iconv(3)



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 buf-
       fer.  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 start-
       ing at *inbuf to a multibyte sequence starting  at  *outbuf.   At  most
       *inbytesleft  bytes,  starting  at *inbuf, will be read.  At most *out-
       bytesleft 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  *out-
       bytesleft 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 func-
       tion 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 4.10 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                               2015-12-28                          ICONV(3)

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