vswprintf.c raw

   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  }
  61