RUNE(3)

NAME
setrunelocale, setinvalidrune, sgetrune, sputrune - rune support for C

SYNOPSIS
#include <rune.h>
#include <errno.h>
int
setrunelocale(char *locale);
void
setinvalidrune(rune_t rune);
rune_t
sgetrune(const char *string, size_t n, char const **result);
int
sputrune(rune_t rune, char *string, size_t n, char **result);

#include <stdio.h>
long
fgetrune(FILE *stream);
int
fungetrune(rune_t rune, FILE *stream);
int
fputrune(rune_t rune, FILE *stream);

DESCRIPTION
The setrunelocale() controls the type of encoding used to represent runes as multibyte strings as well as the properties of the runes as defined in <ctype.h>. The locale argument indicates which locale to load. If the locale is successfully loaded, 0 is returned, otherwise an errno value is returned to indicate the type of error.

The setinvalidrune() function sets the value of the global value _INVALID_RUNE to be rune.

The sgetrune() function tries to read a single multibyte character from string, which is at most n bytes long. If sgetrune() is successful, the rune is returned. If result is not NULL, *result will point to the first byte which was not converted in string. If the first n bytes of string do not describe a full multibyte character, _INVALID_RUNE is returned and *result will point to string. If there is an encoding error at the start of string, _INVALID_RUNE is returned and *result will point to the second character of string.

the sputrune() function tries to encode rune as a multibyte string and store it at string, but no more than n bytes will be stored. If result is not NULL, *result will be set to point to the first byte in string following the new multibyte character. If string is NULL, *result will point to (char *)0 + x, where x is the number of bytes that would be needed to store the multibyte value. If the multibyte character would consist of more than n bytes and result is not NULL, *result will be set to NULL. In all cases, sputrune() will return the number of bytes which would be needed to store rune as a multibyte character.

The fgetrune() function operates the same as sgetrune() with the exception that it attempts to read enough bytes from stream to decode a single rune. It returns either EOF on end of file, _INVALID_RUNE on an encoding error, or the rune decoded if all went well.

The fungetrune() function pushes the multibyte encoding, as provided by sputrune(), of rune onto stream such that the next fgetrune() call will return rune. It returns EOF if it fails and 0 on success.

The fputrune() function writes the multibyte encoding of rune, as provided by sputrune(), onto stream. It returns EOF on failure and 0 on success.

RETURN VALUES
The setrunelocale() function returns one of the following values:

0   setrunelocale was successful.

EFAULT
    locale was NULL.

ENOENT
    The locale could not be found.

EFTYPE
    The file found was not a valid file.

EINVAL
    The encoding indicated by the locale was unknown.

The sgetrune() function either returns the rune read or _INVALID_RUNE. The sputrune() function returns the number of bytes needed to store rune as a multibyte string.

FILES
$PATH_LOCALE/locale/LC_CTYPE
/usr/share/locale/locale/LC_CTYPE
    binary LC_CTYPE file for the locale locale.

SEE ALSO
mbrune(3), setlocale(3), euc(4), utf2(4)

NOTE
The ANSI C type wchar_t is the same as rune_t. Rune_t was chosen to accent the purposeful choice of not basing the system with the ANSI C primitives, which were, shall we say, less aesthetic.

HISTORY
These functions first appeared in 4.4BSD.

The setrunelocale() function and the other non-ANSI rune functions were inspired by Plan 9 from Bell Labs as a much more sane alternative to the ANSI multibyte and wide character support.

All of the ANSI multibyte and wide character support functions are built using the rune functions.