1 /* $OpenBSD: utf8.c,v 1.1 2018/07/29 11:27:15 schwarze Exp $ */
2 /*
3 * Copyright (c) 2018 Ingo Schwarze <schwarze@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <stdlib.h>
19 #include <wchar.h>
20
21 /*
22 * Measure the display width of the multibyte string.
23 * Treat invalid bytes and non-printable characters as width 1.
24 * Truncate the string to a display width of maxwidth.
25 * Return the total width, possibly after truncation.
26 */
27 int
mbswidth_truncate(char * mbs,int maxwidth)28 mbswidth_truncate(char *mbs, int maxwidth)
29 {
30 wchar_t wc;
31 int len, width, sum;
32
33 sum = 0;
34 while (*mbs != '\0') {
35 if ((len = mbtowc(&wc, mbs, MB_CUR_MAX)) == -1)
36 len = width = 1;
37 else if ((width = wcwidth(wc)) < 0)
38 width = 1;
39 if (sum + width > maxwidth) {
40 *mbs = '\0';
41 break;
42 }
43 sum += width;
44 mbs += len;
45 }
46 return sum;
47 }
48