chore: import upstream snapshot with attribution

csrc/fs_io.cpp

@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+#include <Python.h>
+
+#include <unistd.h>
+
+#include <vector>
+
+extern "C" {
+
+static void _batch_lookup(const std::vector<const char*>& paths,
+                          std::vector<int>& exists_flags) {
+  for (size_t i = 0; i < paths.size(); i++) {
+    exists_flags[i] = (access(paths[i], F_OK) == 0) ? 1 : 0;
+  }
+}
+
+/// @brief Check file existence for a batch of paths.
+/// @param paths list[str] – absolute paths to check.
+/// @return list[bool] – True if the corresponding path exists, False otherwise.
+/// @note Releases the GIL for the entire batch. File existence via access(2).
+static PyObject* batch_lookup(PyObject* /*self*/, PyObject* args) {
+  PyObject* path_list;
+  if (!PyArg_ParseTuple(args, "O!", &PyList_Type, &path_list)) {
+    return nullptr;
+  }
+
+  const Py_ssize_t n = PyList_Size(path_list);
+  std::vector<const char*> paths(n);
+  for (Py_ssize_t i = 0; i < n; i++) {
+    paths[i] = PyUnicode_AsUTF8AndSize(PyList_GetItem(path_list, i), nullptr);
+    if (paths[i] == nullptr) {
+      return nullptr;
+    }
+  }
+
+  std::vector<int> exists_flags(n);
+  {
+    Py_BEGIN_ALLOW_THREADS _batch_lookup(paths, exists_flags);
+    Py_END_ALLOW_THREADS
+  }
+
+  PyObject* result = PyList_New(n);
+  if (result == nullptr) {
+    return nullptr;
+  }
+  for (Py_ssize_t i = 0; i < n; i++) {
+    PyList_SetItem(result, i, PyBool_FromLong(exists_flags[i]));
+  }
+  return result;
+}
+
+static PyMethodDef fs_io_C_methods[] = {
+    {"batch_lookup", batch_lookup, METH_VARARGS,
+     "batch_lookup(paths: list[str]) -> list[bool]\n"
+     "\n"
+     "Check file existence for a batch of paths."},
+    {nullptr, nullptr, 0, nullptr},
+};
+
+static struct PyModuleDef fs_io_C_module = {
+    PyModuleDef_HEAD_INIT, "fs_io_C", "Filesystem helpers for KV offload", -1,
+    fs_io_C_methods,
+};
+
+PyMODINIT_FUNC PyInit_fs_io_C(void) { return PyModule_Create(&fs_io_C_module); }
+
+}  // extern "C"