https://invisible-island.net/ncurses/man/
curs_getstr(3x) curs_getstr(3x)
getstr, getnstr, wgetstr, wgetnstr, mvgetstr, mvgetnstr, mvwgetstr,
mvwgetnstr - accept character strings from curses terminal keyboard
#include <curses.h>
int getstr(char *str);
int getnstr(char *str, int n);
int wgetstr(WINDOW *win, char *str);
int wgetnstr(WINDOW *win, char *str, int n);
int mvgetstr(int y, int x, char *str);
int mvwgetstr(WINDOW *win, int y, int x, char *str);
int mvgetnstr(int y, int x, char *str, int n);
int mvwgetnstr(WINDOW *, int y, int x, char *str, int n);
The function getstr is equivalent to a series of calls to getch, until
a newline or carriage return is received (the terminating character is
not included in the returned string). The resulting value is placed in
the area pointed to by the character pointer str, followed by a NUL.
wgetnstr reads at most n characters, thus preventing a possible over-
flow of the input buffer. Any attempt to enter more characters (other
than the terminating newline or carriage return) causes a beep. Func-
tion keys also cause a beep and are ignored. The getnstr function
reads from the stdscr default window.
The user's erase and kill characters are interpreted. If keypad mode
is on for the window, KEY_LEFT and KEY_BACKSPACE are both considered
equivalent to the user's kill character.
Characters input are echoed only if echo is currently on. In that
case, backspace is echoed as deletion of the previous character (typi-
cally a left motion).
All routines return the integer ERR upon failure and an OK (SVr4 speci-
fies only "an integer value other than ERR") upon successful comple-
tion.
X/Open defines no error conditions.
In this implementation, these functions return an error if the window
pointer is null, or if its timeout expires without having any data.
This implementation provides an extension as well. If a SIGWINCH in-
terrupts the function, it will return KEY_RESIZE rather than OK or ERR.
Functions with a "mv" prefix first perform a cursor movement using
wmove, and return an error if the position is outside the window, or if
the window pointer is null.
Note that getstr, mvgetstr, and mvwgetstr may be macros.
These functions are described in the XSI Curses standard, Issue 4.
They read single-byte characters only. The standard does not define
any error conditions. This implementation returns ERR if the window
pointer is null, or if the lower-level wgetch(3x) call returns an ERR.
SVr3 and early SVr4 curses implementations did not reject function
keys; the SVr4.0 documentation claimed that "special keys" (such as
function keys, "home" key, "clear" key, etc.) are "interpreted", with-
out giving details. It lied. In fact, the "character" value appended
to the string by those implementations was predictable but not useful
(being, in fact, the low-order eight bits of the key's KEY_ value).
The functions getnstr, mvgetnstr, and mvwgetnstr were present but not
documented in SVr4.
X/Open Curses issue 5 (2007) stated that these functions "read at most
n bytes" but did not state whether the terminating NUL is counted in
that limit. X/Open Curses issue 7 (2009) changed that to say they
"read at most n-1 bytes" to allow for the terminating NUL. As of 2018,
some implementations do, some do not count it:
o ncurses 6.1 and PDCurses do not count the NUL in the given limit,
while
o Solaris SVr4 and NetBSD curses count the NUL as part of the limit.
o Solaris xcurses provides both: its wide-character wget_nstr re-
serves a NUL, but its wgetnstr does not count the NUL consistently.
In SVr4 curses, a negative value of n tells wgetnstr to assume that the
caller's buffer is large enough to hold the result, i.e., to act like
wgetstr. X/Open Curses does not mention this (or anything related to
negative or zero values of n), however most implementations use the
feature, with different limits:
o Solaris SVr4 curses and PDCurses limit the result to 255 bytes.
Other Unix systems than Solaris are likely to use the same limit.
o Solaris xcurses limits the result to LINE_MAX bytes.
o NetBSD 7 assumes no particular limit for the result from wgetstr.
However, it limits the wgetnstr parameter n to ensure that it is
greater than zero.
A comment in NetBSD's source code states that this is specified in
SUSv2.
o ncurses (before 6.2) assumes no particular limit for the result
from wgetstr, and treats the n parameter of wgetnstr like SVr4
curses.
o ncurses 6.2 uses LINE_MAX, or a larger (system-dependent) value
which the sysconf function may provide. If neither LINE_MAX or
sysconf is available, ncurses uses the POSIX value for LINE_MAX (a
2048 byte limit). In either case, it reserves a byte for the ter-
minating NUL.
curses(3x), curs_getch(3x), curs_variables(3x).
curs_getstr(3x)