Bug description:

curses.tparm() passes all its parameters as integers. But ncurses treats some parameters as char *, for the few capabilities that take strings: pfkey, pfloc, pfx, pln, pfxl, and the extended Cs and Ms of xterm. So passing an integer there crashes:

import curses
curses.setupterm('xterm-256color')
curses.tparm(curses.tigetstr('Ms'), 1)    # Segmentation fault

The same happens with curses.tigetstr('Cs'). There is also no way to pass a string, so these capabilities cannot be used from Python at all.

ncurses takes as strings the parameters for which %s or %l directly follows %pN, but only in the format strings of the capabilities above of the current terminal. For other format strings with such parameters it returns NULL, so a plain b'%p1%s' does not crash: tparm() raises curses.error.

NetBSD curses takes such parameters as strings in any format string, not only in those capabilities, so with it even curses.tparm(b'x%p1%sy', 1) crashes.

Linked PRs

• gh-161571: Fix a crash in curses.tparm() with string parameters #161601