tools/xenstore: move per connection read and write func hooks into a struct

Put the interface type specific functions into an own structure and let
struct connection contain only a pointer to that new function vector.

Don't even define the socket based functions in case of NO_SOCKETS
(Mini-OS).

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>

tools/xenstore/xenstored_core.c

@@ -226,8 +226,8 @@ static bool write_messages(struct connection *conn)
 				sockmsg_string(out->hdr.msg.type),
 				out->hdr.msg.len,
 				out->buffer, conn);
-		ret = conn->write(conn, out->hdr.raw + out->used,
-				  sizeof(out->hdr) - out->used);
+		ret = conn->funcs->write(conn, out->hdr.raw + out->used,
+					 sizeof(out->hdr) - out->used);
 		if (ret < 0)
 			return false;
 
@@ -243,8 +243,8 @@ static bool write_messages(struct connection *conn)
 			return true;
 	}
 
-	ret = conn->write(conn, out->buffer + out->used,
-			  out->hdr.msg.len - out->used);
+	ret = conn->funcs->write(conn, out->buffer + out->used,
+				 out->hdr.msg.len - out->used);
 	if (ret < 0)
 		return false;
 
@@ -1532,8 +1532,8 @@ static void handle_input(struct connection *conn)
 	/* Not finished header yet? */
 	if (in->inhdr) {
 		if (in->used != sizeof(in->hdr)) {
-			bytes = conn->read(conn, in->hdr.raw + in->used,
-					   sizeof(in->hdr) - in->used);
+			bytes = conn->funcs->read(conn, in->hdr.raw + in->used,
+						  sizeof(in->hdr) - in->used);
 			if (bytes < 0)
 				goto bad_client;
 			in->used += bytes;
@@ -1558,8 +1558,8 @@ static void handle_input(struct connection *conn)
 		in->inhdr = false;
 	}
 
-	bytes = conn->read(conn, in->buffer + in->used,
-			   in->hdr.msg.len - in->used);
+	bytes = conn->funcs->read(conn, in->buffer + in->used,
+				  in->hdr.msg.len - in->used);
 	if (bytes < 0)
 		goto bad_client;
 
@@ -1582,7 +1582,7 @@ static void handle_output(struct connection *conn)
 		ignore_connection(conn);
 }
 
-struct connection *new_connection(connwritefn_t *write, connreadfn_t *read)
+struct connection *new_connection(const struct interface_funcs *funcs)
 {
 	struct connection *new;
 
@@ -1592,8 +1592,7 @@ struct connection *new_connection(connwritefn_t *write, connreadfn_t *read)
 
 	new->fd = -1;
 	new->pollfd_idx = -1;
-	new->write = write;
-	new->read = read;
+	new->funcs = funcs;
 	new->is_ignored = false;
 	new->transaction_started = 0;
 	INIT_LIST_HEAD(&new->out_list);
@@ -1622,20 +1621,8 @@ struct connection *get_connection_by_id(unsigned int conn_id)
 static void accept_connection(int sock)
 {
 }
-
-int writefd(struct connection *conn, const void *data, unsigned int len)
-{
-	errno = EBADF;
-	return -1;
-}
-
-int readfd(struct connection *conn, void *data, unsigned int len)
-{
-	errno = EBADF;
-	return -1;
-}
 #else
-int writefd(struct connection *conn, const void *data, unsigned int len)
+static int writefd(struct connection *conn, const void *data, unsigned int len)
 {
 	int rc;
 
@@ -1651,7 +1638,7 @@ int writefd(struct connection *conn, const void *data, unsigned int len)
 	return rc;
 }
 
-int readfd(struct connection *conn, void *data, unsigned int len)
+static int readfd(struct connection *conn, void *data, unsigned int len)
 {
 	int rc;
 
@@ -1673,6 +1660,11 @@ int readfd(struct connection *conn, void *data, unsigned int len)
 	return rc;
 }
 
+const struct interface_funcs socket_funcs = {
+	.write = writefd,
+	.read = readfd,
+};
+
 static void accept_connection(int sock)
 {
 	int fd;
@@ -1682,7 +1674,7 @@ static void accept_connection(int sock)
 	if (fd < 0)
 		return;
 
-	conn = new_connection(writefd, readfd);
+	conn = new_connection(&socket_funcs);
 	if (conn)
 		conn->fd = fd;
 	else

tools/xenstore/xenstored_core.h

@@ -86,8 +86,11 @@ struct delayed_request {
 };
 
 struct connection;
-typedef int connwritefn_t(struct connection *, const void *, unsigned int);
-typedef int connreadfn_t(struct connection *, void *, unsigned int);
+
+struct interface_funcs {
+	int (*write)(struct connection *, const void *, unsigned int);
+	int (*read)(struct connection *, void *, unsigned int);
+};
 
 struct connection
 {
@@ -131,9 +134,8 @@ struct connection
 	/* My watches. */
 	struct list_head watches;
 
-	/* Methods for communicating over this connection: write can be NULL */
-	connwritefn_t *write;
-	connreadfn_t *read;
+	/* Methods for communicating over this connection. */
+	const struct interface_funcs *funcs;
 
 	/* Support for live update: connection id. */
 	unsigned int conn_id;
@@ -196,7 +198,7 @@ int write_node_raw(struct connection *conn, TDB_DATA *key, struct node *node,
 struct node *read_node(struct connection *conn, const void *ctx,
 		       const char *name);
 
-struct connection *new_connection(connwritefn_t *write, connreadfn_t *read);
+struct connection *new_connection(const struct interface_funcs *funcs);
 struct connection *get_connection_by_id(unsigned int conn_id);
 void check_store(void);
 void corrupt(struct connection *conn, const char *fmt, ...);
@@ -256,10 +258,9 @@ void finish_daemonize(void);
 /* Open a pipe for signal handling */
 void init_pipe(int reopen_log_pipe[2]);
 
-int writefd(struct connection *conn, const void *data, unsigned int len);
-int readfd(struct connection *conn, void *data, unsigned int len);
-
-extern struct interface_funcs socket_funcs;
+#ifndef NO_SOCKETS
+extern const struct interface_funcs socket_funcs;
+#endif
 extern xengnttab_handle **xgt_handle;
 
 int remember_string(struct hashtable *hash, const char *str);

tools/xenstore/xenstored_domain.c

@@ -172,6 +172,11 @@ static int readchn(struct connection *conn, void *data, unsigned int len)
 	return len;
 }
 
+static const struct interface_funcs domain_funcs = {
+	.write = writechn,
+	.read = readchn,
+};
+
 static void *map_interface(domid_t domid)
 {
 	return xengnttab_map_grant_ref(*xgt_handle, domid,
@@ -389,7 +394,7 @@ static int new_domain(struct domain *domain, int port, bool restore)
 
 	domain->introduced = true;
 
-	domain->conn = new_connection(writechn, readchn);
+	domain->conn = new_connection(&domain_funcs);
 	if (!domain->conn)  {
 		errno = ENOMEM;
 		return errno;
@@ -1288,10 +1293,14 @@ void read_state_connection(const void *ctx, const void *state)
 	struct domain *domain, *tdomain;
 
 	if (sc->conn_type == XS_STATE_CONN_TYPE_SOCKET) {
-		conn = new_connection(writefd, readfd);
+#ifdef NO_SOCKETS
+		barf("socket based connection without sockets");
+#else
+		conn = new_connection(&socket_funcs);
 		if (!conn)
 			barf("error restoring connection");
 		conn->fd = sc->spec.socket_fd;
+#endif
 	} else {
 		domain = introduce_domain(ctx, sc->spec.ring.domid,
 					  sc->spec.ring.evtchn, true);