diff options
Diffstat (limited to 'winsup/cygwin/fhandler_socket.cc')
| -rw-r--r-- | winsup/cygwin/fhandler_socket.cc | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/winsup/cygwin/fhandler_socket.cc b/winsup/cygwin/fhandler_socket.cc index 07d042df8..33f8ddf7e 100644 --- a/winsup/cygwin/fhandler_socket.cc +++ b/winsup/cygwin/fhandler_socket.cc @@ -1393,7 +1393,13 @@ fhandler_socket::sendto (const void *ptr, size_t len, int flags, if (to && !get_inet_addr (to, tolen, &sst, &tolen)) return SOCKET_ERROR; - WSABUF wsabuf = { len, (char *) ptr }; + /* Never write more than 64K at once to workaround a problem with + Winsock, which creates a temporary buffer with the total incoming + buffer size and copies the whole content over, regardless of + the size of the internal send buffer. A buffer full condition + is only recognized in subsequent calls and, if len is big enough, + the call even might fail with an out-of-memory condition. */ + WSABUF wsabuf = { len > 65536 ? 65536 : len, (char *) ptr }; return send_internal (&wsabuf, 1, flags, (to ? (const struct sockaddr *) &sst : NULL), tolen); } @@ -1411,12 +1417,17 @@ fhandler_socket::sendmsg (const struct msghdr *msg, int flags) } WSABUF wsabuf[msg->msg_iovlen]; - WSABUF *wsaptr = wsabuf + msg->msg_iovlen; - const struct iovec *iovptr = msg->msg_iov + msg->msg_iovlen; - while (--wsaptr >= wsabuf) + WSABUF *wsaptr = wsabuf; + const struct iovec *iovptr = msg->msg_iov; + size_t total = 0; + for (int i = 0; i < msg->msg_iovlen && total < 65536; ++i) { - wsaptr->len = (--iovptr)->iov_len; - wsaptr->buf = (char *) iovptr->iov_base; + if (total + iovptr->iov_len > 65536) /* See above. */ + wsaptr->len = 65536 - total; + else + wsaptr->len = iovptr->iov_len; + total += wsaptr->len; + (wsaptr++)->buf = (char *) (iovptr++)->iov_base; } return send_internal (wsabuf, msg->msg_iovlen, flags, |