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30 .\" $Id: term.5,v 1.60 2023/10/14 19:18:14 tom Exp $
31 .TH term 5 2023-10-14 "ncurses 6.4" "File formats"
56 compiled \fIterminfo\fR terminal description
61 Compiled terminfo descriptions are placed under the directory \fB\*d\fP.
62 Two configurations are supported (when building the \fBncurses\fP libraries):
65 A two-level scheme is used to avoid a linear search
66 of a huge \s-1UNIX\s+1 system directory: \fB\*d/c/name\fP where
68 is the name of the terminal, and
70 is the first character of
74 can be found in the file \fB\*d/a/act4\fP.
75 Synonyms for the same terminal are implemented by multiple
76 links to the same compiled file.
79 Using Berkeley database, two types of records are stored:
80 the terminfo data in the same format as stored in a directory tree with
81 the terminfo's primary name as a key,
82 and records containing only aliases pointing to the primary name.
84 If built to write hashed databases,
85 \fBncurses\fP can still read terminfo databases organized as a directory tree,
86 but cannot write entries into the directory tree.
87 It can write (or rewrite) entries in the hashed database.
89 \fBncurses\fP distinguishes the two cases in the TERMINFO and TERMINFO_DIRS
90 environment variable by assuming a directory tree for entries that
91 correspond to an existing directory,
92 and hashed database otherwise.
93 .SS LEGACY STORAGE FORMAT
94 The format has been chosen so that it will be the same on all hardware.
95 An 8 or more bit byte is assumed, but no assumptions about byte ordering
96 or sign extension are made.
98 The compiled file is created with the \fB@TIC@\fP program,
99 and read by the routine \fBsetupterm\fP(3X).
100 The file is divided into six parts:
105 b) \fIterminal names\fP,
107 c) \fIboolean flags\fP,
111 e) \fIstrings\fP, and
113 f) \fIstring table\fP.
116 The \fIheader\fP section begins the file.
117 This section contains six short integers in the format
122 (1) the \fImagic number\fP (octal 0432);
124 (2) the size, in bytes, of the \fIterminal names\fP section;
126 (3) the number of bytes in the \fIboolean flags\fP section;
128 (4) the number of short integers in the \fInumbers\fP section;
130 (5) the number of offsets (short integers) in the \fIstrings\fP section;
132 (6) the size, in bytes, of the \fIstring table\fP.
135 The capabilities in the
139 sections are in the same order as the file <term.h>.
141 Short integers are signed, in the range \-32768 to 32767.
142 They are stored as two 8-bit bytes.
143 The first byte contains the least significant 8 bits of the value,
144 and the second byte contains the most significant 8 bits.
145 (Thus, the value represented is 256*second+first.)
146 This format corresponds to the hardware of the \s-1VAX\s+1
147 and \s-1PDP\s+1-11 (that is, little-endian machines).
148 Machines where this does not correspond to the hardware must read the
149 integers as two bytes and compute the little-endian value.
151 Numbers in a terminal description,
152 whether they are entries in the \fInumbers\fP or \fIstrings\fP table,
153 are positive integers.
154 Boolean flags are treated as positive one-byte integers.
155 In each case, those positive integers represent a terminal capability.
156 The terminal compiler @TIC@ uses negative integers to handle the cases where
157 a capability is not available:
159 If a capability is absent from this terminal,
160 @TIC@ stores a \-1 in the corresponding table.
162 The integer value \-1 is represented by two bytes 0377, 0377.
164 Absent boolean values are represented by the byte 0 (false).
166 If a capability has been canceled from this terminal,
167 @TIC@ stores a \-2 in the corresponding table.
169 The integer value \-2 is represented by two bytes 0377, 0376.
171 The boolean value \-2 is represented by the byte 0376.
174 Other negative values are illegal.
176 The \fIterminal names\fP section comes after the \fIheader\fP.
177 It contains the first line of the terminfo description,
178 listing the various names for the terminal,
179 separated by the \*(``|\*('' character.
180 The \fIterminal names\fP section is terminated
181 with an \s-1ASCII NUL\s+1 character.
183 The \fIboolean flags\fP section has one byte for each flag.
184 Boolean capabilities are either 1 or 0 (true or false)
185 according to whether the terminal supports the given capability or not.
187 Between the \fIboolean flags\fP section and the \fInumber\fP section,
188 a null byte will be inserted, if necessary,
189 to ensure that the \fInumber\fP section begins on an even byte
190 This is a relic of the PDP\-11's word-addressed architecture,
191 originally designed to avoid traps induced
192 by addressing a word on an odd byte boundary.
193 All short integers are aligned on a short word boundary.
195 The \fInumbers\fP section is similar to the \fIboolean flags\fP section.
196 Each capability takes up two bytes,
197 and is stored as a little-endian short integer.
199 The \fIstrings\fP section is also similar.
200 Each capability is stored as a short integer.
201 The capability value is an index into the \fIstring table\fP.
203 The \fIstring table\fP is the last section.
204 It contains all of the values of string capabilities referenced in
205 the \fIstrings\fP section.
206 Each string is null-terminated.
207 Special characters in \*^X or \ec notation are stored in their
208 interpreted form, not the printing representation.
209 Padding information $<nn> and parameter information %x are
210 stored intact in uninterpreted form.
211 .SS EXTENDED STORAGE FORMAT
212 The previous section describes the conventional terminfo binary format.
213 With some minor variations of the offsets (see PORTABILITY),
214 the same binary format is used in all modern UNIX systems.
215 Each system uses a predefined set of boolean, number or string capabilities.
217 The \fBncurses\fP libraries and applications support
218 extended terminfo binary format,
219 allowing users to define capabilities which are loaded at runtime.
221 extension is made possible by using the fact that the other implementations
222 stop reading the terminfo data when they have reached the end of the size given
224 \fBncurses\fP checks the size,
225 and if it exceeds that due to the predefined data,
226 continues to parse according to its own scheme.
228 First, it reads the extended header (5 short integers):
232 count of extended boolean capabilities
235 count of extended numeric capabilities
238 count of extended string capabilities
241 count of the items in extended string table
244 size of the extended string table in bytes
247 The count- and size-values for the extended string table
248 include the extended capability \fInames\fP as well as
249 extended capability \fIvalues\fP.
251 Using the counts and sizes, \fBncurses\fP allocates arrays and reads data
252 for the extended capabilities in the same order as the header information.
254 The extended string table contains values for string capabilities.
255 After the end of these values, it contains the names for each of
256 the extended capabilities in order, e.g., booleans, then numbers and
259 Applications which manipulate terminal data can use the definitions
260 described in \fBterm_variables\fP(3X) which associate the long capability
261 names with members of a \fBTERMTYPE\fP structure.
263 .SS EXTENDED NUMBER FORMAT
264 On occasion, 16-bit signed integers are not large enough.
265 With \fBncurses\fP 6.1, a new format was introduced by making a few changes
266 to the legacy format:
268 a different magic number (octal 01036)
270 changing the type for the \fInumber\fP array from signed 16-bit integers
271 to signed 32-bit integers.
273 To maintain compatibility, the library presents the same data structures
274 to direct users of the \fBTERMTYPE\fP structure as in previous formats.
275 However, that cannot provide callers with the extended numbers.
276 The library uses a similar but hidden data structure \fBTERMTYPE2\fP
277 to provide data for the terminfo functions.
280 Note that it is possible for
282 to expect a different set of capabilities
283 than are actually present in the file.
284 Either the database may have been updated since
287 (resulting in extra unrecognized entries in the file)
288 or the program may have been recompiled more recently
289 than the database was updated
290 (resulting in missing entries).
293 must be prepared for both possibilities \-
294 this is why the numbers and sizes are included.
295 Also, new capabilities must always be added at the end of the lists
296 of boolean, number, and string capabilities.
298 X/Open Curses does not specify a format for the terminfo database.
299 UNIX System V curses used a directory-tree of binary files,
300 one per terminal description.
302 Despite the consistent use of little-endian for numbers and the otherwise
303 self-describing format, it is not wise to count on portability of binary
304 terminfo entries between commercial UNIX versions.
305 The problem is that there
306 are at least three versions of terminfo (under HP\-UX, AIX, and OSF/1) which
307 diverged from System V terminfo after SVr1, and have added extension
308 capabilities to the string table that (in the binary format) collide with
309 System V and XSI Curses extensions.
310 See \fBterminfo\fP(\*n) for detailed
311 discussion of terminfo source compatibility issues.
313 This implementation is by default compatible with the binary
314 terminfo format used by Solaris curses,
315 except in a few less-used details
316 where it was found that the latter did not match X/Open Curses.
317 The format used by the other Unix versions
318 can be matched by building ncurses
319 with different configuration options.
321 The magic number in a binary terminfo file is the first 16-bits (two bytes).
322 Besides making it more reliable for the library to check that a file
324 utilities such as \fBfile\fP(1) also use that to tell what the file-format is.
325 System V defined more than one magic number,
326 with 0433, 0435 as screen-dumps (see \fBscr_dump\fP(5)).
327 This implementation uses 01036 as a continuation of that sequence,
328 but with a different high-order byte to avoid confusion.
329 .SS The TERMTYPE structure
330 Direct access to the \fBTERMTYPE\fP structure is provided for legacy
332 Portable applications should use the \fBtigetflag\fP and related functions
333 described in \fBcurs_terminfo\fP(3X) for reading terminal capabilities.
334 .SS Mixed-case terminal names
335 A small number of terminal descriptions use uppercase characters in
337 If the underlying filesystem ignores the difference between
338 uppercase and lowercase,
339 \fBncurses\fP represents the \*(``first character\*(''
340 of the terminal name used as
341 the intermediate level of a directory tree in (two-character) hexadecimal form.
343 As an example, here is a description for the Lear-Siegler
344 ADM\-3, a popular though rather stupid early terminal:
351 bel=\*^G, clear=\e032$<1>, cr=\*^M, cub1=\*^H, cud1=\*^J,
352 cuf1=\*^L, cup=\eE=%p1%{32}%+%c%p2%{32}%+%c, cuu1=\*^K,
353 home=\*^\*^, ind=\*^J,
357 and a hexadecimal dump of the compiled terminal description:
363 0000 1a 01 10 00 02 00 03 00 82 00 31 00 61 64 6d 33 ........ ..1.adm3
364 0010 61 7c 6c 73 69 20 61 64 6d 33 61 00 00 01 50 00 a|lsi ad m3a...P.
365 0020 ff ff 18 00 ff ff 00 00 02 00 ff ff ff ff 04 00 ........ ........
366 0030 ff ff ff ff ff ff ff ff 0a 00 25 00 27 00 ff ff ........ ..%.\*'...
367 0040 29 00 ff ff ff ff 2b 00 ff ff 2d 00 ff ff ff ff ).....+. ..\-.....
368 0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
369 0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
370 0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
371 0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
372 0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
373 00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
374 00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
375 00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
376 00d0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
377 00e0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
378 00f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
379 0100 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
380 0110 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
381 0120 ff ff ff ff ff ff 2f 00 07 00 0d 00 1a 24 3c 31 ....../. .....$<1
382 0130 3e 00 1b 3d 25 70 31 25 7b 33 32 7d 25 2b 25 63 >..=%p1% {32}%+%c
383 0140 25 70 32 25 7b 33 32 7d 25 2b 25 63 00 0a 00 1e %p2%{32} %+%c....
384 0150 00 08 00 0c 00 0b 00 0a 00 ........ .
390 total compiled entries cannot exceed 4096 bytes in the legacy format.
392 total compiled entries cannot exceed 32768 bytes in the extended format.
394 the name field cannot exceed 128 bytes.
396 Compiled entries are limited to 32768 bytes because offsets into the
397 \fIstrings table\fP use two-byte integers.
398 The legacy format could have supported 32768-byte entries,
399 but was limited a virtual memory page's 4096 bytes.
403 compiled terminal description database
407 extended terminfo format for ncurses 5.0
409 hashed database support for ncurses 5.6
411 extended number support for ncurses 6.1
415 documented legacy terminfo format, e.g., from \fIpcurses\fP.
418 \fB\%curs_terminfo\fP(3X),
419 \fB\%terminfo\fP(\*n)