Originální popis anglicky:
catopen, catclose - open/close a message catalog
Návod, kniha: Library Functions Manual
#include <nl_types.h>
nl_catd catopen(const char *name, int flag);
int catclose(nl_catd catalog);
The function
catopen() opens a message catalog and returns a catalog
descriptor. The descriptor remains valid until catclose() or exec(). If a file
descriptor is used to implement catalog descriptors then the FD_CLOEXEC flag
will be set.
The argument
name specifies the name of the message catalog to be opened.
If
name specifies and absolute path (i.e., contains a '/'), then
name specifies a pathname for the message catalog. Otherwise, the
environment variable
NLSPATH is used with
name substituted for
%N (see
locale(7)). It is unspecified whether
NLSPATH
will be used when the process has root privileges. If
NLSPATH does not
exist in the environment, or if a message catalog cannot be opened in any of
the paths specified by it, then an implementation defined path is used. This
latter default path may depend on the
LC_MESSAGES locale setting when
the
flag argument is
NL_CAT_LOCALE and on the
LANG
environment variable when the
flag argument is 0. Changing the
LC_MESSAGES part of the locale may invalidate open catalog descriptors.
The
flag argument to
catopen() is used to indicate the source for
the language to use. If it is set to
NL_CAT_LOCALE then it will use the
current locale setting for
LC_MESSAGES. Otherwise it will use the
LANG environment variable.
The function
catclose() closes the message catalog identified by
catalog. It invalidates any subsequent references to the message
catalog defined by
catalog.
The function
catopen() returns a message catalog descriptor of type
nl_catd on success. On failure, it returns (nl_catd) -1 and sets
errno to indicate the error. The possible error values include all
possible values for the
open() call.
The function
catclose() returns 0 on success, or -1 on failure.
- LC_MESSAGES
- May be the source of the LC_MESSAGES locale setting, and
thus determine the language to use if flag is set to
NL_CAT_LOCALE.
- LANG
- The language to use if flag is 0.
The above is the POSIX 1003.1-2001 description. The glibc value for
NL_CAT_LOCALE is 1. (Compare MCLoadAll below.) The default path varies, but
usually looks at a number of places below
/usr/share/locale.
These functions are available for Linux since libc 4.4.4c. In the case of linux
libc4 and libc5, the catalog descriptor
nl_catd is a mmap()'ed area of
memory and not a file descriptor. The
flag argument to
catopen()
should be either
MCLoadBySet (=0) or
MCLoadAll (=1). The former
value indicates that a set from the catalog is to be loaded when needed,
whereas the latter causes the initial call to
catopen() to load the
entire catalog into memory. The default search path varies, but usually looks
at a number of places below
/etc/locale and
/usr/lib/locale.
POSIX 1003.1-2001. In XPG 1987, Vol. 3 it says:
The flag argument of catopen
is reserved for future use and should be set to 0. It is unclear
what the source was for the constants MCLoadBySet and MCLoadAll.
catgets(3),
setlocale(3)
