cgetent, cgetset, cgetmatch, cgetcap, cgetnum, cgetstr,
cgetfirst, cgetnext, cgetclose, cgetusedb - capability
cgetent(char **buf, char **db_array, const char *name);
cgetset(const char *ent);
cgetmatch(char *buf, const char *name);
cgetcap(char *buf, const char *cap, int type);
cgetnum(char *buf, const char *cap, long *num);
cgetstr(char *buf, const char *cap, char **str);
cgetustr(char *buf, const char *cap, char **str);
cgetfirst(char **buf, char **db_array);
cgetnext(char **buf, char **db_array);
The cgetent() function extracts the capability record name
database specified by the null-terminated file array
db_array and returns
a pointer to a copy of it in buf. cgetent() will first look
ending in ``.db'' (see cap_mkdb(1)) before accessing the
ASCII version of
the capability database. buf must be retained through all
calls to cgetmatch(), cgetcap(), cgetnum(), cgetstr(), and
but may then be free'd. On success 0 is returned, 1 if the
record contains an unresolved tc expansion, -1 if the requested record
couldn't be found, -2 if a system error occurred (couldn't
open or read a
file, for example) also setting errno, and -3 if a potential
loop is detected (see tc= comments below).
cgetset() 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
searched first on the call to cgetent(). The entry is
passed in ent. If
ent is NULL, the current entry is removed from the database.
must precede the database traversal. It must be called before cgetent().
If a sequential access is being performed (see below), it
must be called
before the first sequential access call (cgetfirst() or
be directly preceded by a cgetclose() call. On success 0 is
-1 on failure.
cgetmatch() will return 0 if name is one of the names of the
record buf, -1 if not.
cgetcap() searches the capability record buf for the capability cap with
type type. A type 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 cap in buf
on success or NULL if the requested capability couldn't be
end of the capability value is signaled by a `:' or ASCII
NUL (see below
for capability database syntax).
cgetnum() retrieves the value of the numeric capability cap
from the capability
record pointed to by buf. The numeric value is returned in the
long pointed to by num. On success 0 is returned, -1 if the
numeric capability couldn't be found.
cgetstr() retrieves the value of the string capability cap
from the capability
record pointed to by buf. A pointer to a decoded,
malloc'd copy of the string is returned in the char *
pointed to by
str. The number of characters in the decoded string (not
trailing NUL) is returned on success, -1 if the requested
couldn't be found, or -2 if a system error was encountered (storage
cgetustr() is identical to cgetstr() except that it does not
characters, but rather returns each character of the
cgetfirst() and cgetnext() comprise a function group that
sequential access of the null-terminated array of file
cgetfirst() returns the first record in the database and resets the access
to the first record. cgetnext() returns the next
record in the
database with respect to the record returned by the previous
or cgetnext() call. If there is no such previous call, the
in the database is returned. Each record is returned in a
pointed to by buf. tc expansion is done (see tc= comments
completion of the database 0 is returned, 1 is returned upon
return of record with possibly more remaining (we haven't
reached the end
of the database yet), 2 is returned if the record contains
tc expansion, -1 is returned if an system error occurred,
and -2 is returned
if a potential reference loop is detected (see tc=
Upon completion of database (0 return) the database
cgetclose() closes the file descriptor and resets state used
access. If neither the cgetfirst() nor the cgetnext()
have been called, cgetclose() has no effect. Note that it
does not erase
the buffer pushed by a call to cgetset(), nor does it free
the buffer allocated
cgetusedb() allows the user to specify whether to use or ignore database
files ending in ``.db''. If usedb is zero, files ending in
be ignored. If usedb is non-zero, files ending in ``.db''
will be used
in preference to the text version. The default is to process ``.db''
files. cgetusedb() returns the previous setting.
Capability database syntax [Toc] [Back]
Capability databases are normally ASCII and may be edited
text editors. Blank lines and lines beginning with a `#'
and are ignored. Lines ending with a `' indicate that the
next line is
a continuation of the current line; the `' and following
newline are ignored.
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
line. Each record contains a variable number of colon-separated fields
(capabilities). Empty fields consisting entirely of whitespace characters
(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
By convention, the last name is usually a comment and is not
a lookup tag. For example, the ``vt100'' record from the
giving four names that can be used to access the record.
The remaining non-empty capabilities describe a set of
bindings, consisting of a name optionally followed by a
name typeless [boolean] capability name is present
nameTvalue capability (name, T) has value value
name@ no capability name exists
nameT@ capability (name, T) does not exist
Names consist of one or more characters. Names may contain
except `:', but it's usually best to restrict them to the
and avoid use of graphics like `#', `=', `%', `@',
etc. Types are
single characters used to separate capability names from
typed values. Types may be any character except a `:'.
graphics like `#', `=', `%', etc. are used. Values may be
any number of
characters and may contain any character except `:'.
Capability database semantics [Toc] [Back]
Capability records describe a set of (name, value) bindings.
have multiple values bound to them. Different values for a
name are distinguished
by their types. cgetcap() 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
functions cgetnum() and cgetstr() can be used to implement
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
(getcap(buf, name, ':') != NULL)
A special capability, tc= name, is used to indicate that the
by name should be substituted for the tc capability.
may interpolate records which also contain tc capabilities and more
than one tc capability may be used in a record. A tc expansion scope
(i.e., where the argument is searched for) contains the file
in which the
tc is declared and all subsequent files in the file array.
When a database is searched for a capability record, the
record in the search is returned. When a record is scanned
for a capability,
the first matching capability is returned; the capability
:nameT@: will hide any following definition of a value of
type T for
name; and the capability :name@: will prevent any following
name from being seen.
These features combined with tc capabilities can be used to
variations of other databases and records by either adding
overriding definitions with new definitions, or hiding
definitions via `@' capabilities.
cgetnum() and cgetstr() syntax and semantics
Two types are predefined by cgetnum() and cgetstr():
name#number numeric capability name has value number
name=string string capability name has value string
name#@ the numeric capability name does not exist
name=@ the string capability name 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 hexadecimal
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
as a decimal number.
String capability values may contain any character. NonprintCble ASCII
Iodes, new lines, and colons may be conveniently represented
by thI use
0f escape sequences:
0X ('X' & 037) control-X
, T (ASCII 011) tab
0 (ASCII 012) line feed (newline)
,F (ASCIII015)) carriageereturn
\, (ASCII 027) escape
\ ( back slash
nnn (ASCII octal nnn)
A `' followed by up to three octal digits directly specifies
code for a character. The use of ASCII NULs, while easily
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.
example|an example of binding multiple values to
The capability foo has two values bound to it (bar of type
`%' and blah
of type `^') and any other value bindings are hidden. The
also has two values bound but only a value of type `$' is
being defined in the capability record more.
new|new_record|a modification of "old":
old|old_record|an old database record:
The records are extracted by calling cgetent() with file1
file2. In the capability record new in file1, fript=bar
definition of fript=foo interpolated from the capability
record old in
file2, who-cares@ prevents the definition of any who-cares
old from being seen, glork#200 is inherited from old, and
blah and anything
defined by the record extensions is added to those
old. Note that the position of the fript=bar and who-cares@
before tc=old is important here. If they were after, the
old would take precedence.
cgetent(), cgetset(), cgetmatch(), cgetnum(), cgetstr(),
cgetfirst(), and cgetnext() return a value greater than or
equal to 0 on
success and a value less than 0 on failure. cgetcap() returns a character
pointer on success and a NULL on failure.
cgetent() and cgetset() may fail and set errno for any of
specified for the library functions fopen(3), fclose(3),
cgetent(), cgetset(), cgetstr(), and cgetustr() may fail and
set errno as
[ENOMEM] No memory to allocate.
Colon (`:') characters cannot be used in names, types, or
There are no checks for tc=name loops in cgetent().
The buffer added to the database by a call to cgetset() is
not unique to
the database but is rather prepended to any database used.
OpenBSD 3.6 April 19, 1994
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