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GETCAP(3)                   BSD Programmer's Manual                  GETCAP(3)

N\bNA\bAM\bME\bE
     c\bcg\bge\bet\bte\ben\bnt\bt, c\bcg\bge\bet\bts\bse\bet\bt, c\bcg\bge\bet\btm\bma\bat\btc\bch\bh, c\bcg\bge\bet\btc\bca\bap\bp, c\bcg\bge\bet\btn\bnu\bum\bm, c\bcg\bge\bet\bts\bst\btr\br, c\bcg\bge\bet\btu\bus\bst\btr\br,
     c\bcg\bge\bet\btf\bfi\bir\brs\bst\bt, c\bcg\bge\bet\btn\bne\bex\bxt\bt, c\bcg\bge\bet\btc\bcl\blo\bos\bse\be - capability database access routines

S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
     #\b#i\bin\bnc\bcl\blu\bud\bde\be <\b<s\bst\btd\bdl\bli\bib\bb.\b.h\bh>\b>

     _\bi_\bn_\bt
     c\bcg\bge\bet\bte\ben\bnt\bt(_\bc_\bh_\ba_\br _\b*_\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\b*_\bd_\bb_\b__\ba_\br_\br_\ba_\by, _\bc_\bh_\ba_\br _\b*_\bn_\ba_\bm_\be);

     _\bi_\bn_\bt
     c\bcg\bge\bet\bts\bse\bet\bt(_\bc_\bh_\ba_\br _\b*_\be_\bn_\bt);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btm\bma\bat\btc\bch\bh(_\bc_\bh_\ba_\br _\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\bn_\ba_\bm_\be);

     _\bc_\bh_\ba_\br _\b*
     c\bcg\bge\bet\btc\bca\bap\bp(_\bc_\bh_\ba_\br _\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\bc_\ba_\bp, _\bc_\bh_\ba_\br _\bt_\by_\bp_\be);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btn\bnu\bum\bm(_\bc_\bh_\ba_\br _\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\bc_\ba_\bp, _\bl_\bo_\bn_\bg _\b*_\bn_\bu_\bm);

     _\bi_\bn_\bt
     c\bcg\bge\bet\bts\bst\btr\br(_\bc_\bh_\ba_\br _\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\bc_\ba_\bp, _\bc_\bh_\ba_\br _\b*_\b*_\bs_\bt_\br);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btu\bus\bst\btr\br(_\bc_\bh_\ba_\br _\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\bc_\ba_\bp, _\bc_\bh_\ba_\br _\b*_\b*_\bs_\bt_\br);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btf\bfi\bir\brs\bst\bt(_\bc_\bh_\ba_\br _\b*_\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\b*_\bd_\bb_\b__\ba_\br_\br_\ba_\by);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btn\bne\bex\bxt\bt(_\bc_\bh_\ba_\br _\b*_\b*_\bb_\bu_\bf, _\bc_\bh_\ba_\br _\b*_\b*_\bd_\bb_\b__\ba_\br_\br_\ba_\by);

     _\bi_\bn_\bt
     c\bcg\bge\bet\btc\bcl\blo\bos\bse\be(_\bv_\bo_\bi_\bd);

D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
     C\bCg\bge\bet\bte\ben\bnt\bt() extracts the capability rec _\bn_\ba_\bm_\be from the database specified by
     the NULL terminated file array _\bd_\bb_\b__\ba_\br_\br_\ba_\by and returns a pointer to a
     malloc'd  copy of it in _\bb_\bu_\bf. C\bCg\bge\bet\bte\ben\bnt\bt will first look for files ending in
     .\b.d\bdb\bb (see cap_mkdb(1)) before accessing the ASCII file.  _\bB_\bu_\bf must be re-
     tained through all subsequent calls to c\bcg\bge\bet\btm\bma\bat\btc\bch\bh(), c\bcg\bge\bet\btc\bca\bap\bp(), c\bcg\bge\bet\btn\bnu\bum\bm(),
     c\bcg\bge\bet\bts\bst\btr\br(), and c\bcg\bge\bet\btu\bus\bst\btr\br(), but may then be free'd.  On success 0 is re-
     turned, 1 if the returned record contains an unresolved t\btc\bc expansion, -1
     if the requested record couldn't be found, -2 if a system error was en-
     countered (couldn't open/read a file, etc.) also setting _\be_\br_\br_\bn_\bo, and -3 if
     a potential reference loop is detected (see t\btc\bc=\b= comments below).

     C\bCg\bge\bet\bts\bse\bet\bt enables the addition of a character buffer containing a single
     capability record entry to the capability database.  Conceptually, the
     entry is added as the first ``file'' in the database, and is therefore
     searched first on the call to c\bcg\bge\bet\bte\ben\bnt\bt. The entry is passed in _\be_\bn_\bt. If _\be_\bn_\bt
     is NULL, the current entry is removed from the database.  C\bCg\bge\bet\bts\bse\bet\bt must
     precede the database traversal.  It must be called before the c\bcg\bge\bet\bte\ben\bnt\bt
     call. If a sequential access is being performed (see below), it must be
     called before the first sequential access call ( c\bcg\bge\bet\btf\bfi\bir\brs\bst\bt or c\bcg\bge\bet\btn\bne\bex\bxt\bt ),
     or be directly preceded by a c\bcg\bge\bet\btc\bcl\blo\bos\bse\be call.  On success 0 is returned
     and -1 on failure.

     C\bCg\bge\bet\btm\bma\bat\btc\bch\bh will return 0 if _\bn_\ba_\bm_\be is one of the names of the capability
     record _\bb_\bu_\bf, -1 if not.


     C\bCg\bge\bet\btc\bca\bap\bp searches the capability record _\bb_\bu_\bf for the capability _\bc_\ba_\bp with
     type _\bt_\by_\bp_\be. A _\bt_\by_\bp_\be is specified using any single character.  If a colon
     (`:') is used, an untyped capability will be searched for (see below for
     explanation of types).  A pointer to the value of _\bc_\ba_\bp in _\bb_\bu_\bf is returned
     on success, NULL if the requested capability couldn't be found.  The end
     of the capability value is signaled by a `:' or ASCII NUL (see below for
     capability database syntax).

     C\bCg\bge\bet\btn\bnu\bum\bm retrieves the value of the numeric capability _\bc_\ba_\bp from the capa-
     bility record pointed to by _\bb_\bu_\bf. The numeric value is returned in the
     _\bl_\bo_\bn_\bg pointed to by _\bn_\bu_\bm. 0 is returned on success, -1 if the requested nu-
     meric capability couldn't be found.

     C\bCg\bge\bet\bts\bst\btr\br retrieves the value of the string capability _\bc_\ba_\bp from the capa-
     bility record pointed to by _\bb_\bu_\bf. A pointer to a decoded, NUL terminated,
     malloc'd  copy of the string is returned in the _\bc_\bh_\ba_\br _\b* pointed to by _\bs_\bt_\br.
     The number of characters in the decoded string not including the trailing
     NUL is returned on success, -1 if the requested string capability
     couldn't be found, -2 if a system error was encountered (storage alloca-
     tion failure).

     C\bCg\bge\bet\btu\bus\bst\btr\br is identical to c\bcg\bge\bet\bts\bst\btr\br except that it does not expand special
     characters, but rather returns each character of the capability string
     literally.

     C\bCg\bge\bet\btf\bfi\bir\brs\bst\bt, c\bcg\bge\bet\btn\bne\bex\bxt\bt, comprise a function group that provides for sequen-
     tial access of the NULL pointer terminated array of file names, _\bd_\bb_\b__\ba_\br_\br_\ba_\by.
     C\bCg\bge\bet\btf\bfi\bir\brs\bst\bt returns the first record in the database and resets the access
     to the first record.  C\bCg\bge\bet\btn\bne\bex\bxt\bt returns the next record in the database
     with respect to the record returned by the previous c\bcg\bge\bet\btf\bfi\bir\brs\bst\bt or c\bcg\bge\bet\btn\bne\bex\bxt\bt
     call.  If there is no such previous call, the first record in the
     database is returned.  Each record is returned in a malloc'd  copy point-
     ed to by _\bb_\bu_\bf. T\bTc\bc expansion is done (see t\btc\bc=\b= comments below).  Upon com-
     pletion of the database 0 is returned,  1 is returned upon successful re-
     turn of record with possibly more remaining (we haven't reached the end
     of the database yet), 2 is returned if the record contains an unresolved
     t\btc\bc expansion, -1 is returned if an system error occured, and -2 is re-
     turned if a potential reference loop is detected (see t\btc\bc=\b= comments be-
     low).  Upon completion of database (0 return) the database is closed.

     C\bCg\bge\bet\btc\bcl\blo\bos\bse\be closes the sequential access and frees any memory and file de-
     scriptors being used.  Note that it does not erase the buffer pushed by a
     call to c\bcg\bge\bet\bts\bse\bet\bt.

C\bCA\bAP\bPA\bAB\bBI\bIL\bLI\bIT\bTY\bY D\bDA\bAT\bTA\bAB\bBA\bAS\bSE\bE S\bSY\bYN\bNT\bTA\bAX\bX
     Capability databases are normally ASCII and may be edited with standard
     text editors.  Blank lines and lines beginning with a `#' are comments
     and are ignored.  Lines ending with a `\' indicate that the next line is
     a continuation of the current line; the `\' and following newline are ig-
     nored.  Long lines are usually continued onto several physical lines by
     ending each line except the last with a `\'.

     Capability databases consist of a series of records, one per logical
     line.  Each record contains a variable number of `:'-separated fields
     (capabilities).  Empty fields consisting entirely of white space charac-
     ters (spaces and tabs) are ignored.

     The first capability of each record specifies its names, separated by `|'
     characters.  These names are used to reference records in the database.
     By convention, the last name is usually a comment and is not intended as
     a lookup tag.  For example, the _\bv_\bt_\b1_\b0_\b0 record from the t\bte\ber\brm\bmc\bca\bap\bp database
     begins:

           d0|vt100|vt100-am|vt100am|dec vt100:


     giving four names that can be used to access the record.

     The remaining non-empty capabilities describe a set of (name, value)
     bindings, consisting of a names optionally followed by a typed values:

     name          typeless [boolean] capability _\bn_\ba_\bm_\be is present [true]
     name_\bTvalue    capability (_\bn_\ba_\bm_\be, _\bT) has value _\bv_\ba_\bl_\bu_\be
     name@         no capability _\bn_\ba_\bm_\be exists
     name_\bT@        capability (_\bn_\ba_\bm_\be, _\bT) does not exist

     Names consist of one or more characters.  Names may contain any character
     except `:', but it's usually best to restrict them to the printable char-
     acters and avoid use of graphics like `#', `=', `%', `@', etc.  Types are
     single characters used to separate capability names from their associated
     typed values.  Types may be any character except a `:'.  Typically,
     graphics like `#', `=', `%', etc. are used.  Values may be any number of
     characters and may contain any character except `:'.

C\bCA\bAP\bPA\bAB\bBI\bIL\bLI\bIT\bTY\bY D\bDA\bAT\bTA\bAB\bBA\bAS\bSE\bE S\bSE\bEM\bMA\bAN\bNT\bTI\bIC\bCS\bS
     Capability records describe a set of (name, value) bindings.  Names may
     have multiple values bound to them.  Different values for a name are dis-
     tinguished by their _\bt_\by_\bp_\be_\bs. C\bCg\bge\bet\btc\bca\bap\bp will return a pointer to a value of a
     name given the capability name and the type of the value.

     The types `#' and `=' are conventionally used to denote numeric and
     string typed values, but no restriction on those types is enforced.  The
     functions c\bcg\bge\bet\btn\bnu\bum\bm and c\bcg\bge\bet\bts\bst\btr\br can be used to implement the traditional
     syntax and semantics of `#' and `='.  Typeless capabilities are typically
     used to denote boolean objects with presence or absence indicating truth
     and false values respectively.  This interpretation is conveniently rep-
     resented by:

           (getcap(buf, name, ':') != NULL)

     A special capability, t\btc\bc=\b= n\bna\bam\bme\be, is used to indicate that the record spec-
     ified by _\bn_\ba_\bm_\be should be substituted for the t\btc\bc capability.  T\bTc\bc capabili-
     ties may interpolate records which also contain t\btc\bc capabilities and more
     than one t\btc\bc capability may be used in a record.  A t\btc\bc expansion scope
     (i.e., where the argument is searched for) contains the file in which the
     t\btc\bc is declared and all subsequent files in the file array.

     When a database is searched for a capability record, the first matching
     record in the search is returned.  When an record is scanned for a capa-
     bility, the first matching capability is returned; the capability
     :\b:n\bna\bam\bme\beT\bT@\b@:\b: will hide any following definition of a value of type _\bT for
     _\bn_\ba_\bm_\be; and the capability :\b:n\bna\bam\bme\be@\b@:\b: will prevent any following values of
     _\bn_\ba_\bm_\be from being seen.

     These features combined with t\btc\bc capabilities can be used to generate
     variations of other databases and records by either adding new capabili-
     ties, overriding definitions with new definitions, or hiding following
     definitions via `@' capabilities.

E\bEX\bXA\bAM\bMP\bPL\bLE\bES\bS
           example|an example of binding multiple values to names:\
                :foo%bar:foo^blah:foo@:\
                :abc%xyz:abc^frap:abc$@:\
                :tc=more:

     The capability foo has two values bound to it (bar of type `%' and blah
     of type `^') and any other value bindings are hidden.  The capability abc
     also has two values bound but only a value of type `$' is prevented from
     being defined in the capability record more.


           file1:
                new|new_record|a modification of "old":\
                     :fript=bar:who-cares@:tc=old:blah:tc=extensions:
           file2:
                old|old_record|an old database record:\
                     :fript=foo:who-cares:glork#200:

     The records are extracted by calling c\bcg\bge\bet\bte\ben\bnt\bt with file1 preceding file2.
     In the capability record new in file1, fript=bar overrides the definition
     of fript=foo interpolated from the capability record old in file2, who-
     cares@ prevents the definition of any who-cares definitions in old from
     being seen, glork#200 is inherited from old, and blah and anything de-
     fined by the record extensions is added to those definitions in old.
     Note that the position of the fript=bar and who-cares@ definitions before
     tc=old is important here.  If they were after, the definitions in old
     would take precedence.

C\bCG\bGE\bET\bTN\bNU\bUM\bM A\bAN\bND\bD C\bCG\bGE\bET\bTS\bST\bTR\bR S\bSY\bYN\bNT\bTA\bAX\bX A\bAN\bND\bD S\bSE\bEM\bMA\bAN\bNT\bTI\bIC\bCS\bS
     Two types are predefined by c\bcg\bge\bet\btn\bnu\bum\bm and c\bcg\bge\bet\bts\bst\btr\br:

     _\bn_\ba_\bm_\be#_\bn_\bu_\bm_\bb_\be_\br    numeric capability _\bn_\ba_\bm_\be has value _\bn_\bu_\bm_\bb_\be_\br
     _\bn_\ba_\bm_\be=_\bs_\bt_\br_\bi_\bn_\bg    string capability _\bn_\ba_\bm_\be has value _\bs_\bt_\br_\bi_\bn_\bg
     _\bn_\ba_\bm_\be#@         the numeric capability _\bn_\ba_\bm_\be does not exist
     _\bn_\ba_\bm_\be=@         the string capability _\bn_\ba_\bm_\be does not exist

     Numeric capability values may be given in one of three numeric bases.  If
     the number starts with either `0x' or `0X' it is interpreted as a hex-
     adecimal number (both upper and lower case a-f may be used to denote the
     extended hexadecimal digits).  Otherwise, if the number starts with a `0'
     it is interpreted as an octal number.  Otherwise the number is interpret-
     ed as a decimal number.

     String capability values may contain any character.  Non-printable ASCII
     codes, new lines, and colons may be conveniently represented by the use
     of escape sequences:

     ^X        ('_\bX' & 037)          control-_\bX
     \b, \B    (ASCII 010)          backspace
     \t, \T    (ASCII 011)          tab
     \n, \N    (ASCII 012)          line feed (newline)
     \f, \F    (ASCII 014)          form feed
     \r, \R    (ASCII 015)          carriage return
     \e, \E    (ASCII 027)          escape
     \c, \C    (:)                  colon
     \\        (\)                  back slash
     \^        (^)                  caret
     \_\bn_\bn_\bn      (ASCII octal _\bn_\bn_\bn)

     A `\' may be followed by up to three octal digits directly specifies the
     numeric code for a character.  The use of ASCII NULs, while easily encod-
     ed, causes all sorts of problems and must be used with care since NULs
     are typically used to denote the end of strings; many applications use
     `\200' to represent a NUL.

D\bDI\bIA\bAG\bGN\bNO\bOS\bST\bTI\bIC\bCS\bS
     C\bCg\bge\bet\bte\ben\bnt\bt, c\bcg\bge\bet\bts\bse\bet\bt, c\bcg\bge\bet\btm\bma\bat\btc\bch\bh, c\bcg\bge\bet\btn\bnu\bum\bm, c\bcg\bge\bet\bts\bst\btr\br, c\bcg\bge\bet\btu\bus\bst\btr\br, c\bcg\bge\bet\btf\bfi\bir\brs\bst\bt, and
     c\bcg\bge\bet\btn\bne\bex\bxt\bt return a a value greater than or equal to 0 on success and a
     value less than 0 on failure.  C\bCg\bge\bet\btc\bca\bap\bp returns a character pointer on
     success and a NULL on failure.

     C\bCg\bge\bet\bte\ben\bnt\bt, and c\bcg\bge\bet\bts\bse\beq\bq may fail and set _\be_\br_\br_\bn_\bo for any of the errors speci-
     fied for the library functions: fopen(2),  fclose(2),  open(2),  and
     close(2).

     C\bCg\bge\bet\bte\ben\bnt\bt, c\bcg\bge\bet\bts\bse\bet\bt, c\bcg\bge\bet\bts\bst\btr\br, and c\bcg\bge\bet\btu\bus\bst\btr\br may fail and set _\be_\br_\br_\bn_\bo as fol-

     lows:

     [ENOMEM]      No memory to allocate.

S\bSE\bEE\bE A\bAL\bLS\bSO\bO
     cap_mkdb(1),  malloc(3)

B\bBU\bUG\bGS\bS
     Colons (`:') can't be used in names, types, or values.

     There are no checks for t\btc\bc=\b=n\bna\bam\bme\be loops in c\bcg\bge\bet\bte\ben\bnt\bt.

     The buffer added to the database by a call to c\bcg\bge\bet\bts\bse\bet\bt is not unique to
     the database but is rather prepended to any database used.

4.4BSD                           June 4, 1993                                5