[3.8] [3.9] bpo-42681: Fix range checks for color and pair numbers in curses (GH-23874). (GH-24077) (GH-24079)

(cherry picked from commit 1470edd6131c29b8a09ce012cdfee3afa269d553)
(cherry picked from commit b0ee2b492dbf550fbd2a63b82de0a4dc9d67f32e)

5 files changed, 157 insertions, 61 deletions

diff --git a/Doc/library/curses.rst b/Doc/library/curses.rst
index 7cd2025..5a75364 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.
@@ -278,7 +279,7 @@ 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``.
@@ -291,7 +292,8 @@ 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.
 
@@ -441,7 +443,7 @@ 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 b7349d9..e39161f 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, import_module, verbose, SaveSignals
@@ -36,7 +36,17 @@ 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')
+SHORT_MAX = 0x7fff
 
 # If newterm was supported we could use it instead of initscr and not exit
 @unittest.skipIf(not term or term == 'unknown',
@@ -47,6 +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()
@@ -300,18 +312,111 @@ 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)
-        curses.pair_content(min(curses.COLOR_PAIRS - 1, 0x7fff))
-        curses.pair_number(0)
-
-        if hasattr(curses, 'use_default_colors'):
-            curses.use_default_colors()
+
+    def bad_colors(self):
+        return (-2**31 - 1, 2**31, -2**63 - 1, 2**63, 2**64)
+
+    def bad_pairs(self):
+        return (-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(min(curses.COLORS - 1, SHORT_MAX))
+
+        for color in self.bad_colors():
+            self.assertRaises(OverflowError, curses.color_content, color)
+        if curses.COLORS <= SHORT_MAX:
+            self.assertRaises(curses.error, curses.color_content, curses.COLORS)
+        self.assertRaises(curses.error, curses.color_content, -1)
+
+    @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))
+
+        maxcolor = min(curses.COLORS - 1, SHORT_MAX)
+        old = curses.color_content(maxcolor)
+        curses.init_color(maxcolor, *old)
+        self.addCleanup(curses.init_color, maxcolor, *old)
+        curses.init_color(maxcolor, 0, 500, 1000)
+        self.assertEqual(curses.color_content(maxcolor), (0, 500, 1000))
+
+        for color in self.bad_colors():
+            self.assertRaises(OverflowError, curses.init_color, color, 0, 0, 0)
+        if curses.COLORS <= SHORT_MAX:
+            self.assertRaises(curses.error, curses.init_color, curses.COLORS, 0, 0, 0)
+        self.assertRaises(curses.error, curses.init_color, -1, 0, 0, 0)
+        for comp in (-1, 1001):
+            self.assertRaises(curses.error, curses.init_color, 0, comp, 0, 0)
+            self.assertRaises(curses.error, curses.init_color, 0, 0, comp, 0)
+            self.assertRaises(curses.error, 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(min(curses.COLOR_PAIRS - 1, SHORT_MAX))
+
+        for pair in self.bad_pairs():
+            self.assertRaises(OverflowError, curses.pair_content, pair)
+        self.assertRaises(curses.error, curses.pair_content, -1)
+
+    @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))
+        maxcolor = min(curses.COLORS - 1, SHORT_MAX)
+        curses.init_pair(1, maxcolor, maxcolor)
+        self.assertEqual(curses.pair_content(1), (maxcolor, maxcolor))
+        maxpair = min(curses.COLOR_PAIRS - 1, SHORT_MAX)
+        curses.init_pair(maxpair, 2, 3)
+        self.assertEqual(curses.pair_content(maxpair), (2, 3))
+
+        for pair in self.bad_pairs():
+            self.assertRaises(OverflowError, curses.init_pair, pair, 0, 0)
+        self.assertRaises(curses.error, curses.init_pair, -1, 0, 0)
+        for color in self.bad_colors():
+            self.assertRaises(OverflowError, curses.init_pair, 1, color, 0)
+            self.assertRaises(OverflowError, curses.init_pair, 1, 0, color)
+        if curses.COLORS <= SHORT_MAX:
+            self.assertRaises(curses.error, curses.init_pair, 1, curses.COLORS, 0)
+            self.assertRaises(curses.error, curses.init_pair, 1, 0, curses.COLORS)
+
+    @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 ac23d5d..47459d6 100644
--- a/Modules/_cursesmodule.c
+++ b/Modules/_cursesmodule.c
@@ -176,18 +176,6 @@ 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
@@ -618,7 +606,7 @@ _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 {
@@ -2586,7 +2574,7 @@ NoArgOrFlagNoReturnFunctionBody(cbreak, flag)
 _curses.color_content
 
     color_number: short
-        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.
@@ -2597,7 +2585,7 @@ which will be between 0 (no component) and 1000 (maximum amount of component).
 
 static PyObject *
 _curses_color_content_impl(PyObject *module, short color_number)
-/*[clinic end generated code: output=cb15cf3120d4bfc1 input=5555abb1c11e11b7]*/
+/*[clinic end generated code: output=cb15cf3120d4bfc1 input=630f6737514db6ad]*/
 {
     short r,g,b;
 
@@ -2616,8 +2604,8 @@ _curses_color_content_impl(PyObject *module, short color_number)
 /*[clinic input]
 _curses.color_pair
 
-    color_number: short
-        The number of the color (0 - COLORS).
+    pair_number: short
+        The number of the color pair.
     /
 
 Return the attribute value for displaying text in the specified color.
@@ -2627,13 +2615,13 @@ other A_* attributes.  pair_number() is the counterpart to this function.
 [clinic start generated code]*/
 
 static PyObject *
-_curses_color_pair_impl(PyObject *module, short color_number)
-/*[clinic end generated code: output=6a84cb6b29ecaf9a input=a9d3eb6f50e4dc12]*/
+_curses_color_pair_impl(PyObject *module, short pair_number)
+/*[clinic end generated code: output=ce609d238b70dc11 input=8dd0d5da94cb15b5]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
 
-    return  PyLong_FromLong(color_pair_to_attr(color_number));
+    return  PyLong_FromLong(COLOR_PAIR(pair_number));
 }
 
 /*[clinic input]
@@ -3028,7 +3016,7 @@ _curses_has_key_impl(PyObject *module, int key)
 _curses.init_color
 
     color_number: short
-        The number of the color to be changed (0 - COLORS).
+        The number of the color to be changed (0 - (COLORS-1)).
     r: short
         Red component (0 - 1000).
     g: short
@@ -3041,13 +3029,13 @@ 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, short color_number, short r,
                         short g, short b)
-/*[clinic end generated code: output=280236f5efe9776a input=f3a05bd38f619175]*/
+/*[clinic end generated code: output=280236f5efe9776a input=128601b5dc76d548]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
@@ -3061,9 +3049,9 @@ _curses.init_pair
     pair_number: short
         The number of the color-pair to be changed (1 - (COLOR_PAIRS-1)).
     fg: short
-        Foreground color number (0 - COLORS).
+        Foreground color number (-1 - (COLORS-1)).
     bg: short
-        Background color number (0 - COLORS).
+        Background color number (-1 - (COLORS-1)).
     /
 
 Change the definition of a color-pair.
@@ -3075,7 +3063,7 @@ all occurrences of that color-pair are changed to the new definition.
 static PyObject *
 _curses_init_pair_impl(PyObject *module, short pair_number, short fg,
                        short bg)
-/*[clinic end generated code: output=9c2ce39c22f376b6 input=c9f0b11b17a2ac6d]*/
+/*[clinic end generated code: output=9c2ce39c22f376b6 input=12c320ec14396ea2]*/
 {
     PyCursesInitialised;
     PyCursesInitialisedColor;
@@ -3631,7 +3619,7 @@ _curses_pair_content_impl(PyObject *module, short pair_number)
 
     if (pair_content(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;
     }
 
@@ -3656,7 +3644,7 @@ _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 437604c..889c2f6 100644
--- a/Modules/clinic/_cursesmodule.c.h
+++ b/Modules/clinic/_cursesmodule.c.h
@@ -2028,7 +2028,7 @@ 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).");
@@ -2076,13 +2076,13 @@ 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.");
@@ -2091,13 +2091,13 @@ 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, short color_number);
+_curses_color_pair_impl(PyObject *module, short pair_number);
 
 static PyObject *
 _curses_color_pair(PyObject *module, PyObject *arg)
 {
     PyObject *return_value = NULL;
-    short color_number;
+    short pair_number;
 
     if (PyFloat_Check(arg)) {
         PyErr_SetString(PyExc_TypeError,
@@ -2120,10 +2120,10 @@ _curses_color_pair(PyObject *module, PyObject *arg)
             goto exit;
         }
         else {
-            color_number = (short) ival;
+            pair_number = (short) ival;
         }
     }
-    return_value = _curses_color_pair_impl(module, color_number);
+    return_value = _curses_color_pair_impl(module, pair_number);
 
 exit:
     return return_value;
@@ -2699,7 +2699,7 @@ 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"
@@ -2709,7 +2709,7 @@ 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__},
@@ -2841,9 +2841,9 @@ 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.");
@@ -4559,4 +4559,4 @@ _curses_use_default_colors(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=820af7050893ed16 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c5267f2ffe238810 input=a9049054013a1b77]*/