+ size_t size = size_;
+ size_t rest;
+ struct bio_bio_st *b, *peer_b;
+
+ BIO_clear_retry_flags(bio);
+
+ if (!bio->init)
+ return 0;
+
+ b = bio->ptr;
+ assert(b != NULL);
+ assert(b->peer != NULL);
+ peer_b = b->peer->ptr;
+ assert(peer_b != NULL);
+ assert(peer_b->buf != NULL);
+
+ peer_b->request = 0; /* will be set in "retry_read" situation */
+
+ if (buf == NULL || size == 0)
+ return 0;
+
+ if (peer_b->len == 0)
+ {
+ if (peer_b->closed)
+ return 0; /* writer has closed, and no data is left */
+ else
+ {
+ BIO_set_retry_read(bio); /* buffer is empty */
+ if (size <= peer_b->size)
+ peer_b->request = size;
+ else
+ /* don't ask for more than the peer can
+ * deliver in one write */
+ peer_b->request = peer_b->size;
+ return -1;
+ }
+ }
+
+ /* we can read */
+ if (peer_b->len < size)
+ size = peer_b->len;
+
+ /* now read "size" bytes */
+
+ rest = size;
+
+ assert(rest > 0);
+ do /* one or two iterations */
+ {
+ size_t chunk;
+
+ assert(rest <= peer_b->len);
+ if (peer_b->offset + rest <= peer_b->size)
+ chunk = rest;
+ else
+ /* wrap around ring buffer */
+ chunk = peer_b->size - peer_b->offset;
+ assert(peer_b->offset + chunk <= peer_b->size);
+
+ memcpy(buf, peer_b->buf + peer_b->offset, chunk);
+
+ peer_b->len -= chunk;
+ if (peer_b->len)
+ {
+ peer_b->offset += chunk;
+ assert(peer_b->offset <= peer_b->size);
+ if (peer_b->offset == peer_b->size)
+ peer_b->offset = 0;
+ buf += chunk;
+ }
+ else
+ {
+ /* buffer now empty, no need to advance "buf" */
+ assert(chunk == rest);
+ peer_b->offset = 0;
+ }
+ rest -= chunk;
+ }
+ while (rest);
+
+ return size;