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
sw_write(FILE * f,const unsigned char * s,size_t l)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 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
vswprintf(wchar_t * restrict s,size_t n,const wchar_t * restrict fmt,va_list ap)37 int vswprintf(wchar_t *restrict s, size_t n, const wchar_t *restrict fmt, va_list ap)
38 {
39 int r;
40 unsigned char buf[256];
41 struct cookie c = { s, n-1 };
42 FILE f = {
43 .lbf = EOF,
44 .write = sw_write,
45 .lock = -1,
46 .buf = buf,
47 .buf_size = sizeof buf,
48 .cookie = &c,
49 };
50
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