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                 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
  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 }