5 * File descriptor passing
7 * (c) 2003 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Header files ------------------------------------------------------*/
39 #include <sys/types.h>
42 #include <sys/socket.h>
48 /*----- Main code ---------------------------------------------------------*/
50 /* --- @fdpass_send@ --- *
52 * Arguments: @int sock@ = socket to send over
53 * @int fd@ = file descriptor to send
54 * @const void *p@ = pointer to data to send
55 * @size_t sz@ = size of buffer to send
57 * Returns: On error, @-1@, otherwise number of bytes transferred from
60 * Use: Sends a copy of file descriptor @fd@ to the other end of
64 ssize_t
fdpass_send(int sock
, int fd
, const void *p
, size_t sz
)
68 #ifndef HAVE_MSG_ACCRIGHTS
69 char buf
[CMSG_SPACE(sizeof(fd
))];
73 iov
.iov_base
= (/*unconst*/ void *)p
;
79 #ifdef HAVE_MSG_ACCRIGHTS
80 msg
.msg_accrights
= &fd
;
81 msg
.msg_accrightslen
= sizeof(fd
);
84 msg
.msg_control
= buf
;
85 msg
.msg_controllen
= sizeof(buf
);
86 cmsg
= CMSG_FIRSTHDR(&msg
);
87 cmsg
->cmsg_len
= CMSG_LEN(sizeof(fd
));
88 cmsg
->cmsg_level
= SOL_SOCKET
;
89 cmsg
->cmsg_type
= SCM_RIGHTS
;
90 memcpy(CMSG_DATA(cmsg
), &fd
, sizeof(fd
));
92 return (sendmsg(sock
, &msg
, 0));
95 /* --- @fdpass_recv@ --- *
97 * Arguments: @int sock@ = socket to send over
98 * @int *fd@ = where to put received descriptor
99 * @void *p@ = pointer to where to put data
100 * @size_t sz@ = size of buffer
102 * Returns: On error, @-1@, otherwise number of bytes transferred.
104 * Use: Receives a file descriptor. If the call succeeds, and there
105 * was a file descriptor, then @fd@ won't be @-1@ on exit;
106 * otherwise it will. At most one descriptor will be collected.
109 ssize_t
fdpass_recv(int sock
, int *fd
, void *p
, size_t sz
)
114 #ifndef HAVE_MSG_ACCRIGHTS
115 char buf
[CMSG_SPACE(sizeof(fd
))];
116 struct cmsghdr
*cmsg
;
127 #ifdef HAVE_MSG_ACCRIGHTS
128 msg
.msg_accrights
= fd
;
129 msg
.msg_accrightslen
= sizeof(*fd
);
132 msg
.msg_control
= buf
;
133 msg
.msg_controllen
= sizeof(buf
);
135 if ((rc
= recvmsg(sock
, &msg
, 0)) < 0)
137 #ifdef HAVE_MSG_ACCRIGHTS
138 if (msg
.msg_accrightslen
< sizeof(*fd
))
141 for (cmsg
= CMSG_FIRSTHDR(&msg
); cmsg
; cmsg
= CMSG_NXTHDR(&msg
, cmsg
)) {
142 if (cmsg
->cmsg_level
== SOL_SOCKET
&&
143 cmsg
->cmsg_type
== SCM_RIGHTS
&&
144 cmsg
->cmsg_len
>= CMSG_LEN(sizeof(fd
))) {
145 memcpy(&fdtmp
, CMSG_DATA(cmsg
), sizeof(fdtmp
));
156 /*----- That's all, folks -------------------------------------------------*/