1 /*
2 * This code was written by Rich Felker in 2010; no copyright is claimed.
3 * This code is in the public domain. Attribution is appreciated but
4 * unnecessary.
5 */
6
7 #include <wchar.h>
8
mbsnrtowcs(wchar_t * restrict wcs,const char ** restrict src,size_t n,size_t wn,mbstate_t * restrict st)9 size_t mbsnrtowcs(wchar_t *restrict wcs, const char **restrict src, size_t n, size_t wn, mbstate_t *restrict st)
10 {
11 size_t l, cnt=0, n2;
12 wchar_t *ws, wbuf[256];
13 const char *s = *src;
14
15 if (!wcs) ws = wbuf, wn = sizeof wbuf / sizeof *wbuf;
16 else ws = wcs;
17
18 /* making sure output buffer size is at most n/4 will ensure
19 * that mbsrtowcs never reads more than n input bytes. thus
20 * we can use mbsrtowcs as long as it's practical.. */
21
22 while ( s && wn && ( (n2=n/4)>=wn || n2>32 ) ) {
23 if (n2>=wn) n2=wn;
24 n -= n2;
25 l = mbsrtowcs(ws, &s, n2, st);
26 if (!(l+1)) {
27 cnt = l;
28 wn = 0;
29 break;
30 }
31 if (ws != wbuf) {
32 ws += l;
33 wn -= l;
34 }
35 cnt += l;
36 }
37 if (s) while (wn && n) {
38 l = mbrtowc(ws, s, n, st);
39 if (l+2<=2) {
40 if (!(l+1)) {
41 cnt = l;
42 break;
43 }
44 if (!l) {
45 s = 0;
46 break;
47 }
48 /* have to roll back partial character */
49 *(unsigned *)st = 0;
50 break;
51 }
52 s += l; n -= l;
53 /* safe - this loop runs fewer than sizeof(wbuf)/8 times */
54 ws++; wn--;
55 cnt++;
56 }
57 if (wcs) *src = s;
58 return cnt;
59 }
60