1#include "stdio_impl.h"
2#include <sys/uio.h>
3
4size_t __stdio_read(FILE* f, unsigned char* buf, size_t len) {
5    struct iovec iov[2] = {{.iov_base = buf, .iov_len = len - !!f->buf_size},
6                           {.iov_base = f->buf, .iov_len = f->buf_size}};
7    ssize_t cnt = readv(f->fd, iov, 2);
8    if (cnt <= 0) {
9        f->flags |= F_EOF ^ ((F_ERR ^ F_EOF) & cnt);
10        return cnt;
11    }
12    if (cnt <= iov[0].iov_len)
13        return cnt;
14    cnt -= iov[0].iov_len;
15    f->rpos = f->buf;
16    f->rend = f->buf + cnt;
17    if (f->buf_size)
18        buf[len - 1] = *f->rpos++;
19    return len;
20}
21