bpo-42681: Fix range checks for color and pair numbers in curses (GH-23874)

5 files changed, 192 insertions, 93 deletions

diff --git a/Doc/library/curses.rst b/Doc/library/curses.rst
index 3684d54..26121ac 100644
--- a/Doc/library/curses.rst
+++ b/Doc/library/curses.rst
@@ -112,14 +112,15 @@ The module :mod:`curses` defines the following functions:
 .. function:: color_content(color_number)
 
    Return the intensity of the red, green, and blue (RGB) components in the color
-   *color_number*, which must be between ``0`` and :const:`COLORS`.  Return a 3-tuple,
+   *color_number*, which must be between ``0`` and ``COLORS - 1``.  Return a 3-tuple,
    containing the R,G,B values for the given color, which will be between
    ``0`` (no component) and ``1000`` (maximum amount of component).
 
 
-.. function:: color_pair(color_number)
+.. function:: color_pair(pair_number)
 
-   Return the attribute value for displaying text in the specified color.  This
+   Return the attribute value for displaying text in the specified color pair.
+   Only the first 256 color pairs are supported. This
    attribute value can be combined with :const:`A_STANDOUT`, :const:`A_REVERSE`,
    and the other :const:`A_\*` attributes.  :func:`pair_number` is the counterpart
    to this function.
@@ -287,7 +288,7 @@ The module :mod:`curses` defines the following functions:
    Change the definition of a color, taking the number of the color to be changed
    followed by three RGB values (for the amounts of red, green, and blue
    components).  The value of *color_number* must be between ``0`` and
-   :const:`COLORS`.  Each of *r*, *g*, *b*, must be a value between ``0`` and
+   `COLORS - 1`.  Each of *r*, *g*, *b*, must be a value between ``0`` and
    ``1000``.  When :func:`init_color` is used, all occurrences of that color on the
    screen immediately change to the new definition.  This function is a no-op on
    most terminals; it is active only if :func:`can_change_color` returns ``True``.
@@ -300,7 +301,8 @@ The module :mod:`curses` defines the following functions:
    color number.  The value of *pair_number* must be between ``1`` and
    ``COLOR_PAIRS - 1`` (the ``0`` color pair is wired to white on black and cannot
    be changed).  The value of *fg* and *bg* arguments must be between ``0`` and
-   :const:`COLORS`.  If the color-pair was previously initialized, the screen is
+   ``COLORS - 1``, or, after calling :func:`use_default_colors`, ``-1``.
+   If the color-pair was previously initialized, the screen is
    refreshed and all occurrences of that color-pair are changed to the new
    definition.
 
@@ -450,7 +452,7 @@ The module :mod:`curses` defines the following functions:
 .. function:: pair_content(pair_number)
 
    Return a tuple ``(fg, bg)`` containing the colors for the requested color pair.
-   The value of *pair_number* must be between ``1`` and ``COLOR_PAIRS - 1``.
+   The value of *pair_number* must be between ``0`` and ``COLOR_PAIRS - 1``.
 
 
 .. function:: pair_number(attr)
diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index 6811ff9..31fb882 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -4,8 +4,7 @@
 # This script doesn't actually display anything very coherent. but it
 # does call (nearly) every method and function.
 #
-# Functions not tested: {def,reset}_{shell,prog}_mode, getch(), getstr(),
-# init_color()
+# Functions not tested: {def,reset}_{shell,prog}_mode, getch(), getstr()
 # Only called, not tested: getmouse(), ungetmouse()
 #
 
@@ -13,6 +12,7 @@ import os
 import string
 import sys
 import tempfile
+import functools
 import unittest
 
 from test.support import requires, verbose, SaveSignals
@@ -37,6 +37,15 @@ def requires_curses_func(name):
     return unittest.skipUnless(hasattr(curses, name),
                                'requires curses.%s' % name)
 
+def requires_colors(test):
+    @functools.wraps(test)
+    def wrapped(self, *args, **kwargs):
+        if not curses.has_colors():
+            self.skipTest('requires colors support')
+        curses.start_color()
+        test(self, *args, **kwargs)
+    return wrapped
+
 term = os.environ.get('TERM')
 
 # If newterm was supported we could use it instead of initscr and not exit
@@ -48,6 +57,8 @@ class TestCurses(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        if verbose:
+            print(f'TERM={term}', file=sys.stderr, flush=True)
         # testing setupterm() inside initscr/endwin
         # causes terminal breakage
         stdout_fd = sys.__stdout__.fileno()
@@ -306,31 +317,101 @@ class TestCurses(unittest.TestCase):
             curses.use_env(1)
 
     # Functions only available on a few platforms
-    def test_colors_funcs(self):
-        if not curses.has_colors():
-            self.skipTest('requires colors support')
-        curses.start_color()
-        curses.init_pair(2, 1,1)
-        curses.color_content(1)
-        curses.color_pair(2)
+
+    def bad_colors(self):
+        return (-1, curses.COLORS, -2**31 - 1, 2**31, -2**63 - 1, 2**63, 2**64)
+
+    def bad_colors2(self):
+        return (curses.COLORS, 2**31, 2**63, 2**64)
+
+    def bad_pairs(self):
+        return (-1, -2**31 - 1, 2**31, -2**63 - 1, 2**63, 2**64)
+
+    @requires_colors
+    def test_color_content(self):
+        self.assertEqual(curses.color_content(curses.COLOR_BLACK), (0, 0, 0))
+        curses.color_content(0)
+        curses.color_content(curses.COLORS - 1)
+
+        for color in self.bad_colors():
+            self.assertRaises(ValueError, curses.color_content, color)
+
+    @requires_colors
+    def test_init_color(self):
+        if not curses.can_change_color:
+            self.skipTest('cannot change color')
+
+        old = curses.color_content(0)
+        try:
+            curses.init_color(0, *old)
+        except curses.error:
+            self.skipTest('cannot change color (init_color() failed)')
+        self.addCleanup(curses.init_color, 0, *old)
+        curses.init_color(0, 0, 0, 0)
+        self.assertEqual(curses.color_content(0), (0, 0, 0))
+        curses.init_color(0, 1000, 1000, 1000)
+        self.assertEqual(curses.color_content(0), (1000, 1000, 1000))
+
+        old = curses.color_content(curses.COLORS - 1)
+        curses.init_color(curses.COLORS - 1, *old)
+        self.addCleanup(curses.init_color, curses.COLORS - 1, *old)
+        curses.init_color(curses.COLORS - 1, 0, 500, 1000)
+        self.assertEqual(curses.color_content(curses.COLORS - 1), (0, 500, 1000))
+
+        for color in self.bad_colors():
+            self.assertRaises(ValueError, curses.init_color, color, 0, 0, 0)
+        for comp in (-1, 1001):
+            self.assertRaises(ValueError, curses.init_color, 0, comp, 0, 0)
+            self.assertRaises(ValueError, curses.init_color, 0, 0, comp, 0)
+            self.assertRaises(ValueError, curses.init_color, 0, 0, 0, comp)
+
+    @requires_colors
+    def test_pair_content(self):
+        if not hasattr(curses, 'use_default_colors'):
+            self.assertEqual(curses.pair_content(0),
+                             (curses.COLOR_WHITE, curses.COLOR_BLACK))
+        curses.pair_content(0)
         curses.pair_content(curses.COLOR_PAIRS - 1)
-        curses.pair_number(0)
-
-        if hasattr(curses, 'use_default_colors'):
-            curses.use_default_colors()
-
-        self.assertRaises(ValueError, curses.color_content, -1)
-        self.assertRaises(ValueError, curses.color_content, curses.COLORS + 1)
-        self.assertRaises(ValueError, curses.color_content, -2**31 - 1)
-        self.assertRaises(ValueError, curses.color_content, 2**31)
-        self.assertRaises(ValueError, curses.color_content, -2**63 - 1)
-        self.assertRaises(ValueError, curses.color_content, 2**63 - 1)
-        self.assertRaises(ValueError, curses.pair_content, -1)
-        self.assertRaises(ValueError, curses.pair_content, curses.COLOR_PAIRS)
-        self.assertRaises(ValueError, curses.pair_content, -2**31 - 1)
-        self.assertRaises(ValueError, curses.pair_content, 2**31)
-        self.assertRaises(ValueError, curses.pair_content, -2**63 - 1)
-        self.assertRaises(ValueError, curses.pair_content, 2**63 - 1)
+
+        for pair in self.bad_pairs():
+            self.assertRaises(ValueError, curses.pair_content, pair)
+
+    @requires_colors
+    def test_init_pair(self):
+        old = curses.pair_content(1)
+        curses.init_pair(1, *old)
+        self.addCleanup(curses.init_pair, 1, *old)
+
+        curses.init_pair(1, 0, 0)
+        self.assertEqual(curses.pair_content(1), (0, 0))
+        curses.init_pair(1, curses.COLORS - 1, curses.COLORS - 1)
+        self.assertEqual(curses.pair_content(1),
+                         (curses.COLORS - 1, curses.COLORS - 1))
+        curses.init_pair(curses.COLOR_PAIRS - 1, 2, 3)
+        self.assertEqual(curses.pair_content(curses.COLOR_PAIRS - 1), (2, 3))
+
+        for pair in self.bad_pairs():
+            self.assertRaises(ValueError, curses.init_pair, pair, 0, 0)
+        for color in self.bad_colors2():
+            self.assertRaises(ValueError, curses.init_pair, 1, color, 0)
+            self.assertRaises(ValueError, curses.init_pair, 1, 0, color)
+
+    @requires_colors
+    def test_color_attrs(self):
+        for pair in 0, 1, 255:
+            attr = curses.color_pair(pair)
+            self.assertEqual(curses.pair_number(attr), pair, attr)
+            self.assertEqual(curses.pair_number(attr | curses.A_BOLD), pair)
+        self.assertEqual(curses.color_pair(0), 0)
+        self.assertEqual(curses.pair_number(0), 0)
+
+    @requires_curses_func('use_default_colors')
+    @requires_colors
+    def test_use_default_colors(self):
+        self.assertIn(curses.pair_content(0),
+                      ((curses.COLOR_WHITE, curses.COLOR_BLACK), (-1, -1)))
+        curses.use_default_colors()
+        self.assertEqual(curses.pair_content(0), (-1, -1))
 
     @requires_curses_func('keyname')
     def test_keyname(self):
diff --git a/Misc/NEWS.d/next/Library/2020-12-20-22-50-15.bpo-42681.lDO6jb.rst b/Misc/NEWS.d/next/Library/2020-12-20-22-50-15.bpo-42681.lDO6jb.rst
new file mode 100644
index 0000000..34ea74a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-12-20-22-50-15.bpo-42681.lDO6jb.rst
@@ -0,0 +1 @@
+Fixed range checks for color and pair numbers in :mod:`curses`.
diff --git a/Modules/_cursesmodule.c b/Modules/_cursesmodule.c
index 1f4789b..23f6d96 100644
--- a/Modules/_cursesmodule.c
+++ b/Modules/_cursesmodule.c
@@ -155,10 +155,8 @@ typedef chtype attr_t;           /* No attr_t type is available */
 #define _CURSES_PAIR_NUMBER_FUNC        pair_content
 #endif  /* _NCURSES_EXTENDED_COLOR_FUNCS */
 
-#define _CURSES_FUNC_NAME_STR(s)        #s
-
-#define _CURSES_INIT_COLOR_FUNC_NAME    _CURSES_FUNC_NAME_STR(_CURSES_INIT_COLOR_FUNC)
-#define _CURSES_INIT_PAIR_FUNC_NAME     _CURSES_FUNC_NAME_STR(_CURSES_INIT_PAIR_FUNC)
+#define _CURSES_INIT_COLOR_FUNC_NAME    Py_STRINGIFY(_CURSES_INIT_COLOR_FUNC)
+#define _CURSES_INIT_PAIR_FUNC_NAME     Py_STRINGIFY(_CURSES_INIT_PAIR_FUNC)
 
 /*[clinic input]
 module _curses
@@ -202,18 +200,6 @@ static char *screen_encoding = NULL;
 
 /* Utility Functions */
 
-static inline int
-color_pair_to_attr(short color_number)
-{
-    return ((int)color_number << 8);
-}
-
-static inline short
-attr_to_color_pair(int attr)
-{
-    return (short)((attr & A_COLOR) >> 8);
-}
-
 /*
  * Check the return code from a curses function and return None
  * or raise an exception as appropriate.  These are exported using the
@@ -414,7 +400,7 @@ PyCurses_ConvertToString(PyCursesWindowObject *win, PyObject *obj,
 }
 
 static int
-color_converter(PyObject *arg, void *ptr)
+color_allow_default_converter(PyObject *arg, void *ptr)
 {
     long color_number;
     int overflow;
@@ -423,19 +409,31 @@ color_converter(PyObject *arg, void *ptr)
     if (color_number == -1 && PyErr_Occurred())
         return 0;
 
-    if (overflow > 0 || color_number > COLORS) {
+    if (overflow > 0 || color_number >= COLORS) {
         PyErr_Format(PyExc_ValueError,
-                     "Color number is greater than COLORS (%d).",
-                     COLORS);
+                     "Color number is greater than COLORS-1 (%d).",
+                     COLORS - 1);
         return 0;
     }
     else if (overflow < 0 || color_number < 0) {
+        color_number = -1;
+    }
+
+    *(int *)ptr = (int)color_number;
+    return 1;
+}
+
+static int
+color_converter(PyObject *arg, void *ptr)
+{
+    if (!color_allow_default_converter(arg, ptr)) {
+        return 0;
+    }
+    if (*(int *)ptr < 0) {
         PyErr_SetString(PyExc_ValueError,
                         "Color number is less than 0.");
         return 0;
     }
-
-    *(int *)ptr = (int)color_number;
     return 1;
 }
 
@@ -446,6 +444,13 @@ class color_converter(CConverter):
 [python start generated code]*/
 /*[python end generated code: output=da39a3ee5e6b4b0d input=4260d2b6e66b3709]*/
 
+/*[python input]
+class color_allow_default_converter(CConverter):
+    type = 'int'
+    converter = 'color_allow_default_converter'
+[python start generated code]*/
+/*[python end generated code: output=da39a3ee5e6b4b0d input=975602bc058a872d]*/
+
 static int
 pair_converter(PyObject *arg, void *ptr)
 {
@@ -456,15 +461,24 @@ pair_converter(PyObject *arg, void *ptr)
     if (pair_number == -1 && PyErr_Occurred())
         return 0;
 
-    if (overflow > 0 || pair_number > COLOR_PAIRS - 1) {
+#if _NCURSES_EXTENDED_COLOR_FUNCS
+    if (overflow > 0 || pair_number > INT_MAX) {
+        PyErr_Format(PyExc_ValueError,
+                     "Color pair is greater than maximum (%d).",
+                     INT_MAX);
+        return 0;
+    }
+#else
+    if (overflow > 0 || pair_number >= COLOR_PAIRS) {
         PyErr_Format(PyExc_ValueError,
                      "Color pair is greater than COLOR_PAIRS-1 (%d).",
                      COLOR_PAIRS - 1);
         return 0;
     }
-    else if (overflow < 0 || pair_number < 1) {
+#endif
+    else if (overflow < 0 || pair_number < 0) {
         PyErr_SetString(PyExc_ValueError,
-                        "Color pair is less than 1.");
+                        "Color pair is less than 0.");
         return 0;
     }
 
@@ -742,7 +756,7 @@ _curses_window_addch_impl(PyCursesWindowObject *self, int group_left_1,
     if (type == 2) {
         funcname = "add_wch";
         wstr[1] = L'\0';
-        setcchar(&wcval, wstr, attr, attr_to_color_pair(attr), NULL);
+        setcchar(&wcval, wstr, attr, PAIR_NUMBER(attr), NULL);
         if (coordinates_group)
             rtn = mvwadd_wch(self->win,y,x, &wcval);
         else {
@@ -2710,7 +2724,7 @@ NoArgOrFlagNoReturnFunctionBody(cbreak, flag)
 _curses.color_content
 
     color_number: color
-        The number of the color (0 - COLORS).
+        The number of the color (0 - (COLORS-1)).
     /
 
 Return the red, green, and blue (RGB) components of the specified color.
@@ -2721,7 +2735,7 @@ which will be between 0 (no component) and 1000 (maximum amount of component).
 
 static PyObject *
 _curses_color_content_impl(PyObject *module, int color_number)
-/*[clinic end generated code: output=17b466df7054e0de input=c10ef58f694b13ee]*/
+/*[clinic end generated code: output=17b466df7054e0de input=03b5ed0472662aea]*/
 {
     _NCURSES_COLOR_VAL_TYPE r,g,b;
 
@@ -2740,8 +2754,8 @@ _curses_color_content_impl(PyObject *module, int color_number)
 /*[clinic input]
 _curses.color_pair
 
-    color_number: color
-        The number of the color (0 - COLORS).
+    pair_number: int
+        The number of the color pair.
     /
 
 Return the attribute value for displaying text in the specified color.
@@ -2751,13 +2765,13 @@ other A_* attributes.  pair_number() is the counterpart to this function.
 [clinic start generated code]*/
 
 static PyObject *
-_curses_color_pair_impl(PyObject *module, int color_number)
-/*[clinic end generated code: output=3fd752e8e24c93fb input=b049033819ab4ef5]*/
+_curses_color_pair_impl(PyObject *module, int pair_number)
+/*[clinic end generated code: output=60718abb10ce9feb input=6034e9146f343802]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
 
-    return  PyLong_FromLong(color_pair_to_attr(color_number));
+    return  PyLong_FromLong(COLOR_PAIR(pair_number));
 }
 
 /*[clinic input]
@@ -3152,7 +3166,7 @@ _curses_has_key_impl(PyObject *module, int key)
 _curses.init_color
 
     color_number: color
-        The number of the color to be changed (0 - COLORS).
+        The number of the color to be changed (0 - (COLORS-1)).
     r: component
         Red component (0 - 1000).
     g: component
@@ -3165,13 +3179,13 @@ Change the definition of a color.
 
 When init_color() is used, all occurrences of that color on the screen
 immediately change to the new definition.  This function is a no-op on
-most terminals; it is active only if can_change_color() returns 1.
+most terminals; it is active only if can_change_color() returns true.
 [clinic start generated code]*/
 
 static PyObject *
 _curses_init_color_impl(PyObject *module, int color_number, short r, short g,
                         short b)
-/*[clinic end generated code: output=d7ed71b2d818cdf2 input=8a2fe94ca9204aa5]*/
+/*[clinic end generated code: output=d7ed71b2d818cdf2 input=ae2b8bea0f152c80]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
@@ -3184,10 +3198,10 @@ _curses.init_pair
 
     pair_number: pair
         The number of the color-pair to be changed (1 - (COLOR_PAIRS-1)).
-    fg: color
-        Foreground color number (0 - COLORS).
-    bg: color
-        Background color number (0 - COLORS).
+    fg: color_allow_default
+        Foreground color number (-1 - (COLORS-1)).
+    bg: color_allow_default
+        Background color number (-1 - (COLORS-1)).
     /
 
 Change the definition of a color-pair.
@@ -3198,7 +3212,7 @@ all occurrences of that color-pair are changed to the new definition.
 
 static PyObject *
 _curses_init_pair_impl(PyObject *module, int pair_number, int fg, int bg)
-/*[clinic end generated code: output=a0bba03d2bbc3ee6 input=b865583a18061c1f]*/
+/*[clinic end generated code: output=a0bba03d2bbc3ee6 input=54b421b44c12c389]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
@@ -3821,7 +3835,7 @@ NoArgNoReturnFunctionBody(noraw)
 _curses.pair_content
 
     pair_number: pair
-        The number of the color pair (1 - (COLOR_PAIRS-1)).
+        The number of the color pair (0 - (COLOR_PAIRS-1)).
     /
 
 Return a tuple (fg, bg) containing the colors for the requested color pair.
@@ -3829,7 +3843,7 @@ Return a tuple (fg, bg) containing the colors for the requested color pair.
 
 static PyObject *
 _curses_pair_content_impl(PyObject *module, int pair_number)
-/*[clinic end generated code: output=4a726dd0e6885f3f input=b42eacf8a4103852]*/
+/*[clinic end generated code: output=4a726dd0e6885f3f input=03970f840fc7b739]*/
 {
     _NCURSES_COLOR_VAL_TYPE f, b;
 
@@ -3838,7 +3852,7 @@ _curses_pair_content_impl(PyObject *module, int pair_number)
 
     if (_CURSES_PAIR_NUMBER_FUNC(pair_number, &f, &b)==ERR) {
         PyErr_SetString(PyCursesError,
-                        "Argument 1 was out of range. (1..COLOR_PAIRS-1)");
+                        "Argument 1 was out of range. (0..COLOR_PAIRS-1)");
         return NULL;
     }
 
@@ -3863,7 +3877,7 @@ _curses_pair_number_impl(PyObject *module, int attr)
     PyCursesInitialised;
     PyCursesInitialisedColor;
 
-    return PyLong_FromLong(attr_to_color_pair(attr));
+    return PyLong_FromLong(PAIR_NUMBER(attr));
 }
 
 /*[clinic input]
diff --git a/Modules/clinic/_cursesmodule.c.h b/Modules/clinic/_cursesmodule.c.h
index 34e09e4..e46a8e3 100644
--- a/Modules/clinic/_cursesmodule.c.h
+++ b/Modules/clinic/_cursesmodule.c.h
@@ -1958,7 +1958,7 @@ PyDoc_STRVAR(_curses_color_content__doc__,
 "Return the red, green, and blue (RGB) components of the specified color.\n"
 "\n"
 "  color_number\n"
-"    The number of the color (0 - COLORS).\n"
+"    The number of the color (0 - (COLORS-1)).\n"
 "\n"
 "A 3-tuple is returned, containing the R, G, B values for the given color,\n"
 "which will be between 0 (no component) and 1000 (maximum amount of component).");
@@ -1985,13 +1985,13 @@ exit:
 }
 
 PyDoc_STRVAR(_curses_color_pair__doc__,
-"color_pair($module, color_number, /)\n"
+"color_pair($module, pair_number, /)\n"
 "--\n"
 "\n"
 "Return the attribute value for displaying text in the specified color.\n"
 "\n"
-"  color_number\n"
-"    The number of the color (0 - COLORS).\n"
+"  pair_number\n"
+"    The number of the color pair.\n"
 "\n"
 "This attribute value can be combined with A_STANDOUT, A_REVERSE, and the\n"
 "other A_* attributes.  pair_number() is the counterpart to this function.");
@@ -2000,18 +2000,19 @@ PyDoc_STRVAR(_curses_color_pair__doc__,
     {"color_pair", (PyCFunction)_curses_color_pair, METH_O, _curses_color_pair__doc__},
 
 static PyObject *
-_curses_color_pair_impl(PyObject *module, int color_number);
+_curses_color_pair_impl(PyObject *module, int pair_number);
 
 static PyObject *
 _curses_color_pair(PyObject *module, PyObject *arg)
 {
     PyObject *return_value = NULL;
-    int color_number;
+    int pair_number;
 
-    if (!color_converter(arg, &color_number)) {
+    pair_number = _PyLong_AsInt(arg);
+    if (pair_number == -1 && PyErr_Occurred()) {
         goto exit;
     }
-    return_value = _curses_color_pair_impl(module, color_number);
+    return_value = _curses_color_pair_impl(module, pair_number);
 
 exit:
     return return_value;
@@ -2542,7 +2543,7 @@ PyDoc_STRVAR(_curses_init_color__doc__,
 "Change the definition of a color.\n"
 "\n"
 "  color_number\n"
-"    The number of the color to be changed (0 - COLORS).\n"
+"    The number of the color to be changed (0 - (COLORS-1)).\n"
 "  r\n"
 "    Red component (0 - 1000).\n"
 "  g\n"
@@ -2552,7 +2553,7 @@ PyDoc_STRVAR(_curses_init_color__doc__,
 "\n"
 "When init_color() is used, all occurrences of that color on the screen\n"
 "immediately change to the new definition.  This function is a no-op on\n"
-"most terminals; it is active only if can_change_color() returns 1.");
+"most terminals; it is active only if can_change_color() returns true.");
 
 #define _CURSES_INIT_COLOR_METHODDEF    \
     {"init_color", (PyCFunction)(void(*)(void))_curses_init_color, METH_FASTCALL, _curses_init_color__doc__},
@@ -2600,9 +2601,9 @@ PyDoc_STRVAR(_curses_init_pair__doc__,
 "  pair_number\n"
 "    The number of the color-pair to be changed (1 - (COLOR_PAIRS-1)).\n"
 "  fg\n"
-"    Foreground color number (0 - COLORS).\n"
+"    Foreground color number (-1 - (COLORS-1)).\n"
 "  bg\n"
-"    Background color number (0 - COLORS).\n"
+"    Background color number (-1 - (COLORS-1)).\n"
 "\n"
 "If the color-pair was previously initialized, the screen is refreshed and\n"
 "all occurrences of that color-pair are changed to the new definition.");
@@ -2627,10 +2628,10 @@ _curses_init_pair(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
     if (!pair_converter(args[0], &pair_number)) {
         goto exit;
     }
-    if (!color_converter(args[1], &fg)) {
+    if (!color_allow_default_converter(args[1], &fg)) {
         goto exit;
     }
-    if (!color_converter(args[2], &bg)) {
+    if (!color_allow_default_converter(args[2], &bg)) {
         goto exit;
     }
     return_value = _curses_init_pair_impl(module, pair_number, fg, bg);
@@ -3403,7 +3404,7 @@ PyDoc_STRVAR(_curses_pair_content__doc__,
 "Return a tuple (fg, bg) containing the colors for the requested color pair.\n"
 "\n"
 "  pair_number\n"
-"    The number of the color pair (1 - (COLOR_PAIRS-1)).");
+"    The number of the color pair (0 - (COLOR_PAIRS-1)).");
 
 #define _CURSES_PAIR_CONTENT_METHODDEF    \
     {"pair_content", (PyCFunction)_curses_pair_content, METH_O, _curses_pair_content__doc__},
@@ -4288,4 +4289,4 @@ _curses_has_extended_color_support(PyObject *module, PyObject *Py_UNUSED(ignored
 #ifndef _CURSES_USE_DEFAULT_COLORS_METHODDEF
     #define _CURSES_USE_DEFAULT_COLORS_METHODDEF
 #endif /* !defined(_CURSES_USE_DEFAULT_COLORS_METHODDEF) */
-/*[clinic end generated code: output=92bad2172fef9747 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=ae6559aa61200289 input=a9049054013a1b77]*/