These routines are included as a conversion aid for pro-
grams that use the termcap library. Their parameters are
the same and the routines are emulated using the terminfo
@@ -79,34 +76,94 @@
bilities of entries for which a terminfo entry has been
compiled.
- The tgetent routine loads the entry for name. It returns
- 1 on success, 0 if there is no such entry, and -1 if the
- terminfo database could not be found. The emulation ig-
- nores the buffer pointer bp.
+
+ The tgetent routine loads the entry for name. It returns:
+
+ 1 on success,
+
+ 0 if there is no such entry (or that it is a generic
+ type, having too little information for curses ap-
+ plications to run), and
+
+ -1 if the terminfo database could not be found.
+
+ This differs from the termcap library in two ways:
+
+ o The emulation ignores the buffer pointer bp. The
+ termcap library would store a copy of the terminal
+ description in the area referenced by this pointer.
+ However, ncurses stores its terminal descriptions
+ in compiled binary form, which is not the same
+ thing.
+
+ o There is a difference in return codes. The termcap
+ library does not check if the terminal description
+ is marked with the generic capability, or if the
+ terminal description has cursor-addressing.
+
+
+
The tgetflag routine gets the boolean entry for id, or ze-
ro if it is not available.
- The tgetnum routine gets the numeric entry for id, or -1
+ The tgetnum routine gets the numeric entry for id, or -1
if it is not available.
- The tgetstr routine returns the string entry for id, or
- zero if it is not available. Use tputs to output the re-
- turned string. The return value will also be copied to
- the buffer pointed to by area, and the area value will be
- updated to point past the null ending this value.
+ The tgetstr routine returns the string entry for id, or
+ zero if it is not available. Use tputs to output the re-
+ turned string. The area parameter is used as follows:
+
+ o It is assumed to be the address of a pointer to a
+ buffer managed by the calling application.
+
+ o However, ncurses checks to ensure that area is not
+ NULL, and also that the resulting buffer pointer is
+ not NULL. If either check fails, the area parame-
+ ter is ignored.
+
+ o If the checks succeed, ncurses also copies the re-
+ turn value to the buffer pointed to by area, and
+ the area value will be updated to point past the
+ null ending this value.
+
+ o The return value itself is an address in the termi-
+ nal description which is loaded into memory.
Only the first two characters of the id parameter of tget-flag, tgetnum and tgetstr are compared in lookups.
- The tgoto routine instantiates the parameters into the
- given capability. The output from this routine is to be
- passed to tputs.
+
+
+ The tgoto routine expands the given capability using the
+ parameters.
+
+ o Because the capability may have padding characters,
+ the output of tgoto should be passed to tputs rather
+ than some other output function such as printf.
+
+ o While tgoto is assumed to be used for the two-parame-
+ ter cursor positioning capability, termcap applica-
+ tions also use it for single-parameter capabilities.
+
+ Doing this shows a quirk in tgoto: most hardware ter-
+ minals use cursor addressing with row first, but the
+ original developers of the termcap interface chose to
+ put the column parameter first. The tgoto function
+ swaps the order of parameters. It does this also for
+ calls requiring only a single parameter. In that
+ case, the first parameter is merely a placeholder.
+
+ o Normally the ncurses library is compiled with terminfo
+ support. In that case, tgoto uses tparm(3x) (a more
+ capable formatter).
The tputs routine is described on the curs_terminfo(3x)
manual page. It can retrieve capabilities by either term-
cap or terminfo name.
+
+
The variables PC, UP and BC are set by tgetent to the ter-
minfo entry's data for pad_char, cursor_up and
backspace_if_not_bs, respectively. UP is not used by
@@ -116,8 +173,7 @@
minal speed.
-
Except where explicitly noted, routines that return an in-
teger return ERR upon failure and OK (SVr4 only specifies
"an integer value other than ERR") upon successful comple-
@@ -126,8 +182,7 @@
Routines that return pointers return NULL on error.
-
If you call tgetstr to fetch ca or any other parameterized
string, be aware that it will be returned in terminfo no-
tation, not the older and not-quite-compatible termcap no-
@@ -152,8 +207,7 @@
modate termcap's limitation in this respect.
-
The XSI Curses standard, Issue 4 describes these func-
tions. However, they are marked TO BE WITHDRAWN and may
be removed in future versions.
@@ -173,19 +227,53 @@
guishing between input and output. In particular, some
applications are reported to declare and/or modify ospeed.
+ The comment that only the first two characters of the id
+ parameter are used escapes many application developers.
+ The original BSD 4.2 termcap library (and historical
+ relics thereof) did not require a trailing null NUL on the
+ parameter name passed to tgetstr, tgetnum and tgetflag.
+ Some applications assume that the termcap interface does
+ not require the trailing NUL for the parameter name. Tak-
+ ing into account these issues:
-
-
SEE ALSO
- curses(3x), terminfo(5), putc(3).
+ o As a special case, tgetflag matched against a single-
+ character identifier provided that was at the end of
+ the terminal description. You should not rely upon
+ this behavior in portable programs. This implementa-
+ tion disallows matches against single-character capa-
+ bility names.
+
+ o This implementation disallows matches by the termcap
+ interface against extended capability names which are
+ longer than two characters.
+
+
+