1 .\" Copyright (c) 1992, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" This code is derived from software contributed to Berkeley by
5 .\" Casey Leedom of Lawrence Livermore National Laboratory.
7 .\" Redistribution and use in source and binary forms, with or without
8 .\" modification, are permitted provided that the following conditions
10 .\" 1. Redistributions of source code must retain the above copyright
11 .\" notice, this list of conditions and the following disclaimer.
12 .\" 2. Redistributions in binary form must reproduce the above copyright
13 .\" notice, this list of conditions and the following disclaimer in the
14 .\" documentation and/or other materials provided with the distribution.
15 .\" 4. Neither the name of the University nor the names of its contributors
16 .\" may be used to endorse or promote products derived from this software
17 .\" without specific prior written permission.
19 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 .\" @(#)getcap.3 8.4 (Berkeley) 5/13/94
48 .Nd capability database access routines
54 .Fn cgetent "char **buf" "char **db_array" "const char *name"
56 .Fn cgetset "const char *ent"
58 .Fn cgetmatch "const char *buf" "const char *name"
60 .Fn cgetcap "char *buf" "const char *cap" "int type"
62 .Fn cgetnum "char *buf" "const char *cap" "long *num"
64 .Fn cgetstr "char *buf" "const char *cap" "char **str"
66 .Fn cgetustr "char *buf" "const char *cap" "char **str"
68 .Fn cgetfirst "char **buf" "char **db_array"
70 .Fn cgetnext "char **buf" "char **db_array"
76 function extracts the capability
78 from the database specified by the
82 and returns a pointer to a
88 function will first look for files ending in
92 before accessing the ASCII file.
96 must be retained through all subsequent calls to
105 On success 0 is returned, 1 if the returned
106 record contains an unresolved
109 \-1 if the requested record could not be found,
110 \-2 if a system error was encountered (could not open/read a file, etc.) also
113 and \-3 if a potential reference loop is detected (see
119 function enables the addition of a character buffer containing a single capability
121 to the capability database.
122 Conceptually, the entry is added as the first ``file'' in the database, and
123 is therefore searched first on the call to
125 The entry is passed in
131 the current entry is removed from the database.
134 must precede the database traversal.
135 It must be called before the
138 If a sequential access is being performed (see below), it must be called
139 before the first sequential access call
143 or be directly preceded by a
146 On success 0 is returned and \-1 on failure.
150 function will return 0 if
152 is one of the names of the capability record
159 function searches the capability record
167 is specified using any single character.
168 If a colon (`:') is used, an
169 untyped capability will be searched for (see below for explanation of
171 A pointer to the value of
175 is returned on success,
177 if the requested capability could not be
179 The end of the capability value is signaled by a `:' or
182 (see below for capability database syntax).
186 function retrieves the value of the numeric capability
188 from the capability record pointed to by
190 The numeric value is returned in the
194 0 is returned on success, \-1 if the requested numeric capability could not
199 function retrieves the value of the string capability
201 from the capability record pointed to by
203 A pointer to a decoded,
207 copy of the string is returned in the
211 The number of characters in the decoded string not including the trailing
213 is returned on success, \-1 if the requested string capability could not
214 be found, \-2 if a system error was encountered (storage allocation
219 function is identical to
221 except that it does not expand special characters, but rather returns each
222 character of the capability string literally.
228 functions comprise a function group that provides for sequential
231 pointer terminated array of file names,
235 function returns the first record in the database and resets the access
239 function returns the next record in the database with respect to the
240 record returned by the previous
245 If there is no such previous call, the first record in the database is
247 Each record is returned in a
252 expansion is done (see
255 Upon completion of the database 0 is returned, 1 is returned upon successful
256 return of record with possibly more remaining (we have not reached the end of
257 the database yet), 2 is returned if the record contains an unresolved
259 expansion, \-1 is returned if a system error occurred, and \-2
260 is returned if a potential reference loop is detected (see
263 Upon completion of database (0 return) the database is closed.
267 function closes the sequential access and frees any memory and file descriptors
269 Note that it does not erase the buffer pushed by a call to
271 .Sh CAPABILITY DATABASE SYNTAX
272 Capability databases are normally
274 and may be edited with standard
276 Blank lines and lines beginning with a `#' are comments
278 Lines ending with a `\|\e' indicate that the next line
279 is a continuation of the current line; the `\|\e' and following newline
281 Long lines are usually continued onto several physical
282 lines by ending each line except the last with a `\|\e'.
284 Capability databases consist of a series of records, one per logical
286 Each record contains a variable number of `:'-separated fields
288 Empty fields consisting entirely of white space
289 characters (spaces and tabs) are ignored.
291 The first capability of each record specifies its names, separated by `|'
293 These names are used to reference records in the database.
294 By convention, the last name is usually a comment and is not intended as
302 .Dl "d0\||\|vt100\||\|vt100-am\||\|vt100am\||\|dec vt100:"
304 giving four names that can be used to access the record.
306 The remaining non-empty capabilities describe a set of (name, value)
307 bindings, consisting of a names optionally followed by a typed value:
309 .Bl -tag -width "nameTvalue" -compact
311 typeless [boolean] capability
312 .Em name No "is present [true]"
313 .It name Ns Em \&T Ns value
321 .It name Ns Em T Ns \&@
327 Names consist of one or more characters.
328 Names may contain any character
329 except `:', but it is usually best to restrict them to the printable
330 characters and avoid use of graphics like `#', `=', `%', `@', etc.
332 are single characters used to separate capability names from their
333 associated typed values.
334 Types may be any character except a `:'.
335 Typically, graphics like `#', `=', `%', etc.\& are used.
337 number of characters and may contain any character except `:'.
338 .Sh CAPABILITY DATABASE SEMANTICS
339 Capability records describe a set of (name, value) bindings.
341 have multiple values bound to them.
342 Different values for a name are
343 distinguished by their
347 function will return a pointer to a value of a name given the capability
348 name and the type of the value.
350 The types `#' and `=' are conventionally used to denote numeric and
351 string typed values, but no restriction on those types is enforced.
357 can be used to implement the traditional syntax and semantics of `#'
359 Typeless capabilities are typically used to denote boolean objects with
360 presence or absence indicating truth and false values respectively.
361 This interpretation is conveniently represented by:
363 .Dl "(getcap(buf, name, ':') != NULL)"
365 A special capability,
367 is used to indicate that the record specified by
369 should be substituted for the
373 capabilities may interpolate records which also contain
375 capabilities and more than one
377 capability may be used in a record.
380 expansion scope (i.e., where the argument is searched for) contains the
383 is declared and all subsequent files in the file array.
385 When a database is searched for a capability record, the first matching
386 record in the search is returned.
387 When a record is scanned for a
388 capability, the first matching capability is returned; the capability
390 will hide any following definition of a value of type
396 will prevent any following values of
400 These features combined with
402 capabilities can be used to generate variations of other databases and
403 records by either adding new capabilities, overriding definitions with new
404 definitions, or hiding following definitions via `@' capabilities.
406 .Bd -unfilled -offset indent
407 example\||\|an example of binding multiple values to names:\e
408 :foo%bar:foo^blah:foo@:\e
409 :abc%xyz:abc^frap:abc$@:\e
413 The capability foo has two values bound to it (bar of type `%' and blah of
414 type `^') and any other value bindings are hidden.
416 also has two values bound but only a value of type `$' is prevented from
417 being defined in the capability record more.
418 .Bd -unfilled -offset indent
420 new\||\|new_record\||\|a modification of "old":\e
421 :fript=bar:who-cares@:tc=old:blah:tc=extensions:
423 old\||\|old_record\||\|an old database record:\e
424 :fript=foo:who-cares:glork#200:
427 The records are extracted by calling
429 with file1 preceding file2.
430 In the capability record new in file1, fript=bar overrides the definition
431 of fript=foo interpolated from the capability record old in file2,
432 who-cares@ prevents the definition of any who-cares definitions in old
433 from being seen, glork#200 is inherited from old, and blah and anything
434 defined by the record extensions is added to those definitions in old.
435 Note that the position of the fript=bar and who-cares@ definitions before
436 tc=old is important here.
437 If they were after, the definitions in old
438 would take precedence.
439 .Sh CGETNUM AND CGETSTR SYNTAX AND SEMANTICS
440 Two types are predefined by
445 .Bl -tag -width "nameXnumber" -compact
446 .It Em name Ns \&# Ns Em number
451 .It Em name Ns = Ns Em string
457 the numeric capability
461 the string capability
466 Numeric capability values may be given in one of three numeric bases.
467 If the number starts with either
471 it is interpreted as a hexadecimal number (both upper and lower case a-f
472 may be used to denote the extended hexadecimal digits).
473 Otherwise, if the number starts with a
475 it is interpreted as an octal number.
476 Otherwise the number is interpreted as a decimal number.
478 String capability values may contain any character.
481 codes, new lines, and colons may be conveniently represented by the use
483 .Bl -column "\e\|X,X\e\|X" "(ASCII octal nnn)"
484 ^X ('X' & 037) control-X
485 \e\|b, \e\|B (ASCII 010) backspace
486 \e\|t, \e\|T (ASCII 011) tab
487 \e\|n, \e\|N (ASCII 012) line feed (newline)
488 \e\|f, \e\|F (ASCII 014) form feed
489 \e\|r, \e\|R (ASCII 015) carriage return
490 \e\|e, \e\|E (ASCII 027) escape
491 \e\|c, \e\|C (:) colon
492 \e\|\e (\e\|) back slash
494 \e\|nnn (ASCII octal nnn)
497 A `\|\e' may be followed by up to three octal digits directly specifies
498 the numeric code for a character.
503 encoded, causes all sorts of problems and must be used with care since
505 are typically used to denote the end of strings; many applications
506 use `\e\|200' to represent a
520 return a value greater than or equal to 0 on success and a value less
524 function returns a character pointer on success and a
532 functions may fail and set
534 for any of the errors specified for the library functions:
553 No memory to allocate.
559 Colons (`:') cannot be used in names, types, or values.
561 There are no checks for
562 .Ic tc Ns = Ns Ic name
566 The buffer added to the database by a call to
568 is not unique to the database but is rather prepended to any database used.