- Compiled terminfo descriptions are placed under the direc-
- tory /usr/share/terminfo. In order to avoid a linear
- search of a huge UNIX system directory, a two-level scheme
- is used: /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 /usr/share/terminfo/a/act4. Synonyms
- for the same terminal are implemented by multiple links to
- the same compiled file.
-
- 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. The file is divided into
- six parts: the header, terminal names, boolean flags, num-
- bers, strings, and 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 names section; (3) the number of
- bytes in the boolean 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.
-
- Short integers are stored in 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 hard-
- ware 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.
-
- The terminal names section comes next. It contains the
- first line of the terminfo description, listing the vari-
- ous names for the terminal, separated by the `|' charac-
- ter. The section is terminated with an ASCII NUL charac-
- ter.
-
- 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>.
-
- Between the boolean 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 in to avoid IOT 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 flags 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.
-
- 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. Special characters in ^X or \c notation are
- stored in their interpreted form, not the printing repre-
- sentation. Padding information $<nn> and parameter infor-
- mation %x are stored intact in uninterpreted form.
-
- 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.
-
- Note that it is possible for setupterm to expect a differ-
- ent 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 unrecog-
- nized 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.
-
- 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 discus-
- sion of terminfo source compatibility issues.
-
- As an example, here is a hex dump of the description for
- the Lear-Siegler ADM-3, a popular though rather stupid
- early terminal:
+
+ Compiled terminfo descriptions are placed under the directory
+ /usr/share/terminfo. Two configurations are supported (when building
+ the ncurses libraries):
+
+ directorytree
+ A two-level scheme is used to avoid a linear search of a huge UNIX
+ system directory: /usr/share/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 /usr/share/terminfo/a/act4. Syn-
+ onyms for the same terminal are implemented by multiple links to
+ the same compiled file.
+
+ hasheddatabase
+ Using Berkeley database, two types of records are stored: the ter-
+ minfo 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 ter-
+ minfo 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 TER-
+ MINFO_DIRS environment variable by assuming a directory tree for
+ entries that correspond to an existing directory, and hashed data-
+ base otherwise.
+
+
+
+ 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 order-
+ ing or sign extension are made.
+
+ The compiled file is created with the tic program, and read by the rou-
+ tine setupterm(3x). The file is divided into six parts: the header,
+ terminal names, boolean flags, numbers, strings, and 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 names section;
+
+ (3) the number of bytes in the boolean 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.
+
+ Short integers are stored in 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*sec-
+ ond+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 VAX and PDP-11 (that is, lit-
+ tle-endian machines). Machines where this does not correspond to the
+ hardware must read the integers as two bytes and compute the little-
+ endian value.
+
+ The terminal names section comes next. 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
+ ASCII NUL character.
+
+ 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>.
+
+ Between the boolean 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 in to avoid IOT 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 flags 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.
+
+ 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 begin-
+ ning of the string table. 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.
+
+ 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.
+
+
+
+ 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 run-
+ time. 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) size of the extended string table in bytes.
+
+ (5) last offset of the extended string table in bytes.
+
+ 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.
+
+
+
+ Note that it is possible for setupterm to expect a different set of
+ capabilities than are actually present in the file. Either the data-
+ base may have been updated since setupterm has been recompiled (result-
+ ing 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 bool-
+ ean, number, and string capabilities.
+
+ Despite the consistent use of little-endian for numbers and the other-
+ wise 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.
+
+
+