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ICONV(3)                   Library Functions Manual                   ICONV(3)

NAME
     iconv_open, iconv_close, iconv - codeset conversion functions

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <iconv.h>

     iconv_t
     iconv_open(const char *dstname, const char *srcname);

     int
     iconv_close(iconv_t cd);

     size_t
     iconv(iconv_t cd, char ** restrict src, size_t * restrict srcleft,
         char ** restrict dst, size_t * restrict dstleft);

DESCRIPTION
     The iconv_open() function opens a converter from the codeset srcname to
     the codeset dstname and returns its descriptor.

     The iconv_close() function closes the specified converter cd.

     The iconv() function converts the string in the buffer *src of length
     *srcleft bytes and stores the converted string in the buffer *dst of size
     *dstleft bytes.  After calling iconv(), the values pointed to by src,
     srcleft, dst, and dstleft are updated as follows:

           *src      Pointer to the byte just after the last character
                     fetched.

           *srcleft  Number of remaining bytes in the source buffer.

           *dst      Pointer to the byte just after the last character stored.

           *dstleft  Number of remainder bytes in the destination buffer.

     If the string pointed to by *src contains a byte sequence which is not a
     valid character in the source codeset, the conversion stops just after
     the last successful conversion.  If the output buffer is too small to
     store the converted character, the conversion also stops in the same way.
     In these cases, the values pointed to by src, srcleft, dst, and dstleft
     are updated to the state just after the last successful conversion.

     If the string pointed to by *src contains a character which is valid
     under the source codeset but can not be converted to the destination
     codeset, the character is replaced by an "invalid character" which
     depends on the destination codeset, e.g., `?', and the conversion is
     continued.  iconv() returns the number of such "invalid conversions".

     If src or *src is NULL and the source and/or destination codesets are
     stateful, iconv() places these into their initial state.

           1.   If both dst and *dst are non-NULL, iconv() stores the shift
                sequence for the destination switching to the initial state in
                the buffer pointed to by *dst.  The buffer size is specified
                by the value pointed to by dstleft as above.  iconv() will
                fail if the buffer is too small to store the shift sequence.

           2.   On the other hand, dst or *dst may be NULL.  In this case, the
                shift sequence for the destination switching to the initial
                state is discarded.

RETURN VALUES
     Upon successful completion of iconv_open(), it returns a conversion
     descriptor.  Otherwise, iconv_open() returns (iconv_t)-1 and sets errno
     to indicate the error.

     Upon successful completion of iconv_close(), it returns 0.  Otherwise,
     iconv_close() returns -1 and sets errno to indicate the error.

     Upon successful completion of iconv(), it returns the number of "invalid"
     conversions.  Otherwise, iconv() returns (size_t)-1 and sets errno to
     indicate the error.

ERRORS
     The iconv_open() function may cause an error in the following cases:

     [EINVAL]           There is no converter specified by srcname and
                        dstname.

     [ENOMEM]           Memory is exhausted.

     The iconv_close() function may cause an error in the following case:

     [EBADF]            The conversion descriptor specified by cd is invalid.

     The iconv() function may cause an error in the following cases:

     [E2BIG]            The output buffer pointed to by *dst is too small to
                        store the result string.

     [EBADF]            The conversion descriptor specified by cd is invalid.

     [EILSEQ]           The string pointed to by *src contains a byte sequence
                        which does not describe a valid character of the
                        source codeset.

     [EINVAL]           The string pointed to by *src terminates with an
                        incomplete character or shift sequence.

SEE ALSO
     iconv(1)

STANDARDS
     iconv_open(), iconv_close(), and iconv() conform to IEEE Std 1003.1-2001
     ("POSIX.1").

     Historically, the definition of iconv has not been consistent across
     operating systems.  This is due to an unfortunate historical mistake,
     documented in this e-mail:
     https://www5.opengroup.org/sophocles2/show_mail.tpl?&source=L&listname=austin-group-l&id=7404.
     The standards page for the header file <iconv.h> defined the second
     argument of iconv() as char **, but the standards page for the iconv()
     implementation defined it as const char **.  The standards committee
     later chose to change the function definition to follow the header file
     definition (without const), even though the version with const is
     arguably more correct.  NetBSD used initially the const form.  It was
     decided to reject the committee's regression and become (technically)
     incompatible.

     This decision was changed in NetBSD 10 and the iconv() prototype was
     synchronized with the standard.

BUGS
     If iconv() is aborted due to the occurrence of some error, the "invalid
     conversion" count mentioned above is unfortunately lost.

NetBSD 10.99                   October 24, 2019                   NetBSD 10.99