catopen, catclose — open/close a message catalog
#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 execve(2). 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(2) 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.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(2)'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.1-2001. It is unclear what the source was for the constants MCLoadBySet and MCLoadAll.
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