket_value->value));
+        }
+      }
+      break;
+    }
     default:
       break;
   }

tests/python/CMakeLists.txt

@@ -424,6 +424,13 @@ add_blender_test(
   --python ${CMAKE_CURRENT_LIST_DIR}/bl_geometry_attributes.py
 )
 
+add_blender_test(
+  geonode_file_reporting
+  --python ${CMAKE_CURRENT_LIST_DIR}/bl_geonode_file_reporting.py
+  --
+  --testdir "${TEST_SRC_DIR}/io_tests"
+)
+
 # ------------------------------------------------------------------------------
 # MODIFIERS TESTS
 # ------------------------------------------------------------------------------

tests/python/bl_geonode_file_reporting.py

@@ -0,0 +1,55 @@
+# SPDX-FileCopyrightText: 2024 Blender Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# blender -b -P tests/python/bl_geonode_file_reporting.py -- --verbose --testdir tests/files/io_tests
+import unittest
+from pathlib import Path
+
+import bpy
+
+
+class TestFileImportNodes(unittest.TestCase):
+    """Test that the imported OBJ file is reported via bpy.data.file_path_map()."""
+
+    testdir: Path
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.testdir = args.testdir
+
+    def test_obj_import_node(self):
+        blend_path = self.testdir / "blend_scene/geonodes_import_obj.blend"
+
+        bpy.ops.wm.open_mainfile(filepath=str(blend_path))
+
+        node_tree = bpy.data.node_groups['Import OBJ']
+        file_path_map: dict[bpy.types.ID, set[str]] = bpy.data.file_path_map()
+
+        # Go through Path(...) to ensure platform-native slashes.
+        relative_path = f"//{Path('../obj/all_tris.obj')!s}"
+
+        self.assertIn(node_tree, file_path_map)
+        self.assertEqual({relative_path}, file_path_map[node_tree],
+                         "The path to the OBJ file should be reported, as relative path")
+
+
+def main():
+    global args
+    import argparse
+    import sys
+
+    if '--' in sys.argv:
+        argv = [sys.argv[0]] + sys.argv[sys.argv.index('--') + 1:]
+    else:
+        argv = sys.argv
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--testdir', required=True, type=Path)
+    args, remaining = parser.parse_known_args(argv)
+
+    unittest.main(argv=remaining, verbosity=0)
+
+
+if __name__ == "__main__":
+    main()