| 1 | #include <wchar.h> |
| 2 | |
| 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 | } |