return ret;
}
+/*
+ * Send a message accompanied by fd(s) over a unix socket.
+ * Only use for non blocking socket.
+ *
+ * Returns the size of data sent, or negative error value.
+ */
+LTTNG_HIDDEN
+ssize_t lttcomm_send_fds_unix_sock_non_block(int sock, const int *fds, size_t nb_fd)
+{
+ struct msghdr msg;
+ struct cmsghdr *cmptr;
+ struct iovec iov[1];
+ ssize_t ret = -1;
+ unsigned int sizeof_fds = nb_fd * sizeof(int);
+ char tmp[CMSG_SPACE(sizeof_fds)];
+ char dummy = 0;
+
+ memset(&msg, 0, sizeof(msg));
+ memset(tmp, 0, sizeof(tmp));
+
+ if (nb_fd > LTTCOMM_MAX_SEND_FDS)
+ return -EINVAL;
+
+ msg.msg_control = (caddr_t)tmp;
+ msg.msg_controllen = CMSG_LEN(sizeof_fds);
+
+ cmptr = CMSG_FIRSTHDR(&msg);
+ if (!cmptr) {
+ return -1;
+ }
+
+ cmptr->cmsg_level = SOL_SOCKET;
+ cmptr->cmsg_type = SCM_RIGHTS;
+ cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
+ memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
+ /* Sum of the length of all control messages in the buffer: */
+ msg.msg_controllen = cmptr->cmsg_len;
+
+ iov[0].iov_base = &dummy;
+ iov[0].iov_len = 1;
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 1;
+
+retry:
+ ret = sendmsg(sock, &msg, 0);
+ if (ret < 0) {
+ if (errno == EINTR) {
+ goto retry;
+ } else {
+ /*
+ * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected.
+ */
+ if (errno == EAGAIN || errno == EWOULDBLOCK) {
+ /*
+ * This can happen in non blocking mode.
+ * Nothing was sent.
+ */
+ ret = 0;
+ goto end;
+ }
+
+ if (errno == EPIPE) {
+ /* Expected error, pass error to caller */
+ DBG3("EPIPE on sendmsg");
+ ret = -1;
+ goto end;
+ }
+
+ /* Unexpected error */
+ PERROR("sendmsg");
+ ret = -1;
+ goto end;
+ }
+ }
+
+end:
+ return ret;
+}
+
/*
* Recv a message accompanied by fd(s) from a unix socket.
*
msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
msg.msg_flags = 0;
- do {
- ret = recvmsg(sock, &msg, 0);
- } while (ret < 0 && errno == EINTR);
+retry:
+ ret = lttng_recvmsg_nosigpipe(sock, &msg);
if (ret < 0) {
- PERROR("recvmsg fds");
+ if (errno == EINTR) {
+ goto retry;
+ } else {
+ /* We consider EPIPE and EAGAIN as expected. */
+ if (!lttng_opt_quiet &&
+ (errno != EPIPE && errno != EAGAIN)) {
+ PERROR("recvmsg");
+ }
+ goto end;
+ }
+ }
+
+ if (ret != 1) {
+ fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
+ ret, 1);
+ goto end;
+ }
+
+ if (msg.msg_flags & MSG_CTRUNC) {
+ fprintf(stderr, "Error: Control message truncated.\n");
+ ret = -1;
goto end;
}
+ /*
+ * If the socket was configured with SO_PASSCRED, the kernel will add a
+ * control message (cmsg) to the ancillary data of the unix socket. We
+ * need to expect a cmsg of the SCM_CREDENTIALS as the first control
+ * message.
+ */
+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_level != SOL_SOCKET) {
+ fprintf(stderr, "Error: The socket needs to be of type SOL_SOCKET\n");
+ ret = -1;
+ goto end;
+ }
+ if (cmsg->cmsg_type == SCM_RIGHTS) {
+ /*
+ * We found the controle message for file descriptors,
+ * now copy the fds to the fds ptr and return success.
+ */
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
+ fprintf(stderr, "Error: Received %zu bytes of"
+ "ancillary data for FDs, expected %zu\n",
+ (size_t) cmsg->cmsg_len,
+ (size_t) CMSG_LEN(sizeof_fds));
+ ret = -1;
+ goto end;
+ }
+ memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
+ ret = sizeof_fds;
+ goto end;
+ }
+#ifdef __linux__
+ if (cmsg->cmsg_type == SCM_CREDENTIALS) {
+ /*
+ * Expect credentials to be sent when expecting fds even
+ * if no credential were include in the send(). The
+ * kernel adds them...
+ */
+ ret = -1;
+ }
+#endif /* __linux__ */
+ }
+end:
+ return ret;
+}
+
+/*
+ * Recv a message accompanied by fd(s) from a non-blocking unix socket.
+ * Only use with non-blocking sockets.
+ *
+ * Returns the size of received data, or negative error value.
+ *
+ * Expect at most "nb_fd" file descriptors.
+ *
+ * Note that based on our comprehension, partial reception of fds is not
+ * possible since the FDs are actually in the control message. It is all or
+ * nothing, still the sender side can send the wrong number of fds.
+ */
+LTTNG_HIDDEN
+ssize_t lttcomm_recv_fds_unix_sock_non_block(int sock, int *fds, size_t nb_fd)
+{
+ struct iovec iov[1];
+ ssize_t ret = 0;
+ struct cmsghdr *cmsg;
+ size_t sizeof_fds = nb_fd * sizeof(int);
+
+#ifdef __linux__
+/* Account for the struct ucred cmsg in the buffer size */
+#define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds) + CMSG_SPACE(sizeof(struct ucred))
+#else
+#define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds)
+#endif /* __linux__ */
+
+ char recv_buf[LTTNG_SOCK_RECV_FDS_BUF_SIZE];
+ struct msghdr msg;
+ char dummy;
+
+ memset(&msg, 0, sizeof(msg));
+
+ /* Prepare to receive the structures */
+ iov[0].iov_base = &dummy;
+ iov[0].iov_len = 1;
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 1;
+
+ cmsg = (struct cmsghdr *) recv_buf;
+ cmsg->cmsg_len = CMSG_LEN(sizeof_fds);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+
+ msg.msg_control = cmsg;
+ msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
+ msg.msg_flags = 0;
+
+retry:
+ ret = lttng_recvmsg_nosigpipe(sock, &msg);
+ if (ret < 0) {
+ if (errno == EINTR) {
+ goto retry;
+ } else {
+ /*
+ * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected.
+ */
+ if (errno == EAGAIN || errno == EWOULDBLOCK) {
+ /*
+ * This can happen in non blocking mode.
+ * Nothing was recv.
+ */
+ ret = 0;
+ goto end;
+ }
+
+ if (errno == EPIPE) {
+ /* Expected error, pass error to caller */
+ DBG3("EPIPE on recvmsg");
+ ret = -1;
+ goto end;
+ }
+
+ /* Unexpected error */
+ PERROR("recvmsg");
+ ret = -1;
+ goto end;
+ }
+ }
+
if (ret != 1) {
fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
ret, 1);
projects / lttng-tools.git / commitdiff
