github.com/afumu/libc@v0.0.6/musl/src/stdio/ungetwc.c (about)

     1  #include "stdio_impl.h"
     2  #include "locale_impl.h"
     3  #include <wchar.h>
     4  #include <limits.h>
     5  #include <ctype.h>
     6  #include <string.h>
     7  
     8  wint_t ungetwc(wint_t c, FILE *f)
     9  {
    10  	unsigned char mbc[MB_LEN_MAX];
    11  	int l;
    12  	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
    13  
    14  	FLOCK(f);
    15  
    16  	if (f->mode <= 0) fwide(f, 1);
    17  	*ploc = f->locale;
    18  
    19  	if (!f->rpos) __toread(f);
    20  	if (!f->rpos || c == WEOF || (l = wcrtomb((void *)mbc, c, 0)) < 0 ||
    21  	    f->rpos < f->buf - UNGET + l) {
    22  		FUNLOCK(f);
    23  		*ploc = loc;
    24  		return WEOF;
    25  	}
    26  
    27  	if (isascii(c)) *--f->rpos = c;
    28  	else memcpy(f->rpos -= l, mbc, l);
    29  
    30  	f->flags &= ~F_EOF;
    31  
    32  	FUNLOCK(f);
    33  	*ploc = loc;
    34  	return c;
    35  }