1/* Recode strings between character sets, using iconv.
2 Copyright (C) 2002-2017 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1, or (at
7 your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with this program; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#ifdef HAVE_CONFIG_H
19# include <config.h>
20#endif
21
22/* Get prototype. */
23#include "iconvme.h"
24
25/* Get malloc. */
26#include <stdlib.h>
27
28/* Get strcmp. */
29#include <string.h>
30
31/* Get errno. */
32#include <errno.h>
33
34#ifdef _LIBC
35# define HAVE_ICONV 1
36#else
37/* Get strdup. */
38# include "strdup.h"
39#endif
40
41#if HAVE_ICONV
42/* Get iconv etc. */
43# include <iconv.h>
44/* Get MB_LEN_MAX, CHAR_BIT. */
45# include <limits.h>
46#endif
47
48#ifndef SIZE_MAX
49# define SIZE_MAX ((size_t) -1)
50#endif
51
52/* Convert a zero-terminated string STR from the FROM_CODSET code set
53 to the TO_CODESET code set. The returned string is allocated using
54 malloc, and must be dellocated by the caller using free. On
55 failure, NULL is returned and errno holds the error reason. Note
56 that if TO_CODESET uses \0 for anything but to terminate the
57 string, the caller of this function may have difficulties finding
58 out the length of the output string. */
59char *
60iconv_string (const char *str, const char *from_codeset,
61 const char *to_codeset)
62{
63 char *dest = NULL;
64#if HAVE_ICONV
65 iconv_t cd;
66 char *outp;
67 char *p = (char *) str;
68 size_t inbytes_remaining = strlen (p);
69 /* Guess the maximum length the output string can have. */
70 size_t outbuf_size = inbytes_remaining + 1;
71 size_t outbytes_remaining;
72 size_t err;
73 int have_error = 0;
74
75 /* Use a worst-case output size guess, so long as that wouldn't be
76 too large for comfort. It's OK if the guess is wrong so long as
77 it's nonzero. */
78 size_t approx_sqrt_SIZE_MAX = SIZE_MAX >> (sizeof (size_t) * CHAR_BIT / 2);
79 if (outbuf_size <= approx_sqrt_SIZE_MAX / MB_LEN_MAX)
80 outbuf_size *= MB_LEN_MAX;
81 outbytes_remaining = outbuf_size - 1;
82#endif
83
84 if (strcmp (to_codeset, from_codeset) == 0)
85 return strdup (str);
86
87#if HAVE_ICONV
88 cd = iconv_open (to_codeset, from_codeset);
89 if (cd == (iconv_t) -1)
90 return NULL;
91
92 outp = dest = (char *) malloc (outbuf_size);
93 if (dest == NULL)
94 goto out;
95
96again:
97 err = iconv (cd, &p, &inbytes_remaining, &outp, &outbytes_remaining);
98
99 if (err == (size_t) - 1)
100 {
101 switch (errno)
102 {
103 case EINVAL:
104 /* Incomplete text, do not report an error */
105 break;
106
107 case E2BIG:
108 {
109 size_t used = outp - dest;
110 size_t newsize = outbuf_size * 2;
111 char *newdest;
112
113 if (newsize <= outbuf_size)
114 {
115 errno = ENOMEM;
116 have_error = 1;
117 goto out;
118 }
119 newdest = (char *) realloc (dest, newsize);
120 if (newdest == NULL)
121 {
122 have_error = 1;
123 goto out;
124 }
125 dest = newdest;
126 outbuf_size = newsize;
127
128 outp = dest + used;
129 outbytes_remaining = outbuf_size - used - 1; /* -1 for NUL */
130
131 goto again;
132 }
133 break;
134
135 case EILSEQ:
136 have_error = 1;
137 break;
138
139 default:
140 have_error = 1;
141 break;
142 }
143 }
144
145 *outp = '\0';
146
147out:
148 {
149 int save_errno = errno;
150
151 if (iconv_close (cd) < 0 && !have_error)
152 {
153 /* If we didn't have a real error before, make sure we restore
154 the iconv_close error below. */
155 save_errno = errno;
156 have_error = 1;
157 }
158
159 if (have_error && dest)
160 {
161 free (dest);
162 dest = NULL;
163 errno = save_errno;
164 }
165 }
166#else
167 errno = ENOSYS;
168#endif
169
170 return dest;
171}
172