illumos: manual page: kiconv.9f

KICONV(9F) Kernel Functions for Drivers KICONV(9F)

NAME

kiconv - buffer-based code conversion function

SYNOPSIS

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

size_t kiconv(kiconv_t cd, char **inbuf, size_t *inbytesleft,
char **outbuf, size_t *outbytesleft, int *errno);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

The parameters for the kiconv function are as follows:

cd
Code conversion descriptor indicating the code conversion
and conversion state.

inbuf
Points to an address of a buffer containing a sequence of
character bytes in fromcode codeset to be converted.
After the conversion, the variable is updated to point to
the byte following the last byte that was successfully
used in the conversion.

inbytesleft
As an input parameter, the number of bytes to be
converted in inbuf. As an output parameter, the number of
bytes in inbuf still not converted after the conversion.

outbuf
Points to an address of a buffer where converted
character bytes in tocode codeset can be saved. After the
conversion, the variable is updated to point to the byte
following the last byte of converted output data.

outbytesleft
As an input parameter, the number of available bytes at
outbuf where converted character bytes can be saved. As
an output parameter, the number of bytes still available
at outbuf after the conversion.

errno
Indicates the error when conversion is not completed or
failed. The following are possible values:

EILSEQ
The input conversion was stopped due to an
input byte that does not belong to the input
codeset.

E2BIG
The input conversion was stopped due to lack
of space in the output buffer.

EINVAL
The input conversion was stopped due to an
incomplete character or shift sequence at
the end of the input buffer.

EBADF
The cd input parameter is not a valid open
code conversion descriptor.

DESCRIPTION

The kiconv() function converts the sequence of characters from one
codeset, in the array specified by inbuf, into a sequence of
corresponding characters in another codeset, in the array specified by
outbuf. The codesets are those specified in the kiconv_open() call that
returned the code conversion descriptor, cd. The inbuf parameter points
to a variable that points to the first character in the input buffer and
inbytesleft indicates the number of bytes to the end of the buffer to be
converted. The outbuf parameter points to a variable that points to the
first available byte in the output buffer and outbytesleft indicates the
number of the available bytes to the end of the buffer.

For state-dependent encodings, the conversion descriptor cd is placed
into its initial shift state by a call for which inbuf is a null pointer,
or for which inbuf points to a null pointer. When kiconv() is called in
this way, and if outbuf is not a null pointer or a pointer to a null
pointer, and outbytesleft points to a positive value, kiconv() places, if
any, into the output buffer, the byte sequence to change the output
buffer to its initial shift state. If the output buffer is not large
enough to hold the entire reset sequence, kiconv() fails and sets errno
to E2BIG. Subsequent calls with inbuf as other than a null pointer or a
pointer to a null pointer cause the conversion to take place from the
current state of the conversion descriptor.

If a sequence of input bytes does not form a valid character in the
specified codeset, conversion stops after the previous successfully
converted character. If the input buffer ends with an incomplete
character or shift sequence, conversion stops after the previous
successfully converted bytes. If the output buffer is not large enough to
hold the entire converted input, conversion stops just prior to the input
bytes that would cause the output buffer to overflow. The variable
pointed to by inbuf is updated to point to the byte following the last
byte that was successfully used in the conversion. The value pointed to
by inbytesleft is decremented to reflect the number of bytes still not
converted in the input buffer. The variable pointed to by outbuf is
updated to point to the byte following the last byte of converted output
data. The value pointed to by outbytesleft is decremented to reflect the
number of bytes still available in the output buffer. For state-dependent
encodings, the conversion descriptor is updated to reflect the shift
state in effect at the end of the last successfully converted byte
sequence.

If kiconv() encounters a character in the input buffer that is legal, but
for which an identical character does not exist in the target codeset,
kiconv() performs an implementation-defined conversion (that is, a non-
identical conversion) on this character.

RETURN VALUES

The kiconv() function updates the variables pointed to by the parameters
to reflect the extent of the conversion and returns the number of non-
identical conversions performed. If the entire string in the input buffer
is converted, the value pointed to by inbytesleft is 0. If the input
conversion is stopped due to any conditions mentioned above, the value
pointed to by inbytesleft is non-zero and errno is set to indicate the
condition. If such and other error occurs, kiconv() returns (size_t)-1
and sets errno to indicate the error.

CONTEXT

kiconv() can be called from user or interrupt context.

EXAMPLES

Example 1: Performing a Simple Conversion

The following example shows how to perform a simple conversion using
kiconv() with a limited size of output buffer:

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

int
doconversion(char *fromcode, char *tocode, char *inbuf, char *outbuf,
size_t inlen, size_t *outlen)
{
kiconv_t cd;
size_t ileft, ret;
int err;

cd = kiconv_open((const char *)tocode, (const char *)fromcode);
if (cd == (kiconv_t)-1) {
/* Cannot open conversion. */
return (-1);
}

ret = kiconv(cd, &inbuf, &inlen, &outbuf, outlen, &err);
if (ret == (size_t)-1)
goto doconv_error_return;

/*
* Reset the conversion descriptor. This will also
* make sure to write to output buffer any saved bytes
* in the conversion descriptor state.
*/
ileft = 0;
ret = kiconv(cd, (char *)NULL, &ileft, &outbuf, outlen, &err);
if (ret == (size_t)-1)
goto doconv_error_return;

(void) kiconv_close(cd);

return (0);

doconv_error_return:
(void) kiconv_close(cd);

/* Need more output buffer. */
if (err == E2BIG)
return (-2);

/* Illegal sequence? */
if (err == EILSEQ)
return (-3);

/* Incomplete character? */
if (err == EINVAL)
return (-4);

/*
* Bad code conversion descriptor or any other unknown error.
*/
return (-5);
}

ATTRIBUTES

NOTES

The iconv(3C) man page also has a good example code that can be
referenced.

October 16, 2007 KICONV(9F)