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

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       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at https://www.kernel.org/doc/man-pages/.