1ICONV(3P) POSIX Programmer's Manual ICONV(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 iconv — codeset conversion function
13
15 #include <iconv.h>
16 size_t iconv(iconv_t cd, char **restrict inbuf,
18 size_t *restrict inbytesleft, char **restrict outbuf,
19 size_t *restrict outbytesleft);
20
22 The iconv() function shall convert the sequence of characters from one
23 codeset, in the array specified by inbuf, into a sequence of corre‐
24 sponding characters in another codeset, in the array specified by out‐
25 buf. The codesets are those specified in the iconv_open() call that
26 returned the conversion descriptor, cd. The inbuf argument points to a
27 variable that points to the first character in the input buffer and
28 inbytesleft indicates the number of bytes to the end of the buffer to
29 be converted. The outbuf argument points to a variable that points to
30 the first available byte in the output buffer and outbytesleft indi‐
31 cates the number of the available bytes to the end of the buffer.
32 For state-dependent encodings, the conversion descriptor cd is placed
34 into its initial shift state by a call for which inbuf is a null
35 pointer, or for which inbuf points to a null pointer. When iconv() is
36 called in this way, and if outbuf is not a null pointer or a pointer to
37 a null pointer, and outbytesleft points to a positive value, iconv()
38 shall place, into the output buffer, the byte sequence to change the
39 output buffer to its initial shift state. If the output buffer is not
40 large enough to hold the entire reset sequence, iconv() shall fail and
41 set errno to [E2BIG]. Subsequent calls with inbuf as other than a null
42 pointer or a pointer to a null pointer cause the conversion to take
43 place from the current state of the conversion descriptor.
44 If a sequence of input bytes does not form a valid character in the
46 specified codeset, conversion shall stop after the previous success‐
47 fully converted character. If the input buffer ends with an incomplete
48 character or shift sequence, conversion shall stop after the previous
49 successfully converted bytes. If the output buffer is not large enough
50 to hold the entire converted input, conversion shall stop just prior to
51 the input bytes that would cause the output buffer to overflow. The
52 variable pointed to by inbuf shall be updated to point to the byte fol‐
53 lowing the last byte successfully used in the conversion. The value
54 pointed to by inbytesleft shall be decremented to reflect the number of
55 bytes still not converted in the input buffer. The variable pointed to
56 by outbuf shall be updated to point to the byte following the last byte
57 of converted output data. The value pointed to by outbytesleft shall be
58 decremented to reflect the number of bytes still available in the out‐
59 put buffer. For state-dependent encodings, the conversion descriptor
60 shall be updated to reflect the shift state in effect at the end of the
61 last successfully converted byte sequence.
62 If iconv() encounters a character in the input buffer that is valid,
64 but for which an identical character does not exist in the target code‐
65 set, iconv() shall perform an implementation-defined conversion on this
66 character.
67
69 The iconv() function shall update the variables pointed to by the argu‐
70 ments to reflect the extent of the conversion and return the number of
71 non-identical conversions performed. If the entire string in the input
72 buffer is converted, the value pointed to by inbytesleft shall be 0. If
73 the input conversion is stopped due to any conditions mentioned above,
74 the value pointed to by inbytesleft shall be non-zero and errno shall
75 be set to indicate the condition. If an error occurs, iconv() shall
76 return (size_t)-1 and set errno to indicate the error.
77
79 The iconv() function shall fail if:
80 EILSEQ Input conversion stopped due to an input byte that does not
82 belong to the input codeset.
83 E2BIG Input conversion stopped due to lack of space in the output buf‐
85 fer.
86 EINVAL Input conversion stopped due to an incomplete character or shift
88 sequence at the end of the input buffer.
89 The iconv() function may fail if:
91 EBADF The cd argument is not a valid open conversion descriptor.
93 The following sections are informative.
95
97 None.
98
100 The inbuf argument indirectly points to the memory area which contains
101 the conversion input data. The outbuf argument indirectly points to the
102 memory area which is to contain the result of the conversion. The
103 objects indirectly pointed to by inbuf and outbuf are not restricted to
104 containing data that is directly representable in the ISO C standard
105 language char data type. The type of inbuf and outbuf, char **, does
106 not imply that the objects pointed to are interpreted as null-termi‐
107 nated C strings or arrays of characters. Any interpretation of a byte
108 sequence that represents a character in a given character set encoding
109 scheme is done internally within the codeset converters. For example,
110 the area pointed to indirectly by inbuf and/or outbuf can contain all
111 zero octets that are not interpreted as string terminators but as coded
112 character data according to the respective codeset encoding scheme. The
113 type of the data (char, short, long, and so on) read or stored in the
114 objects is not specified, but may be inferred for both the input and
115 output data by the converters determined by the fromcode and tocode
116 arguments of iconv_open().
117 Regardless of the data type inferred by the converter, the size of the
119 remaining space in both input and output objects (the intbytesleft and
120 outbytesleft arguments) is always measured in bytes.
121 For implementations that support the conversion of state-dependent
123 encodings, the conversion descriptor must be able to accurately reflect
124 the shift-state in effect at the end of the last successful conversion.
125 It is not required that the conversion descriptor itself be updated,
126 which would require it to be a pointer type. Thus, implementations are
127 free to implement the descriptor as a handle (other than a pointer
128 type) by which the conversion information can be accessed and updated.
129
131 None.
132
134 None.
135
137 iconv_open(), iconv_close(), mbsrtowcs()
138 The Base Definitions volume of POSIX.1‐2017, <iconv.h>
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142 Portions of this text are reprinted and reproduced in electronic form
143 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
144 table Operating System Interface (POSIX), The Open Group Base Specifi‐
145 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
146 Electrical and Electronics Engineers, Inc and The Open Group. In the
147 event of any discrepancy between this version and the original IEEE and
148 The Open Group Standard, the original IEEE and The Open Group Standard
149 is the referee document. The original Standard can be obtained online
150 at http://www.opengroup.org/unix/online.html .
151 Any typographical or formatting errors that appear in this page are
153 most likely to have been introduced during the conversion of the source
154 files to man page format. To report such errors, see https://www.ker‐
155 nel.org/doc/man-pages/reporting_bugs.html .
156IEEE/The Open Group 2017 ICONV(3P)