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https://gitlab.freedesktop.org/dbus/dbus.git
synced 2026-05-05 11:08:03 +02:00
sysdeps-unix: add basic IO primitives for unix fd passing
This introduces three new functions: _dbus_read_socket_with_unix_fds _dbus_write_socket_with_unix_fds _dbus_read_socket_with_unix_fds_two These work exactly like their counterpart sans 'with_unix_fds' except that they also send/recieve file descriptors along with the actual payload data.
This commit is contained in:
Lennart Poettering
parent
64c63db21e
commit
4c4db7f9da
3 changed files with 268 additions and 1 deletions
10
configure.in
10
configure.in
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@ -1094,6 +1094,16 @@ else
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AC_MSG_RESULT(no)
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fi
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# Check for SCM_RIGHTS
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AC_MSG_CHECKING([for SCM_RIGHTS])
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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#include <sys/socket.h>
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#include <sys/un.h>
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static int x = SCM_RIGHTS;
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]], [[]])],
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[ AC_MSG_RESULT([supported])
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AC_DEFINE([HAVE_UNIX_FD_PASSING], [1], [Supports sending UNIX file descriptors]) ],
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[ AC_MSG_RESULT([not supported]) ])
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#### Set up final flags
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DBUS_CLIENT_CFLAGS=
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@ -199,6 +199,241 @@ _dbus_write_socket (int fd,
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#endif
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}
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/**
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* Like _dbus_read_socket() but also tries to read unix fds from the
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* socket. When there are more fds to read than space in the array
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* passed this function will fail with ENOSPC.
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*
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* @param fd the socket
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* @param buffer string to append data to
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* @param count max amount of data to read
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* @param fds array to place read file descriptors in
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* @param n_fds on input space in fds array, on output how many fds actually got read
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* @returns number of bytes appended to string
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*/
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int
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_dbus_read_socket_with_unix_fds (int fd,
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DBusString *buffer,
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int count,
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int *fds,
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int *n_fds) {
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#ifndef HAVE_UNIX_FD_PASSING
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int r;
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if ((r = _dbus_read_socket(fd, buffer, count)) < 0)
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return r;
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*n_fds = 0;
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return r;
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#else
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int bytes_read;
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int start;
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struct msghdr m;
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struct iovec iov;
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_dbus_assert (count >= 0);
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_dbus_assert (*n_fds >= 0);
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start = _dbus_string_get_length (buffer);
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if (!_dbus_string_lengthen (buffer, count))
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{
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errno = ENOMEM;
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return -1;
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}
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_DBUS_ZERO(iov);
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iov.iov_base = _dbus_string_get_data_len (buffer, start, count);
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iov.iov_len = count;
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_DBUS_ZERO(m);
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m.msg_iov = &iov;
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m.msg_iovlen = 1;
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/* Hmm, we have no clue how long the control data will actually be
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that is queued for us. The least we can do is assume that the
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caller knows. Hence let's make space for the number of fds that
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we shall read at max plus the cmsg header. */
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m.msg_controllen = CMSG_SPACE(*n_fds * sizeof(int));
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/* It's probably safe to assume that systems with SCM_RIGHTS also
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know alloca() */
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m.msg_control = alloca(m.msg_controllen);
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memset(m.msg_control, 0, m.msg_controllen);
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again:
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bytes_read = recvmsg(fd, &m, 0
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#ifdef MSG_CMSG_CLOEXEC
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|MSG_CMSG_CLOEXEC
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#endif
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);
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if (bytes_read < 0)
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{
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if (errno == EINTR)
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goto again;
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else
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{
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/* put length back (note that this doesn't actually realloc anything) */
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_dbus_string_set_length (buffer, start);
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return -1;
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}
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}
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else
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{
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struct cmsghdr *cm;
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dbus_bool_t found = FALSE;
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if (m.msg_flags & MSG_CTRUNC)
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{
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/* Hmm, apparently the control data was truncated. The bad
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thing is that we might have completely lost a couple of fds
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without chance to recover them. Hence let's treat this as a
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serious error. */
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errno = ENOSPC;
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_dbus_string_set_length (buffer, start);
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return -1;
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}
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for (cm = CMSG_FIRSTHDR(&m); cm; cm = CMSG_NXTHDR(&m, cm))
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if (cm->cmsg_level == SOL_SOCKET && cm->cmsg_type == SCM_RIGHTS)
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{
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unsigned i;
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_dbus_assert(cm->cmsg_len <= CMSG_LEN(*n_fds * sizeof(int)));
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*n_fds = (cm->cmsg_len - CMSG_LEN(0)) / sizeof(int);
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memcpy(fds, CMSG_DATA(cm), *n_fds * sizeof(int));
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found = TRUE;
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/* Linux doesn't tell us whether MSG_CMSG_CLOEXEC actually
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worked, hence we need to go through this list and set
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CLOEXEC everywhere in any case */
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for (i = 0; i < *n_fds; i++)
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_dbus_fd_set_close_on_exec(fds[i]);
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break;
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}
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if (!found)
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*n_fds = 0;
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/* put length back (doesn't actually realloc) */
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_dbus_string_set_length (buffer, start + bytes_read);
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#if 0
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if (bytes_read > 0)
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_dbus_verbose_bytes_of_string (buffer, start, bytes_read);
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#endif
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return bytes_read;
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}
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#endif
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}
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int
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_dbus_write_socket_with_unix_fds(int fd,
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const DBusString *buffer,
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int start,
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int len,
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const int *fds,
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int n_fds) {
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#ifndef HAVE_UNIX_FD_PASSING
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if (n_fds > 0) {
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errno = ENOTSUP;
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return -1;
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}
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return _dbus_write_socket(fd, buffer, start, len);
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#else
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return _dbus_write_socket_with_unix_fds_two(fd, buffer, start, len, NULL, 0, 0, fds, n_fds);
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#endif
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}
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int
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_dbus_write_socket_with_unix_fds_two(int fd,
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const DBusString *buffer1,
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int start1,
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int len1,
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const DBusString *buffer2,
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int start2,
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int len2,
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const int *fds,
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int n_fds) {
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#ifndef HAVE_UNIX_FD_PASSING
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if (n_fds > 0) {
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errno = ENOTSUP;
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return -1;
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}
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return _dbus_write_socket_two(fd,
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buffer1, start1, len1,
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buffer2, start2, len2);
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#else
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struct msghdr m;
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struct cmsghdr *cm;
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struct iovec iov[2];
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int bytes_written;
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_dbus_assert (len1 >= 0);
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_dbus_assert (len2 >= 0);
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_dbus_assert (n_fds >= 0);
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_DBUS_ZERO(iov);
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iov[0].iov_base = (char*) _dbus_string_get_const_data_len (buffer1, start1, len1);
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iov[0].iov_len = len1;
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if (buffer2)
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{
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iov[1].iov_base = (char*) _dbus_string_get_const_data_len (buffer2, start2, len2);
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iov[1].iov_len = len2;
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}
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_DBUS_ZERO(m);
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m.msg_iov = iov;
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m.msg_iovlen = buffer2 ? 2 : 1;
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if (n_fds > 0)
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{
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m.msg_controllen = CMSG_SPACE(n_fds * sizeof(int));
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m.msg_control = alloca(m.msg_controllen);
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memset(m.msg_control, 0, m.msg_controllen);
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cm = CMSG_FIRSTHDR(&m);
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cm->cmsg_level = SOL_SOCKET;
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cm->cmsg_type = SCM_RIGHTS;
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cm->cmsg_len = CMSG_LEN(n_fds * sizeof(int));
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memcpy(CMSG_DATA(cm), fds, n_fds * sizeof(int));
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}
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again:
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bytes_written = sendmsg (fd, &m, 0
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#ifdef MSG_NOSIGNAL
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|MSG_NOSIGNAL
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#endif
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);
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if (bytes_written < 0 && errno == EINTR)
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goto again;
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#if 0
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if (bytes_written > 0)
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_dbus_verbose_bytes_of_string (buffer, start, bytes_written);
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#endif
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return bytes_written;
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#endif
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}
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/**
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* write data to a pipe.
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*
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@ -301,7 +536,7 @@ _dbus_write_socket_two (int fd,
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vectors[1].iov_base = (char*) data2;
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vectors[1].iov_len = len2;
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memset(&m, 0, sizeof(m));
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_DBUS_ZERO(m);
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m.msg_iov = vectors;
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m.msg_iovlen = data2 ? 2 : 1;
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@ -153,6 +153,28 @@ int _dbus_write_socket_two (int fd,
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const DBusString *buffer2,
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int start2,
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int len2);
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int _dbus_read_socket_with_unix_fds (int fd,
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DBusString *buffer,
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int count,
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int *fds,
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int *n_fds);
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int _dbus_write_socket_with_unix_fds (int fd,
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const DBusString *buffer,
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int start,
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int len,
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const int *fds,
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int n_fds);
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int _dbus_write_socket_with_unix_fds_two (int fd,
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const DBusString *buffer1,
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int start1,
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int len1,
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const DBusString *buffer2,
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int start2,
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int len2,
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const int *fds,
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int n_fds);
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int _dbus_connect_tcp_socket (const char *host,
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const char *port,
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const char *family,
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