GH-158628: Implement sys._wasi_info

Author: brettcannon

Doc/library/sys.rst

@@ -418,6 +418,29 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    .. versionadded:: 3.11
 
 
+.. data:: _wasi_info
+
+   An object containing information about the build on the WebAssembly WASI
+   platform. The object is provisional and may change in the future.
+
+   .. attribute:: _wasi_info.wasi_version
+
+      The WASI target version as a string: ``'p1'``, ``'p2'``, or ``'p3'``.
+
+   .. attribute:: _wasi_info.wasi_sdk_version
+
+      The full WASI SDK version as a string, such as ``'34.0'``.
+
+   .. attribute:: _wasi_info.cooperative_threads
+
+      ``True`` if wasi-libc was compiled with cooperative multithreading
+      support, ``False`` otherwise.
+
+   .. availability:: WASI.
+
+   .. versionadded:: next
+
+
 .. data:: pycache_prefix
 
    If this is set (not ``None``), Python will write bytecode-cache ``.pyc``

Lib/test/test_sys.py

@@ -824,6 +824,16 @@ def test_emscripten_info(self):
         self.assertIsInstance(sys._emscripten_info.pthreads, bool)
         self.assertIsInstance(sys._emscripten_info.shared_memory, bool)
 
+    @unittest.skipUnless(support.is_wasi, "only available on WASI")
+    def test_wasi_info(self):
+        info = sys._wasi_info
+        self.assertIn(info.wasi_version, {'p1', 'p2', 'p3'})
+        self.assertIn('.', info.wasi_sdk_version)
+        sdk_major, _, sdk_minor = info.wasi_sdk_version.partition('.')
+        self.assertGreaterEqual(int(sdk_major), 1)
+        self.assertGreaterEqual(int(sdk_minor), 0)
+        self.assertIsInstance(info.cooperative_threads, bool)
+
     def test_43581(self):
         # Can't use sys.stdout, as this is a StringIO object when
         # the test runs under regrtest.

Misc/NEWS.d/next/Library/2026-10-08-11-58-52.gh-issue-158628.NJxwuw.rst

@@ -0,0 +1 @@
+Implement :data:`sys._wasi_info` for exposing WASI-specific system details.

Python/sysmodule.c

@@ -64,6 +64,10 @@ extern const char *PyWin_DLLVersionString;
 #  include <emscripten.h>
 #endif
 
+#ifdef __wasi__
+#  include <wasi/version.h>
+#endif
+
 #ifdef HAVE_FCNTL_H
 #  include <fcntl.h>
 #endif
@@ -3837,6 +3841,49 @@ make_abi_info(void)
 }
 
 
+#ifdef __wasi__
+
+static PyObject *
+make_wasi_info(void)
+{
+#if defined(__wasip1__)
+    const char *wasi_version = "p1";
+#elif defined(__wasip2__)
+    const char *wasi_version = "p2";
+#elif defined(__wasip3__)
+    const char *wasi_version = "p3";
+#else
+#  error "Unknown WASI target version"
+#endif
+
+    // The SDK version is only defined for SDK builds of wasi-libc.
+#ifdef __wasi_sdk_version__
+    const char *wasi_sdk_version = __wasi_sdk_version__;
+#else
+#  error "Unknown WASI SDK version"
+#endif
+
+#ifdef __wasi_cooperative_threads__
+    PyObject *cooperative_threads = Py_True;
+#else
+    PyObject *cooperative_threads = Py_False;
+#endif
+
+    PyObject *wasi_info = Py_BuildValue(
+        "{s:s,s:s,s:O}",
+        "wasi_version", wasi_version,
+        "wasi_sdk_version", wasi_sdk_version,
+        "cooperative_threads", cooperative_threads);
+    if (wasi_info == NULL) {
+        return NULL;
+    }
+    PyObject *ns = _PyNamespace_New(wasi_info);
+    Py_DECREF(wasi_info);
+    return ns;
+}
+
+#endif // __wasi__
+
 #ifdef __EMSCRIPTEN__
 
 PyDoc_STRVAR(emscripten_info__doc__,
@@ -4084,6 +4131,10 @@ _PySys_InitCore(PyThreadState *tstate, PyObject *sysdict)
 
     SET_SYS("abi_info", make_abi_info());
 
+#ifdef __wasi__
+    SET_SYS("_wasi_info", make_wasi_info());
+#endif
+
     /* initialize asyncgen_hooks */
     if (_PyStructSequence_InitBuiltin(interp, &AsyncGenHooksType,
                                       &asyncgen_hooks_desc) < 0)