NAME
iconv - codeset conversion function
SYNOPSIS
#include <iconv.h>
size_t iconv(iconv_t cd, char **restrict inbuf,
size_t *restrict inbytesleft, char **restrict outbuf,
size_t *restrict outbytesleft);
DESCRIPTION
The iconv() function shall convert 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 iconv_open() call that
returned the conversion descriptor, cd. The inbuf argument 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 argument 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 iconv() 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, iconv()
shall place, 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, iconv() shall fail and
set 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 shall stop after the previous
successfully converted character. If the input buffer ends with an
incomplete character or shift sequence, conversion shall stop after the
previous successfully converted bytes. If the output buffer is not
large enough to hold the entire converted input, conversion shall stop
just prior to the input bytes that would cause the output buffer to
overflow. The variable pointed to by inbuf shall be updated to point to
the byte following the last byte successfully used in the conversion.
The value pointed to by inbytesleft shall be decremented to reflect the
number of bytes still not converted in the input buffer. The variable
pointed to by outbuf shall be updated to point to the byte following
the last byte of converted output data. The value pointed to by
outbytesleft shall be decremented to reflect the number of bytes still
available in the output buffer. For state-dependent encodings, the
conversion descriptor shall be updated to reflect the shift state in
effect at the end of the last successfully converted byte sequence.
If iconv() encounters a character in the input buffer that is valid,
but for which an identical character does not exist in the target
codeset, iconv() shall perform an implementation-defined conversion on
this character.
RETURN VALUE
The iconv() function shall update the variables pointed to by the
arguments to reflect the extent of the conversion and return the number
of non-identical conversions performed. If the entire string in the
input buffer is converted, the value pointed to by inbytesleft shall be
0. If the input conversion is stopped due to any conditions mentioned
above, the value pointed to by inbytesleft shall be non-zero and errno
shall be set to indicate the condition. If an error occurs, iconv()
shall return (size_t)-1 and set errno to indicate the error.
ERRORS
The iconv() function shall fail if:
EILSEQ Input conversion stopped due to an input byte that does not
belong to the input codeset.
E2BIG Input conversion stopped due to lack of space in the output
buffer.
EINVAL Input conversion stopped due to an incomplete character or shift
sequence at the end of the input buffer.
The iconv() function may fail if:
EBADF The cd argument is not a valid open conversion descriptor.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The inbuf argument indirectly points to the memory area which contains
the conversion input data. The outbuf argument indirectly points to the
memory area which is to contain the result of the conversion. The
objects indirectly pointed to by inbuf and outbuf are not restricted to
containing data that is directly representable in the ISO C standard
language char data type. The type of inbuf and outbuf, char **, does
not imply that the objects pointed to are interpreted as null-
terminated C strings or arrays of characters. Any interpretation of a
byte sequence that represents a character in a given character set
encoding scheme is done internally within the codeset converters. For
example, the area pointed to indirectly by inbuf and/or outbuf can
contain all zero octets that are not interpreted as string terminators
but as coded character data according to the respective codeset
encoding scheme. The type of the data ( char, short, long, and so on)
read or stored in the objects is not specified, but may be inferred for
both the input and output data by the converters determined by the
fromcode and tocode arguments of iconv_open().
Regardless of the data type inferred by the converter, the size of the
remaining space in both input and output objects (the intbytesleft and
outbytesleft arguments) is always measured in bytes.
For implementations that support the conversion of state-dependent
encodings, the conversion descriptor must be able to accurately reflect
the shift-state in effect at the end of the last successful conversion.
It is not required that the conversion descriptor itself be updated,
which would require it to be a pointer type. Thus, implementations are
free to implement the descriptor as a handle (other than a pointer
type) by which the conversion information can be accessed and updated.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
iconv_open() , iconv_close() , the Base Definitions volume of
IEEE Std 1003.1-2001, <iconv.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .