Support marshalling of file descriptors

connection.c

@@ -47,6 +47,8 @@ struct wl_buffer {
 
 struct wl_connection {
 	struct wl_buffer in, out;
+	struct wl_buffer fds_in, fds_out;
+	int fds_in_tail;
 	int fd;
 	void *data;
 	wl_connection_update_func_t update;
@@ -169,13 +171,68 @@ void
 wl_connection_consume(struct wl_connection *connection, size_t size)
 {
 	connection->in.tail += size;
+	connection->fds_in.tail = connection->fds_in_tail;
 }
 
-int wl_connection_data(struct wl_connection *connection, uint32_t mask)
+static void
+build_cmsg(struct wl_buffer *buffer, char *data, int *clen)
+{
+	struct cmsghdr *cmsg;
+	size_t size;
+
+	size = buffer->head - buffer->tail;
+	if (size > 0) {
+		cmsg = (struct cmsghdr *) data;
+		cmsg->cmsg_level = SOL_SOCKET;
+		cmsg->cmsg_type = SCM_RIGHTS;
+		cmsg->cmsg_len = CMSG_LEN(size);
+		wl_buffer_copy(buffer, CMSG_DATA(cmsg), size);
+		*clen = cmsg->cmsg_len;
+	} else {
+		*clen = 0;
+	}
+}
+
+static void
+close_fds(struct wl_buffer *buffer)
+{
+	int fds[32], i, count;
+	size_t size;
+
+	size = buffer->head - buffer->tail;
+	if (size == 0)
+		return;
+
+	wl_buffer_copy(buffer, fds, size);
+	count = size / 4;
+	for (i = 0; i < count; i++)
+		close(fds[i]);
+	buffer->tail += size;
+}
+
+static void
+decode_cmsg(struct wl_buffer *buffer, struct msghdr *msg)
+{
+	struct cmsghdr *cmsg;
+	size_t size;
+
+	for (cmsg = CMSG_FIRSTHDR(msg); cmsg != NULL;
+	     cmsg = CMSG_NXTHDR(msg, cmsg)) {
+		if (cmsg->cmsg_level == SOL_SOCKET &&
+		    cmsg->cmsg_type == SCM_RIGHTS) {
+			size = cmsg->cmsg_len - CMSG_LEN(0);
+			wl_buffer_put(buffer, CMSG_DATA(cmsg), size);
+		}
+	}
+}
+
+int
+wl_connection_data(struct wl_connection *connection, uint32_t mask)
 {
 	struct iovec iov[2];
 	struct msghdr msg;
-	int len, count;
+	char cmsg[128];
+	int len, count, clen;
 
 	if (mask & WL_CONNECTION_READABLE) {
 		wl_buffer_put_iov(&connection->in, iov, &count);
@@ -184,8 +241,9 @@ int wl_connection_data(struct wl_connection *connection, uint32_t mask)
 		msg.msg_namelen = 0;
 		msg.msg_iov = iov;
 		msg.msg_iovlen = count;
-		msg.msg_control = NULL;
-		msg.msg_controllen = 0;
+		msg.msg_control = cmsg;
+		msg.msg_controllen = sizeof cmsg;
+		msg.msg_flags = 0;
 
 		do {
 			len = recvmsg(connection->fd, &msg, 0);
@@ -201,28 +259,37 @@ int wl_connection_data(struct wl_connection *connection, uint32_t mask)
 			return -1;
 		}
 
+		decode_cmsg(&connection->fds_in, &msg);
+
 		connection->in.head += len;
 	}	
 
 	if (mask & WL_CONNECTION_WRITABLE) {
 		wl_buffer_get_iov(&connection->out, iov, &count);
 
+		build_cmsg(&connection->fds_out, cmsg, &clen);
+
 		msg.msg_name = NULL;
 		msg.msg_namelen = 0;
 		msg.msg_iov = iov;
 		msg.msg_iovlen = count;
-		msg.msg_control = NULL;
-		msg.msg_controllen = 0;
+		msg.msg_control = cmsg;
+		msg.msg_controllen = clen;
+		msg.msg_flags = 0;
 
 		do {
 			len = sendmsg(connection->fd, &msg, 0);
 		} while (len < 0 && errno == EINTR);
 
 		if (len < 0) {
-			fprintf(stderr, "write error for connection %p: %m\n", connection);
+			fprintf(stderr,
+				"write error for connection %p, fd %d: %m\n",
+				connection, connection->fd);
 			return -1;
 		}
 
+		close_fds(&connection->fds_out);
+
 		connection->out.tail += len;
 		if (connection->out.tail == connection->out.head)
 			connection->update(connection,
@@ -254,9 +321,10 @@ wl_connection_vmarshal(struct wl_connection *connection,
 {
 	struct wl_object *object;
 	uint32_t args[32], length, *p, size;
+	int32_t dup_fd;
 	struct wl_array *array;
 	const char *s;
-	int i, count;
+	int i, count, fd;
 
 	count = strlen(message->signature);
 	assert(count <= ARRAY_LENGTH(args));
@@ -290,6 +358,16 @@ wl_connection_vmarshal(struct wl_connection *connection,
 			memcpy(p, array->data, array->size);
 			p = (void *) p + array->size;
 			break;
+		case 'h':
+			fd = va_arg(ap, int);
+			dup_fd = dup(fd);
+			if (dup_fd < 0) {
+				fprintf(stderr, "dup failed: %m");
+				abort();
+			}
+			wl_buffer_put(&connection->fds_out,
+				      &dup_fd, sizeof dup_fd);
+			break;
 		default:
 			assert(0);
 			break;
@@ -313,7 +391,7 @@ wl_connection_demarshal(struct wl_connection *connection,
 	ffi_type *types[20];
 	ffi_cif cif;
 	uint32_t *p, *next, *end, result, length;
-	int i, count, ret = 0;
+	int i, count, fds_tail, ret = 0;
 	union {
 		uint32_t uint32;
 		char *string;
@@ -347,6 +425,7 @@ wl_connection_demarshal(struct wl_connection *connection,
 	wl_connection_copy(connection, buffer, size);
 	p = &buffer[2];
 	end = (uint32_t *) ((char *) (p + size));
+	fds_tail = connection->fds_in.tail;
 	for (i = 2; i < count; i++) {
 		if (p + 1 > end) {
 			printf("message too short, "
@@ -441,6 +520,13 @@ wl_connection_demarshal(struct wl_connection *connection,
 			memcpy(values[i].array->data, p, length);
 			p = next;
 			break;
+		case 'h':
+			types[i] = &ffi_type_uint32;
+			wl_buffer_copy(&connection->fds_in,
+				       &values[i].uint32,
+				       sizeof values[i].uint32);
+			connection->fds_in.tail += sizeof values[i].uint32;
+			break;
 		default:
 			printf("unknown type\n");
 			assert(0);
@@ -452,6 +538,11 @@ wl_connection_demarshal(struct wl_connection *connection,
 	ffi_prep_cif(&cif, FFI_DEFAULT_ABI, count, &ffi_type_uint32, types);
 	ffi_call(&cif, func, &result, args);
 
+	/* Slight hack here.  We store the tail of fds_in here and
+	 * consume will set fds_in.tail to that value */
+	connection->fds_in_tail = connection->fds_in.tail;
+	connection->fds_in.tail = fds_tail;
+
  out:
 	count = i;
 	for (i = 2; i < count; i++) {

scanner.c

@@ -82,7 +82,8 @@ enum arg_type {
 	UNSIGNED,
 	STRING,
 	OBJECT,
-	ARRAY
+	ARRAY,
+	FD
 };
 
 struct arg {
@@ -189,6 +190,8 @@ start_element(void *data, const char *element_name, const char **atts)
 			arg->type = STRING;
 		else if (strcmp(type, "array") == 0)
 			arg->type = ARRAY;
+		else if (strcmp(type, "fd") == 0)
+			arg->type = FD;
 		else if (strcmp(type, "new_id") == 0) {
 			if (interface_name == NULL) {
 				fprintf(stderr, "no interface name given\n");
@@ -236,7 +239,8 @@ emit_type(struct arg *a)
 	switch (a->type) {
 	default:
 	case INT:
-		printf("int32_t ");
+	case FD:
+		printf("int ");
 		break;
 	case NEW_ID:
 	case UNSIGNED:
@@ -536,6 +540,9 @@ emit_messages(struct wl_list *message_list,
 			case ARRAY:
 				printf("a");
 				break;
+			case FD:
+				printf("h");
+				break;
 			}
 		}
 		printf("\" },\n");