man-pages/man3p/iconv.3p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "ICONV" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" iconv 
.SH NAME
iconv \- codeset conversion function
.SH SYNOPSIS
.LP
\fB#include <iconv.h>
.br
.sp
size_t iconv(iconv_t\fP \fIcd\fP\fB, char **restrict\fP \fIinbuf\fP\fB,
.br
\ \ \ \ \ \  size_t *restrict\fP \fIinbytesleft\fP\fB, char **restrict\fP
\fIoutbuf\fP\fB,
.br
\ \ \ \ \ \  size_t *restrict\fP \fIoutbytesleft\fP\fB); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIiconv\fP() function shall convert the sequence of characters
from one codeset, in the array specified by \fIinbuf\fP,
into a sequence of corresponding characters in another codeset, in
the array specified by \fIoutbuf\fP. The codesets are those
specified in the \fIiconv_open\fP() call that returned the conversion
descriptor,
\fIcd\fP. The \fIinbuf\fP argument points to a variable that points
to the first character in the input buffer and
\fIinbytesleft\fP indicates the number of bytes to the end of the
buffer to be converted. The \fIoutbuf\fP argument points to a
variable that points to the first available byte in the output buffer
and \fIoutbytesleft\fP indicates the number of the available
bytes to the end of the buffer.
.LP
For state-dependent encodings, the conversion descriptor \fIcd\fP
is placed into its initial shift state by a call for which
\fIinbuf\fP is a null pointer, or for which \fIinbuf\fP points to
a null pointer. When \fIiconv\fP() is called in this way, and
if \fIoutbuf\fP is not a null pointer or a pointer to a null pointer,
and \fIoutbytesleft\fP points to a positive value,
\fIiconv\fP() 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\fP() shall fail and set \fIerrno\fP to [E2BIG].
Subsequent calls with \fIinbuf\fP 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.
.LP
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
\fIinbuf\fP shall be updated to point to the byte following the last
byte successfully used in the conversion. The value pointed
to by \fIinbytesleft\fP shall be decremented to reflect the number
of bytes still not converted in the input buffer. The variable
pointed to by \fIoutbuf\fP shall be updated to point to the byte following
the last byte of converted output data. The value
pointed to by \fIoutbytesleft\fP 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.
.LP
If \fIiconv\fP() encounters a character in the input buffer that is
valid, but for which an identical character does not exist
in the target codeset, \fIiconv\fP() shall perform an implementation-defined
conversion on this character.
.SH RETURN VALUE
.LP
The \fIiconv\fP() 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 \fIinbytesleft\fP shall be 0. If the input conversion is stopped
due to any conditions mentioned above, the value pointed to
by \fIinbytesleft\fP shall be non-zero and \fIerrno\fP shall be set
to indicate the condition. If an error occurs, \fIiconv\fP()
shall return (\fBsize_t\fP)-1 and set \fIerrno\fP to indicate the
error.
.SH ERRORS
.LP
The \fIiconv\fP() function shall fail if:
.TP 7
.B EILSEQ
Input conversion stopped due to an input byte that does not belong
to the input codeset.
.TP 7
.B E2BIG
Input conversion stopped due to lack of space in the output buffer.
.TP 7
.B EINVAL
Input conversion stopped due to an incomplete character or shift sequence
at the end of the input buffer.
.sp
.LP
The \fIiconv\fP() function may fail if:
.TP 7
.B EBADF
The \fIcd\fP argument is not a valid open conversion descriptor.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
The \fIinbuf\fP argument indirectly points to the memory area which
contains the conversion input data. The \fIoutbuf\fP
argument indirectly points to the memory area which is to contain
the result of the conversion. The objects indirectly pointed to
by \fIinbuf\fP and \fIoutbuf\fP are not restricted to containing data
that is directly representable in the ISO\ C standard
language \fBchar\fP data type. The type of \fIinbuf\fP and \fIoutbuf\fP,
\fBchar **\fP, 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 \fIinbuf\fP and/or \fIoutbuf\fP 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 ( \fBchar\fP, \fBshort\fP,
\fBlong\fP, 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 \fIfromcode\fP and \fItocode\fP arguments
of \fIiconv_open\fP().
.LP
Regardless of the data type inferred by the converter, the size of
the remaining space in both input and output objects (the
\fIintbytesleft\fP and \fIoutbytesleft\fP arguments) is always measured
in bytes.
.LP
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
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIiconv_open\fP() , \fIiconv_close\fP() , the Base Definitions
volume of IEEE\ Std\ 1003.1-2001, \fI<iconv.h>\fP
.SH 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 .