src/multibyte/wcsrtombs.c

   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
   9 size_t wcsrtombs(char *restrict s, const wchar_t **restrict ws, size_t n, mbstate_t *restrict st)
  10 {
  11         const wchar_t *ws2;
  12         char buf[4];
  13         size_t N = n, l;
  14         if (!s) {
  15                 for (n=0, ws2=*ws; *ws2; ws2++) {
  16                         if (*ws2 >= 0x80u) {
  17                                 l = wcrtomb(buf, *ws2, 0);
  18                                 if (!(l+1)) return -1;
  19                                 n += l;
  20                         } else n++;
  21                 }
  22                 return n;
  23         }
  24         while (n>=4 && **ws) {
  25                 if (**ws >= 0x80u) {
  26                         l = wcrtomb(s, **ws, 0);
  27                         if (!(l+1)) return -1;
  28                         s += l;
  29                         n -= l;
  30                 } else {
  31                         *s++ = **ws;
  32                         n--;
  33                 }
  34                 (*ws)++;
  35         }
  36         while (n && **ws) {
  37                 if (**ws >= 0x80u) {
  38                         l = wcrtomb(buf, **ws, 0);
  39                         if (!(l+1)) return -1;
  40                         if (l>n) return N-n;
  41                         wcrtomb(s, **ws, 0);
  42                         s += l;
  43                         n -= l;
  44                 } else {
  45                         *s++ = **ws;
  46                         n--;
  47                 }
  48                 (*ws)++;
  49         }
  50         if (n) *s = 0;
  51         *ws = 0;
  52         return N-n;
  53 }