iconv

ICONV(3)                   Linux Programmer's Manual                  ICONV(3)



NAME
       iconv - perform character set conversion

SYNOPSIS
       #include <iconv.h>

       size_t iconv(iconv_t cd,
                    char **inbuf, size_t *inbytesleft,
                    char **outbuf, size_t *outbytesleft);

DESCRIPTION
       The iconv() function converts a sequence of characters in one character
       encoding to a sequence of characters in another character encoding.
       The cd argument is a conversion descriptor, previously created by a
       call to iconv_open(3); the conversion descriptor defines the character
       encodings that iconv() uses for the conversion.  The inbuf argument is
       the address of a variable that points to the first character of the
       input sequence; inbytesleft indicates the number of bytes in that
       buffer.  The outbuf argument is the address of a variable that points
       to the first byte available in the output buffer; outbytesleft
       indicates the number of bytes available in the output buffer.

       The main case is when inbuf is not NULL and *inbuf is not NULL.  In
       this case, the iconv() function converts the multibyte sequence
       starting at *inbuf to a multibyte sequence starting at *outbuf.  At
       most *inbytesleft bytes, starting at *inbuf, will be read.  At most
       *outbytesleft bytes, starting at *outbuf, will be written.

       The iconv() function converts one multibyte character at a time, and
       for each character conversion it increments *inbuf and decrements
       *inbytesleft by the number of converted input bytes, it increments
       *outbuf and decrements *outbytesleft by the number of converted output
       bytes, and it updates the conversion state contained in cd.  If the
       character encoding of the input is stateful, the iconv() function can
       also convert a sequence of input bytes to an update to the conversion
       state without producing any output bytes; such input is called a shift
       sequence.  The conversion can stop for four reasons:

       1. An invalid multibyte sequence is encountered in the input.  In this
          case, it sets errno to EILSEQ and returns (size_t) -1.  *inbuf is
          left pointing to the beginning of the invalid multibyte sequence.

       2. The input byte sequence has been entirely converted, that is,
          *inbytesleft has gone down to 0.  In this case, iconv() returns the
          number of nonreversible conversions performed during this call.

       3. An incomplete multibyte sequence is encountered in the input, and
          the input byte sequence terminates after it.  In this case, it sets
          errno to EINVAL and returns (size_t) -1.  *inbuf is left pointing to
          the beginning of the incomplete multibyte sequence.

       4. The output buffer has no more room for the next converted character.
          In this case, it sets errno to E2BIG and returns (size_t) -1.

       A different case is when inbuf is NULL or *inbuf is NULL, but outbuf is
       not NULL and *outbuf is not NULL.  In this case, the iconv() function
       attempts to set cd's conversion state to the initial state and store a
       corresponding shift sequence at *outbuf.  At most *outbytesleft bytes,
       starting at *outbuf, will be written.  If the output buffer has no more
       room for this reset sequence, it sets errno to E2BIG and returns
       (size_t) -1.  Otherwise, it increments *outbuf and decrements
       *outbytesleft by the number of bytes written.

       A third case is when inbuf is NULL or *inbuf is NULL, and outbuf is
       NULL or *outbuf is NULL.  In this case, the iconv() function sets cd's
       conversion state to the initial state.

RETURN VALUE
       The iconv() function returns the number of characters converted in a
       nonreversible way during this call; reversible conversions are not
       counted.  In case of error, it sets errno and returns (size_t) -1.

ERRORS
       The following errors can occur, among others:

       E2BIG  There is not sufficient room at *outbuf.

       EILSEQ An invalid multibyte sequence has been encountered in the input.

       EINVAL An incomplete multibyte sequence has been encountered in the
              input.

VERSIONS
       This function is available in glibc since version 2.1.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────┬───────────────┬─────────────────┐
       │Interface Attribute     Value           │
       ├──────────┼───────────────┼─────────────────┤
       │iconv()   │ Thread safety │ MT-Safe race:cd │
       └──────────┴───────────────┴─────────────────┘
       The iconv() function is MT-Safe, as long as callers arrange for mutual
       exclusion on the cd argument.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

NOTES
       In each series of calls to iconv(), the last should be one with inbuf
       or *inbuf equal to NULL, in order to flush out any partially converted
       input.

       Although inbuf and outbuf are typed as char **, this does not mean that
       the objects they point can be interpreted as C strings or as arrays of
       characters: the interpretation of character byte sequences is handled
       internally by the conversion functions.  In some encodings, a zero byte
       may be a valid part of a multibyte character.

       The caller of iconv() must ensure that the pointers passed to the
       function are suitable for accessing characters in the appropriate
       character set.  This includes ensuring correct alignment on platforms
       that have tight restrictions on alignment.

SEE ALSO
       iconv_close(3), iconv_open(3), iconvconfig(8)

COLOPHON
       This page is part of release 5.03 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



GNU                               2017-09-15                          ICONV(3)