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30 .\" $Id: term.5,v 1.43 2021/12/25 21:28:59 tom Exp $
57 term \- format of compiled term file.
62 Compiled terminfo descriptions are placed under the directory \fB\*d\fP.
63 Two configurations are supported (when building the \fBncurses\fP libraries):
66 A two-level scheme is used to avoid a linear search
67 of a huge \s-1UNIX\s+1 system directory: \fB\*d/c/name\fP where
69 is the name of the terminal, and
71 is the first character of
75 can be found in the file \fB\*d/a/act4\fP.
76 Synonyms for the same terminal are implemented by multiple
77 links to the same compiled file.
80 Using Berkeley database, two types of records are stored:
81 the terminfo data in the same format as stored in a directory tree with
82 the terminfo's primary name as a key,
83 and records containing only aliases pointing to the primary name.
85 If built to write hashed databases,
86 \fBncurses\fP can still read terminfo databases organized as a directory tree,
87 but cannot write entries into the directory tree.
88 It can write (or rewrite) entries in the hashed database.
90 \fBncurses\fP distinguishes the two cases in the TERMINFO and TERMINFO_DIRS
91 environment variable by assuming a directory tree for entries that
92 correspond to an existing directory,
93 and hashed database otherwise.
94 .SS LEGACY STORAGE FORMAT
95 The format has been chosen so that it will be the same on all hardware.
96 An 8 or more bit byte is assumed, but no assumptions about byte ordering
97 or sign extension are made.
99 The compiled file is created with the \fB@TIC@\fP program,
100 and read by the routine \fBsetupterm\fP(3X).
101 The file is divided into six parts:
106 b) \fIterminal names\fP,
108 c) \fIboolean flags\fP,
112 e) \fIstrings\fP, and
114 f) \fIstring table\fP.
117 The \fIheader\fP section begins the file.
118 This section contains six short integers in the format
123 (1) the \fImagic number\fP (octal 0432);
125 (2) the size, in bytes, of the \fIterminal names\fP section;
127 (3) the number of bytes in the \fIboolean flags\fP section;
129 (4) the number of short integers in the \fInumbers\fP section;
131 (5) the number of offsets (short integers) in the \fIstrings\fP section;
133 (6) the size, in bytes, of the \fIstring table\fP.
136 The capabilities in the
140 sections are in the same order as the file <term.h>.
142 Short integers are signed, in the range \-32768 to 32767.
143 They are stored as two 8-bit bytes.
144 The first byte contains the least significant 8 bits of the value,
145 and the second byte contains the most significant 8 bits.
146 (Thus, the value represented is 256*second+first.)
147 This format corresponds to the hardware of the \s-1VAX\s+1
148 and \s-1PDP\s+1-11 (that is, little-endian machines).
149 Machines where this does not correspond to the hardware must read the
150 integers as two bytes and compute the little-endian value.
152 Numbers in a terminal description,
153 whether they are entries in the \fInumbers\fP or \fIstrings\fP table,
154 are positive integers.
155 Boolean flags are treated as positive one-byte integers.
156 In each case, those positive integers represent a terminal capability.
157 The terminal compiler @TIC@ uses negative integers to handle the cases where
158 a capability is not available:
160 If a capability is absent from this terminal,
161 @TIC@ stores a \-1 in the corresponding table.
163 The integer value \-1 is represented by two bytes 0377, 0377.
165 Absent boolean values are represented by the byte 0 (false).
167 If a capability has been canceled from this terminal,
168 @TIC@ stores a \-2 in the corresponding table.
170 The integer value \-2 is represented by two bytes 0377, 0376.
172 The boolean value \-2 is represented by the byte 0376.
175 Other negative values are illegal.
177 The \fIterminal names\fP section comes after the \fIheader\fP.
178 It contains the first line of the terminfo description,
179 listing the various names for the terminal,
180 separated by the \*(``|\*('' character.
181 The \fIterminal names\fP section is terminated
182 with an \s-1ASCII NUL\s+1 character.
184 The \fIboolean flags\fP section has one byte for each flag.
185 Boolean capabilities are either 1 or 0 (true or false)
186 according to whether the terminal supports the given capability or not.
188 Between the \fIboolean flags\fP section and the \fInumber\fP section,
189 a null byte will be inserted, if necessary,
190 to ensure that the \fInumber\fP section begins on an even byte
191 This is a relic of the PDP\-11's word-addressed architecture,
192 originally designed to avoid traps induced
193 by addressing a word on an odd byte boundary.
194 All short integers are aligned on a short word boundary.
196 The \fInumbers\fP section is similar to the \fIboolean flags\fP section.
197 Each capability takes up two bytes,
198 and is stored as a little-endian short integer.
200 The \fIstrings\fP section is also similar.
201 Each capability is stored as a short integer.
202 The capability value is an index into the \fIstring table\fP.
204 The \fIstring table\fP is the last section.
205 It contains all of the values of string capabilities referenced in
206 the \fIstrings\fP section.
207 Each string is null-terminated.
208 Special characters in ^X or \ec notation are stored in their
209 interpreted form, not the printing representation.
210 Padding information $<nn> and parameter information %x are
211 stored intact in uninterpreted form.
212 .SS EXTENDED STORAGE FORMAT
213 The previous section describes the conventional terminfo binary format.
214 With some minor variations of the offsets (see PORTABILITY),
215 the same binary format is used in all modern UNIX systems.
216 Each system uses a predefined set of boolean, number or string capabilities.
218 The \fBncurses\fP libraries and applications support
219 extended terminfo binary format,
220 allowing users to define capabilities which are loaded at runtime.
222 extension is made possible by using the fact that the other implementations
223 stop reading the terminfo data when they have reached the end of the size given
225 \fBncurses\fP checks the size,
226 and if it exceeds that due to the predefined data,
227 continues to parse according to its own scheme.
229 First, it reads the extended header (5 short integers):
233 count of extended boolean capabilities
236 count of extended numeric capabilities
239 count of extended string capabilities
242 count of the items in extended string table
245 size of the extended string table in bytes
248 The count- and size-values for the extended string table
249 include the extended capability \fInames\fP as well as
250 extended capability \fIvalues\fP.
252 Using the counts and sizes, \fBncurses\fP allocates arrays and reads data
253 for the extended capabilities in the same order as the header information.
255 The extended string table contains values for string capabilities.
256 After the end of these values, it contains the names for each of
257 the extended capabilities in order, e.g., booleans, then numbers and
260 Applications which manipulate terminal data can use the definitions
261 described in \fBterm_variables\fP(3X) which associate the long capability
262 names with members of a \fBTERMTYPE\fP structure.
264 .SS EXTENDED NUMBER FORMAT
266 On occasion, 16-bit signed integers are not large enough.
267 With \fBncurses\fP 6.1, a new format was introduced by making a few changes
268 to the legacy format:
270 a different magic number (octal 01036)
272 changing the type for the \fInumber\fP array from signed 16-bit integers
273 to signed 32-bit integers.
275 To maintain compatibility, the library presents the same data structures
276 to direct users of the \fBTERMTYPE\fP structure as in previous formats.
277 However, that cannot provide callers with the extended numbers.
278 The library uses a similar but hidden data structure \fBTERMTYPE2\fP
279 to provide data for the terminfo functions.
283 Note that it is possible for
285 to expect a different set of capabilities
286 than are actually present in the file.
287 Either the database may have been updated since
290 (resulting in extra unrecognized entries in the file)
291 or the program may have been recompiled more recently
292 than the database was updated
293 (resulting in missing entries).
296 must be prepared for both possibilities \-
297 this is why the numbers and sizes are included.
298 Also, new capabilities must always be added at the end of the lists
299 of boolean, number, and string capabilities.
302 X/Open Curses does not specify a format for the terminfo database.
303 UNIX System V curses used a directory-tree of binary files,
304 one per terminal description.
306 Despite the consistent use of little-endian for numbers and the otherwise
307 self-describing format, it is not wise to count on portability of binary
308 terminfo entries between commercial UNIX versions.
309 The problem is that there
310 are at least three versions of terminfo (under HP\-UX, AIX, and OSF/1) which
311 diverged from System V terminfo after SVr1, and have added extension
312 capabilities to the string table that (in the binary format) collide with
313 System V and XSI Curses extensions.
314 See \fBterminfo\fP(\*n) for detailed
315 discussion of terminfo source compatibility issues.
317 This implementation is by default compatible with the binary
318 terminfo format used by Solaris curses,
319 except in a few less-used details
320 where it was found that the latter did not match X/Open Curses.
321 The format used by the other Unix versions
322 can be matched by building ncurses
323 with different configuration options.
326 The magic number in a binary terminfo file is the first 16-bits (two bytes).
327 Besides making it more reliable for the library to check that a file
329 utilities such as \fBfile\fP(1) also use that to tell what the file-format is.
330 System V defined more than one magic number,
331 with 0433, 0435 as screen-dumps (see \fBscr_dump\fP(5)).
332 This implementation uses 01036 as a continuation of that sequence,
333 but with a different high-order byte to avoid confusion.
334 .SS The TERMTYPE structure
336 Direct access to the \fBTERMTYPE\fP structure is provided for legacy
338 Portable applications should use the \fBtigetflag\fP and related functions
339 described in \fBcurs_terminfo\fP(3X) for reading terminal capabilities.
340 .SS Mixed-case terminal names
342 A small number of terminal descriptions use uppercase characters in
344 If the underlying filesystem ignores the difference between
345 uppercase and lowercase,
346 \fBncurses\fP represents the \*(``first character\*(''
347 of the terminal name used as
348 the intermediate level of a directory tree in (two-character) hexadecimal form.
350 As an example, here is a description for the Lear-Siegler
351 ADM\-3, a popular though rather stupid early terminal:
356 bel=^G, clear=\032$<1>, cr=^M, cub1=^H, cud1=^J,
357 cuf1=^L, cup=\\E=%p1%{32}%+%c%p2%{32}%+%c, cuu1=^K,
361 and a hexadecimal dump of the compiled terminal description:
364 \s-20000 1a 01 10 00 02 00 03 00 82 00 31 00 61 64 6d 33 ........ ..1.adm3
365 0010 61 7c 6c 73 69 20 61 64 6d 33 61 00 00 01 50 00 a|lsi ad m3a...P.
366 0020 ff ff 18 00 ff ff 00 00 02 00 ff ff ff ff 04 00 ........ ........
367 0030 ff ff ff ff ff ff ff ff 0a 00 25 00 27 00 ff ff ........ ..%.'...
368 0040 29 00 ff ff ff ff 2b 00 ff ff 2d 00 ff ff ff ff ).....+. ..-.....
369 0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
370 0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
371 0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
372 0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
373 0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
374 00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
375 00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
376 00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
377 00d0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
378 00e0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
379 00f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
380 0100 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
381 0110 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
382 0120 ff ff ff ff ff ff 2f 00 07 00 0d 00 1a 24 3c 31 ....../. .....$<1
383 0130 3e 00 1b 3d 25 70 31 25 7b 33 32 7d 25 2b 25 63 >..=%p1% {32}%+%c
384 0140 25 70 32 25 7b 33 32 7d 25 2b 25 63 00 0a 00 1e %p2%{32} %+%c....
385 0150 00 08 00 0c 00 0b 00 0a 00 ........ .\s+2
392 total compiled entries cannot exceed 4096 bytes in the legacy format.
394 total compiled entries cannot exceed 32768 bytes in the extended format.
396 the name field cannot exceed 128 bytes.
398 Compiled entries are limited to 32768 bytes because offsets into the
399 \fIstrings table\fP use two-byte integers.
400 The legacy format could have supported 32768-byte entries,
401 but was limited a virtual memory page's 4096 bytes.
403 \*d/*/* compiled terminal capability database
405 \fBcurses\fP(3X), \fBterminfo\fP(\*n).
409 extended terminfo format for ncurses 5.0
411 hashed database support for ncurses 5.6
413 extended number support for ncurses 6.1
417 documented legacy terminfo format, e.g., from \fIpcurses\fP.