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, ^[XSI]  the environment variable NLSPATH is used with name substituted for the %N conversion specification (see XBD 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. ^[XSI] When searching NLSPATH , catopen() shall ignore any files it finds that are not valid message catalog files.

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 XBD 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 name argument contains a '/' and does not name an existing message catalog, the name argument does not contain a '/' and searching ^[XSI] NLSPATH (if set) and then  the implementation-defined default path for a message catalog with that name failed, one or more files exist but all are of an invalid format, 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.

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

XBD 8. Environment Variables , <fcntl.h> , <nl_types.h> ,

CHANGE HISTORY

First released in Issue 2.

Issue 7

Austin Group Interpretation 1003.1-2001 #143 is applied.

SD5-XBD-ERN-4 is applied, changing the definition of the [EMFILE] error.

The catopen() function is moved from the XSI option to the Base.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0045 [324] is applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0054 [645], XSH/TC2-2008/0055 [497], and XSH/TC2-2008/0056 [497] are applied.

Issue 8

Austin Group Defect 1122 is applied, clarifying that catopen() ignores files that are not valid message catalog files when performing an NLSPATH search.

Austin Group Defect 1516 is applied, adding XSI shading to text relating to NLSPATH .