iconv.3p (7780B)
- '\" 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 .