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[mLib] / fdpass.c
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759ef658 1/* -*-c-*-
2 *
1a6043f9 3 * $Id$
759ef658 4 *
5 * File descriptor passing
6 *
7 * (c) 2003 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
759ef658 30/*----- Header files ------------------------------------------------------*/
31
32#include <errno.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36
37#include <sys/types.h>
38#include <sys/time.h>
39#include <unistd.h>
40#include <sys/socket.h>
41#include <sys/uio.h>
42#include <sys/un.h>
43
44#include "fdpass.h"
45
46/*----- Main code ---------------------------------------------------------*/
47
48/* --- @fdpass_send@ --- *
49 *
50 * Arguments: @int sock@ = socket to send over
51 * @int fd@ = file descriptor to send
52 * @const void *p@ = pointer to data to send
53 * @size_t sz@ = size of buffer to send
54 *
55 * Returns: On error, @-1@, otherwise number of bytes transferred from
56 * @p@.
57 *
58 * Use: Sends a copy of file descriptor @fd@ to the other end of
59 * @sock@.
60 */
61
62ssize_t fdpass_send(int sock, int fd, const void *p, size_t sz)
63{
64 struct iovec iov;
65 struct msghdr msg;
66#ifndef HAVE_MSG_ACCRIGHTS
67 char buf[CMSG_SPACE(sizeof(fd))];
68 struct cmsghdr *cmsg;
69#endif
70
71 iov.iov_base = (/*unconst*/ void *)p;
72 iov.iov_len = sz;
73 msg.msg_name = 0;
74 msg.msg_namelen = 0;
75 msg.msg_iov = &iov;
76 msg.msg_iovlen = 1;
759ef658 77#ifdef HAVE_MSG_ACCRIGHTS
78 msg.msg_accrights = &fd;
79 msg.msg_accrightslen = sizeof(fd);
80#else
1a6043f9 81 msg.msg_flags = 0;
759ef658 82 msg.msg_control = buf;
83 msg.msg_controllen = sizeof(buf);
84 cmsg = CMSG_FIRSTHDR(&msg);
85 cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
86 cmsg->cmsg_level = SOL_SOCKET;
87 cmsg->cmsg_type = SCM_RIGHTS;
88 memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
89#endif
90 return (sendmsg(sock, &msg, 0));
91}
92
93/* --- @fdpass_recv@ --- *
94 *
95 * Arguments: @int sock@ = socket to send over
96 * @int *fd@ = where to put received descriptor
97 * @void *p@ = pointer to where to put data
98 * @size_t sz@ = size of buffer
99 *
100 * Returns: On error, @-1@, otherwise number of bytes transferred.
101 *
102 * Use: Receives a file descriptor. If the call succeeds, and there
103 * was a file descriptor, then @fd@ won't be @-1@ on exit;
104 * otherwise it will. At most one descriptor will be collected.
105 */
106
107ssize_t fdpass_recv(int sock, int *fd, void *p, size_t sz)
108{
109 struct iovec iov;
110 struct msghdr msg;
111 ssize_t rc;
112#ifndef HAVE_MSG_ACCRIGHTS
113 char buf[CMSG_SPACE(sizeof(fd))];
114 struct cmsghdr *cmsg;
115 int fdtmp;
116#endif
117
118 *fd = -1;
119 iov.iov_base = p;
120 iov.iov_len = sz;
121 msg.msg_name = 0;
122 msg.msg_namelen = 0;
123 msg.msg_iov = &iov;
124 msg.msg_iovlen = 1;
759ef658 125#ifdef HAVE_MSG_ACCRIGHTS
126 msg.msg_accrights = fd;
127 msg.msg_accrightslen = sizeof(*fd);
128#else
1a6043f9 129 msg.msg_flags = 0;
759ef658 130 msg.msg_control = buf;
131 msg.msg_controllen = sizeof(buf);
132#endif
133 if ((rc = recvmsg(sock, &msg, 0)) < 0)
134 return (rc);
135#ifdef HAVE_MSG_ACCRIGHTS
136 if (msg.msg_accrightslen < sizeof(*fd))
137 *fd = -1;
138#else
139 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
140 if (cmsg->cmsg_level == SOL_SOCKET &&
141 cmsg->cmsg_type == SCM_RIGHTS &&
142 cmsg->cmsg_len >= CMSG_LEN(sizeof(fd))) {
143 memcpy(&fdtmp, CMSG_DATA(cmsg), sizeof(fdtmp));
144 if (*fd == -1)
145 *fd = fdtmp;
146 else
147 close(fdtmp);
148 }
149 }
150#endif
151 return (rc);
152}
153
154/*----- That's all, folks -------------------------------------------------*/