CATOPEN(3)                 POSIX Programmer's Manual                CATOPEN(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       catopen -- open a message catalog

SYNOPSIS
       #include <nl_types.h>

       nl_catd catopen(const char *name, int oflag);

DESCRIPTION
       The catopen() function shall open a message catalog and return a
       message catalog descriptor. The name argument specifies the name of the
       message catalog to be opened. If name contains a ''//'', then name
       specifies a pathname for the message catalog. Otherwise, the
       environment variable NLSPATH is used with name substituted for the %N
       conversion specification (see the Base Definitions volume of
       POSIX.1-2017, Chapter _8, Environment Variables); if NLSPATH exists in
       the environment when the process starts, then if the process has
       appropriate privileges, the behavior of catopen() is undefined. If
       NLSPATH does not exist in the environment, or if a message catalog
       cannot be found in any of the components specified by NLSPATH, then an
       implementation-defined default path shall be used. This default may be
       affected by the setting of LC__MESSAGES if the value of oflag is
       NL_CAT_LOCALE, or the LANG environment variable if oflag is 0.

       A message catalog descriptor shall remain 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 catalogs.

       If a file descriptor is used to implement message catalog descriptors,
       the FD_CLOEXEC flag shall be set; see <fcntl.h>.

       If the value of the oflag argument is 0, the LANG environment variable
       is used to locate the catalog 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 catalog (see the Base
       Definitions volume of POSIX.1-2017, Section 8.2, Internationalization
       Variables).

RETURN VALUE
       Upon successful completion, catopen() shall return a message catalog
       descriptor for use on subsequent calls to catgets() and catclose().
       Otherwise, catopen() shall return (nl_catd) -1 and set 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 catalog or read permission is denied for the
              message catalog.

       EMFILE All file descriptors available to the process are currently
              open.

       ENAMETOOLONG
              The length of a component of a pathname is longer than
              {NAME_MAX}.

       ENAMETOOLONG
              The length of a pathname exceeds {PATH_MAX}, or pathname
              resolution of a symbolic link produced an intermediate result
              with a length that exceeds {PATH_MAX}.

       ENFILE Too many files are currently open in the system.

       ENOENT The message catalog does not exist or the name argument points
              to an empty string.

       ENOMEM Insufficient storage space is available.

       ENOTDIR
              A component of the path prefix of the message catalog names an
              existing file that is neither a directory nor a symbolic link to
              a directory, or the pathname of the message catalog contains at
              least one non-<slash> character and ends with one or more
              trailing <slash> characters and the last pathname component
              names an existing file that is neither a directory nor a
              symbolic link to a directory.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       Some implementations of catopen() use malloc() to allocate space for
       internal buffer areas. The catopen() function may fail if there is
       insufficient storage space available to accommodate these buffers.

       Conforming applications must assume that message catalog descriptors
       are not valid after a call to one of the exec functions.

       Application developers should be aware that guidelines for the location
       of message catalogs have not yet been developed. Therefore they should
       take care to avoid conflicting with catalogs used by other applications
       and the standard utilities.

       To be sure that messages produced by an application running with
       appropriate privileges cannot be used by an attacker setting an
       unexpected value for NLSPATH in the environment to confuse a system
       administrator, such applications should use pathnames containing a ''//''
       to get defined behavior when using catopen() to open a message catalog.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       catclose(), catgets()

       The Base Definitions volume of POSIX.1-2017, Chapter _8, Environment
       Variables, <fcntl.h>, <nl_types.h>,

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                           CATOPEN(3)
