1 /*
2 * Copyright (C) 2014 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <errno.h>
30 #include <uchar.h>
31 #include <wchar.h>
32
33 #include "private/bionic_mbstate.h"
34
c32rtomb(char * s,char32_t c32,mbstate_t * ps)35 size_t c32rtomb(char* s, char32_t c32, mbstate_t* ps) {
36 static mbstate_t __private_state;
37 mbstate_t* state = (ps == nullptr) ? &__private_state : ps;
38
39 if (s == nullptr) {
40 // Equivalent to c32rtomb(buf, U'\0', ps).
41 return mbstate_reset_and_return(1, state);
42 }
43
44 // POSIX states that if char32_t is a null wide character, a null byte shall
45 // be stored, preceded by any shift sequence needed to restore the initial
46 // shift state. Since shift states are not supported, only the null byte is
47 // stored.
48 if (c32 == U'\0') {
49 *s = '\0';
50 return mbstate_reset_and_return(1, state);
51 }
52
53 if (!mbstate_is_initial(state)) {
54 return mbstate_reset_and_return_illegal(EILSEQ, state);
55 }
56
57 if ((c32 & ~0x7f) == 0) {
58 // Fast path for plain ASCII characters.
59 *s = c32;
60 return 1;
61 }
62
63 // Determine the number of octets needed to represent this character.
64 // We always output the shortest sequence possible. Also specify the
65 // first few bits of the first octet, which contains the information
66 // about the sequence length.
67 uint8_t lead;
68 size_t length;
69 // We already handled the 1-byte case above, so we go straight to 2-bytes...
70 if ((c32 & ~0x7ff) == 0) {
71 lead = 0xc0;
72 length = 2;
73 } else if ((c32 & ~0xffff) == 0) {
74 lead = 0xe0;
75 length = 3;
76 } else if ((c32 & ~0x1fffff) == 0) {
77 lead = 0xf0;
78 length = 4;
79 } else {
80 errno = EILSEQ;
81 return BIONIC_MULTIBYTE_RESULT_ILLEGAL_SEQUENCE;
82 }
83
84 // Output the octets representing the character in chunks
85 // of 6 bits, least significant last. The first octet is
86 // a special case because it contains the sequence length
87 // information.
88 for (size_t i = length - 1; i > 0; i--) {
89 s[i] = (c32 & 0x3f) | 0x80;
90 c32 >>= 6;
91 }
92 *s = (c32 & 0xff) | lead;
93
94 return length;
95 }
96