socket_util.c revision 269847 
1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "apr_network_io.h"
18#include "apr_poll.h"
19
20APR_DECLARE(apr_status_t) apr_socket_atreadeof(apr_socket_t *sock, int *atreadeof)
21{
22    apr_pollfd_t pfds[1];
23    apr_status_t rv;
24    apr_int32_t  nfds;
25
26    /* The purpose here is to return APR_SUCCESS only in cases in
27     * which it can be unambiguously determined whether or not the
28     * socket will return EOF on next read.  In case of an unexpected
29     * error, return that. */
30
31    pfds[0].reqevents = APR_POLLIN;
32    pfds[0].desc_type = APR_POLL_SOCKET;
33    pfds[0].desc.s = sock;
34
35    do {
36        rv = apr_poll(&pfds[0], 1, &nfds, 0);
37    } while (APR_STATUS_IS_EINTR(rv));
38
39    if (APR_STATUS_IS_TIMEUP(rv)) {
40        /* Read buffer empty -> subsequent reads would block, so,
41         * definitely not at EOF. */
42        *atreadeof = 0;
43        return APR_SUCCESS;
44    }
45    else if (rv) {
46        /* Some other error -> unexpected error. */
47        return rv;
48    }
49    /* Many platforms return only APR_POLLIN; OS X returns APR_POLLHUP|APR_POLLIN */
50    else if (nfds == 1 && (pfds[0].rtnevents & APR_POLLIN)  == APR_POLLIN) {
51        apr_sockaddr_t unused;
52        apr_size_t len = 1;
53        char buf;
54
55        /* The socket is readable - peek to see whether it returns EOF
56         * without consuming bytes from the socket buffer. */
57        rv = apr_socket_recvfrom(&unused, sock, MSG_PEEK, &buf, &len);
58        if (rv == APR_EOF) {
59            *atreadeof = 1;
60            return APR_SUCCESS;
61        }
62        else if (rv) {
63            /* Read error -> unexpected error. */
64            return rv;
65        }
66        else {
67            *atreadeof = 0;
68            return APR_SUCCESS;
69        }
70    }
71
72    /* Should not fall through here. */
73    return APR_EGENERAL;
74}
75
76