catclose(3C)
NAME
catopen, catclose - open/close a message catalog
SYNOPSIS
#include <nl_types.h>
nl_catd catopen(const char *name, int oflag);
int catclose(nl_catd catd);
DESCRIPTION
The catopen() function opens a message catalog and returns a
message catalog descriptor. name specifies the name of the
message catalog to be opened. If name contains a "/", then
name specifies a complete pathname for the message catalog;
otherwise, the environment variable NLSPATH is used and
/usr/lib/locale/locale/LC_MESSAGES must exist. If NLSPATH
does not exist in the environment, or if a message catalog
cannot be opened in any of the paths specified by NLSPATH,
then the default path /usr/lib/locale/locale/LC_MESSAGES is
used. In the "C" locale, catopen() will always succeed
without checking the default search path.
The names of message catalogs and their location in the
filesystem can vary from one system to another. Individual
applications can choose to name or locate message catalogs
according to their own special needs. A mechanism is there-
fore required to specify where the catalog resides.
The NLSPATH variable provides both the location of message
catalogs, in the form of a search path, and the naming con-
ventions associated with message catalog files. For exam-
ple:
NLSPATH=/nlslib/%L/%N.cat:/nlslib/%N/%L
The metacharacter % introduces a substitution field, where
%L substitutes the current setting of either the LANG
environment variable, if the value of oflag is 0, or the
LC_MESSAGES category, if the value of oflag is
NL_CAT_LOCALE, and %N substitutes the value of the name
parameter passed to catopen(). Thus, in the above example,
catopen() will search in /nlslib/$LANG/name.cat, if oflag
is 0, or in /nlslib/{LC_MESSAGES}/name.cat, if oflag is
NL_CAT_LOCALE.
The NLSPATH variable will normally be set up on a system
wide basis (in /etc/profile) and thus makes the location and
naming conventions associated with message catalogs tran-
sparent to both programs and users.
The full set of metacharacters is:
%N The value of the name parameter passed to catopen().
%L The value of LANG or LC_MESSAGES.
%l The value of the language element of LANG or
LC_MESSAGES.
%t The value of the territory element of LANG or
LC_MESSAGES.
%c The value of the codeset element of LANG or
LC_MESSAGES.
%% A single %.
The LANG environment variable provides the ability to
specify the user's requirements for native languages, local
customs and character set, as an ASCII string in the form
LANG=language[_territory[.codeset]]
A user who speaks German as it is spoken in Austria and has
a terminal which operates in ISO 8859/1 codeset, would want
the setting of the LANG variable to be
LANG=De_A.88591
With this setting it should be possible for that user to
find any relevant catalogs should they exist.
Should the LANG variable not be set, the value of
LC_MESSAGES as returned by setlocale() is used. If this is
NULL, the default path as defined in <nl_types.h> is used.
A message catalogue descriptor remains valid in a process
until that process closes it, or a successful call to one of
the exec functions. A change in the setting of the
LC_MESSAGES category may invalidate existing open catalo-
gues.
If a file descriptor is used to implement message catalogue
descriptors, the FD_CLOEXEC flag will be set; see <fcntl.h>.
If the value of oflag argument is 0, the LANG environment
variable is used to locate the catalogue without regard to
the LC_MESSAGES category. If the oflag argument is
NL_CAT_LOCALE, the LC_MESSAGES category is used to locate
the message catalogue.
The catclose() function closes the message catalog identi-
fied by catd. If a file descriptor is used to implement the
type nl_catd, that file descriptor will be closed.
RETURN VALUES
Upon successful completion, catopen() returns a message
catalog descriptor for use on subsequent calls to cat-
gets() and catclose(). Otherwise it returns (nl_catd) -1.
Upon successful completion, catclose() returns 0. Otherwise
it returns -1 and sets errno to indicate the error.
ERRORS
The catopen() function may fail if:
EACCES
Search permission is denied for the component of the
path prefix of the message catalogue or read permis-
sion is denied for the message catalogue.
EMFILE
There are OPEN_MAX file descriptors currently open in
the calling process.
ENAMETOOLONG
The length of the pathname of the message catalogue
exceeds PATH_MAX, or a pathname component is longer
than NAME_MAX.
ENAMETOOLONG
Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds PATH_MAX.
ENFILE
Too many files are currently open in the system.
ENOENT
The message catalogue does not exist or the name argu-
ment points to an empty string.
ENOMEM
Insufficient storage space is available.
ENOTDIR
A component of the path prefix of the message catalo-
gue is not a directory.
The catclose() function may fail if:
EBADF The catalogue descriptor is not valid.
EINTR The catclose() function was interrupted by a signal.
USAGE
The catopen() and catclose() functions can be used safely in
multithreaded applications, as long as setlocale(3C) is not
being called to change the locale.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Standard |
|_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
SEE ALSO
gencat(1), catgets(3C), gettext(3C), nl_types(3HEAD),
setlocale(3C), attributes(5), environ(5)
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