.\"***************************************************************************
-.\" Copyright 2018,2020 Thomas E. Dickey *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
.\" Copyright 1998-2016,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_initscr.3x,v 1.33 2020/10/17 23:20:48 tom Exp $
-.TH curs_initscr 3X ""
+.\" $Id: curs_initscr.3x,v 1.69 2024/04/20 21:24:19 tom Exp $
+.TH curs_initscr 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
..
-.ie \n(.g .ds `` \(lq
-.el .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el .ds '' ''
-.na
-.hy 0
.SH NAME
-\fBinitscr\fR,
-\fBnewterm\fR,
-\fBendwin\fR,
-\fBisendwin\fR,
-\fBset_term\fR,
-\fBdelscreen\fR \- \fBcurses\fR screen initialization and manipulation routines
-.ad
-.hy
+\fB\%initscr\fP,
+\fB\%newterm\fP,
+\fB\%endwin\fP,
+\fB\%isendwin\fP,
+\fB\%set_term\fP,
+\fB\%delscreen\fP \-
+initialize, manipulate, or tear down \fIcurses\fR terminal interface
.SH SYNOPSIS
-\fB#include <curses.h>\fR
-.sp
-\fBWINDOW *initscr(void);\fR
-.br
-\fBint endwin(void);\fR
-.sp
-\fBbool isendwin(void);\fR
-.sp
-\fBSCREEN *newterm(const char *\fP\fItype\fP\fB, FILE *\fP\fIoutfd\fP\fB, FILE *\fP\fIinfd\fP\fB);\fR
-.br
-\fBSCREEN *set_term(SCREEN *\fP\fInew\fP\fB);\fR
-.br
-\fBvoid delscreen(SCREEN* \fP\fIsp\fP\fB);\fR
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fBWINDOW *initscr(void);
+\fBint endwin(void);
+.PP
+\fBbool isendwin(void);
+.PP
+\fBSCREEN *newterm(const char *\fItype\fP, FILE *\fIoutf\fP, FILE *\fIinf\fP);
+\fBSCREEN *set_term(SCREEN *\fInew\fP);
+\fBvoid delscreen(SCREEN* \fIsp\fP);
+.fi
.SH DESCRIPTION
.SS initscr
-\fBinitscr\fR is normally the first \fBcurses\fR routine to call when
+\fBinitscr\fP is normally the first \fBcurses\fP routine to call when
initializing a program.
A few special routines sometimes need to be called before it;
-these are \fBslk_init\fR(3X), \fBfilter\fR, \fBripoffline\fR,
-\fBuse_env\fR.
+these are \fBslk_init\fP(3X), \fBfilter\fP, \fBripoffline\fP,
+\fBuse_env\fP.
For multiple-terminal applications,
-\fBnewterm\fR may be called before \fBinitscr\fR.
+\fBnewterm\fP may be called before \fBinitscr\fP.
.PP
-The initscr code determines the terminal type and initializes all \fBcurses\fR
+The initscr code determines the terminal type and initializes all \fBcurses\fP
data structures.
-\fBinitscr\fR also causes the first call to \fBrefresh\fR(3X)
+\fBinitscr\fP also causes the first call to \fBrefresh\fP(3X)
to clear the screen.
-If errors occur, \fBinitscr\fR writes an appropriate error
+If errors occur, \fBinitscr\fP writes an appropriate error
message to standard error and exits;
-otherwise, a pointer is returned to \fBstdscr\fR.
+otherwise, a pointer is returned to \fBstdscr\fP.
.SS newterm
-.PP
-A program that outputs to more than one terminal should use the \fBnewterm\fR
-routine for each terminal instead of \fBinitscr\fR.
+A program that outputs to more than one terminal should use the \fBnewterm\fP
+routine for each terminal instead of \fBinitscr\fP.
A program that needs to inspect capabilities,
so it can continue to run in a line-oriented mode if the
terminal cannot support a screen-oriented program, would also use
-\fBnewterm\fR.
-The routine \fBnewterm\fR should be called once for each terminal.
-It returns a variable of type \fBSCREEN *\fR which should be saved
+\fBnewterm\fP.
+.PP
+The routine \fBnewterm\fP should be called once for each terminal.
+It returns a variable of type \fISCREEN *\fP which should be saved
as a reference to that terminal.
\fBnewterm\fP's arguments are
.bP
-the \fItype\fR of the terminal to be used in place of \fB$TERM\fR,
+the \fItype\fP of the terminal to be used in place of \fB$TERM\fP,
.bP
-a file pointer for output to the terminal, and
+an output stream connected to the terminal, and
.bP
-another file pointer for input from the terminal
+an input stream connected to the terminal
.PP
-If the \fItype\fR parameter is \fBNULL\fR, \fB$TERM\fR will be used.
-.SS endwin
+If the \fItype\fP parameter is \fBNULL\fP, \fB$TERM\fP will be used.
.PP
+The file descriptor of the output stream is passed to \fBsetupterm\fP(3X),
+which returns a pointer to a \fI\%TERMINAL\fP structure.
+\fBnewterm\fP's return value holds a pointer to the \fI\%TERMINAL\fP structure.
+.SS endwin
The program must also call
-\fBendwin\fR for each terminal being used before exiting from \fBcurses\fR.
-If \fBnewterm\fR is called more than once for the same terminal, the first
-terminal referred to must be the last one for which \fBendwin\fR is called.
+\fBendwin\fP for each terminal being used before exiting from \fBcurses\fP.
+If \fBnewterm\fP is called more than once for the same terminal, the first
+terminal referred to must be the last one for which \fBendwin\fP is called.
.PP
-A program should always call \fBendwin\fR before exiting or escaping from
-\fBcurses\fR mode temporarily.
+A program should always call \fBendwin\fP before exiting or escaping from
+\fBcurses\fP mode temporarily.
This routine
.bP
resets colors to correspond with the default color pair 0,
.bP
restores tty modes (see \fBreset_shell_mode\fP(3X)).
.PP
-Calling \fBrefresh\fR(3X) or \fBdoupdate\fR(3X) after a
+Calling \fBrefresh\fP(3X) or \fBdoupdate\fP(3X) after a
temporary escape causes the program to resume visual mode.
.SS isendwin
-.PP
-The \fBisendwin\fR routine returns \fBTRUE\fR if \fBendwin\fR has been
-called without any subsequent calls to \fBwrefresh\fR,
-and \fBFALSE\fR otherwise.
+The \fBisendwin\fP routine returns \fBTRUE\fP if \fBendwin\fP has been
+called without any subsequent calls to \fBwrefresh\fP,
+and \fBFALSE\fP otherwise.
.SS set_term
-.PP
-The \fBset_term\fR routine is used to switch between different terminals.
-The screen reference \fBnew\fR becomes the new current terminal.
+The \fBset_term\fP routine is used to switch between different terminals.
+The screen reference \fInew\fP becomes the new current terminal.
The previous terminal is returned by the routine.
-This is the only routine which manipulates \fBSCREEN\fR pointers;
+This is the only routine which manipulates \fISCREEN\fP pointers;
all other routines affect only the current terminal.
.SS delscreen
-.PP
-The \fBdelscreen\fR routine frees storage associated with the
-\fBSCREEN\fR data structure.
-The \fBendwin\fR routine does not do
-this, so \fBdelscreen\fR should be called after \fBendwin\fR if a
-particular \fBSCREEN\fR is no longer needed.
+The \fBdelscreen\fP routine frees storage associated with the
+\fISCREEN\fP data structure.
+The \fBendwin\fP routine does not do
+this, so \fBdelscreen\fP should be called after \fBendwin\fP if a
+particular \fISCREEN\fP is no longer needed.
.SH RETURN VALUE
-\fBendwin\fR returns the integer \fBERR\fR upon failure and \fBOK\fR
+\fBendwin\fP returns the integer \fBERR\fP upon failure and \fBOK\fP
upon successful completion.
.PP
-Routines that return pointers always return \fBNULL\fR on error.
+Routines that return pointers always return \fBNULL\fP on error.
.PP
X/Open defines no error conditions.
In this implementation
.bP
-\fBendwin\fP returns an error if the terminal was not initialized.
+\fBendwin\fP returns an error if
+.RS
+.bP
+the terminal was not initialized, or
+.bP
+\fBendwin\fP is called more than once without updating the screen, or
+.bP
+\fBreset_shell_mode\fP(3X) returns an error.
+.RE
.bP
\fBnewterm\fP
returns an error if it cannot allocate the data structures for the screen,
\fBset_term\fP
returns no error.
.SH PORTABILITY
-These functions were described in the XSI Curses standard, Issue 4.
+These functions were described in X/Open Curses, Issue 4.
As of 2015, the current document is X/Open Curses, Issue 7.
.SS Differences
-X/Open specifies that portable applications must not
-call \fBinitscr\fR more than once:
+X/Open Curses specifies that portable applications must not
+call \fBinitscr\fP more than once:
.bP
The portable way to use \fBinitscr\fP is once only,
-using \fBrefresh\fP (see curs_refresh(3X))
+using \fB\%refresh\fP(3X)
to restore the screen after \fBendwin\fP.
.bP
This implementation allows using \fBinitscr\fP after \fBendwin\fP.
.PP
-Old versions of curses, e.g., BSD 4.4, may have returned a null pointer
-from \fBinitscr\fR when an error is detected, rather than exiting.
-It is safe but redundant to check the return value of \fBinitscr\fR
-in XSI Curses.
-.SS Unset TERM Variable
+Old versions of curses, e.g., BSD 4.4, would return a null pointer
+from \fBinitscr\fP when an error is detected, rather than exiting.
+It is safe but redundant to check the return value of \fBinitscr\fP
+in X/Open Curses.
.PP
-If the TERM variable is missing or empty, \fBinitscr\fP uses the
+Calling \fBendwin\fP does not dispose of the memory allocated in \fBinitscr\fP
+or \fBnewterm\fP.
+Deleting a \fISCREEN\fP provides a way to do this:
+.bP
+X/Open Curses does not say what happens to \fI\%WINDOW\fPs when \fBdelscreen\fP
+\*(``frees storage associated with the \fISCREEN\fP\*(''
+nor does the SVr4 documentation help,
+adding that it should be called after \fBendwin\fP if a \fISCREEN\fP
+is no longer needed.
+.bP
+However, \fI\%WINDOW\fPs are implicitly associated with a \fISCREEN\fP.
+so that it is reasonable to expect \fBdelscreen\fP to deal with these.
+.bP
+SVr4 curses deletes the standard \fI\%WINDOW\fP structures
+\fBstdscr\fP and \fBcurscr\fP as well as a work area \fBnewscr\fP.
+SVr4 curses ignores other windows.
+.bP
+Since version 4.0 (1996),
+\fI\%ncurses\fP has maintained a list of all windows for each screen,
+using that information to delete those windows when \fBdelscreen\fP is called.
+.bP
+NetBSD copied this feature of \fI\%ncurses\fP in 2001.
+PDCurses follows the SVr4 model,
+deleting only the standard \fI\%WINDOW\fP structures.
+.SS "High-level versus Low-level"
+Different implementations may disagree regarding the level of some functions.
+For example, \fISCREEN\fP (returned by \fBnewterm\fP) and
+\fI\%TERMINAL\fP (returned by \fBsetupterm\fP(3X)) hold file descriptors for
+the output stream.
+If an application switches screens using \fBset_term\fR,
+or switches terminals using \fBset_curterm\fP(3X),
+applications which use the output file descriptor can have different
+behavior depending on which structure holds the corresponding descriptor.
+.PP
+For example
+.bP
+NetBSD's \fBbaudrate\fP(3X) function uses the descriptor in \fI\%TERMINAL\fP.
+\fI\%ncurses\fP and SVr4 use the descriptor in \fISCREEN\fP.
+.bP
+NetBSD and \fI\%ncurses\fP use the descriptor
+in \fI\%TERMINAL\fP
+for terminal I/O modes,
+e.g.,
+\fBdef_shell_mode\fP(3X),
+\fBdef_prog_mode\fP(3X).
+SVr4 curses uses the descriptor in \fISCREEN\fP.
+.SS "Unset \fITERM\fP Variable"
+If the \fITERM\fP variable is missing or empty, \fBinitscr\fP uses the
value \*(``unknown\*('',
which normally corresponds to a terminal entry with the \fIgeneric\fP
(\fIgn\fP) capability.
-Generic entries are detected by \fBsetupterm\fP
-(see curs_terminfo(3X)) and cannot be used for full-screen operation.
-Other implementations may handle a missing/empty TERM variable differently.
-.SS Signal Handlers
-.PP
-Quoting from X/Open Curses, section 3.1.1:
+Generic entries are detected by \fBsetupterm\fP(3X)
+and cannot be used for full-screen operation.
+Other implementations may handle
+a missing/empty \fITERM\fP variable differently.
+.SS "Signal Handlers"
+Quoting from X/Open Curses Issue 7, section 3.1.1:
.RS 5
.PP
-\fICurses implementations may provide for special handling of the \fBSIGINT\fP,
-\fBSIGQUIT\fP and \fBSIGTSTP\fP signals
-if their disposition is \fBSIG_DFL\fP at the time
-\fBinitscr\fP is called \fP...
+Curses implementations may provide for special handling of the
+\%SIGINT,
+\%SIGQUIT,
+and \%SIGTSTP signals if their disposition is \%SIG_DFL at the time
+.I \%initscr
+is called.\|.\|.
.PP
-\fIAny special handling for these signals may remain in effect for the
+Any special handling for these signals may remain in effect for the
life of the process or until the process changes the disposition of
-the signal.\fP
+the signal.
.PP
-\fINone of the Curses functions are required to be safe
-with respect to signals \fP...
+None of the Curses functions are required to be safe
+with respect to signals.\|.\|.
.RE
.PP
This implementation establishes signal handlers during initialization,
handlers \fIafter\fP initializing the library:
.TP 5
.B SIGINT
-The handler \fIattempts\fP to cleanup the screen on exit.
+The handler \fIattempts\fP to clean up the screen on exit.
Although it \fIusually\fP works as expected, there are limitations:
.RS 5
.bP
-Walking the \fBSCREEN\fP list is unsafe, since all list management
+Walking the \fISCREEN\fP list is unsafe, since all list management
is done without any signal blocking.
.bP
On systems which have \fBREENTRANT\fP turned on, \fBset_term\fP uses
functions which could deadlock or misbehave in other ways.
.bP
-\fBendwin\fP calls other functions, many of which use stdio or
-other library functions which are clearly unsafe.
+\fBendwin\fP calls other functions,
+many of which use \fI\%stdio\fP(3) or other library functions which are
+clearly unsafe.
.RE
.TP 5
.B SIGTERM
.B SIGTSTP
This handles the \fIstop\fP signal, used in job control.
When resuming the process, this implementation discards pending
-input with \fBflushinput\fP (see curs_util(3X)), and repaints the screen
+input with \fB\%flushinp\fP(3X), and repaints the screen
assuming that it has been completely altered.
-It also updates the saved terminal modes with \fBdef_shell_mode\fP
-(see \fBcurs_kernel\fR(3X)).
+It also updates the saved terminal modes with
+\fB\%def_shell_mode\fP(3X).
.TP 5
.B SIGWINCH
This handles the window-size changes which were ignored in
the standardization efforts.
The handler sets a (signal-safe) variable
-which is later tested in \fBwgetch\fP (see curs_getch(3X)).
+which is later tested in \fB\%wgetch\fP(3X).
If \fBkeypad\fP has been enabled for the corresponding window,
\fBwgetch\fP returns the key symbol \fBKEY_RESIZE\fP.
At the same time, \fBwgetch\fP calls \fBresizeterm\fP to adjust the
standard screen \fBstdscr\fP,
and update other data such as \fBLINES\fP and \fBCOLS\fP.
.SH SEE ALSO
-\fBcurses\fR(3X),
-\fBcurs_kernel\fR(3X),
-\fBcurs_refresh\fR(3X),
-\fBcurs_slk\fR(3X),
-\fBcurs_terminfo\fR(3X),
-\fBcurs_util\fR(3X),
-\fBcurs_variables\fR(3X).
+\fB\%curses\fP(3X),
+\fB\%curs_kernel\fP(3X),
+\fB\%curs_refresh\fP(3X),
+\fB\%curs_slk\fP(3X),
+\fB\%curs_terminfo\fP(3X),
+\fB\%curs_util\fP(3X),
+\fB\%curs_variables\fP(3X)
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