56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
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#include <wchar.h>
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size_t mbsnrtowcs(wchar_t *restrict wcs, const char **restrict src, size_t n, size_t wn, mbstate_t *restrict st)
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{
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size_t l, cnt=0, n2;
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wchar_t *ws, wbuf[256];
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const char *s = *src;
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const char *tmp_s;
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if (!wcs) ws = wbuf, wn = sizeof wbuf / sizeof *wbuf;
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else ws = wcs;
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/* making sure output buffer size is at most n/4 will ensure
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* that mbsrtowcs never reads more than n input bytes. thus
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* we can use mbsrtowcs as long as it's practical.. */
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while ( s && wn && ( (n2=n/4)>=wn || n2>32 ) ) {
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if (n2>=wn) n2=wn;
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tmp_s = s;
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l = mbsrtowcs(ws, &s, n2, st);
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if (!(l+1)) {
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cnt = l;
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wn = 0;
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break;
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}
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if (ws != wbuf) {
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ws += l;
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wn -= l;
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}
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n = s ? n - (s - tmp_s) : 0;
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cnt += l;
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}
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if (s) while (wn && n) {
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l = mbrtowc(ws, s, n, st);
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if (l+2<=2) {
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if (!(l+1)) {
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cnt = l;
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break;
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}
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if (!l) {
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s = 0;
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break;
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}
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/* have to roll back partial character */
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*(unsigned *)st = 0;
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break;
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}
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s += l; n -= l;
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/* safe - this loop runs fewer than sizeof(wbuf)/8 times */
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ws++; wn--;
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cnt++;
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}
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if (wcs) *src = s;
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return cnt;
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}
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