CATOPEN(3POSIX)

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

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 .