Disallow passing NULL

python · lysnikolaou · Jul 1, 2025 · Jul 1, 2025 · Jul 1, 2025 · Jul 1, 2025
commit 6a974c44b5767aa95319e412de0091bae02fea18
diff --git a/Doc/c-api/unicode.rst b/Doc/c-api/unicode.rst
@@ -312,9 +312,8 @@ These APIs can be used for fast direct character conversions:
    Convert *ch* to lower case, store result in *buffer*, which should be
    able to hold as many characters needed for *ch* to be lower cased
    (e.g. a maximum of two character for Unicode 16.0), and
-   return the number of characters stored. Passing a ``NULL`` buffer returns
-   the buffer size needed. If at some point a buffer overflow is detected,
-   an :exc:`ValueError` is raised and ``-1`` is returned.
+   return the number of characters stored. If at some point a buffer overflow
+   is detected, an :exc:`ValueError` is raised and ``-1`` is returned.
 
    .. versionadded:: next
 
@@ -324,9 +323,8 @@ These APIs can be used for fast direct character conversions:
    Convert *ch* to upper case, store result in *buffer*, which should be
    able to hold as many characters needed for *ch* to be upper cased
    (e.g. a maximum of three character for Unicode 16.0), and
-   return the number of characters stored. Passing a ``NULL`` buffer returns
-   the buffer size needed. If at some point a buffer overflow is detected,
-   an :exc:`ValueError` is raised and ``-1`` is returned.
+   return the number of characters stored. If at some point a buffer overflow
+   is detected, an :exc:`ValueError` is raised and ``-1`` is returned.
 
    .. versionadded:: next
 
@@ -336,9 +334,8 @@ These APIs can be used for fast direct character conversions:
    Convert *ch* to title case, store result in *buffer*, which should be
    able to hold as many characters needed for *ch* to be title cased
    (e.g. a maximum of three character for Unicode 16.0), and
-   return the number of characters stored. Passing a ``NULL`` buffer returns
-   the buffer size needed. If at some point a buffer overflow is detected,
-   an :exc:`ValueError` is raised and ``-1`` is returned.
+   return the number of characters stored. If at some point a buffer overflow
+   is detected, an :exc:`ValueError` is raised and ``-1`` is returned.
 
    .. versionadded:: next
 
@@ -348,9 +345,8 @@ These APIs can be used for fast direct character conversions:
    Foldcase *ch*, store result in *buffer*, which should be
    able to hold as many characters needed for *ch* to be foldcased
    (e.g. a maximum of three character for Unicode 16.0), and
-   return the number of characters stored. Passing a ``NULL`` buffer returns
-   the buffer size needed. If at some point a buffer overflow is detected,
-   an :exc:`ValueError` is raised and ``-1`` is returned.
+   return the number of characters stored. If at some point a buffer overflow
+   is detected, an :exc:`ValueError` is raised and ``-1`` is returned.
 
    .. versionadded:: next
 

diff --git a/Objects/unicodectype.c b/Objects/unicodectype.c
@@ -207,24 +207,20 @@ int PyUnicode_ToLower(Py_UCS4 ch, Py_UCS4 *res, int size)
         int n = ctype->lower >> 24;
         int i;
         for (i = 0; i < n; i++) {
-            if (res != NULL) {
-                if (i >= size) {
-                    PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-                    return -1;
-                }
-                res[i] = _PyUnicode_ExtendedCase[index + i];
+            if (i >= size) {
+                PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+                return -1;
             }
+            res[i] = _PyUnicode_ExtendedCase[index + i];
         }
         return n;
     }
 
-    if (res != NULL) {
-        if (0 >= size) {
-            PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-            return -1;
-        }
-        res[0] = ch + ctype->lower;
+    if (0 >= size) {
+        PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+        return -1;
     }
+    res[0] = ch + ctype->lower;
     return 1;
 }
 
@@ -237,23 +233,20 @@ int PyUnicode_ToTitle(Py_UCS4 ch, Py_UCS4 *res, int size)
         int n = ctype->title >> 24;
         int i;
         for (i = 0; i < n; i++) {
-            if (res != NULL) {
-                if (i >= size) {
-                    PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-                    return -1;
-                }
-                res[i] = _PyUnicode_ExtendedCase[index + i];
+            if (i >= size) {
+                PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+                return -1;
             }
+            res[i] = _PyUnicode_ExtendedCase[index + i];
         }
         return n;
     }
-    if (res != NULL) {
-        if (0 >= size) {
-            PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-            return -1;
-        }
-        res[0] = ch + ctype->title;
+
+    if (0 >= size) {
+        PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+        return -1;
     }
+    res[0] = ch + ctype->title;
     return 1;
 }
 
@@ -266,23 +259,20 @@ int PyUnicode_ToUpper(Py_UCS4 ch, Py_UCS4 *res, int size)
         int n = ctype->upper >> 24;
         int i;
         for (i = 0; i < n; i++) {
-            if (res != NULL) {
-                if (i >= size) {
-                    PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-                    return -1;
-                }
-                res[i] = _PyUnicode_ExtendedCase[index + i];
+            if (i >= size) {
+                PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+                return -1;
             }
+            res[i] = _PyUnicode_ExtendedCase[index + i];
         }
         return n;
     }
-    if (res != NULL) {
-        if (0 >= size) {
-            PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-            return -1;
-        }
-        res[0] = ch + ctype->upper;
+
+    if (0 >= size) {
+        PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+        return -1;
     }
+    res[0] = ch + ctype->upper;
     return 1;
 }
 
@@ -295,16 +285,15 @@ int PyUnicode_ToFolded(Py_UCS4 ch, Py_UCS4 *res, int size)
         int n = (ctype->lower >> 20) & 7;
         int i;
         for (i = 0; i < n; i++) {
-            if (res != NULL) {
-                if (i >= size) {
-                    PyErr_SetString(PyExc_ValueError, "output buffer is too small");
-                    return -1;
-                }
-                res[i] = _PyUnicode_ExtendedCase[index + i];
+            if (i >= size) {
+                PyErr_SetString(PyExc_ValueError, "output buffer is too small");
+                return -1;
             }
+            res[i] = _PyUnicode_ExtendedCase[index + i];
         }
         return n;
     }
+
     return PyUnicode_ToLower(ch, res, size);
 }