iconv_open
, iconv_open_into
,
iconv_close
, iconv
—
codeset conversion functions
Standard C Library (libc, -lc)
#include <iconv.h>
iconv_t
iconv_open
(const
char *dstname, const char
*srcname);
int
iconv_open_into
(const
char *dstname, const char
*srcname,
iconv_allocation_t
*ptr);
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);
size_t
__iconv
(iconv_t
cd, char ** restrict
src, size_t * restrict
srcleft, char ** restrict
dst, size_t * restrict
dstleft, uint32_t
flags, size_t *
invalids);
The iconv_open
() function opens a converter from the
codeset srcname to the codeset
dstname and returns its descriptor. The arguments
srcname and dstname accept
"" and "char", which refer to the current locale encoding.
The iconv_open_into
() creates a conversion
descriptor on a preallocated space. The
iconv_allocation_t is used as a spaceholder type when
allocating such space. The dstname and
srcname arguments are the same as in the case of
iconv_open
(). The ptr argument
is a pointer of iconv_allocation_t to the preallocated
space.
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”.
There are two special cases of
iconv
():
- src == NULL || *src == NULL
- If the source and/or destination codesets are stateful,
iconv
() places these into their initial state.
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.
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.
The __iconv
() function works just like
iconv
() but if iconv
()
fails, the invalid character count is lost there. This is a not bug rather a
limitation of IEEE Std 1003.1-2008
(“POSIX.1”), so __iconv
() is
provided as an alternative but non-standard interface. It also has a flags
argument, where currently the following flags can be passed:
- __ICONV_F_HIDE_INVALID
- Skip invalid characters, instead of returning with an error.
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_open_into
(), it returns 0. Otherwise,
iconv_open_into
() returns -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.
The iconv_open
() function may cause an error in the
following cases:
- [
ENOMEM
]
- Memory is exhausted.
- [
EINVAL
]
- There is no converter specified by srcname and
dstname.
The iconv_open_into
() function may cause an error in the
following cases:
- [
EINVAL
]
- There is no converter specified by srcname and
dstname.
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:
- [
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.
- [
E2BIG
]
- The output buffer pointed to by *dst is too small to
store the result string.
- [
EINVAL
]
- The string pointed to by *src terminates with an
incomplete character or shift sequence.
The iconv_open
(), iconv_close
(),
and iconv
() functions conform to IEEE
Std 1003.1-2008 (“POSIX.1”).
The iconv_open_into
() function is a
GNU-specific extension and it is not part of any standard, thus its use may
break portability. The __iconv
() function is an own
extension and it is not part of any standard, thus its use may break
portability.