-.TH curs_util 3X ""
+'\" t
+.\"***************************************************************************
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
+.\" Copyright 1998-2015,2017 Free Software Foundation, Inc. *
+.\" *
+.\" Permission is hereby granted, free of charge, to any person obtaining a *
+.\" copy of this software and associated documentation files (the *
+.\" "Software"), to deal in the Software without restriction, including *
+.\" without limitation the rights to use, copy, modify, merge, publish, *
+.\" distribute, distribute with modifications, sublicense, and/or sell *
+.\" copies of the Software, and to permit persons to whom the Software is *
+.\" furnished to do so, subject to the following conditions: *
+.\" *
+.\" The above copyright notice and this permission notice shall be included *
+.\" in all copies or substantial portions of the Software. *
+.\" *
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
+.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
+.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
+.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
+.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
+.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
+.\" *
+.\" Except as contained in this notice, the name(s) of the above copyright *
+.\" holders shall not be used in advertising or otherwise to promote the *
+.\" sale, use or other dealings in this Software without prior written *
+.\" authorization. *
+.\"***************************************************************************
+.\"
+.\" $Id: curs_util.3x,v 1.101 2024/04/20 21:20:07 tom Exp $
+.TH curs_util 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
+.de bP
+.ie n .IP \(bu 4
+.el .IP \(bu 2
+..
.SH NAME
-\fBunctrl\fR, \fBkeyname\fR, \fBfilter\fR,
-\fBuse_env\fR, \fBputwin\fR, \fBgetwin\fR, \fBdelay_output\fR,
-\fBflushinp\fR - miscellaneous \fBcurses\fR utility routines
+\fB\%delay_output\fP,
+\fB\%filter\fP,
+\fB\%flushinp\fP,
+\fB\%getwin\fP,
+\fB\%key_name\fP,
+\fB\%keyname\fP,
+\fB\%nofilter\fP,
+\fB\%putwin\fP,
+\fB\%unctrl\fP,
+\fB\%use_env\fP,
+\fB\%use_tioctl\fP,
+\fB\%wunctrl\fP \-
+miscellaneous \fIcurses\fR utility routines
.SH SYNOPSIS
-\fB#include <curses.h>\fR
-
-\fBchar *unctrl(chtype c);\fR
-.br
-\fBchar *keyname(int c);\fR
-.br
-\fBvoid filter(void);\fR
-.br
-\fBvoid use_env(char bool);\fR
-.br
-\fBint putwin(WINDOW *win, FILE *filep);\fR
-.br
-\fBWINDOW *getwin(FILE *filep);\fR
-.br
-\fBint delay_output(int ms);\fR
-.br
-\fBint flushinp(void);\fR
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fBconst char *unctrl(chtype \fIch\fP);
+\fBwchar_t *wunctrl(cchar_t *\fIwch\fP);
+.PP
+\fBconst char *keyname(int \fIc\fP);
+\fBconst char *key_name(wchar_t \fIwc\fP);
+.PP
+\fBvoid filter(void);
+.PP
+\fBvoid use_env(bool \fIf\fP);
+.PP
+\fBint putwin(WINDOW *\fIwin\fP, FILE *\fIfilep\fP);
+\fBWINDOW *getwin(FILE *\fIfilep\fP);
+.PP
+\fBint delay_output(int \fIms\fP);
+\fBint flushinp(void);
+.PP
+\fI/* extensions */
+\fBvoid nofilter(void);
+\fBvoid use_tioctl(bool \fIf\fP);
+.fi
.SH DESCRIPTION
-The \fBunctrl\fR macro expands to a character string which is a printable
-representation of the character \fIc\fR. Control characters are displayed in
-the \fB^\fR\fIX\fR notation. Printing characters are displayed as is.
-
-The \fBkeyname\fR routine returns a character string corresponding to
-the key \fIc\fR.
-
-The \fBfilter\fR routine, if used, must be called before \fBinitscr\fR or
-\fBnewterm\fR are called. The effect is that, during those calls, \fBLINES\fR
-is set to 1; the capabilities \fBclear\fR, \fBcup\fR, \fBcud\fR, \fBcud1\fR,
-\fBcuu1\fR, \fBcuu\fR, \fBvpa\fR are disabled; and the \fBhome\fR string is
-set to the value of \fBcr\fR.
-
-The \fBuse_env\fR routine, if used, is called before \fBinitscr\fR or
-\fBnewterm\fR are called. When called with \fBFALSE\fR as an
-argument, the values of \fBlines\fR and \fBcolumns\fR specified in the
-\fIterminfo\fR database will be used, even if environment variables
-\fBLINES\fR and \fBCOLUMNS\fR (used by default) are set, or if
-\fBcurses\fR is running in a window (in which case default behavior
-would be to use the window size if \fBLINES\fR and \fBCOLUMNS\fR are
-not set).
-
-The \fBputwin\fR routine writes all data associated with window \fIwin\fR into
-the file to which \fIfilep\fR points. This information can be later retrieved
-using the \fBgetwin\fR function.
-
-The \fBgetwin\fR routine reads window related data stored in the file by
-\fBputwin\fR. The routine then creates and initializes a new window using that
-data. It returns a pointer to the new window.
-
-The \fBdelay_output\fR routine inserts an \fIms\fR millisecond pause
-in output. This routine should not be used extensively because
-padding characters are used rather than a CPU pause.
-
-The \fBflushinp\fR routine throws away any typeahead that has been typed by the
+.SS unctrl
+The \fBunctrl\fP routine returns a character string which is a printable
+representation of the character \fIch\fP:
+.bP
+Printable characters are displayed as themselves,
+e.g., a one-character string containing the key.
+.bP
+Control characters are displayed in the \fB^\fIX\fR notation.
+.bP
+Printing characters are displayed as is.
+.bP
+DEL (character 127) is displayed as \fB^?\fP.
+.bP
+Values above 128 are either meta characters
+(if the screen has not been initialized,
+or if \fBmeta\fP(3X) has been called with a \fBTRUE\fP parameter),
+shown in the \fBM\-\fIX\fR notation,
+or are displayed as themselves.
+In the latter case, the values may not be printable;
+this follows the X/Open specification.
+.PP
+The corresponding \fBwunctrl\fP returns a printable representation of
+a complex character \fIwch\fP.
+.PP
+In both \fBunctrl\fP and \fBwunctrl\fP the attributes and color associated
+with the character parameter are ignored.
+.SS "keyname, key_name"
+The \fBkeyname\fP routine returns a character string
+corresponding to the key \fIc\fP.
+Key codes are different from character codes.
+.bP
+Key codes below 256 are characters.
+They are displayed using \fBunctrl\fP.
+.bP
+Values above 256 may be the codes for function keys.
+The function key name is displayed.
+.bP
+Otherwise (if there is no corresponding name and the key is not a character)
+the function returns null, to denote an error.
+X/Open also lists an \*(``UNKNOWN KEY\*('' return value,
+which some implementations return rather than null.
+.LP
+The corresponding \fBkey_name\fP returns
+a multibyte character string corresponding
+to the wide-character value \fIw\fP.
+The two functions (\fBkeyname\fP and \fBkey_name\fP)
+do not return the same set of strings:
+.bP
+\fBkeyname\fP returns null where \fBkey_name\fP would display a meta character.
+.bP
+\fBkey_name\fP does not return the name of a function key.
+.SS "filter, nofilter"
+The \fBfilter\fP routine, if used, must be called before \fBinitscr\fP or
+\fBnewterm\fP are called.
+Calling \fBfilter\fP causes these changes in initialization:
+.bP
+\fBLINES\fP is set to 1;
+.bP
+the capabilities
+\fBclear\fP,
+\fBcud1\fP,
+\fBcud\fP,
+\fBcup\fP,
+\fBcuu1\fP,
+\fBcuu\fP,
+\fBvpa\fP
+are disabled;
+.bP
+the capability \fBed\fP is disabled if \fBbce\fP is set;
+.bP
+and the \fBhome\fP string is set to the value of \fBcr\fP.
+.PP
+The \fBnofilter\fP routine cancels the effect of a preceding \fBfilter\fP
+call.
+That allows the caller to initialize a screen on a different device,
+using a different value of \fB$TERM\fP.
+The limitation arises because the \fBfilter\fP routine modifies the
+in-memory copy of the terminal information.
+.SS use_env
+The \fBuse_env\fP routine, if used,
+should be called before \fBinitscr\fP or
+\fBnewterm\fP are called
+(because those compute the screen size).
+It modifies the way \fI\%ncurses\fP treats environment variables
+when determining the screen size.
+.bP
+Normally \fI\%ncurses\fP looks first at the terminal database for the
+screen size.
+.IP
+If \fBuse_env\fP was called with \fBFALSE\fP for parameter,
+it stops here unless
+\fBuse_tioctl\fP was also called with \fBTRUE\fP for parameter.
+.bP
+Then it asks for the screen size via operating system calls.
+If successful,
+it overrides the values from the terminal database.
+.bP
+Finally (unless \fBuse_env\fP was called with \fBFALSE\fP parameter),
+\fI\%ncurses\fP examines the \fILINES\fP or \fI\%COLUMNS\fP environment
+variables,
+using a value in those to override the results
+from the operating system or terminal database.
+.IP
+\fI\%curses\fP also updates the screen size in response to
+\fBSIGWINCH\fP,
+unless overridden by the \fILINES\fP or \fI\%COLUMNS\fP environment
+variables,
+.SS use_tioctl
+The \fBuse_tioctl\fP routine, if used,
+should be called before \fBinitscr\fP or \fBnewterm\fP are called
+(because those compute the screen size).
+After \fBuse_tioctl\fP is called with \fBTRUE\fP as an argument,
+\fI\%ncurses\fP modifies the last step in its computation
+of screen size as follows:
+.bP
+checks if the \fILINES\fP and \fI\%COLUMNS\fP environment variables
+are set to a number greater than zero.
+.bP
+for each, \fI\%ncurses\fP updates the corresponding environment variable
+with the value that it has obtained via operating system call
+or from the terminal database.
+.bP
+\fI\%ncurses\fP re-fetches the value of the environment variables so
+that it is still the environment variables which set the screen size.
+.PP
+The \fB\%use_env\fP and \fB\%use_tioctl\fP routines combine as follows.
+.IP
+.TS
+lB lB lB
+lB lB lx.
+use_env use_tioctl Summary
+_
+TRUE FALSE T{
+This is the default behavior.
+\fI\%ncurses\fP uses operating system calls
+unless overridden by \fILINES\fP or \fI\%COLUMNS\fP environment
+variables;
+default.
+T}
+TRUE TRUE T{
+\fI\%ncurses\fP updates \fILINES\fP and \fI\%COLUMNS\fP based on
+operating system calls.
+T}
+FALSE TRUE T{
+\fI\%ncurses\fP ignores \fILINES\fP and \fI\%COLUMNS\fP,
+using operating system calls to obtain size.
+T}
+.TE
+.SS "putwin, getwin"
+The \fBputwin\fP routine writes all data associated
+with window (or pad) \fIwin\fP into
+the file to which \fIfilep\fP points.
+This information can be later retrieved
+using the \fBgetwin\fP function.
+.PP
+The \fBgetwin\fP routine reads window related data stored in the file by
+\fBputwin\fP.
+The routine then creates and initializes a new window using that
+data.
+It returns a pointer to the new window.
+There are a few caveats:
+.bP
+the data written is a copy of the \fI\%WINDOW\fP structure,
+and its associated character cells.
+The format differs between the wide-character (\fI\%ncursesw\fP) and
+non-wide (\fI\%ncurses\fP) libraries.
+You can transfer data between the two, however.
+.bP
+the retrieved window is always created as a top-level window (or pad),
+rather than a subwindow.
+.bP
+the window's character cells contain the color pair \fIvalue\fP,
+but not the actual color \fInumbers\fP.
+If cells in the retrieved window use color pairs which have not been
+created in the application using \fBinit_pair\fP,
+they will not be colored when the window is refreshed.
+.SS delay_output
+The \fBdelay_output\fP routine inserts an \fIms\fP millisecond pause
+in output.
+Employ this function judiciously when terminal output uses padding,
+because \fI\%ncurses\fP transmits null characters
+(consuming CPU and I/O resources)
+instead of sleeping and requesting resumption from the operating system.
+Padding is used unless:
+.bP
+the terminal description has \fBnpc\fP (\fBno_pad_char\fP) capability, or
+.bP
+the environment variable \fB\%NCURSES_NO_PADDING\fP is set.
+.PP
+If padding is not in use,
+\fI\%ncurses\fP uses \fBnapms\fP to perform the delay.
+If the value of \fIms\fP exceeds 30,000
+(thirty seconds),
+it is capped at that value.
+.SS flushinp
+The \fBflushinp\fP routine throws away any typeahead that has been typed by the
user and has not yet been read by the program.
.SH RETURN VALUE
-Except for \fBflushinp\fR, routines that return an integer return \fBERR\fR
-upon failure and \fBOK\fR (SVr4 specifies only "an integer value other than
-\fBERR\fR") upon successful completion.
-
-\fBflushinp\fR always returns \fBOK\fR.
-
-Routines that return pointers return \fBNULL\fR on error.
+Except for \fBflushinp\fP, routines that return an integer return \fBERR\fP
+upon failure and \fBOK\fP (SVr4 specifies only "an integer value other than
+\fBERR\fP") upon successful completion.
+.PP
+Routines that return pointers return \fBNULL\fP on error.
+.PP
+X/Open Curses does not specify any error conditions.
+In this implementation
+.RS 3
+.TP 5
+\fBflushinp\fP
+returns an error if the terminal was not initialized.
+.TP 5
+\fBputwin\fP
+returns an error if the associated \fBfwrite\fP calls return an error.
+.RE
.SH PORTABILITY
-The XSI Curses standard, Issue 4 describes these functions.
-
-The SVr4 documentation describes the action of \fBfilter\fR only in the vaguest
-terms. The description here is adapted from the XSI Curses standard (which
-erroneously fails to describe the disabling of \fBcuu\fR).
-.SH NOTES
-Note that \fBunctrl\fR is a macro, which is defined in <\fBunctrl.h\fR>.
+.SS filter
+The SVr4 documentation describes the action of \fBfilter\fP only in the vaguest
+terms.
+The description here is adapted from X/Open Curses (which
+erroneously fails to describe the disabling of \fBcuu\fP).
+.SS "delay_output padding"
+The limitation to 30 seconds
+and the use of \fBnapms\fP
+differ from other implementations.
+.bP
+SVr4 curses does not delay if no padding character is available.
+.bP
+NetBSD curses uses \fBnapms\fP when no padding character is available,
+but does not take timing into account when using the padding character.
+.PP
+Neither limits the delay.
+.SS keyname
+The \fBkeyname\fP function may return the names of user-defined
+string capabilities which are defined in the terminfo entry via the \fB\-x\fP
+option of \fB@TIC@\fP.
+This implementation automatically assigns at run-time keycodes to
+user-defined strings which begin with \*(``k\*(''.
+The keycodes start at KEY_MAX, but are not guaranteed to be
+the same value for different runs because user-defined codes are
+merged from all terminal descriptions which have been loaded.
+The \fBuse_extended_names\fP(3X) function controls whether this data is
+loaded when the terminal description is read by the library.
+.SS "nofilter, use_tioctl"
+The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to
+\fI\%ncurses\fP.
+They were not supported on Version 7, BSD or System V implementations.
+It is recommended that any code depending on \fI\%ncurses\fP extensions
+be conditioned using \fBNCURSES_VERSION\fP.
+.SS "putwin/getwin file-format"
+The \fBputwin\fP and \fBgetwin\fP functions have several issues with
+portability:
+.bP
+The files written and read by these functions
+use an implementation-specific format.
+Although the format is an obvious target for standardization,
+it has been overlooked.
+.IP
+Interestingly enough, according to the copyright dates in Solaris source,
+the functions (along with \fBscr_init\fP, etc.) originated with
+the University of California, Berkeley (in 1982)
+and were later (in 1988) incorporated into SVr4.
+Oddly, there are no such functions in the 4.3BSD curses sources.
+.bP
+Most implementations simply dump the binary \fI\%WINDOW\fP structure
+to the file.
+These include SVr4 curses, NetBSD and PDCurses,
+as well as older \fI\%ncurses\fP versions.
+This implementation
+(as well as the X/Open variant of Solaris curses, dated 1995)
+uses textual dumps.
+.IP
+The implementations which use binary dumps use block-I/O
+(the \fBfwrite\fP and \fBfread\fP functions).
+Those that use textual dumps use buffered-I/O.
+A few applications may happen to write extra data in the file using
+these functions.
+Doing that can run into problems mixing block- and buffered-I/O.
+This implementation reduces the problem on writes by flushing the output.
+However, reading from a file written using mixed schemes may not be successful.
+.SS "unctrl, wunctrl"
+X/Open Curses, Issue 4 describes these functions.
+It states that \fBunctrl\fP and \fBwunctrl\fP will return a null pointer if
+unsuccessful, but does not define any error conditions.
+This implementation checks for three cases:
+.bP
+the parameter is a 7-bit US\-ASCII code.
+This is the case that X/Open Curses documented.
+.bP
+the parameter is in the range 128\-159, i.e., a C1 control code.
+If \fBuse_legacy_coding\fP(3X) has been called with a \fB2\fP parameter,
+\fBunctrl\fP returns the parameter, i.e., a one-character string with
+the parameter as the first character.
+Otherwise, it returns \*(``~@\*('', \*(``~A\*('', etc.,
+analogous to \*(``^@\*('', \*(``^A\*('', C0 controls.
+.IP
+X/Open Curses does not document whether \fBunctrl\fP can be called before
+initializing curses.
+This implementation permits that,
+and returns the \*(``~@\*('', etc., values in that case.
+.bP
+parameter values outside the 0 to 255 range.
+\fBunctrl\fP returns a null pointer.
+.PP
+The strings returned by \fBunctrl\fP in this implementation are determined
+at compile time,
+showing C1 controls from the upper-128 codes
+with a \*(``~\*('' prefix rather than \*(``^\*(''.
+Other implementations have different conventions.
+For example, they may show both sets of control characters with \*(``^\*('',
+and strip the parameter to 7 bits.
+Or they may ignore C1 controls and treat all of the upper-128 codes as
+printable.
+This implementation uses 8 bits but does not modify the string to reflect
+locale.
+The \fBuse_legacy_coding\fP(3X) function allows the caller to
+change the output of \fBunctrl\fP.
+.PP
+Likewise, the \fBmeta\fP(3X) function allows the caller to change the
+output of \fBkeyname\fP, i.e.,
+it determines whether to use the \*(``M\-\*('' prefix
+for \*(``meta\*('' keys (codes in the range 128 to 255).
+Both \fBuse_legacy_coding\fP(3X) and \fBmeta\fP(3X) succeed only after
+curses is initialized.
+X/Open Curses does not document the treatment of codes 128 to 159.
+When treating them as \*(``meta\*('' keys
+(or if \fBkeyname\fP is called before initializing curses),
+this implementation returns strings \*(``M\-^@\*('', \*(``M\-^A\*('', etc.
+.PP
+X/Open Curses documents \fBunctrl\fP as declared in \fB<unctrl.h>\fP,
+which \fI\%ncurses\fP does.
+However, \fI\%ncurses\fP' \fB<curses.h>\fP includes \fB<unctrl.h>\fP,
+matching the behavior of SVr4 curses.
+Other implementations may not do that.
+.SS "use_env, use_tioctl"
+If \fI\%ncurses\fP is configured to provide the sp-functions extension,
+the state of \fBuse_env\fP and \fBuse_tioctl\fP may be updated before
+creating each \fIscreen\fP rather than once only
+(\fBcurs_sp_funcs\fP(3X)).
+This feature of \fBuse_env\fP
+is not provided by other implementations of curses.
.SH SEE ALSO
-\fBcurses\fR(3X), \fBcurs_initscr\fR(3X), \fBcurs_scr_dump\fR(3X).
-.\"#
-.\"# The following sets edit modes for GNU EMACS
-.\"# Local Variables:
-.\"# mode:nroff
-.\"# fill-column:79
-.\"# End:
+\fB\%curses\fP(3X),
+\fB\%curs_initscr\fP(3X),
+\fB\%curs_inopts\fP(3X),
+\fB\%curs_kernel\fP(3X),
+\fB\%curs_scr_dump\fP(3X),
+\fB\%curs_sp_funcs\fP(3X),
+\fB\%curs_variables\fP(3X),
+\fB\%legacy_coding\fP(3X)
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