ICONV(3P) POSIX Programmer's Manual ICONV(3P)
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
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 corre-
sponding characters in another codeset, in the array specified by out-
buf. 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 indi-
cates 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 success-
fully 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 fol-
lowing 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 out-
put 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 code-
set, iconv() shall perform an implementation-defined conversion on this
character.
RETURN VALUE
The iconv() function shall update the variables pointed to by the argu-
ments 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 buf-
fer.
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-termi-
nated 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(), mbsrtowcs()
The Base Definitions volume of POSIX.1-2008, <iconv.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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.ker-
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ICONV(3P)
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