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+ * Copyright 2018-2022,2023 Thomas E. Dickey *
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- * @Id: curs_termcap.3x,v 1.34 2017/11/18 23:47:37 tom Exp @
+ * @Id: curs_termcap.3x,v 1.57 2023/04/08 21:43:01 tom Exp @
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<H1 class="no-header">curs_termcap 3x</H1>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>PC</STRONG>, <STRONG>UP</STRONG>, <STRONG>BC</STRONG>, <STRONG>ospeed</STRONG>, <STRONG>tgetent</STRONG>, <STRONG>tgetflag</STRONG>, <STRONG>tgetnum</STRONG>, <STRONG>tgetstr</STRONG>, <STRONG>tgoto</STRONG>, <STRONG>tputs</STRONG> -
- direct <STRONG>curses</STRONG> interface to the terminfo capability database
+ <STRONG>curses</STRONG> emulation of termcap
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>extern</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <STRONG>BC;</STRONG>
<STRONG>extern</STRONG> <STRONG>short</STRONG> <STRONG>ospeed;</STRONG>
- <STRONG>int</STRONG> <STRONG>tgetent(char</STRONG> <STRONG>*bp,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*name);</STRONG>
- <STRONG>int</STRONG> <STRONG>tgetflag(char</STRONG> <STRONG>*id);</STRONG>
- <STRONG>int</STRONG> <STRONG>tgetnum(char</STRONG> <STRONG>*id);</STRONG>
- <STRONG>char</STRONG> <STRONG>*tgetstr(char</STRONG> <STRONG>*id,</STRONG> <STRONG>char</STRONG> <STRONG>**area);</STRONG>
- <STRONG>char</STRONG> <STRONG>*tgoto(const</STRONG> <STRONG>char</STRONG> <STRONG>*cap,</STRONG> <STRONG>int</STRONG> <STRONG>col,</STRONG> <STRONG>int</STRONG> <STRONG>row);</STRONG>
- <STRONG>int</STRONG> <STRONG>tputs(const</STRONG> <STRONG>char</STRONG> <STRONG>*str,</STRONG> <STRONG>int</STRONG> <STRONG>affcnt,</STRONG> <STRONG>int</STRONG> <STRONG>(*putc)(int));</STRONG>
+ <STRONG>int</STRONG> <STRONG>tgetent(char</STRONG> <STRONG>*</STRONG><EM>bp</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>name</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>tgetflag(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>tgetnum(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>);</STRONG>
+ <STRONG>char</STRONG> <STRONG>*tgetstr(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>,</STRONG> <STRONG>char</STRONG> <STRONG>**</STRONG><EM>area</EM><STRONG>);</STRONG>
+ <STRONG>char</STRONG> <STRONG>*tgoto(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>cap</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>col</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>row</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>tputs(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>str</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>affcnt</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>(*</STRONG><EM>putc</EM><STRONG>)(int));</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
These routines are included as a conversion aid for programs that use
- the <EM>termcap</EM> library. Their parameters are the same and the routines
+ the <EM>termcap</EM> library. Their parameters are the same, but the routines
are emulated using the <EM>terminfo</EM> database. Thus, they can only be used
to query the capabilities of entries for which a terminfo entry has
been compiled.
-</PRE><H3><a name="h3-I
NITIALIZATION">INITIALIZATION</a></H3><PRE>
+</PRE><H3><a name="h3-I
nitialization">Initialization</a></H3><PRE>
The <STRONG>tgetent</STRONG> routine loads the entry for <EM>name</EM>. It returns:
1 on success,
ing.
-</PRE><H3><a name="h3-C
APABILITY-VALUES">CAPABILITY VALUES</a></H3><PRE>
+</PRE><H3><a name="h3-C
apability-Values">Capability Values</a></H3><PRE>
The <STRONG>tgetflag</STRONG> routine gets the boolean entry for <EM>id</EM>, or zero if it is
not available.
and <STRONG>tgetstr</STRONG> are compared in lookups.
-</PRE><H3><a name="h3-F
ORMATTING-CAPABILITIES">FORMATTING CAPABILITIES</a></H3><PRE>
+</PRE><H3><a name="h3-F
ormatting-Capabilities">Formatting Capabilities</a></H3><PRE>
The <STRONG>tgoto</STRONG> routine expands the given capability using the parameters.
<STRONG>o</STRONG> Because the capability may have padding characters, the output of
<STRONG>tgoto</STRONG> should be passed to <STRONG>tputs</STRONG> rather than some other output func-
- tion such as <STRONG>printf</STRONG>.
+ tion such as <STRONG>printf(3)</STRONG>.
<STRONG>o</STRONG> While <STRONG>tgoto</STRONG> is assumed to be used for the two-parameter cursor po-
sitioning capability, termcap applications also use it for single-
first parameter is merely a placeholder.
<STRONG>o</STRONG> Normally the ncurses library is compiled with terminfo support. In
- that case, <STRONG>tgoto</STRONG> uses <STRONG><A HREF="curs_terminfo.3x.html">tparm(3x)</A></STRONG> (a more capable formatter).
+ that case, <STRONG>tgoto</STRONG> uses an internal version of <STRONG><A HREF="curs_terminfo.3x.html">tparm(3x)</A></STRONG> (a more ca-
+ pable formatter).
+
+ With terminfo support, <STRONG>tgoto</STRONG> is able to use some of the terminfo
+ features, but not all. In particular, it allows only numeric pa-
+ rameters; <STRONG>tparm</STRONG> supports string parameters.
+
+ However, <STRONG>tparm</STRONG> is not a <EM>termcap</EM> feature, and portable <EM>termcap</EM> ap-
+ plications should not rely upon its availability.
The <STRONG>tputs</STRONG> routine is described on the <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG> manual page.
It can retrieve capabilities by either termcap or terminfo name.
-</PRE><H3><a name="h3-G
LOBAL-VARIABLES">GLOBAL VARIABLES</a></H3><PRE>
+</PRE><H3><a name="h3-G
lobal-Variables">Global Variables</a></H3><PRE>
The variables <STRONG>PC</STRONG>, <STRONG>UP</STRONG> and <STRONG>BC</STRONG> are set by <STRONG>tgetent</STRONG> to the terminfo entry's
data for <STRONG>pad_char</STRONG>, <STRONG>cursor_up</STRONG> and <STRONG>backspace_if_not_bs</STRONG>, respectively. <STRONG>UP</STRONG>
is not used by ncurses. <STRONG>PC</STRONG> is used in the <STRONG>tdelay_output</STRONG> function. <STRONG>BC</STRONG>
in a system-specific coding to reflect the terminal speed.
+</PRE><H3><a name="h3-Releasing-Memory">Releasing Memory</a></H3><PRE>
+ The termcap functions provide no means for freeing memory, because
+ legacy termcap implementations used only the buffer areas provided by
+ the caller via <STRONG>tgetent</STRONG> and <STRONG>tgetstr</STRONG>. Those buffers are unused in ter-
+ minfo.
+
+ On the other hand, terminfo allocates memory. It uses <STRONG>setupterm</STRONG> to re-
+ trieve the data used by <STRONG>tgetent</STRONG> and the functions which return capabil-
+ ity values such as <STRONG>tgetstr</STRONG>. One could use
+
+ <STRONG>del_curterm(cur_term);</STRONG>
+
+
+ to free this memory, but there is an additional complication with
+ ncurses. It uses a fixed-size <EM>pool</EM> of storage locations, one per set-
+ ting of the <STRONG>TERM</STRONG> variable when <STRONG>tgetent</STRONG> is called. The <STRONG>screen(1)</STRONG> pro-
+ gram relies upon this arrangement, to improve its performance.
+
+ An application which uses only the low-level termcap functions could
+ free the memory using <STRONG>del_curterm</STRONG>, because the pool is freed using oth-
+ er functions (see <STRONG><A HREF="curs_memleaks.3x.html">curs_memleaks(3x)</A></STRONG>).
+
+
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
Except where explicitly noted, routines that return an integer return
<STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4 only specifies "an integer value other
Routines that return pointers return <STRONG>NULL</STRONG> on error.
+ A few special cases apply:
+
+ <STRONG>o</STRONG> If the terminal database has not been initialized, these return an
+ error.
+
+ <STRONG>o</STRONG> The calls with a string parameter (<STRONG>tgoto</STRONG>, <STRONG>tputs</STRONG>) check if the
+ string is null, or cancelled. Those return an error.
+
+ <STRONG>o</STRONG> A call to <STRONG>tgoto</STRONG> using a capability with string parameters is an er-
+ ror.
+
+ <STRONG>o</STRONG> A call to <STRONG>tgoto</STRONG> using a capability with no parameters, or more than
+ two is an error.
+
</PRE><H2><a name="h2-BUGS">BUGS</a></H2><PRE>
If you call <STRONG>tgetstr</STRONG> to fetch <STRONG>ca</STRONG> or any other parameterized string, be
style parser if the string does not appear to be terminfo).
Because terminfo conventions for representing padding in string capa-
- bilities differ from termcap's, <STRONG>tputs("50");</STRONG> will put out a literal
- "50" rather than busy-waiting for 50 milliseconds. Cope with it.
+ bilities differ from termcap's, users can be surprised:
- Note that termcap has nothing analogous to terminfo's <STRONG>sgr</STRONG> string. One
- consequence of this is that termcap applications assume me (terminfo
- <STRONG>sgr0</STRONG>) does not reset the alternate character set. This implementation
+ <STRONG>o</STRONG> <STRONG>tputs("50")</STRONG> in a terminfo system will put out a literal "50" rather
+ than busy-waiting for 50 milliseconds.
+
+ <STRONG>o</STRONG> However, if ncurses is configured to support termcap, it may also
+ have been configured to support the BSD-style padding.
+
+ In that case, <STRONG>tputs</STRONG> inspects strings passed to it, looking for dig-
+ its at the beginning of the string.
+
+ <STRONG>tputs("50")</STRONG> in a termcap system may wait for 50 milliseconds rather
+ than put out a literal "50"
+
+ Note that termcap has nothing analogous to terminfo's <STRONG>sgr</STRONG> string. One
+ consequence of this is that termcap applications assume <STRONG>me</STRONG> (terminfo
+ <STRONG>sgr0</STRONG>) does not reset the alternate character set. This implementation
checks for, and modifies the data shown to the termcap interface to ac-
commodate termcap's limitation in this respect.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- The XSI Curses standard, Issue 4 describes these functions. However,
- they are marked TO BE WITHDRAWN and may be removed in future versions.
+
+</PRE><H3><a name="h3-Standards">Standards</a></H3><PRE>
+ These functions are provided for supporting legacy applications, and
+ should not be used in new programs:
+
+ <STRONG>o</STRONG> The XSI Curses standard, Issue 4 describes these functions. Howev-
+ er, they are marked TO BE WITHDRAWN and may be removed in future
+ versions.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 5 (December 2007) marked the termcap interface
+ (along with <STRONG>vwprintw</STRONG> and <STRONG>vwscanw</STRONG>) as withdrawn.
Neither the XSI Curses standard nor the SVr4 man pages documented the
return values of <STRONG>tgetent</STRONG> correctly, though all three were in fact re-
bility with the <EM>termcap</EM> library, that is a defect in XCurses, Issue 4,
Version 2 rather than in ncurses.
+
+</PRE><H3><a name="h3-Compatibility-with-BSD-Termcap">Compatibility with BSD Termcap</a></H3><PRE>
External variables are provided for support of certain termcap applica-
tions. However, termcap applications' use of those variables is poorly
documented, e.g., not distinguishing between input and output. In par-
against extended capability names which are longer than two charac-
ters.
+ The BSD termcap function <STRONG>tgetent</STRONG> returns the text of a termcap entry in
+ the buffer passed as an argument. This library (like other terminfo
+ implementations) does not store terminal descriptions as text. It sets
+ the buffer contents to a null-terminated string.
+
+
+</PRE><H3><a name="h3-Other-Compatibility">Other Compatibility</a></H3><PRE>
+ This library includes a termcap.h header, for compatibility with other
+ implementations. But the header is rarely used because the other im-
+ plementations are not strictly compatible.
+
+ The original BSD termcap (through 4.3BSD) had no header file which gave
+ function prototypes, because that was a feature of ANSI C. BSD termcap
+ was written several years before C was standardized. However, there
+ were two different termcap.h header files in the BSD sources:
+
+ <STRONG>o</STRONG> One was used internally by the <STRONG>jove</STRONG> editor in 2BSD through 4.4BSD.
+ It defined global symbols for the termcap variables which it used.
+
+ <STRONG>o</STRONG> The other appeared in 4.4BSD Lite Release 2 (mid-1993) as part of
+ <EM>libedit</EM> (also known as the <EM>editline</EM> library). The CSRG source his-
+ tory shows that this was added in mid-1992. The <EM>libedit</EM> header
+ file was used internally, as a convenience for compiling the <EM>edit-</EM>
+ <EM>line</EM> library. It declared function prototypes, but no global vari-
+ ables.
+
+ The header file from <EM>libedit</EM> was added to NetBSD's termcap library in
+ mid-1994.
+
+ Meanwhile, GNU termcap was under development, starting in 1990. The
+ first release (termcap 1.0) in 1991 included a termcap.h header. The
+ second release (termcap 1.1) in September 1992 modified the header to
+ use <STRONG>const</STRONG> for the function prototypes in the header where one would ex-
+ pect the parameters to be read-only. This was a difference versus the
+ original BSD termcap. The prototype for <STRONG>tputs</STRONG> also differed, but in
+ that instance, it was <EM>libedit</EM> which differed from BSD termcap.
+
+ A copy of GNU termcap 1.3 was bundled with <EM>bash</EM> in mid-1993, to support
+ the <STRONG>readline(3)</STRONG> library.
+
+ A termcap.h file was provided in ncurses 1.8.1 (November 1993). That
+ reflected influence by <STRONG>emacs(1)</STRONG> (rather than <STRONG>jove(1)</STRONG>) and GNU termcap:
+
+ <STRONG>o</STRONG> it provided declarations for a few global symbols used by <STRONG>emacs</STRONG>
+
+ <STRONG>o</STRONG> it provided function prototypes (using <STRONG>const</STRONG>).
+
+ <STRONG>o</STRONG> a prototype for <STRONG>tparam</STRONG> (a GNU termcap feature) was provided.
+
+ Later (in mid-1996) the <STRONG>tparam</STRONG> function was removed from ncurses. As a
+ result, there are differences between any of the four implementations,
+ which must be taken into account by programs which can work with all
+ termcap library interfaces.
+
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>, <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG>putc(3)</STRONG>.
+ <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG>putc(3)</STRONG>, <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>.
- http://invisible-island.net/ncurses/tctest.html
+ https://invisible-island.net/ncurses/tctest.html
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
-<li><a href="#h3-INITIALIZATION">INITIALIZATION</a></li>
-<li><a href="#h3-CAPABILITY-VALUES">CAPABILITY VALUES</a></li>
-<li><a href="#h3-FORMATTING-CAPABILITIES">FORMATTING CAPABILITIES</a></li>
-<li><a href="#h3-GLOBAL-VARIABLES">GLOBAL VARIABLES</a></li>
+<li><a href="#h3-Initialization">Initialization</a></li>
+<li><a href="#h3-Capability-Values">Capability Values</a></li>
+<li><a href="#h3-Formatting-Capabilities">Formatting Capabilities</a></li>
+<li><a href="#h3-Global-Variables">Global Variables</a></li>
+<li><a href="#h3-Releasing-Memory">Releasing Memory</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-BUGS">BUGS</a></li>
-<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
+<li><a href="#h2-PORTABILITY">PORTABILITY</a>
+<ul>
+<li><a href="#h3-Standards">Standards</a></li>
+<li><a href="#h3-Compatibility-with-BSD-Termcap">Compatibility with BSD Termcap</a></li>
+<li><a href="#h3-Other-Compatibility">Other Compatibility</a></li>
+</ul>
+</li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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