Fix T93960: Asset Catalogs I/O fails with unicode file paths on Windows

On Windows, encode file paths as UTF-16 before trying to open the file
for reading/writing.

This introduces a new class `blender::fstream`, which wraps
`std::fstream` and provides this UTF-16 encoding. This class should also
be used in other areas, like the Alembic importer/exporter.

Manifest Task: T93960

Reviewed By: JacquesLucke

Differential Revision: https://developer.blender.org/D13633

1 files changed, 40 insertions, 0 deletions

diff --git a/source/blender/blenlib/tests/BLI_fileops_test.cc b/source/blender/blenlib/tests/BLI_fileops_test.cc
new file mode 100644
index 00000000000..e2a792647dc
--- /dev/null
+++ b/source/blender/blenlib/tests/BLI_fileops_test.cc
@@ -0,0 +1,40 @@
+/* Apache License, Version 2.0 */
+
+#include "BLI_fileops.hh"
+
+#include "testing/testing.h"
+
+namespace blender::tests {
+
+TEST(fileops, fstream_open_string_filename)
+{
+  const std::string test_files_dir = blender::tests::flags_test_asset_dir();
+  if (test_files_dir.empty()) {
+    FAIL();
+  }
+
+  const std::string filepath = test_files_dir + "/asset_library/новый/blender_assets.cats.txt";
+  fstream in(filepath, std::ios_base::in);
+  ASSERT_TRUE(in.is_open()) << "could not open " << filepath;
+  in.close(); /* This should not crash. */
+
+  /* Reading the file not tested here. That's deferred to `std::fstream` anyway. */
+}
+
+TEST(fileops, fstream_open_charptr_filename)
+{
+  const std::string test_files_dir = blender::tests::flags_test_asset_dir();
+  if (test_files_dir.empty()) {
+    FAIL();
+  }
+
+  const std::string filepath_str = test_files_dir + "/asset_library/новый/blender_assets.cats.txt";
+  const char *filepath = filepath_str.c_str();
+  fstream in(filepath, std::ios_base::in);
+  ASSERT_TRUE(in.is_open()) << "could not open " << filepath;
+  in.close(); /* This should not crash. */
+
+  /* Reading the file not tested here. That's deferred to `std::fstream` anyway. */
+}
+
+}  // namespace blender::tests