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
 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		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
38int 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#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
47		.lock = -1,
48#endif
49		.buf = buf,
50		.buf_size = sizeof buf,
51		.cookie = &c,
52	};
53
54	if (!n) {
55		return -1;
56	}
57	r = vfwprintf(&f, fmt, ap);
58	sw_write(&f, 0, 0);
59	return r>=n ? -1 : r;
60}