curs_terminfo(3) Library calls curs_terminfo(3)
NAME
del_curterm, mvcur, putp, restartterm, set_curterm, setupterm,
tigetflag, tigetnum, tigetstr, tiparm, tiparm_s, tiscan_s, tparm,
tputs, vid_attr, vid_puts, vidattr, vidputs - curses interfaces to
terminfo database
SYNOPSIS
#include <curses.h>
#include <term.h>
TERMINAL *cur_term;
const char * const boolnames[];
const char * const boolcodes[];
const char * const boolfnames[];
const char * const numnames[];
const char * const numcodes[];
const char * const numfnames[];
const char * const strnames[];
const char * const strcodes[];
const char * const strfnames[];
int setupterm(const char *term, int filedes, int *errret);
TERMINAL *set_curterm(TERMINAL *nterm);
int del_curterm(TERMINAL *oterm);
int restartterm(const char *term, int filedes, int *errret);
char *tparm(const char *str, ...);
/* or */
char *tparm(const char *str, long p1 ... long p9);
int tputs(const char *str, int affcnt, int (*putc)(int));
int putp(const char *str);
int vidputs(chtype attrs, int (*putc)(int));
int vidattr(chtype attrs);
int vid_puts(attr_t attrs, short pair, void *opts, int (*putc)(int));
int vid_attr(attr_t attrs, short pair, void *opts);
int mvcur(int oldrow, int oldcol, int newrow, int newcol);
int tigetflag(const char *cap-code);
int tigetnum(const char *cap-code);
char *tigetstr(const char *cap-code);
char *tiparm(const char *str, ...);
/* extensions */
char *tiparm_s(int expected, int mask, const char *str, ...);
int tiscan_s(int *expected, int *mask, const char *str);
/* deprecated */
int setterm(const char *term);
DESCRIPTION
These low-level functions must be called by programs that deal directly
with the terminfo database to handle certain terminal capabilities,
such as programming function keys. For all other functionality, curses
functions are more suitable and their use is recommended.
None of these functions use (or are aware of) multibyte character
strings such as UTF-8.
o Capability names and codes use the POSIX portable character set.
o Capability string values have no associated encoding; they are
strings of 8-bit characters.
Initialization
Initially, setupterm should be called. The high-level curses functions
initscr and newterm call setupterm to initialize the low-level set of
terminal-dependent variables listed in term_variables(3X).
Applications can use the terminal capabilities either directly (via
header definitions), or by special functions. The header files
curses.h and term.h should be included (in that order) to get the
definitions for these strings, numbers, and flags.
The terminfo variables lines and columns are initialized by setupterm
as follows.
o If use_env(FALSE) has been called, values for lines and columns
specified in terminfo are used.
o Otherwise, if the environment variables LINES and COLUMNS exist,
their values are used. If these environment variables do not exist
and the program is running in a window, the current window size is
used. Otherwise, if the environment variables do not exist, the
values for lines and columns specified in the terminfo database are
used.
Parameterized strings should be passed through tparm to instantiate
them. All terminfo strings (including the output of tparm) should be
sent to the terminal device with tputs or putp. Call reset_shell_mode
to restore the terminal modes before exiting; see curs_kernel(3X).
Programs that use cursor addressing should
o output enter_ca_mode upon startup and
o output exit_ca_mode before exiting.
Programs that execute shell subprocesses should
o call reset_shell_mode and output exit_ca_mode before the shell is
called and
o output enter_ca_mode and call reset_prog_mode after returning from
the shell.
setupterm reads in the terminfo database, initializing the terminfo
structures, but does not set up the output virtualization structures
used by curses. Its parameters follow.
term is the terminal type, a character string. If term is null, the
environment variable TERM is read.
filedes
is the file descriptor used for getting and setting terminal
I/O modes.
Higher-level applications use newterm(3X) to initialize the
terminal, passing an output stream rather than a descriptor.
In curses, the two are the same because newterm calls
setupterm, passing the file descriptor derived from its output
stream parameter.
errret
points to an optional location where an error status can be
returned to the caller. If errret is not null, then setupterm
returns OK or ERR and stores a status value in the integer
pointed to by errret. A return value of OK combined with
status of 1 in errret is normal.
If ERR is returned, examine errret:
1 means that the terminal is hardcopy, and cannot be used
for curses applications.
setupterm determines if the entry is a hardcopy type by
checking the hardcopy (hc) capability.
0 means that the terminal could not be found, or that it is
a generic type, having too little information for curses
applications to run.
setupterm determines if the entry is a generic type by
checking the generic_type (gn) capability.
-1 means that the terminfo database could not be found.
If errret is null, setupterm reports an error message upon
finding an error and exits. Thus, the simplest call is:
setupterm((char *)0, 1, (int *)0);
which uses all the defaults and sends the output to stdout.
The Terminal State
setupterm stores its information about the terminal in a TERMINAL
structure pointed to by the global variable cur_term. If it detects an
error, or decides that the terminal is unsuitable (hardcopy or
generic), it discards this information, making it not available to
applications.
If setupterm is called repeatedly for the same terminal type, it will
reuse the information. It maintains only one copy of a given
terminal's capabilities in memory. If it is called for different
terminal types, setupterm allocates new storage for each set of
terminal capabilities.
set_curterm sets cur_term to nterm, and makes all of the terminfo
Boolean, numeric, and string variables use the values from nterm. It
returns the old value of cur_term.
del_curterm frees the space pointed to by oterm and makes it available
for further use. If oterm is the same as cur_term, references to any
of the terminfo Boolean, numeric, and string variables thereafter may
refer to invalid memory locations until another setupterm has been
called.
restartterm is similar to setupterm and initscr, except that it is
called after restoring memory to a previous state (for example, when
reloading a game saved as a core image dump). restartterm assumes that
the windows and the input and output options are the same as when
memory was saved, but the terminal type and baud rate may be different.
Accordingly, restartterm saves various terminal state bits, calls
setupterm, and then restores the bits.
Formatting Output
tparm instantiates the string str with parameters pi. A pointer is
returned to the result of str with the parameters applied. Application
developers should keep in mind these quirks of the interface:
o Although tparm's actual parameters may be integers or strings, the
prototype expects long (integer) values.
o Aside from the set_attributes (sgr) capability, most terminal
capabilities require no more than one or two parameters.
o Padding information is ignored by tparm; it is interpreted by
tputs.
o The capability string is null-terminated. Use "\200" where an
ASCII NUL is needed in the output.
tiparm is a newer form of tparm which uses stdarg.h rather than a
fixed-parameter list. Its numeric parameters are ints rather than
longs.
Both tparm and tiparm assume that the application passes parameters
consistent with the terminal description. Two extensions are provided
as alternatives to deal with untrusted data.
o tiparm_s is an extension which is a safer formatting function than
tparm or tiparm, because it allows the developer to tell the curses
library how many parameters to expect in the parameter list, and
which may be string parameters.
The mask parameter has one bit set for each of the parameters (up
to 9) passed as char pointers rather than numbers.
o The extension tiscan_s allows the application to inspect a
formatting capability to see what the curses library would assume.
Output Functions
String capabilities can contain padding information, a time delay
(accommodating performance limitations of hardware terminals) expressed
as $<n>, where n is a nonnegative integral count of milliseconds. If n
exceeds 30,000 (thirty seconds), it is capped at that value.
tputs interprets time-delay information in the string str and outputs
it, executing the delays:
o The str parameter must be a terminfo string variable or the return
value of tparm, tiparm, tgetstr, or tgoto.
The tgetstr and tgoto functions are part of the termcap interface,
which happens to share these function names with the terminfo API.
o affcnt is the number of lines affected, or 1 if not applicable.
o putc is a putchar-like function to which the characters are passed,
one at a time.
If tputs processes a time-delay, it uses the delay_output(3X)
function, routing any resulting padding characters through this
function.
putp calls "tputs(str, 1, putchar)". The output of putp always goes to
stdout, rather than the filedes specified in setupterm.
vidputs displays the string on the terminal in the video attribute mode
attrs, which is any combination of the attributes listed in curses(3X).
The characters are passed to the putchar-like function putc.
vidattr is like vidputs, except that it outputs through putchar(3).
vid_attr and vid_puts correspond to vidattr and vidputs, respectively.
They use multiple parameters to represent the character attributes and
color; namely,
o attrs, of type attr_t, for the attributes and
o pair, of type short, for the color pair number.
Use the attribute constants prefixed with "WA_" with vid_attr and
vid_puts.
X/Open Curses reserves the opts argument for future use, saying that
applications must provide a null pointer for that argument; but see
section "EXTENSIONS" below.
mvcur provides low-level cursor motion. It takes effect immediately
(rather than at the next refresh). Unlike the other low-level output
functions, which either write to the standard output or pass an output
function parameter, mvcur uses an output file descriptor derived from
the output stream parameter of newterm(3X).
While putp and mvcur are low-level functions that do not use high-level
curses state, ncurses declares them in curses.h because System V did
this (see section "HISTORY" below).
Terminal Capability Functions
tigetflag, tigetnum, and tigetstr return the value of the capability
corresponding to the terminfo cap-code, such as xenl, passed to them.
The cap-code for each capability is given in the table column entitled
cap-code code in the capabilities section of terminfo(5).
These functions return special values to denote errors.
tigetflag returns
-1 if cap-code is not a Boolean capability, or
0 if it is canceled or absent from the terminal description.
tigetnum returns
-2 if cap-code is not a numeric capability, or
-1 if it is canceled or absent from the terminal description.
tigetstr returns
(char *)-1
if cap-code is not a string capability, or
0 if it is canceled or absent from the terminal description.
Terminal Capability Names
These null-terminated arrays contain
o the short terminfo names ("codes"),
o the termcap names ("names"), and
o the long terminfo names ("fnames")
for each of the predefined terminfo variables:
const char *boolnames[], *boolcodes[], *boolfnames[]
const char *numnames[], *numcodes[], *numfnames[]
const char *strnames[], *strcodes[], *strfnames[]
Releasing Memory
Each successful call to setupterm allocates memory to hold the terminal
description. As a side effect, it sets cur_term to point to this
memory. If an application calls
del_curterm(cur_term);
the memory will be freed.
The formatting functions tparm and tiparm extend the storage allocated
by setupterm as follows.
o They add the "static" terminfo variables [a-z]. Before ncurses
6.3, those were shared by all screens. With ncurses 6.3, those are
allocated per screen. See terminfo(5).
o To improve performance, ncurses 6.3 caches the result of analyzing
terminfo strings for their parameter types. That is stored as a
binary tree referenced from the TERMINAL structure.
The higher-level initscr and newterm functions use setupterm. Normally
they do not free this memory, but it is possible to do that using the
delscreen(3X) function.
RETURN VALUE
X/Open Curses defines no failure conditions. In ncurses,
del_curtem
fails if its terminal parameter is null.
putp calls tputs, returning the same error codes.
restartterm
fails if the associated call to setupterm returns an error.
setupterm
fails if it cannot allocate enough memory, or create the initial
windows (stdscr, curscr, and newscr) Other error conditions are
documented above.
tparm
returns a null pointer if the capability would require unexpected
parameters; that is, too many, too few, or incorrect types
(strings where integers are expected, or vice versa).
tputs
fails if the string parameter is null. It does not detect I/O
errors: X/Open Curses states that tputs ignores the return value
of the output function putc.
NOTES
The vid_attr function in ncurses is a special case. It was originally
implemented based on a draft of X/Open Curses, as a macro, before other
parts of the ncurses wide-character API were developed, and unlike the
other wide-character functions, is also provided in the non-wide-
character configuration.
EXTENSIONS
The functions marked as extensions were designed for ncurses, and are
not found in SVr4 curses, 4.4BSD curses, or any other previous curses
implementation.
ncurses allows opts to be a pointer to int, which overrides the pair
(short) argument.
PORTABILITY
setterm is not described by X/Open and must be considered non-portable.
All other functions are as described by X/Open.
Compatibility Macros
This implementation provides a few macros for compatibility with
systems before SVr4 (see section "HISTORY" below). They include
Bcrmode, Bfixterm, Bgettmode, Bnocrmode, Bresetterm, Bsaveterm, and
Bsetterm.
In SVr4, these are found in curses.h, but except for setterm, are
likewise macros. The one function, setterm, is mentioned in the manual
page. It further notes that setterm was replaced by setupterm, stating
that the call
setupterm(term, 1, (int *)0)
provides the same functionality as setterm(term), discouraging the
latter for new programs. ncurses implements each of these symbols as
macros for BSD curses compatibility.
Legacy Data
setupterm copies the terminal name to the array ttytype. This is not
part of X/Open Curses, but is assumed by some applications.
Other implementions may not declare the capability name arrays. Some
provide them without declaring them. X/Open Curses does not specify
them.
Extended terminal capability names, as defined by "tic -x", are not
stored in the arrays described here.
Output Buffering
Older versions of ncurses assumed that the file descriptor passed to
setupterm from initscr or newterm uses buffered I/O, and would write to
the corresponding stream. In addition to the limitation that the
terminal was left in block-buffered mode on exit (like System V
curses), it was problematic because ncurses did not allow a reliable
way to clean up on receiving SIGTSTP.
The current version (ncurses6) uses output buffers managed directly by
ncurses. Some of the low-level functions described in this manual page
write to the standard output. They are not signal-safe. The high-
level functions in ncurses employ alternate versions of these functions
using the more reliable buffering scheme.
Function Prototypes
The X/Open Curses prototypes are based on the SVr4 curses header
declarations, which were defined at the same time the C language was
first standardized in the late 1980s.
o X/Open Curses uses const less effectively than a later design
might, sometimes applying it needlessly to values that are already
constant, and in most cases overlooking parameters that normally
would use const. Passing const-qualified parameters to functions
that do not declare them const may prevent the program from
compiling. On the other hand, "writable strings" are an
obsolescent feature.
As an extension, this implementation can be configured to change
the function prototypes to use the const keyword. The ncurses ABI
6 enables this feature by default.
o X/Open Curses prototypes tparm with a fixed number of parameters,
rather than a variable argument list.
This implementation uses a variable argument list, but can be
configured to use the fixed-parameter list. Portable applications
should provide nine parameters after the format; zeroes are fine
for this purpose.
In response to review comments by Thomas E. Dickey, X/Open Curses
Issue 7 proposed the tiparm function in mid-2009.
While tiparm is always provided in ncurses, the older form is only
available as a build-time configuration option. If not specially
configured, tparm is the same as tiparm.
Both forms of tparm have drawbacks:
o Most of the calls to tparm use only one or two parameters. Passing
nine on each call is awkward.
Using long for the numeric parameter type is a workaround to make
the parameter use the same amount of stack as a pointer. That
approach dates back to the mid-1980s, before C was standardized.
Since then, there is a standard (and pointers are not required to
fit in a long).
o Providing the right number of parameters for a variadic function
such as tiparm can be a problem, in particular for string
parameters. However, only a few terminfo capabilities use string
parameters (for instance, the ones used for programmable function
keys).
The ncurses library checks usage of these capabilities, and returns
an error if the capability mishandles string parameters. But it
cannot check if a calling program provides strings in the right
places for the tparm calls.
The tput(1) program checks its use of these capabilities with a
table, so that it calls tparm correctly.
Special TERM treatment
If configured to use the terminal driver, as with the MinGW port,
o setupterm interprets a missing/empty TERM variable as the special
value "unknown".
SVr4 curses uses the special value "dumb".
The difference between the two is that the former uses the
generic_type (gn) terminfo capability, while the latter does not.
A generic terminal is unsuitable for full-screen applications.
o setupterm allows explicit use of the the windows console driver by
checking if $TERM is set to "#win32con" or an abbreviation of that
string.
Other Portability Issues
In SVr4, set_curterm returns an int, OK or ERR. We have chosen to
implement the X/Open Curses semantics.
In SVr4, the third argument of tputs has the type "int (*putc)(char)".
At least one implementation of X/Open Curses (Solaris) returns a value
other than OK or ERR from tputs. It instead returns the length of the
string, and does no error checking.
X/Open Curses notes that after calling mvcur, the curses state may not
match the actual terminal state, and that an application should touch
and refresh the window before resuming normal curses calls. Both
ncurses and SVr4 curses implement mvcur using the SCREEN data allocated
in either initscr or newterm. So though it is documented as a terminfo
function, mvcur is really a curses function that is not well specified.
X/Open Curses states that the old location must be given for mvcur to
accommodate terminals that lack absolute cursor positioning. ncurses
allows the caller to use -1 for either or both old coordinates. The -1
tells ncurses that the old location is unknown, and that it must use
only absolute motion, as with the cursor_address (cup) capability,
rather than the least costly combination of absolute and relative
motion.
HISTORY
SVr2 (1984) introduced the terminfo feature. Its programming manual
mentioned the following low-level functions.
Function Description
------------------------------------------------------------------------
fixterm restore terminal to "in curses" state
gettmode establish current terminal modes
mvcur low level cursor motion
putp use tputs to send characters via putchar
resetterm set terminal modes to "out of curses" state
resetty reset terminal flags to stored value
saveterm save current modes as "in curses" state
savetty store current terminal flags
setterm establish terminal with given type
setupterm establish terminal with given type
tparm interpolate parameters into string capability
tputs apply padding information to a string
vidattr like vidputs, but output through putchar
vidputs write string to terminal, applying specified attributes
The programming manual also mentioned functions provided for termcap
compatibility (commenting that they "may go away at a later date").
Function Description
------------------------------------------------------------------------
tgetent look up termcap entry for given name
tgetflag get Boolean entry for given id
tgetnum get numeric entry for given id
tgetstr get string entry for given id
tgoto apply parameters to given capability
tputs write characters via a function parameter, applying padding
Early terminfo programs obtained capability values from the TERMINAL
structure initialized by setupterm.
SVr3 (1987) extended terminfo by adding functions to retrieve
capability values (like the termcap interface), and reusing tgoto and
tputs.
Function Description
------------------------------------------------------------------------
tigetflag get Boolean entry for given id
tigetnum get numeric entry for given id
tigetstr get string entry for given id
SVr3 also replaced several of the SVr2 terminfo functions that had no
counterpart in the termcap interface, documenting them as obsolete.
Function Replaced by
------------------------------------------------------------------------
crmode cbreak
fixterm reset_prog_mode
gettmode n/a
nocrmode nocbreak
resetterm reset_shell_mode
saveterm def_prog_mode
setterm setupterm
SVr3 kept the mvcur, vidattr, and vidputs functions, along with putp,
tparm, and tputs. The latter were needed to support padding, and to
handle capabilities accessed by functions such as vidattr (which used
more than the two parameters supported by tgoto).
SVr3 introduced the functions for switching between terminal
descriptions; for example, set_curterm. Some changes reflected
incremental improvements to the SVr2 library.
o The TERMINAL type definition was introduced in SVr3.01, for the
term structure provided in SVr2.
o Various global variables such as boolnames were mentioned in the
programming manual at this point, though the variables had been
provided in SVr2.
SVr4 (1989) added the vid_attr and vid_puts functions.
Other low-level functions are declared in the curses header files of
Unix systems, but none are documented. Those noted as "obsolete" by
SVr3 remained in use by System V's vi(1) editor.
SEE ALSO
curses(3X), curs_initscr(3X), curs_kernel(3X), curs_memleaks(3X),
curs_termcap(3X), curs_variables(3X), putc(3), term_variables(3X),
terminfo(5)
ncurses 6.5 2024-04-13 curs_terminfo(3)
ncurses 6.5 - Generated Sat May 4 09:08:26 CDT 2024