gh-81548: Deprecate octal escape sequences with value larger than 0o377 (GH-91668)

1 files changed, 24 insertions, 5 deletions

diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 510a836..b5066d0 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -1113,6 +1113,12 @@ PyObject *_PyBytes_DecodeEscape(const char *s,
                 if (s < end && '0' <= *s && *s <= '7')
                     c = (c<<3) + *s++ - '0';
             }
+            if (c > 0377) {
+                if (*first_invalid_escape == NULL) {
+                    *first_invalid_escape = s-3; /* Back up 3 chars, since we've
+                                                    already incremented s. */
+                }
+            }
             *p++ = c;
             break;
         case 'x':
@@ -1179,11 +1185,24 @@ PyObject *PyBytes_DecodeEscape(const char *s,
     if (result == NULL)
         return NULL;
     if (first_invalid_escape != NULL) {
-        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
-                             "invalid escape sequence '\\%c'",
-                             (unsigned char)*first_invalid_escape) < 0) {
-            Py_DECREF(result);
-            return NULL;
+        unsigned char c = *first_invalid_escape;
+        if ('4' <= c && c <= '7') {
+            if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                                 "invalid octal escape sequence '\\%.3s'",
+                                 first_invalid_escape) < 0)
+            {
+                Py_DECREF(result);
+                return NULL;
+            }
+        }
+        else {
+            if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                                 "invalid escape sequence '\\%c'",
+                                 c) < 0)
+            {
+                Py_DECREF(result);
+                return NULL;
+            }
         }
     }
     return result;