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#include "stdio_impl.h"
struct cookie {
wchar_t *ws;
size_t l;
};
static size_t sw_write(FILE *f, const unsigned char *s, size_t l)
{
size_t l0 = l;
int i = 0;
struct cookie *c = f->cookie;
if (s!=f->wbase && sw_write(f, f->wbase, f->wpos-f->wbase)==-1)
return -1;
while (c->l && l && (i=mbtowc(c->ws, (void *)s, l))>=0) {
s+=i;
l-=i;
c->l--;
c->ws++;
}
*c->ws = 0;
return i<0 ? i : l0;
}
int vswprintf(wchar_t *s, size_t n, const wchar_t *fmt, va_list ap)
{
int r;
FILE f;
unsigned char buf[256];
struct cookie c = { s, n-1 };
memset(&f, 0, sizeof(FILE));
f.lbf = EOF;
f.write = sw_write;
f.buf_size = sizeof buf;
f.buf = buf;
f.lock = -1;
f.cookie = &c;
if (!n) {
return -1;
} else if (n > INT_MAX) {
errno = EOVERFLOW;
return -1;
}
r = vfwprintf(&f, fmt, ap);
sw_write(&f, 0, 0);
return r>=n ? -1 : r;
}
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