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#include "stdio_impl.h"
int __underflow(FILE *f)
{
ssize_t cnt;
/* Read from buffer (Do we ever get called when this is true??) */
if (f->rpos < f->rstop) return *f->rpos;
/* Initialize if we're not already reading */
if (!f->rstop) {
/* Fail immediately if unreadable, eof, or error state. */
if (f->flags & (F_EOF|F_ERR|F_NORD)) return EOF;
/* Set byte orientation -1,0=>-1; 1=>1 */
f->mode |= f->mode-1;
/* Flush any unwritten output; fail on error. */
if (f->wpos > f->buf && __oflow(f)) return EOF;
/* Disallow writes to buffer. */
f->wstop = 0;
}
/* Perform the underlying read operation */
if ((cnt=f->read(f, f->buf, f->buf_size)) + 1 <= 1) {
/* Set flags and leave read mode */
f->flags |= F_EOF | (cnt & F_ERR);
f->rpos = f->rend = f->rstop = 0;
return EOF;
}
/* Setup buffer pointers for reading from buffer */
f->rpos = f->buf;
f->rend = f->rstop = f->buf + cnt;
return *f->rpos;
}
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