int
cgetent(
char **buf
const char * const *db_array, const char *name
)
int
cgetset(
const char *ent
)
int
cgetmatch(
const char *buf
, const char *name
)
char
*
cgetcap(
char *buf
, const char *cap
, int type
)
int
cgetnum(
char *buf
, const char *cap
, long *num
)
int
cgetstr(
char *buf
, const char *cap
, char **str
)
int
cgetustr(
char *buf
, const char *cap
, char **str
)
int
cgetfirst(
char **buf
)const char * const *db_array
int
cgetnext(
char **buf
)const char * const *db_array
int
cgetclose(
void
)
void
csetexpandtc(
int expandtc
)
)
extracts the capability
name
from the database specified by the
NULL
terminated file array
db_array
and returns a pointer to a
malloc(3)Ap d
copy of it in
buf
.
cgetent(
)
will first look for files ending in
.db
(see
cap_mkdb(1))
before accessing the
ASCII
file.
buf
must be retained through all subsequent calls to
cgetmatch(),
cgetcap(
),
cgetnum(
),
cgetstr(
),
and
cgetustr(
),
but may then be
free(3)Ap d.
On success 0 is returned, 1 if the returned record contains an unresolved "tc expansion, -1 if the requested record couldn't be found, -2 if a system error was encountered (couldn't open/read a file, etc.) also setting errno, and -3 if a potential reference loop is detected (see "tc=name 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 therefore 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.
cgetset()
must precede the database traversal.
It must be called before the
cgetent(
)
call.
If a sequential access is being performed (see below), it must be called
before the first sequential access call
(cgetfirst(
) or cgetnext(
),)
or be directly preceded by a
cgetclose(
)
call.
On success 0 is returned and -1 on failure.
cgetmatch()
will return 0 if
name
is one of the names of the capability 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
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).
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
.
0 is returned on success,
-1 if the requested 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,
NUL
terminated,
malloc(3)Ap d
copy of the string is returned in the
char
*
pointed to by
str
.
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 allocation
failure).
cgetustr()
is identical to
cgetstr(
)
except that it does not expand special characters, but rather returns each
character of the capability string literally.
cgetfirst(),
cgetnext(
),
comprise a function group that provides for sequential access of the
NULL
pointer terminated array of file names,
db_array
.
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
cgetfirst(
)
or
cgetnext(
)
call.
If there is no such previous call,
the first record in the database is returned.
Each record is returned in a
malloc(3)Ap d
copy pointed to by
buf
.
"tc
expansion is done (see
"tc=name
comments below).
Upon completion of the database 0 is returned, 1 is returned upon successful return 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 "tc expansion, -1 is returned if an system error occurred, and -2 is returned if a potential reference loop is detected (see "tc=name comments below). Upon completion of database (0 return) the database is closed.
cgetclose()
closes the sequential access and frees any memory and file descriptors
being used.
Note that it does not erase the buffer pushed by a call to
cgetset(
).
Capability databases consist of a series of records, one per logical line. Each record contains a variable number of :`.blm Pp-separated ' fields (capabilities). Empty fields consisting entirely of white space 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 the database.
By convention, the last name is usually a comment and is not intended as
a lookup tag.
For example, the
vt100
record from the
termcap
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 name optionally followed by a typed value:
name | typeless [boolean] capability name is present [true] |
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 any character except `:', but it's usually best to restrict them to the printable characters 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 `:'.
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 enforced.
The functions
cgetnum()
and
cgetstr(
)
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 represented by:
(getcap(buf, name, ':') != NULL)
A special capability,
"tc=name,
is used to indicate that the record specified by
name
should be substituted for the
"tc
capability.
"tc
capabilities 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.
csetexpandtc()
can be used to control if
"tc
expansion is performed or not.
When a database is searched for a capability record, the first matching
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 values of
name
from being seen.
These features combined with "tc capabilities can be used to generate variations of other databases and records by either adding new capabilities, overriding definitions with new definitions, or hiding following definitions via `@' capabilities.
example|an example of binding multiple values to names:\ :foo%bar:foo^blah:foo@:\ :abc%xyz:abc^frap:abc$@:\ :tc=more:
The capability foo has two values bound to it of type `%' and blah of type `^' (bar) and any other value bindings are hidden. The capability abc also has two values bound but only a value of type `$' 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
cgetent()
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 defined 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.
)
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 is interpreted 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:
A
`\'
followed by up to three octal digits directly specifies
the numeric code for a character.
The use of
ASCII
NUL
s,
while easily
encoded, causes all sorts of problems and must be used with care since
NUL
s
are typically used to denote the end of strings; many applications
use
`\200'
to represent a
NUL
.
),
cgetset(
),
cgetmatch(
),
cgetnum(
),
cgetstr(
),
cgetustr(
),
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.
cgetclose(),
cgetent(
),
cgetfirst(
),
and
cgetnext(
)
may fail and set
errno
for any of the errors specified for the library functions:
fopen(3),
fclose(3),
open(2),
and
close(2).
cgetent(),
cgetset(
),
cgetstr(
),
and
cgetustr(
)
may fail and set
errno
as follows:
ENOMEM
]
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.