Continue support of negative values.

Author: serhiy-storchaka

Doc/whatsnew/3.15.rst

@@ -560,6 +560,12 @@ Porting to Python 3.15
   The |pythoncapi_compat_project| can be used to get most of these new
   functions on Python 3.14 and older.
 
+* :data:`resource.RLIM_INFINITY` is now always positive.
+  Passing a negative integer value that corresponded to its old value
+  (such as ``-1`` or ``-3``, depending on platform) to
+  :func:`resource.setrlimit` and :func:`resource.prlimit` is now deprecated.
+  (Contributed by Serhiy Storchaka in :gh:`137044`.)
+
 
 Deprecated C APIs
 -----------------

Lib/test/test_resource.py

@@ -150,11 +150,19 @@ def expected(cur):
     def test_fsize_negative(self):
         self.assertGreater(resource.RLIM_INFINITY, 0)
         (cur, max) = resource.getrlimit(resource.RLIMIT_FSIZE)
-        for value in -5, -3, -1, -2**31, -2**32-5, -2**63, -2**64-5, -2**1000:
+        for value in -5, -2**31, -2**32-5, -2**63, -2**64-5, -2**1000:
             with self.subTest(value=value):
                 self.assertRaises(ValueError, resource.setrlimit, resource.RLIMIT_FSIZE, (value, max))
                 self.assertRaises(ValueError, resource.setrlimit, resource.RLIMIT_FSIZE, (cur, value))
 
+        if resource.RLIM_INFINITY in (2**32-3, 2**32-1, 2**64-3, 2**64-1):
+            value = (resource.RLIM_INFINITY & 0xffff) - 0x10000
+            with self.assertWarnsRegex(DeprecationWarning, "RLIM_INFINITY"):
+                resource.setrlimit(resource.RLIMIT_FSIZE, (value, max))
+            with self.assertWarnsRegex(DeprecationWarning, "RLIM_INFINITY"):
+                resource.setrlimit(resource.RLIMIT_FSIZE, (cur, value))
+
+
     @unittest.skipUnless(hasattr(resource, "getrusage"), "needs getrusage")
     def test_getrusage(self):
         self.assertRaises(TypeError, resource.getrusage)

Modules/resource.c

@@ -156,22 +156,26 @@ py2rlim(PyObject *obj, rlim_t *out)
         return -1;
     }
     int neg = PyLong_IsNegative(obj);
-    if (neg) {
-        PyErr_SetString(PyExc_ValueError,
-            "Cannot convert negative int");
-        Py_DECREF(obj);
-        return -1;
-    }
     assert(neg >= 0);
     Py_ssize_t bytes = PyLong_AsNativeBytes(obj, out, sizeof(*out),
                                             Py_ASNATIVEBYTES_NATIVE_ENDIAN |
-                                            Py_ASNATIVEBYTES_UNSIGNED_BUFFER |
-                                            Py_ASNATIVEBYTES_REJECT_NEGATIVE |
-                                            Py_ASNATIVEBYTES_ALLOW_INDEX);
+                                            Py_ASNATIVEBYTES_UNSIGNED_BUFFER);
     Py_DECREF(obj);
     if (bytes < 0) {
         return -1;
     }
+    else if (neg && *out == RLIM_INFINITY && bytes <= (Py_ssize_t)sizeof(*out)) {
+        if (PyErr_WarnEx(PyExc_DeprecationWarning,
+            "Use RLIM_INFINITY instead of negative limit value.", 1))
+        {
+            return -1;
+        }
+    }
+    else if (neg) {
+        PyErr_SetString(PyExc_ValueError,
+            "Cannot convert negative int");
+        return -1;
+    }
     else if (bytes > (Py_ssize_t)sizeof(*out)) {
         PyErr_SetString(PyExc_OverflowError,
             "Python int too large to convert to C rlim_t");