musl/src/stdio/__towrite.c

#include "stdio_impl.h"

int __towrite(FILE *f)
{
	f->mode |= f->mode-1;
	if (f->flags & (F_NOWR)) {
		f->flags |= F_ERR;
		return EOF;
	}
	/* Clear read buffer (easier than summoning nasal demons) */
	f->rpos = f->rend = 0;

	/* Activate write through the buffer. */
	f->wpos = f->wbase = f->buf;
	f->wend = f->buf + f->buf_size;

	return 0;
}

/* Link flush-on-exit code iff any stdio write functions are linked. */
void __fflush_on_exit()
{
	fflush(0);
}