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#include "stdio_impl.h"
wint_t ungetwc(wint_t c, FILE *f)
{
unsigned char mbc[MB_LEN_MAX];
int l=1;
if (c == WEOF) return c;
/* Try conversion early so we can fail without locking if invalid */
if (!isascii(c) && (l = wctomb(mbc, c)) < 0)
return WEOF;
FLOCK(f);
f->mode |= f->mode+1;
/* Fail if unreadable or writing and unable to flush */
if ((f->flags & (F_ERR|F_NORD)) || (f->wpos && __oflow(f))) {
FUNLOCK(f);
return EOF;
}
/* Clear write mode */
f->wpos = f->wstop = f->wend = 0;
/* Put the file in read mode */
if (!f->rpos) f->rpos = f->rend = f->buf;
/* If unget buffer is nonempty, fail. */
if (f->rpos < f->buf) {
FUNLOCK(f);
return WEOF;
}
/* Put character back into the buffer */
if (isascii(c)) *--f->rpos = c;
else memcpy(f->rpos -= l, mbc, l);
/* Clear EOF */
f->flags &= ~F_EOF;
FUNLOCK(f);
return c;
}
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