+ b->len += chunk;
+
+ assert(b->len <= b->size);
+
+ rest -= chunk;
+ buf += chunk;
+ }
+ while (rest);
+
+ return num;
+}
+
+/*-
+ * non-copying interface: provide pointer to region to write to
+ * bio_nwrite0: check how much space is available
+ * bio_nwrite: also increase length
+ * (example usage: bio_nwrite0(), write to buffer, bio_nwrite()
+ * or just bio_nwrite(), write to buffer)
+ */
+static ossl_ssize_t bio_nwrite0(BIO *bio, char **buf)
+{
+ struct bio_bio_st *b;
+ size_t num;
+ size_t write_offset;
+
+ BIO_clear_retry_flags(bio);
+
+ if (!bio->init)
+ return 0;
+
+ b = bio->ptr;
+ assert(b != NULL);
+ assert(b->peer != NULL);
+ assert(b->buf != NULL);
+
+ b->request = 0;
+ if (b->closed) {
+ BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);
+ return -1;
+ }
+
+ assert(b->len <= b->size);
+
+ if (b->len == b->size) {
+ BIO_set_retry_write(bio);
+ return -1;
+ }
+
+ num = b->size - b->len;
+ write_offset = b->offset + b->len;
+ if (write_offset >= b->size)
+ write_offset -= b->size;
+ if (write_offset + num > b->size)
+ /*
+ * no ring buffer wrap-around for non-copying interface (to fulfil
+ * the promise by BIO_ctrl_get_write_guarantee, BIO_nwrite may have
+ * to be called twice)
+ */
+ num = b->size - write_offset;
+
+ if (buf != NULL)
+ *buf = b->buf + write_offset;
+ assert(write_offset + num <= b->size);
+
+ return num;
+}
+
+static ossl_ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)
+{
+ struct bio_bio_st *b;
+ ossl_ssize_t num, space;
+
+ if (num_ > SSIZE_MAX)
+ num = SSIZE_MAX;
+ else
+ num = (ossl_ssize_t) num_;
+
+ space = bio_nwrite0(bio, buf);
+ if (num > space)
+ num = space;
+ if (num <= 0)
+ return num;
+ b = bio->ptr;
+ assert(b != NULL);
+ b->len += num;
+ assert(b->len <= b->size);
+
+ return num;
+}
+
+static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
+{
+ long ret;
+ struct bio_bio_st *b = bio->ptr;
+
+ assert(b != NULL);
+
+ switch (cmd) {
+ /* specific CTRL codes */
+
+ case BIO_C_SET_WRITE_BUF_SIZE:
+ if (b->peer) {
+ BIOerr(BIO_F_BIO_CTRL, BIO_R_IN_USE);
+ ret = 0;
+ } else if (num == 0) {
+ BIOerr(BIO_F_BIO_CTRL, BIO_R_INVALID_ARGUMENT);
+ ret = 0;
+ } else {
+ size_t new_size = num;
+
+ if (b->size != new_size) {
+ OPENSSL_free(b->buf);
+ b->buf = NULL;
+ b->size = new_size;
+ }
+ ret = 1;
+ }
+ break;
+
+ case BIO_C_GET_WRITE_BUF_SIZE:
+ ret = (long)b->size;
+ break;
+
+ case BIO_C_MAKE_BIO_PAIR:
+ {
+ BIO *other_bio = ptr;
+
+ if (bio_make_pair(bio, other_bio))
+ ret = 1;
+ else
+ ret = 0;
+ }
+ break;
+
+ case BIO_C_DESTROY_BIO_PAIR:
+ /*
+ * Affects both BIOs in the pair -- call just once! Or let
+ * BIO_free(bio1); BIO_free(bio2); do the job.
+ */
+ bio_destroy_pair(bio);
+ ret = 1;
+ break;
+
+ case BIO_C_GET_WRITE_GUARANTEE:
+ /*
+ * How many bytes can the caller feed to the next write without
+ * having to keep any?
+ */
+ if (b->peer == NULL || b->closed)
+ ret = 0;
+ else
+ ret = (long)b->size - b->len;
+ break;
+
+ case BIO_C_GET_READ_REQUEST:
+ /*
+ * If the peer unsuccessfully tried to read, how many bytes were
+ * requested? (As with BIO_CTRL_PENDING, that number can usually be
+ * treated as boolean.)
+ */
+ ret = (long)b->request;
+ break;
+
+ case BIO_C_RESET_READ_REQUEST:
+ /*
+ * Reset request. (Can be useful after read attempts at the other
+ * side that are meant to be non-blocking, e.g. when probing SSL_read
+ * to see if any data is available.)
+ */
+ b->request = 0;
+ ret = 1;
+ break;
+
+ case BIO_C_SHUTDOWN_WR:
+ /* similar to shutdown(..., SHUT_WR) */
+ b->closed = 1;
+ ret = 1;
+ break;
+
+ case BIO_C_NREAD0:
+ /* prepare for non-copying read */
+ ret = (long)bio_nread0(bio, ptr);
+ break;
+
+ case BIO_C_NREAD:
+ /* non-copying read */
+ ret = (long)bio_nread(bio, ptr, (size_t)num);
+ break;
+
+ case BIO_C_NWRITE0:
+ /* prepare for non-copying write */
+ ret = (long)bio_nwrite0(bio, ptr);
+ break;
+
+ case BIO_C_NWRITE:
+ /* non-copying write */
+ ret = (long)bio_nwrite(bio, ptr, (size_t)num);
+ break;
+
+ /* standard CTRL codes follow */
+
+ case BIO_CTRL_RESET:
+ if (b->buf != NULL) {
+ b->len = 0;
+ b->offset = 0;
+ }
+ ret = 0;
+ break;
+
+ case BIO_CTRL_GET_CLOSE:
+ ret = bio->shutdown;
+ break;
+
+ case BIO_CTRL_SET_CLOSE:
+ bio->shutdown = (int)num;
+ ret = 1;
+ break;
+
+ case BIO_CTRL_PENDING:
+ if (b->peer != NULL) {
+ struct bio_bio_st *peer_b = b->peer->ptr;
+
+ ret = (long)peer_b->len;
+ } else
+ ret = 0;
+ break;
+
+ case BIO_CTRL_WPENDING:
+ if (b->buf != NULL)
+ ret = (long)b->len;
+ else
+ ret = 0;
+ break;
+
+ case BIO_CTRL_DUP:
+ /* See BIO_dup_chain for circumstances we have to expect. */
+ {
+ BIO *other_bio = ptr;
+ struct bio_bio_st *other_b;
+
+ assert(other_bio != NULL);
+ other_b = other_bio->ptr;
+ assert(other_b != NULL);
+
+ assert(other_b->buf == NULL); /* other_bio is always fresh */
+
+ other_b->size = b->size;
+ }
+
+ ret = 1;
+ break;
+
+ case BIO_CTRL_FLUSH:
+ ret = 1;
+ break;
+
+ case BIO_CTRL_EOF:
+ {
+ BIO *other_bio = ptr;
+
+ if (other_bio) {
+ struct bio_bio_st *other_b = other_bio->ptr;
+
+ assert(other_b != NULL);
+ ret = other_b->len == 0 && other_b->closed;
+ } else
+ ret = 1;
+ }
+ break;
+
+ default:
+ ret = 0;
+ }
+ return ret;
+}
+
+static int bio_puts(BIO *bio, const char *str)
+{
+ return bio_write(bio, str, strlen(str));
+}