'\" et
.TH ICONV "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH 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.
.\"
.SH NAME
iconv
\(em codeset conversion function
.SH SYNOPSIS
.LP
.nf
#include <iconv.h>
.P
size_t iconv(iconv_t \fIcd\fP, char **restrict \fIinbuf\fP,
    size_t *restrict \fIinbytesleft\fP, char **restrict \fIoutbuf\fP,
    size_t *restrict \fIoutbytesleft\fP);
.fi
.SH DESCRIPTION
The
\fIiconv\fR()
function shall convert the sequence of characters from one codeset,
in the array specified by
.IR inbuf ,
into a sequence of corresponding characters in another codeset, in the
array specified by
.IR outbuf .
The codesets are those specified in the
\fIiconv_open\fR()
call that returned the conversion descriptor,
.IR cd .
The
.IR inbuf
argument points to a variable that points to the first character in the
input buffer and
.IR inbytesleft
indicates the number of bytes to the end of the buffer to be
converted. The
.IR outbuf
argument points to a variable that points to the first available byte
in the output buffer and
.IR outbytesleft
indicates the number of the available bytes to the end of the buffer.
.P
For state-dependent encodings, the conversion descriptor
.IR cd
is placed into its initial shift state by a call for which
.IR inbuf
is a null pointer, or for which
.IR inbuf
points to a null pointer. When
\fIiconv\fR()
is called in this way, and if
.IR outbuf
is not a null pointer or a pointer to a null pointer, and
.IR outbytesleft
points to a positive value,
\fIiconv\fR()
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,
\fIiconv\fR()
shall fail and set
.IR errno
to
.BR [E2BIG] .
Subsequent calls with
.IR 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.
.P
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
.IR inbuf
shall be updated to point to the byte following the last byte
successfully used in the conversion. The value pointed to by
.IR inbytesleft
shall be decremented to reflect the number of bytes still not converted
in the input buffer. The variable pointed to by
.IR outbuf
shall be updated to point to the byte following the last byte of
converted output data. The value pointed to by
.IR 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.
.P
If
\fIiconv\fR()
encounters a character in the input buffer that is valid, but for which
an identical character does not exist in the target codeset,
\fIiconv\fR()
shall perform an implementation-defined conversion on this character.
.SH "RETURN VALUE"
The
\fIiconv\fR()
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
.IR inbytesleft
shall be 0. If the input conversion is stopped due to any conditions
mentioned above, the value pointed to by
.IR inbytesleft
shall be non-zero and
.IR errno
shall be set to indicate the condition. If an error occurs,
\fIiconv\fR()
shall return (\fBsize_t\fP)\-1 and set
.IR errno
to indicate the error.
.SH ERRORS
The
\fIiconv\fR()
function shall fail if:
.TP
.BR EILSEQ
Input conversion stopped due to an input byte that does not belong to
the input codeset.
.TP
.BR E2BIG
Input conversion stopped due to lack of space in the output buffer.
.TP
.BR EINVAL
Input conversion stopped due to an incomplete character or shift
sequence at the end of the input buffer.
.P
The
\fIiconv\fR()
function may fail if:
.TP
.BR EBADF
The
.IR cd
argument is not a valid open conversion descriptor.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
The
.IR inbuf
argument indirectly points to the memory area which contains the
conversion input data. The
.IR outbuf
argument indirectly points to the memory area which is to contain the
result of the conversion. The objects indirectly pointed to by
.IR inbuf
and
.IR outbuf
are not restricted to containing data that is directly representable in
the ISO\ C standard language
.BR char
data type. The type of
.IR inbuf
and
.IR outbuf ,
.BR "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
.IR inbuf
and/or
.IR 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 (\c
.BR char ,
.BR short ,
.BR 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
.IR fromcode
and
.IR tocode
arguments of
\fIiconv_open\fR().
.P
Regardless of the data type inferred by the converter, the size of the
remaining space in both input and output objects (the
.IR intbytesleft
and
.IR outbytesleft
arguments) is always measured in bytes.
.P
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.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIiconv_open\fR\^(\|)",
.IR "\fIiconv_close\fR\^(\|)",
.IR "\fImbsrtowcs\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<iconv.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 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 .
.PP
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.kernel.org/doc/man-pages/reporting_bugs.html .