формат скомпилированного файла терминов (format of compiled term file.)
Имя (Name)
term - format of compiled term file.
Синопсис (Synopsis)
term
Описание (Description)
STORAGE LOCATION
Compiled terminfo descriptions are placed under the directory
@TERMINFO@. Two configurations are supported (when building the
ncurses libraries):
directory tree
A two-level scheme is used to avoid a linear search of a
huge UNIX system directory: @TERMINFO@/c/name where name is
the name of the terminal, and c is the first character of
name. Thus, act4 can be found in the file
@TERMINFO@/a/act4. Synonyms for the same terminal are
implemented by multiple links to the same compiled file.
hashed database
Using Berkeley database, two types of records are stored:
the terminfo data in the same format as stored in a
directory tree with the terminfo's primary name as a key,
and records containing only aliases pointing to the primary
name.
If built to write hashed databases, ncurses 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.
ncurses 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.
LEGACY STORAGE FORMAT
The format has been chosen so that it will be the same on all
hardware. An 8 or more bit byte is assumed, but no assumptions
about byte ordering or sign extension are made.
The compiled file is created with the @TIC@ program, and read by
the routine setupterm(3X). The file is divided into six parts:
a) header,
b) terminal names,
c) boolean flags,
d) numbers,
e) strings, and
f) string table.
The header section begins the file. This section contains six
short integers in the format described below. These integers are
(1) the magic number (octal 0432);
(2) the size, in bytes, of the terminal names section;
(3) the number of bytes in the boolean flags section;
(4) the number of short integers in the numbers section;
(5) the number of offsets (short integers) in the strings
section;
(6) the size, in bytes, of the string table.
The capabilities in the boolean flags, numbers, and strings
sections are in the same order as the file <term.h>.
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.) This format corresponds to the hardware of
the VAX and PDP-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.
Numbers in a terminal description, whether they are entries in
the numbers or strings 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:
• If a capability is absent from this terminal, @TIC@ stores a
-1 in the corresponding table.
The integer value -1 is represented by two bytes 0377, 0377.
Absent boolean values are represented by the byte 0 (false).
• If a capability has been canceled from this terminal, @TIC@
stores a -2 in the corresponding table.
The integer value -2 is represented by two bytes 0377, 0376.
The boolean value -2 is represented by the byte 0376.
• Other negative values are illegal.
The terminal names section comes after the header. It contains
the first line of the terminfo description, listing the various
names for the terminal, separated by the '|' character. The
terminal names section is terminated with an ASCII NUL character.
The boolean flags 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.
Between the boolean flags section and the number 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 to avoid traps
induced by addressing a word on an odd byte boundary. All short
integers are aligned on a short word boundary.
The numbers section is similar to the boolean flags section.
Each capability takes up two bytes, and is stored as a little-
endian short integer.
The strings section is also similar. Each capability is stored
as a short integer. The capability value is an index into the
string table.
The string table is the last section. It contains all of the
values of string capabilities referenced in the strings section.
Each string is null-terminated. Special characters in ^X or \c
notation are stored in their interpreted form, not the printing
representation. Padding information $<nn> and parameter
information %x are stored intact in uninterpreted form.
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.
The ncurses 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, continues to parse according to its own
scheme.
First, it reads the extended header (5 short integers):
(1) count of extended boolean capabilities
(2) count of extended numeric capabilities
(3) count of extended string capabilities
(4) count of the items in extended string table
(5) size of the extended string table in bytes
The count- and size-values for the extended string table include
the extended capability names as well as extended capability
values.
Using the counts and sizes, ncurses allocates arrays and reads
data for the extended capabilities in the same order as the
header information.
The extended string table contains values for string
capabilities. After the end of these values, it contains the
names for each of the extended capabilities in order, e.g.,
booleans, then numbers and finally strings.
Applications which manipulate terminal data can use the
definitions described in term_variables(3X) which associate the
long capability names with members of a TERMTYPE structure.
EXTENDED NUMBER FORMAT
On occasion, 16-bit signed integers are not large enough. With
ncurses 6.1, a new format was introduced by making a few changes
to the legacy format:
• a different magic number (octal 01036)
• changing the type for the number array from signed 16-bit
integers to signed 32-bit integers.
To maintain compatibility, the library presents the same data
structures to direct users of the TERMTYPE structure as in
previous formats. However, that cannot provide callers with the
extended numbers. The library uses a similar but hidden data
structure TERMTYPE2 to provide data for the terminfo functions.
Портативность (Portability)
setupterm
Note that it is possible for setupterm to expect a different set
of capabilities than are actually present in the file. Either
the database may have been updated since setupterm has been
recompiled (resulting in extra unrecognized entries in the file)
or the program may have been recompiled more recently than the
database was updated (resulting in missing entries). The routine
setupterm must be prepared for both possibilities - 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.
Binary format
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.
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 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 terminfo(5)
for detailed discussion of terminfo source compatibility issues.
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.
Magic codes
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 file 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
scr_dump(5)). This implementation uses 01036 as a continuation
of that sequence, but with a different high-order byte to avoid
confusion.
The TERMTYPE structure
Direct access to the TERMTYPE structure is provided for legacy
applications. Portable applications should use the tigetflag and
related functions described in curs_terminfo(3X) for reading
terminal capabilities.
Mixed-case terminal names
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 the
intermediate level of a directory tree in (two-character)
hexadecimal form.
Примеры (Examples)
As an example, here is a description for the Lear-Siegler ADM-3,
a popular though rather stupid early terminal:
adm3a|lsi adm3a,
am,
cols#80, lines#24,
bel=^G, clear= 32$<1>, cr=^M, cub1=^H, cud1=^J,
cuf1=^L, cup=\E=%p1%{32}%+%c%p2%{32}%+%c, cuu1=^K,
home=^^, ind=^J,
and a hexadecimal dump of the compiled terminal description:
0000 1a 01 10 00 02 00 03 00 82 00 31 00 61 64 6d 33 ........ ..1.adm3
0010 61 7c 6c 73 69 20 61 64 6d 33 61 00 00 01 50 00 a|lsi ad m3a...P.
0020 ff ff 18 00 ff ff 00 00 02 00 ff ff ff ff 04 00 ........ ........
0030 ff ff ff ff ff ff ff ff 0a 00 25 00 27 00 ff ff ........ ..%.'...
0040 29 00 ff ff ff ff 2b 00 ff ff 2d 00 ff ff ff ff ).....+. ..-.....
0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00d0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00e0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0100 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0110 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0120 ff ff ff ff ff ff 2f 00 07 00 0d 00 1a 24 3c 31 ....../. .....$<1
0130 3e 00 1b 3d 25 70 31 25 7b 33 32 7d 25 2b 25 63 >..=%p1% {32}%+%c
0140 25 70 32 25 7b 33 32 7d 25 2b 25 63 00 0a 00 1e %p2%{32} %+%c....
0150 00 08 00 0c 00 0b 00 0a 00 ........ .
LIMITS
Some limitations:
• total compiled entries cannot exceed 4096 bytes in the legacy
format.
• total compiled entries cannot exceed 32768 bytes in the
extended format.
• the name field cannot exceed 128 bytes.
Compiled entries are limited to 32768 bytes because offsets into
the strings table use two-byte integers. The legacy format could
have supported 32768-byte entries, but was limited a virtual
memory page's 4096 bytes.
Файлы (Files)
@TERMINFO@/*/* compiled terminal capability data base
Смотри также (See also)
curses(3X), terminfo(5).
