1ICONV(P) POSIX Programmer's Manual ICONV(P)
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6 iconv - codeset conversion function
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9 #include <iconv.h>
10 size_t iconv(iconv_t cd, char **restrict inbuf,
12 size_t *restrict inbytesleft, char **restrict outbuf,
13 size_t *restrict outbytesleft);
14
17 The iconv() function shall convert the sequence of characters from one
18 codeset, in the array specified by inbuf, into a sequence of corre‐
19 sponding characters in another codeset, in the array specified by out‐
20 buf. The codesets are those specified in the iconv_open() call that
21 returned the conversion descriptor, cd. The inbuf argument points to a
22 variable that points to the first character in the input buffer and
23 inbytesleft indicates the number of bytes to the end of the buffer to
24 be converted. The outbuf argument points to a variable that points to
25 the first available byte in the output buffer and outbytesleft indi‐
26 cates the number of the available bytes to the end of the buffer.
27 For state-dependent encodings, the conversion descriptor cd is placed
29 into its initial shift state by a call for which inbuf is a null
30 pointer, or for which inbuf points to a null pointer. When iconv() is
31 called in this way, and if outbuf is not a null pointer or a pointer to
32 a null pointer, and outbytesleft points to a positive value, iconv()
33 shall place, into the output buffer, the byte sequence to change the
34 output buffer to its initial shift state. If the output buffer is not
35 large enough to hold the entire reset sequence, iconv() shall fail and
36 set errno to [E2BIG]. Subsequent calls with inbuf as other than a null
37 pointer or a pointer to a null pointer cause the conversion to take
38 place from the current state of the conversion descriptor.
39 If a sequence of input bytes does not form a valid character in the
41 specified codeset, conversion shall stop after the previous success‐
42 fully converted character. If the input buffer ends with an incomplete
43 character or shift sequence, conversion shall stop after the previous
44 successfully converted bytes. If the output buffer is not large enough
45 to hold the entire converted input, conversion shall stop just prior to
46 the input bytes that would cause the output buffer to overflow. The
47 variable pointed to by inbuf shall be updated to point to the byte fol‐
48 lowing the last byte successfully used in the conversion. The value
49 pointed to by inbytesleft shall be decremented to reflect the number of
50 bytes still not converted in the input buffer. The variable pointed to
51 by outbuf shall be updated to point to the byte following the last byte
52 of converted output data. The value pointed to by outbytesleft shall be
53 decremented to reflect the number of bytes still available in the out‐
54 put buffer. For state-dependent encodings, the conversion descriptor
55 shall be updated to reflect the shift state in effect at the end of the
56 last successfully converted byte sequence.
57 If iconv() encounters a character in the input buffer that is valid,
59 but for which an identical character does not exist in the target code‐
60 set, iconv() shall perform an implementation-defined conversion on this
61 character.
62
64 The iconv() function shall update the variables pointed to by the argu‐
65 ments to reflect the extent of the conversion and return the number of
66 non-identical conversions performed. If the entire string in the input
67 buffer is converted, the value pointed to by inbytesleft shall be 0. If
68 the input conversion is stopped due to any conditions mentioned above,
69 the value pointed to by inbytesleft shall be non-zero and errno shall
70 be set to indicate the condition. If an error occurs, iconv() shall
71 return (size_t)-1 and set errno to indicate the error.
72
74 The iconv() function shall fail if:
75 EILSEQ Input conversion stopped due to an input byte that does not
77 belong to the input codeset.
78 E2BIG Input conversion stopped due to lack of space in the output buf‐
80 fer.
81 EINVAL Input conversion stopped due to an incomplete character or shift
83 sequence at the end of the input buffer.
84 The iconv() function may fail if:
87 EBADF The cd argument is not a valid open conversion descriptor.
89 The following sections are informative.
92
94 None.
95
97 The inbuf argument indirectly points to the memory area which contains
98 the conversion input data. The outbuf argument indirectly points to the
99 memory area which is to contain the result of the conversion. The
100 objects indirectly pointed to by inbuf and outbuf are not restricted to
101 containing data that is directly representable in the ISO C standard
102 language char data type. The type of inbuf and outbuf, char **, does
103 not imply that the objects pointed to are interpreted as null-termi‐
104 nated C strings or arrays of characters. Any interpretation of a byte
105 sequence that represents a character in a given character set encoding
106 scheme is done internally within the codeset converters. For example,
107 the area pointed to indirectly by inbuf and/or outbuf can contain all
108 zero octets that are not interpreted as string terminators but as coded
109 character data according to the respective codeset encoding scheme. The
110 type of the data ( char, short, long, and so on) read or stored in the
111 objects is not specified, but may be inferred for both the input and
112 output data by the converters determined by the fromcode and tocode
113 arguments of iconv_open().
114 Regardless of the data type inferred by the converter, the size of the
116 remaining space in both input and output objects (the intbytesleft and
117 outbytesleft arguments) is always measured in bytes.
118 For implementations that support the conversion of state-dependent
120 encodings, the conversion descriptor must be able to accurately reflect
121 the shift-state in effect at the end of the last successful conversion.
122 It is not required that the conversion descriptor itself be updated,
123 which would require it to be a pointer type. Thus, implementations are
124 free to implement the descriptor as a handle (other than a pointer
125 type) by which the conversion information can be accessed and updated.
126
128 None.
129
131 None.
132
134 iconv_open() , iconv_close() , the Base Definitions volume of
135 IEEE Std 1003.1-2001, <iconv.h>
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138 Portions of this text are reprinted and reproduced in electronic form
139 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
140 -- Portable Operating System Interface (POSIX), The Open Group Base
141 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
142 Electrical and Electronics Engineers, Inc and The Open Group. In the
143 event of any discrepancy between this version and the original IEEE and
144 The Open Group Standard, the original IEEE and The Open Group Standard
145 is the referee document. The original Standard can be obtained online
146 at http://www.opengroup.org/unix/online.html .
147IEEE/The Open Group 2003 ICONV(P)