1 #include <wchar.h>
2
mbsnrtowcs(wchar_t * restrict wcs,const char ** restrict src,size_t n,size_t wn,mbstate_t * restrict st)3 size_t mbsnrtowcs(wchar_t *restrict wcs, const char **restrict src, size_t n, size_t wn, mbstate_t *restrict st)
4 {
5 size_t l, cnt=0, n2;
6 wchar_t *ws, wbuf[256];
7 const char *s = *src;
8 const char *tmp_s;
9
10 if (!wcs) ws = wbuf, wn = sizeof wbuf / sizeof *wbuf;
11 else ws = wcs;
12
13 /* making sure output buffer size is at most n/4 will ensure
14 * that mbsrtowcs never reads more than n input bytes. thus
15 * we can use mbsrtowcs as long as it's practical.. */
16
17 while ( s && wn && ( (n2=n/4)>=wn || n2>32 ) ) {
18 if (n2>=wn) n2=wn;
19 tmp_s = s;
20 l = mbsrtowcs(ws, &s, n2, st);
21 if (!(l+1)) {
22 cnt = l;
23 wn = 0;
24 break;
25 }
26 if (ws != wbuf) {
27 ws += l;
28 wn -= l;
29 }
30 n = s ? n - (s - tmp_s) : 0;
31 cnt += l;
32 }
33 if (s) while (wn && n) {
34 l = mbrtowc(ws, s, n, st);
35 if (l+2<=2) {
36 if (!(l+1)) {
37 cnt = l;
38 break;
39 }
40 if (!l) {
41 s = 0;
42 break;
43 }
44 /* have to roll back partial character */
45 *(unsigned *)st = 0;
46 break;
47 }
48 s += l; n -= l;
49 /* safe - this loop runs fewer than sizeof(wbuf)/8 times */
50 ws++; wn--;
51 cnt++;
52 }
53 if (wcs) *src = s;
54 return cnt;
55 }
56