Skip to content

[3.13] gh-154855: Ask non-ncurses curses for one more character (GH-154870) #156285

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
serhiy-storchaka merged 1 commit into from
Aug 23, 2026
+36 −8
Merged

[3.13] gh-154855: Ask non-ncurses curses for one more character (GH-154870) #156285

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2026-07-29-14-20-40.gh-issue-154855.vfF453.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix :meth:`curses.window.instr` returning one character too few when the
:mod:`curses` module is built against a curses library that counts the
terminator in the requested length, such as the NetBSD one.
41 changes: 33 additions & 8 deletions Modules/_cursesmodule.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -185,6 +185,14 @@ static int initialisedcolors = FALSE;
while these functions are still in use. */
static char *screen_encoding = NULL;

/* ncurses and PDCurses store n characters and add a terminator; NetBSD
curses counts the terminator in n. Ask an unknown library for one more. */
#if defined(NCURSES_VERSION) || defined(PDCURSES)
# define CURSES_STR_EXTRA 0
#else
# define CURSES_STR_EXTRA 1
#endif

/* Utility Macros */
#define PyCursesSetupTermCalled \
if (initialised_setupterm != TRUE) { \
Expand Down Expand Up @@ -1839,13 +1847,13 @@ bytes are read.
static PyObject *
PyCursesWindow_InStr(PyCursesWindowObject *self, PyObject *args)
{
int x, y, n;
int x = 0, y = 0, n;
char rtn[1024]; /* This should be big enough.. I hope */
int rtn2;
int rtn2, use_xy = 0;

switch (PyTuple_Size(args)) {
case 0:
rtn2 = winnstr(self->win,rtn, 1023);
n = 1023;
break;
case 1:
if (!PyArg_ParseTuple(args,"i;n", &n))
Expand All @@ -1854,12 +1862,13 @@ PyCursesWindow_InStr(PyCursesWindowObject *self, PyObject *args)
PyErr_SetString(PyExc_ValueError, "'n' must be nonnegative");
return NULL;
}
rtn2 = winnstr(self->win, rtn, Py_MIN(n, 1023));
n = Py_MIN(n, 1023);
break;
case 2:
if (!PyArg_ParseTuple(args,"ii;y,x",&y,&x))
return NULL;
rtn2 = mvwinnstr(self->win,y,x,rtn,1023);
n = 1023;
use_xy = 1;
break;
case 3:
if (!PyArg_ParseTuple(args, "iii;y,x,n", &y, &x, &n))
Expand All @@ -1868,15 +1877,31 @@ PyCursesWindow_InStr(PyCursesWindowObject *self, PyObject *args)
PyErr_SetString(PyExc_ValueError, "'n' must be nonnegative");
return NULL;
}
rtn2 = mvwinnstr(self->win, y, x, rtn, Py_MIN(n,1023));
n = Py_MIN(n, 1023);
use_xy = 1;
break;
default:
PyErr_SetString(PyExc_TypeError, "instr requires 0 or 3 arguments");
return NULL;
}

/* Read again if the library stored more than asked: truncating could
split a multibyte character. */
for (int ask = n + CURSES_STR_EXTRA; ; ask = n) {
if (use_xy) {
rtn2 = mvwinnstr(self->win, y, x, rtn, ask);
}
else {
rtn2 = winnstr(self->win, rtn, ask);
}
if (rtn2 == ERR || rtn2 <= n) {
break;
}
}

if (rtn2 == ERR)
rtn[0] = 0;
return PyBytes_FromString(rtn);
return PyBytes_FromStringAndSize(NULL, 0);
return PyBytes_FromStringAndSize(rtn, rtn2);
}

/*[clinic input]
Expand Down
Loading