src/stdio/vswprintf.c

   1 #include "stdio_impl.h"
   2 #include <limits.h>
   3 #include <errno.h>
   4 #include <stdint.h>
   5 #include <stdlib.h>
   6 #include <wchar.h>
   7
   8 struct cookie {
   9         wchar_t *ws;
  10         size_t l;
  11 };
  12
  13 static size_t sw_write(FILE *f, const unsigned char *s, size_t l)
  14 {
  15         size_t l0 = l;
  16         int i = 0;
  17         struct cookie *c = f->cookie;
  18         if (s!=f->wbase && sw_write(f, f->wbase, f->wpos-f->wbase)==-1)
  19                 return -1;
  20         while (c->l && l && (i=mbtowc(c->ws, (void *)s, l))>=0) {
  21                 if (!i) i=1;
  22                 s+=i;
  23                 l-=i;
  24                 c->l--;
  25                 c->ws++;
  26         }
  27         *c->ws = 0;
  28         if (i < 0) {
  29                 f->wpos = f->wbase = f->wend = 0;
  30                 f->flags |= F_ERR;
  31                 return i;
  32         }
  33         f->wend = f->buf + f->buf_size;
  34         f->wpos = f->wbase = f->buf;
  35         return l0;
  36 }
  37
  38 int vswprintf(wchar_t *restrict s, size_t n, const wchar_t *restrict fmt, va_list ap)
  39 {
  40         int r;
  41         unsigned char buf[256];
  42         struct cookie c = { s, n-1 };
  43         FILE f = {
  44                 .lbf = EOF,
  45                 .write = sw_write,
  46                 .lock = -1,
  47                 .buf = buf,
  48                 .buf_size = sizeof buf,
  49                 .cookie = &c,
  50         };
  51
  52         if (!n) {
  53                 return -1;
  54         }
  55         r = vfwprintf(&f, fmt, ap);
  56         sw_write(&f, 0, 0);
  57         return r>=n ? -1 : r;
  58 }