.\"***************************************************************************
-.\" Copyright (c) 1998-2016,2017 Free Software Foundation, Inc. *
+.\" Copyright 2018-2019,2020 Thomas E. Dickey *
+.\" Copyright 1998-2016,2017 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: term.5,v 1.27 2017/12/16 21:27:20 tom Exp $
+.\" $Id: term.5,v 1.38 2020/07/25 21:56:02 tom Exp $
.TH term 5
.ie \n(.g .ds `` \(lq
.el .ds `` ``
.de NE
.fi
.ft R
-.in -4
+.ie n .in -4
+.el .in -2
..
.de bP
.ie n .IP \(bu 4
.SH DESCRIPTION
.SS STORAGE LOCATION
Compiled terminfo descriptions are placed under the directory \fB\*d\fP.
-Two configurations are supported (when building the ncurses libraries):
+Two configurations are supported (when building the \fBncurses\fP libraries):
.TP 5
.B directory tree
A two-level scheme is used to avoid a linear search
and records containing only aliases pointing to the primary name.
.IP
If built to write hashed databases,
-ncurses can still read terminfo databases organized as a directory tree,
+\fBncurses\fP can still read terminfo databases organized as a directory tree,
but cannot write entries into the directory tree.
It can write (or rewrite) entries in the hashed database.
.IP
-ncurses distinguishes the two cases in the TERMINFO and TERMINFO_DIRS
+\fBncurses\fP distinguishes the two cases in the TERMINFO and TERMINFO_DIRS
environment variable by assuming a directory tree for entries that
correspond to an existing directory,
and hashed database otherwise.
The compiled file is created with the \fB@TIC@\fP program,
and read by the routine \fBsetupterm\fP(3X).
The file is divided into six parts:
-the header,
-terminal names,
-boolean flags,
-numbers,
-strings,
-and
-string table.
+.RS 5
+.TP 3
+a) \fIheader\fP,
+.TP 3
+b) \fIterminal names\fP,
+.TP 3
+c) \fIboolean flags\fP,
+.TP 3
+d) \fInumbers\fP,
+.TP 3
+e) \fIstrings\fP, and
+.TP 3
+f) \fIstring table\fP.
+.RE
.PP
-The header section begins the file.
+The \fIheader\fP section begins the file.
This section contains six short integers in the format
described below.
These integers are
.RS 5
.TP 5
-(1) the magic number (octal 0432);
+(1) the \fImagic number\fP (octal 0432);
.TP 5
-(2) the size, in bytes, of the names section;
+(2) the size, in bytes, of the \fIterminal names\fP section;
.TP 5
-(3) the number of bytes in the boolean section;
+(3) the number of bytes in the \fIboolean flags\fP section;
.TP 5
-(4) the number of short integers in the numbers section;
+(4) the number of short integers in the \fInumbers\fP section;
.TP 5
-(5) the number of offsets (short integers) in the strings section;
+(5) the number of offsets (short integers) in the \fIstrings\fP section;
.TP 5
-(6) the size, in bytes, of the string table.
+(6) the size, in bytes, of the \fIstring table\fP.
.RE
.PP
-Short integers are stored in two 8-bit bytes.
+The capabilities in the
+\fIboolean flags\fP,
+\fInumbers\fP, and
+\fIstrings\fP
+sections are in the same order as the file <term.h>.
+.PP
+Short integers are signed, in the range \-32768 to 32767.
+They are stored as two 8-bit bytes.
The first byte contains the least significant 8 bits of the value,
and the second byte contains the most significant 8 bits.
(Thus, the value represented is 256*second+first.)
-The value \-1 is represented by the two bytes 0377, 0377; other negative
-values are illegal. This value generally
-means that the corresponding capability is missing from this terminal.
-Note that this format corresponds to the hardware of the \s-1VAX\s+1
+This format corresponds to the hardware of the \s-1VAX\s+1
and \s-1PDP\s+1-11 (that is, little-endian machines).
Machines where this does not correspond to the hardware must read the
integers as two bytes and compute the little-endian value.
.PP
-The terminal names section comes next.
+Numbers in a terminal description,
+whether they are entries in the \fInumbers\fP or \fIstrings\fP table,
+are positive integers.
+Boolean flags are treated as positive one-byte integers.
+In each case, those positive integers represent a terminal capability.
+The terminal compiler @TIC@ uses negative integers to handle the cases where
+a capability is not available:
+.bP
+If a capability is absent from this terminal,
+@TIC@ stores a \-1 in the corresponding table.
+.IP
+The integer value \-1 is represented by two bytes 0377, 0377.
+.br
+Absent boolean values are represented by the byte 0 (false).
+.bP
+If a capability has been canceled from this terminal,
+@TIC@ stores a \-2 in the corresponding table.
+.IP
+The integer value \-2 is represented by two bytes 0377, 0376.
+.br
+The boolean value \-2 is represented by the byte 0376.
+.br
+.bP
+Other negative values are illegal.
+.PP
+The \fIterminal names\fP section comes after the \fIheader\fP.
It contains the first line of the terminfo description,
listing the various names for the terminal,
separated by the \*(``|\*('' character.
-The section is terminated with an \s-1ASCII NUL\s+1 character.
+The \fIterminal names\fP section is terminated
+with an \s-1ASCII NUL\s+1 character.
.PP
-The boolean flags have one byte for each flag.
-This byte is either 0 or 1 as the flag is present or absent.
-The capabilities are in the same order as the file <term.h>.
+The \fIboolean flags\fP section has one byte for each flag.
+Boolean capabilities are either 1 or 0 (true or false)
+according to whether the terminal supports the given capability or not.
.PP
-Between the boolean section and the number section,
+Between the \fIboolean flags\fP section and the \fInumber\fP section,
a null byte will be inserted, if necessary,
-to ensure that the number section begins on an even byte (this is a
-relic of the PDP\-11's word-addressed architecture, originally
-designed in to avoid IOT traps induced by addressing a word on an
-odd byte boundary).
+to ensure that the \fInumber\fP section begins on an even byte
+This is a relic of the PDP\-11's word-addressed architecture,
+originally designed to avoid traps induced
+by addressing a word on an odd byte boundary.
All short integers are aligned on a short word boundary.
.PP
-The numbers section is similar to the flags section.
+The \fInumbers\fP section is similar to the \fIboolean flags\fP section.
Each capability takes up two bytes,
and is stored as a little-endian short integer.
-If the value represented is \-1, the capability is taken to be missing.
.PP
-The strings section is also similar.
-Each capability is stored as a short integer, in the format above.
-A value of \-1 means the capability is missing.
-Otherwise, the value is taken as an offset from the beginning
-of the string table.
+The \fIstrings\fP section is also similar.
+Each capability is stored as a short integer.
+The capability value is an index into the \fIstring table\fP.
+.PP
+The \fIstring table\fP is the last section.
+It contains all of the values of string capabilities referenced in
+the \fIstrings\fP section.
+Each string is null-terminated.
Special characters in ^X or \ec notation are stored in their
interpreted form, not the printing representation.
Padding information $<nn> and parameter information %x are
stored intact in uninterpreted form.
-.PP
-The final section is the string table.
-It contains all the values of string capabilities referenced in
-the string section.
-Each string is null terminated.
.SS EXTENDED STORAGE FORMAT
The previous section describes the conventional terminfo binary format.
With some minor variations of the offsets (see PORTABILITY),
the same binary format is used in all modern UNIX systems.
Each system uses a predefined set of boolean, number or string capabilities.
.PP
-The ncurses libraries and applications support extended terminfo binary format,
-allowing users to define capabilities which are loaded at runtime. This
+The \fBncurses\fP libraries and applications support
+extended terminfo binary format,
+allowing users to define capabilities which are loaded at runtime.
+This
extension is made possible by using the fact that the other implementations
stop reading the terminfo data when they have reached the end of the size given
in the header.
-ncurses checks the size, and if it exceeds that due to the predefined data,
+\fBncurses\fP checks the size,
+and if it exceeds that due to the predefined data,
continues to parse according to its own scheme.
.PP
First, it reads the extended header (5 short integers):
count of extended string capabilities
.TP 5
(4)
-size of the extended string table in bytes.
+count of the items in extended string table
.TP 5
(5)
-last offset of the extended string table in bytes.
+size of the extended string table in bytes
.RE
.PP
-Using the counts and sizes, ncurses allocates arrays and reads data
+The count- and size-values for the extended string table
+include the extended capability \fInames\fP as well as
+extended capability \fIvalues\fP.
+.PP
+Using the counts and sizes, \fBncurses\fP allocates arrays and reads data
for the extended capabilities in the same order as the header information.
.PP
The extended string table contains values for string capabilities.
.SS EXTENDED NUMBER FORMAT
.PP
On occasion, 16-bit signed integers are not large enough.
-With ncurses 6.1, a new format is introduced by making a few changes
+With \fBncurses\fP 6.1, a new format was introduced by making a few changes
to the legacy format:
.bP
-a different magic number (0542)
+a different magic number (octal 01036)
.bP
changing the type for the \fInumber\fP array from signed 16-bit integers
to signed 32-bit integers.
The library uses a similar but hidden data structure \fBTERMTYPE2\fP
to provide data for the terminfo functions.
.SH PORTABILITY
+.SS setupterm
+.PP
Note that it is possible for
.B setupterm
to expect a different set of capabilities
this is why the numbers and sizes are included.
Also, new capabilities must always be added at the end of the lists
of boolean, number, and string capabilities.
+.SS Binary format
+.PP
+X/Open Curses does not specify a format for the terminfo database.
+UNIX System V curses used a directory-tree of binary files,
+one per terminal description.
.PP
Despite the consistent use of little-endian for numbers and the otherwise
self-describing format, it is not wise to count on portability of binary
-terminfo entries between commercial UNIX versions. The problem is that there
+terminfo entries between commercial UNIX versions.
+The problem is that there
are at least three versions of terminfo (under HP\-UX, AIX, and OSF/1) which
diverged from System V terminfo after SVr1, and have added extension
capabilities to the string table that (in the binary format) collide with
-System V and XSI Curses extensions. See \fBterminfo\fR(\*n) for detailed
+System V and XSI Curses extensions.
+See \fBterminfo\fR(\*n) for detailed
discussion of terminfo source compatibility issues.
.PP
+This implementation is by default compatible with the binary
+terminfo format used by Solaris curses,
+except in a few less-used details
+where it was found that the latter did not match X/Open Curses.
+The format used by the other Unix versions
+can be matched by building ncurses
+with different configuration options.
+.SS Magic codes
+.PP
+The magic number in a binary terminfo file is the first 16-bits (two bytes).
+Besides making it more reliable for the library to check that a file
+is terminfo,
+utilities such as \fBfile\fP also use that to tell what the file-format is.
+System V defined more than one magic number,
+with 0433, 0435 as screen-dumps (see \fBscr_dump\fP(5)).
+This implementation uses 01036 as a continuation of that sequence,
+but with a different high-order byte to avoid confusion.
+.SS The TERMTYPE structure
+.PP
Direct access to the \fBTERMTYPE\fP structure is provided for legacy
applications.
Portable applications should use the \fBtigetflag\fP and related functions
described in \fBcurs_terminfo\fP(3X) for reading terminal capabilities.
+.SS Mixed-case terminal names
.PP
A small number of terminal descriptions use uppercase characters in
their names.
If the underlying filesystem ignores the difference between
uppercase and lowercase,
-ncurses represents the \*(``first character\*('' of the terminal name used as
+\fBncurses\fP represents the \*(``first character\*(''
+of the terminal name used as
the intermediate level of a directory tree in (two-character) hexadecimal form.
.SH EXAMPLE
As an example, here is a description for the Lear-Siegler
total compiled entries cannot exceed 32768 bytes in the extended format.
.bP
the name field cannot exceed 128 bytes.
+.PP
+Compiled entries are limited to 32768 bytes because offsets into the
+\fIstrings table\fP use two-byte integers.
+The legacy format could have supported 32768-byte entries,
+but was limited a virtual memory page's 4096 bytes.
.SH FILES
\*d/*/* compiled terminal capability data base
.SH SEE ALSO
projects / ncurses.git / blobdiff