1#include "stdio_impl.h"
2#include <limits.h>
3#include <string.h>
4#include <errno.h>
5#include <stdint.h>
6#include <wchar.h>
7
8struct cookie {
9	wchar_t *ws;
10	size_t l;
11};
12
13static 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		s+=i;
22		l-=i;
23		c->l--;
24		c->ws++;
25	}
26	*c->ws = 0;
27	if (i < 0) {
28		f->wpos = f->wbase = f->wend = 0;
29		f->flags |= F_ERR;
30		return i;
31	}
32	f->wend = f->buf + f->buf_size;
33	f->wpos = f->wbase = f->buf;
34	return l0;
35}
36
37int vswprintf(wchar_t *restrict s, size_t n, const wchar_t *restrict fmt, va_list ap)
38{
39	int r;
40	FILE f;
41	unsigned char buf[256];
42	struct cookie c = { s, n-1 };
43
44	memset(&f, 0, sizeof(FILE));
45	f.lbf = EOF;
46	f.write = sw_write;
47	f.buf_size = sizeof buf;
48	f.buf = buf;
49	f.lock = -1;
50	f.cookie = &c;
51	if (!n) {
52		return -1;
53	} else if (n > INT_MAX) {
54		errno = EOVERFLOW;
55		return -1;
56	}
57	r = vfwprintf(&f, fmt, ap);
58	sw_write(&f, 0, 0);
59	return r>=n ? -1 : r;
60}
61