patch-0008-xenstore-let-command-functions-return-error-or-succe.patch

From ea13030de9bfb18a54c2d73d3f1c2e5b6f499d43 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Mon, 5 Dec 2016 08:48:49 +0100
Subject: [PATCH 08/25] xenstore: let command functions return error or success

Add a return value to all wire command functions of xenstored. If such
a function returns an error send the error message in
process_message().

Only code refactoring, no change in behavior expected.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 tools/xenstore/xenstored_core.c        | 215 +++++++++++--------------
 tools/xenstore/xenstored_domain.c      | 170 ++++++++-----------
 tools/xenstore/xenstored_domain.h      |  14 +-
 tools/xenstore/xenstored_transaction.c |  50 +++---
 tools/xenstore/xenstored_transaction.h |   4 +-
 tools/xenstore/xenstored_watch.c       |  46 +++---
 tools/xenstore/xenstored_watch.h       |   4 +-
 7 files changed, 213 insertions(+), 290 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index aef72f37c48a..f7760cc8fe1e 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -775,33 +775,31 @@ bool check_event_node(const char *node)
 	return true;
 }
 
-static void send_directory(struct connection *conn, struct buffered_data *in)
+static int send_directory(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
 	const char *name = onearg(in);
 
 	name = canonicalize(conn, name);
 	node = get_node(conn, in, name, XS_PERM_READ);
-	if (!node) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!node)
+		return errno;
 
 	send_reply(conn, XS_DIRECTORY, node->children, node->childlen);
+
+	return 0;
 }
 
-static void send_directory_part(struct connection *conn,
-				struct buffered_data *in)
+static int send_directory_part(struct connection *conn,
+			       struct buffered_data *in)
 {
 	unsigned int off, len, maxlen, genlen;
 	char *name, *child, *data;
 	struct node *node;
 	char gen[24];
 
-	if (xs_count_strings(in->buffer, in->used) != 2) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (xs_count_strings(in->buffer, in->used) != 2)
+		return EINVAL;
 
 	/* First arg is node name. */
 	name = canonicalize(conn, in->buffer);
@@ -810,10 +808,8 @@ static void send_directory_part(struct connection *conn,
 	off = atoi(in->buffer + strlen(in->buffer) + 1);
 
 	node = get_node(conn, in, name, XS_PERM_READ);
-	if (!node) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!node)
+		return errno;
 
 	genlen = snprintf(gen, sizeof(gen), "%"PRIu64, node->generation) + 1;
 
@@ -821,7 +817,7 @@ static void send_directory_part(struct connection *conn,
 	if (off >= node->childlen) {
 		gen[genlen] = 0;
 		send_reply(conn, XS_DIRECTORY_PART, gen, genlen + 1);
-		return;
+		return 0;
 	}
 
 	len = 0;
@@ -836,10 +832,8 @@ static void send_directory_part(struct connection *conn,
 	}
 
 	data = talloc_array(in, char, genlen + len + 1);
-	if (!data) {
-		send_error(conn, ENOMEM);
-		return;
-	}
+	if (!data)
+		return ENOMEM;
 
 	memcpy(data, gen, genlen);
 	memcpy(data + genlen, node->children + off, len);
@@ -849,21 +843,23 @@ static void send_directory_part(struct connection *conn,
 	}
 
 	send_reply(conn, XS_DIRECTORY_PART, data, genlen + len);
+
+	return 0;
 }
 
-static void do_read(struct connection *conn, struct buffered_data *in)
+static int do_read(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
 	const char *name = onearg(in);
 
 	name = canonicalize(conn, name);
 	node = get_node(conn, in, name, XS_PERM_READ);
-	if (!node) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!node)
+		return errno;
 
 	send_reply(conn, XS_READ, node->data, node->datalen);
+
+	return 0;
 }
 
 static void delete_node_single(struct connection *conn, struct node *node,
@@ -982,7 +978,7 @@ static struct node *create_node(struct connection *conn,
 }
 
 /* path, data... */
-static void do_write(struct connection *conn, struct buffered_data *in)
+static int do_write(struct connection *conn, struct buffered_data *in)
 {
 	unsigned int offset, datalen;
 	struct node *node;
@@ -990,10 +986,8 @@ static void do_write(struct connection *conn, struct buffered_data *in)
 	char *name;
 
 	/* Extra "strings" can be created by binary data. */
-	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec)) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec))
+		return EINVAL;
 
 	offset = strlen(vec[0]) + 1;
 	datalen = in->used - offset;
@@ -1002,39 +996,32 @@ static void do_write(struct connection *conn, struct buffered_data *in)
 	node = get_node(conn, in, name, XS_PERM_WRITE);
 	if (!node) {
 		/* No permissions, invalid input? */
-		if (errno != ENOENT) {
-			send_error(conn, errno);
-			return;
-		}
+		if (errno != ENOENT)
+			return errno;
 		node = create_node(conn, name, in->buffer + offset, datalen);
-		if (!node) {
-			send_error(conn, errno);
-			return;
-		}
+		if (!node)
+			return errno;
 	} else {
 		node->data = in->buffer + offset;
 		node->datalen = datalen;
-		if (!write_node(conn, node)){
-			send_error(conn, errno);
-			return;
-		}
+		if (!write_node(conn, node))
+			return errno;
 	}
 
 	wrl_apply_debit_direct(conn);
 	fire_watches(conn, in, name, false);
 	send_ack(conn, XS_WRITE);
+
+	return 0;
 }
 
-static void do_mkdir(struct connection *conn, struct buffered_data *in)
+static int do_mkdir(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
 	const char *name = onearg(in);
 
-	if (!name) {
-		errno = EINVAL;
-		send_error(conn, errno);
-		return;
-	}
+	if (!name)
+		return EINVAL;
 
 	name = canonicalize(conn, name);
 	node = get_node(conn, in, name, XS_PERM_WRITE);
@@ -1042,19 +1029,17 @@ static void do_mkdir(struct connection *conn, struct buffered_data *in)
 	/* If it already exists, fine. */
 	if (!node) {
 		/* No permissions? */
-		if (errno != ENOENT) {
-			send_error(conn, errno);
-			return;
-		}
+		if (errno != ENOENT)
+			return errno;
 		node = create_node(conn, name, NULL, 0);
-		if (!node) {
-			send_error(conn, errno);
-			return;
-		}
+		if (!node)
+			return errno;
 		wrl_apply_debit_direct(conn);
 		fire_watches(conn, in, name, false);
 	}
 	send_ack(conn, XS_MKDIR);
+
+	return 0;
 }
 
 static void delete_node(struct connection *conn, struct node *node,
@@ -1124,18 +1109,14 @@ static int _rm(struct connection *conn, struct node *node, const char *name)
 	   happen is the child will continue to take up space, but will
 	   otherwise be unreachable. */
 	struct node *parent = read_node(conn, name, get_parent(name, name));
-	if (!parent) {
-		send_error(conn, EINVAL);
-		return 0;
-	}
+	if (!parent)
+		return EINVAL;
 
-	if (!delete_child(conn, parent, basename(name))) {
-		send_error(conn, EINVAL);
-		return 0;
-	}
+	if (!delete_child(conn, parent, basename(name)))
+		return EINVAL;
 
 	delete_node(conn, node, true);
-	return 1;
+	return 0;
 }
 
 
@@ -1150,9 +1131,10 @@ static void internal_rm(const char *name)
 }
 
 
-static void do_rm(struct connection *conn, struct buffered_data *in)
+static int do_rm(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
+	int ret;
 	const char *name = onearg(in);
 
 	name = canonicalize(conn, name);
@@ -1163,29 +1145,30 @@ static void do_rm(struct connection *conn, struct buffered_data *in)
 			node = read_node(conn, in, get_parent(in, name));
 			if (node) {
 				send_ack(conn, XS_RM);
-				return;
+				return 0;
 			}
 			/* Restore errno, just in case. */
 			errno = ENOENT;
 		}
-		send_error(conn, errno);
-		return;
+		return errno;
 	}
 
-	if (streq(name, "/")) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (streq(name, "/"))
+		return EINVAL;
 
-	if (_rm(conn, node, name)) {
-		wrl_apply_debit_direct(conn);
-		fire_watches(conn, in, name, true);
-		send_ack(conn, XS_RM);
-	}
+	ret = _rm(conn, node, name);
+	if (ret)
+		return ret;
+
+    wrl_apply_debit_direct(conn);
+	fire_watches(conn, in, name, true);
+	send_ack(conn, XS_RM);
+
+	return 0;
 }
 
 
-static void do_get_perms(struct connection *conn, struct buffered_data *in)
+static int do_get_perms(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
 	const char *name = onearg(in);
@@ -1194,19 +1177,19 @@ static void do_get_perms(struct connection *conn, struct buffered_data *in)
 
 	name = canonicalize(conn, name);
 	node = get_node(conn, in, name, XS_PERM_READ);
-	if (!node) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!node)
+		return errno;
 
 	strings = perms_to_strings(node, node->perms, node->num_perms, &len);
 	if (!strings)
-		send_error(conn, errno);
-	else
-		send_reply(conn, XS_GET_PERMS, strings, len);
+		return errno;
+
+	send_reply(conn, XS_GET_PERMS, strings, len);
+
+	return 0;
 }
 
-static void do_set_perms(struct connection *conn, struct buffered_data *in)
+static int do_set_perms(struct connection *conn, struct buffered_data *in)
 {
 	unsigned int num;
 	struct xs_permissions *perms;
@@ -1214,10 +1197,8 @@ static void do_set_perms(struct connection *conn, struct buffered_data *in)
 	struct node *node;
 
 	num = xs_count_strings(in->buffer, in->used);
-	if (num < 2) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (num < 2)
+		return EINVAL;
 
 	/* First arg is node name. */
 	name = canonicalize(conn, in->buffer);
@@ -1226,55 +1207,44 @@ static void do_set_perms(struct connection *conn, struct buffered_data *in)
 
 	/* We must own node to do this (tools can do this too). */
 	node = get_node(conn, in, name, XS_PERM_WRITE|XS_PERM_OWNER);
-	if (!node) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!node)
+		return errno;
 
 	perms = talloc_array(node, struct xs_permissions, num);
-	if (!xs_strings_to_perms(perms, num, permstr)) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!xs_strings_to_perms(perms, num, permstr))
+		return errno;
 
 	/* Unprivileged domains may not change the owner. */
-	if (domain_is_unprivileged(conn) &&
-	    perms[0].id != node->perms[0].id) {
-		send_error(conn, EPERM);
-		return;
-	}
+	if (domain_is_unprivileged(conn) && perms[0].id != node->perms[0].id)
+		return EPERM;
 
 	domain_entry_dec(conn, node);
 	node->perms = perms;
 	node->num_perms = num;
 	domain_entry_inc(conn, node);
 
-	if (!write_node(conn, node)) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!write_node(conn, node))
+		return errno;
 
 	wrl_apply_debit_direct(conn);
 	fire_watches(conn, in, name, false);
 	send_ack(conn, XS_SET_PERMS);
+
+	return 0;
 }
 
-static void do_debug(struct connection *conn, struct buffered_data *in)
+static int do_debug(struct connection *conn, struct buffered_data *in)
 {
 	int num;
 
-	if (conn->id != 0) {
-		send_error(conn, EACCES);
-		return;
-	}
+	if (conn->id != 0)
+		return EACCES;
 
 	num = xs_count_strings(in->buffer, in->used);
 
 	if (streq(in->buffer, "print")) {
-		if (num < 2) {
-			send_error(conn, EINVAL);
-			return;
-		}
+		if (num < 2)
+			return EINVAL;
 		xprintf("debug: %s", in->buffer + get_string(in, 0));
 	}
 
@@ -1282,11 +1252,13 @@ static void do_debug(struct connection *conn, struct buffered_data *in)
 		check_store();
 
 	send_ack(conn, XS_DEBUG);
+
+	return 0;
 }
 
 static struct {
 	const char *str;
-	void (*func)(struct connection *conn, struct buffered_data *in);
+	int (*func)(struct connection *conn, struct buffered_data *in);
 } const wire_funcs[XS_TYPE_COUNT] = {
 	[XS_DEBUG]             = { "DEBUG",             do_debug },
 	[XS_DIRECTORY]         = { "DIRECTORY",         send_directory },
@@ -1329,6 +1301,7 @@ static void process_message(struct connection *conn, struct buffered_data *in)
 {
 	struct transaction *trans;
 	enum xsd_sockmsg_type type = in->hdr.msg.type;
+	int ret;
 
 	trans = transaction_lookup(conn, in->hdr.msg.tx_id);
 	if (IS_ERR(trans)) {
@@ -1340,11 +1313,13 @@ static void process_message(struct connection *conn, struct buffered_data *in)
 	conn->transaction = trans;
 
 	if ((unsigned)type < XS_TYPE_COUNT && wire_funcs[type].func)
-		wire_funcs[type].func(conn, in);
+		ret = wire_funcs[type].func(conn, in);
 	else {
 		eprintf("Client unknown operation %i", type);
-		send_error(conn, ENOSYS);
+		ret = ENOSYS;
 	}
+	if (ret)
+		send_error(conn, ret);
 
 	conn->transaction = NULL;
 }
diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index 17a66be33929..3fc997fafed9 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -357,7 +357,7 @@ static void domain_conn_reset(struct domain *domain)
 }
 
 /* domid, mfn, evtchn, path */
-void do_introduce(struct connection *conn, struct buffered_data *in)
+int do_introduce(struct connection *conn, struct buffered_data *in)
 {
 	struct domain *domain;
 	char *vec[3];
@@ -367,40 +367,32 @@ void do_introduce(struct connection *conn, struct buffered_data *in)
 	int rc;
 	struct xenstore_domain_interface *interface;
 
-	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec)) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec))
+		return EINVAL;
 
-	if (domain_is_unprivileged(conn) || !conn->can_write) {
-		send_error(conn, EACCES);
-		return;
-	}
+	if (domain_is_unprivileged(conn) || !conn->can_write)
+		return EACCES;
 
 	domid = atoi(vec[0]);
 	mfn = atol(vec[1]);
 	port = atoi(vec[2]);
 
 	/* Sanity check args. */
-	if (port <= 0) { 
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (port <= 0)
+		return EINVAL;
 
 	domain = find_domain_by_domid(domid);
 
 	if (domain == NULL) {
 		interface = map_interface(domid, mfn);
-		if (!interface) {
-			send_error(conn, errno);
-			return;
-		}
+		if (!interface)
+			return errno;
 		/* Hang domain off "in" until we're finished. */
 		domain = new_domain(in, domid, port);
 		if (!domain) {
+			rc = errno;
 			unmap_interface(interface);
-			send_error(conn, errno);
-			return;
+			return rc;
 		}
 		domain->interface = interface;
 		domain->mfn = mfn;
@@ -416,165 +408,137 @@ void do_introduce(struct connection *conn, struct buffered_data *in)
 		rc = xenevtchn_bind_interdomain(xce_handle, domid, port);
 		domain->port = (rc == -1) ? 0 : rc;
 		domain->remote_port = port;
-	} else {
-		send_error(conn, EINVAL);
-		return;
-	}
+	} else
+		return EINVAL;
 
 	domain_conn_reset(domain);
 
 	send_ack(conn, XS_INTRODUCE);
+
+	return 0;
 }
 
-void do_set_target(struct connection *conn, struct buffered_data *in)
+int do_set_target(struct connection *conn, struct buffered_data *in)
 {
 	char *vec[2];
 	unsigned int domid, tdomid;
         struct domain *domain, *tdomain;
-	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec)) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec))
+		return EINVAL;
 
-	if (domain_is_unprivileged(conn) || !conn->can_write) {
-		send_error(conn, EACCES);
-		return;
-	}
+	if (domain_is_unprivileged(conn) || !conn->can_write)
+		return EACCES;
 
 	domid = atoi(vec[0]);
 	tdomid = atoi(vec[1]);
 
         domain = find_domain_by_domid(domid);
-	if (!domain) {
-		send_error(conn, ENOENT);
-		return;
-	}
-        if (!domain->conn) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domain)
+		return ENOENT;
+        if (!domain->conn)
+		return EINVAL;
 
         tdomain = find_domain_by_domid(tdomid);
-	if (!tdomain) {
-		send_error(conn, ENOENT);
-		return;
-	}
+	if (!tdomain)
+		return ENOENT;
 
-        if (!tdomain->conn) {
-		send_error(conn, EINVAL);
-		return;
-	}
+        if (!tdomain->conn)
+		return EINVAL;
 
         talloc_reference(domain->conn, tdomain->conn);
         domain->conn->target = tdomain->conn;
 
 	send_ack(conn, XS_SET_TARGET);
+
+	return 0;
 }
 
 /* domid */
-void do_release(struct connection *conn, struct buffered_data *in)
+int do_release(struct connection *conn, struct buffered_data *in)
 {
 	const char *domid_str = onearg(in);
 	struct domain *domain;
 	unsigned int domid;
 
-	if (!domid_str) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid_str)
+		return EINVAL;
 
 	domid = atoi(domid_str);
-	if (!domid) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid)
+		return EINVAL;
 
-	if (domain_is_unprivileged(conn)) {
-		send_error(conn, EACCES);
-		return;
-	}
+	if (domain_is_unprivileged(conn))
+		return EACCES;
 
 	domain = find_domain_by_domid(domid);
-	if (!domain) {
-		send_error(conn, ENOENT);
-		return;
-	}
+	if (!domain)
+		return ENOENT;
 
-	if (!domain->conn) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domain->conn)
+		return EINVAL;
 
 	talloc_free(domain->conn);
 
 	send_ack(conn, XS_RELEASE);
+
+	return 0;
 }
 
-void do_resume(struct connection *conn, struct buffered_data *in)
+int do_resume(struct connection *conn, struct buffered_data *in)
 {
 	struct domain *domain;
 	unsigned int domid;
 	const char *domid_str = onearg(in);
 
-	if (!domid_str) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid_str)
+		return EINVAL;
 
 	domid = atoi(domid_str);
-	if (!domid) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid)
+		return EINVAL;
 
-	if (domain_is_unprivileged(conn)) {
-		send_error(conn, EACCES);
-		return;
-	}
+	if (domain_is_unprivileged(conn))
+		return EACCES;
 
 	domain = find_domain_by_domid(domid);
-	if (!domain) {
-		send_error(conn, ENOENT);
-		return;
-	}
+	if (!domain)
+		return ENOENT;
 
-	if (!domain->conn) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domain->conn)
+		return EINVAL;
 
 	domain->shutdown = 0;
 	
 	send_ack(conn, XS_RESUME);
+
+	return 0;
 }
 
-void do_get_domain_path(struct connection *conn, struct buffered_data *in)
+int do_get_domain_path(struct connection *conn, struct buffered_data *in)
 {
 	char *path;
 	const char *domid_str = onearg(in);
 
-	if (!domid_str) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid_str)
+		return EINVAL;
 
 	path = talloc_domain_path(conn, atoi(domid_str));
 
 	send_reply(conn, XS_GET_DOMAIN_PATH, path, strlen(path) + 1);
 
 	talloc_free(path);
+
+	return 0;
 }
 
-void do_is_domain_introduced(struct connection *conn, struct buffered_data *in)
+int do_is_domain_introduced(struct connection *conn, struct buffered_data *in)
 {
 	int result;
 	unsigned int domid;
 	const char *domid_str = onearg(in);
 
-	if (!domid_str) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!domid_str)
+		return EINVAL;
 
 	domid = atoi(domid_str);
 	if (domid == DOMID_SELF)
@@ -583,15 +547,19 @@ void do_is_domain_introduced(struct connection *conn, struct buffered_data *in)
 		result = (find_domain_by_domid(domid) != NULL);
 
 	send_reply(conn, XS_IS_DOMAIN_INTRODUCED, result ? "T" : "F", 2);
+
+	return 0;
 }
 
 /* Allow guest to reset all watches */
-void do_reset_watches(struct connection *conn, struct buffered_data *in)
+int do_reset_watches(struct connection *conn, struct buffered_data *in)
 {
 	conn_delete_all_watches(conn);
 	conn_delete_all_transactions(conn);
 
 	send_ack(conn, XS_RESET_WATCHES);
+
+	return 0;
 }
 
 static int close_xc_handle(void *_handle)
diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
index 561ab5daff3d..4aa80db2c92a 100644
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -22,25 +22,25 @@
 void handle_event(void);
 
 /* domid, mfn, eventchn, path */
-void do_introduce(struct connection *conn, struct buffered_data *in);
+int do_introduce(struct connection *conn, struct buffered_data *in);
 
 /* domid */
-void do_is_domain_introduced(struct connection *conn, struct buffered_data *in);
+int do_is_domain_introduced(struct connection *conn, struct buffered_data *in);
 
 /* domid */
-void do_release(struct connection *conn, struct buffered_data *in);
+int do_release(struct connection *conn, struct buffered_data *in);
 
 /* domid */
-void do_resume(struct connection *conn, struct buffered_data *in);
+int do_resume(struct connection *conn, struct buffered_data *in);
 
 /* domid, target */
-void do_set_target(struct connection *conn, struct buffered_data *in);
+int do_set_target(struct connection *conn, struct buffered_data *in);
 
 /* domid */
-void do_get_domain_path(struct connection *conn, struct buffered_data *in);
+int do_get_domain_path(struct connection *conn, struct buffered_data *in);
 
 /* Allow guest to reset all watches */
-void do_reset_watches(struct connection *conn, struct buffered_data *in);
+int do_reset_watches(struct connection *conn, struct buffered_data *in);
 
 void domain_init(void);
 
diff --git a/tools/xenstore/xenstored_transaction.c b/tools/xenstore/xenstored_transaction.c
index 3d1090197a48..9797fa501692 100644
--- a/tools/xenstore/xenstored_transaction.c
+++ b/tools/xenstore/xenstored_transaction.c
@@ -150,21 +150,17 @@ struct transaction *transaction_lookup(struct connection *conn, uint32_t id)
 	return ERR_PTR(-ENOENT);
 }
 
-void do_transaction_start(struct connection *conn, struct buffered_data *in)
+int do_transaction_start(struct connection *conn, struct buffered_data *in)
 {
 	struct transaction *trans, *exists;
 	char id_str[20];
 
 	/* We don't support nested transactions. */
-	if (conn->transaction) {
-		send_error(conn, EBUSY);
-		return;
-	}
+	if (conn->transaction)
+		return EBUSY;
 
-	if (conn->id && conn->transaction_started > quota_max_transaction) {
-		send_error(conn, ENOSPC);
-		return;
-	}
+	if (conn->id && conn->transaction_started > quota_max_transaction)
+		return ENOSPC;
 
 	/* Attach transaction to input for autofree until it's complete */
 	trans = talloc_zero(in, struct transaction);
@@ -174,10 +170,8 @@ void do_transaction_start(struct connection *conn, struct buffered_data *in)
 	trans->tdb_name = talloc_asprintf(trans, "%s.%p",
 					  xs_daemon_tdb(), trans);
 	trans->tdb = tdb_copy(tdb_context(conn), trans->tdb_name);
-	if (!trans->tdb) {
-		send_error(conn, errno);
-		return;
-	}
+	if (!trans->tdb)
+		return errno;
 	/* Make it close if we go away. */
 	talloc_steal(trans, trans->tdb);
 
@@ -196,24 +190,22 @@ void do_transaction_start(struct connection *conn, struct buffered_data *in)
 
 	snprintf(id_str, sizeof(id_str), "%u", trans->id);
 	send_reply(conn, XS_TRANSACTION_START, id_str, strlen(id_str)+1);
+
+	return 0;
 }
 
-void do_transaction_end(struct connection *conn, struct buffered_data *in)
+int do_transaction_end(struct connection *conn, struct buffered_data *in)
 {
 	const char *arg = onearg(in);
 	struct changed_node *i;
 	struct changed_domain *d;
 	struct transaction *trans;
 
-	if (!arg || (!streq(arg, "T") && !streq(arg, "F"))) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (!arg || (!streq(arg, "T") && !streq(arg, "F")))
+		return EINVAL;
 
-	if ((trans = conn->transaction) == NULL) {
-		send_error(conn, ENOENT);
-		return;
-	}
+	if ((trans = conn->transaction) == NULL)
+		return ENOENT;
 
 	conn->transaction = NULL;
 	list_del(&trans->list);
@@ -224,17 +216,13 @@ void do_transaction_end(struct connection *conn, struct buffered_data *in)
 
 	if (streq(arg, "T")) {
 		/* FIXME: Merge, rather failing on any change. */
-		if (trans->generation != generation) {
-			send_error(conn, EAGAIN);
-			return;
-		}
+		if (trans->generation != generation)
+			return EAGAIN;
 
 		wrl_apply_debit_trans_commit(conn);
 
-		if (!replace_tdb(trans->tdb_name, trans->tdb)) {
-			send_error(conn, errno);
-			return;
-		}
+		if (!replace_tdb(trans->tdb_name, trans->tdb))
+			return errno;
 		/* Don't close this: we won! */
 		trans->tdb = NULL;
 
@@ -248,6 +236,8 @@ void do_transaction_end(struct connection *conn, struct buffered_data *in)
 		generation += trans->trans_gen;
 	}
 	send_ack(conn, XS_TRANSACTION_END);
+
+	return 0;
 }
 
 void transaction_entry_inc(struct transaction *trans, unsigned int domid)
diff --git a/tools/xenstore/xenstored_transaction.h b/tools/xenstore/xenstored_transaction.h
index 7f0a78179235..aeeac3dcedb4 100644
--- a/tools/xenstore/xenstored_transaction.h
+++ b/tools/xenstore/xenstored_transaction.h
@@ -21,8 +21,8 @@
 
 struct transaction;
 
-void do_transaction_start(struct connection *conn, struct buffered_data *node);
-void do_transaction_end(struct connection *conn, struct buffered_data *in);
+int do_transaction_start(struct connection *conn, struct buffered_data *node);
+int do_transaction_end(struct connection *conn, struct buffered_data *in);
 
 struct transaction *transaction_lookup(struct connection *conn, uint32_t id);
 
diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index 856750ebcd9b..8cfc5b088234 100644
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -121,46 +121,36 @@ static int destroy_watch(void *_watch)
 	return 0;
 }
 
-void do_watch(struct connection *conn, struct buffered_data *in)
+int do_watch(struct connection *conn, struct buffered_data *in)
 {
 	struct watch *watch;
 	char *vec[2];
 	bool relative;
 
-	if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec)) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec))
+		return EINVAL;
 
 	if (strstarts(vec[0], "@")) {
 		relative = false;
-		if (strlen(vec[0]) > XENSTORE_REL_PATH_MAX) {
-			send_error(conn, EINVAL);
-			return;
-		}
+		if (strlen(vec[0]) > XENSTORE_REL_PATH_MAX)
+			return EINVAL;
 		/* check if valid event */
 	} else {
 		relative = !strstarts(vec[0], "/");
 		vec[0] = canonicalize(conn, vec[0]);
-		if (!is_valid_nodename(vec[0])) {
-			send_error(conn, EINVAL);
-			return;
-		}
+		if (!is_valid_nodename(vec[0]))
+			return EINVAL;
 	}
 
 	/* Check for duplicates. */
 	list_for_each_entry(watch, &conn->watches, list) {
 		if (streq(watch->node, vec[0]) &&
-		    streq(watch->token, vec[1])) {
-			send_error(conn, EEXIST);
-			return;
-		}
+		    streq(watch->token, vec[1]))
+			return EEXIST;
 	}
 
-	if (domain_watch(conn) > quota_nb_watch_per_domain) {
-		send_error(conn, E2BIG);
-		return;
-	}
+	if (domain_watch(conn) > quota_nb_watch_per_domain)
+		return E2BIG;
 
 	watch = talloc(conn, struct watch);
 	watch->node = talloc_strdup(watch, vec[0]);
@@ -180,17 +170,17 @@ void do_watch(struct connection *conn, struct buffered_data *in)
 
 	/* We fire once up front: simplifies clients and restart. */
 	add_event(conn, in, watch, watch->node);
+
+	return 0;
 }
 
-void do_unwatch(struct connection *conn, struct buffered_data *in)
+int do_unwatch(struct connection *conn, struct buffered_data *in)
 {
 	struct watch *watch;
 	char *node, *vec[2];
 
-	if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec)) {
-		send_error(conn, EINVAL);
-		return;
-	}
+	if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec))
+		return EINVAL;
 
 	node = canonicalize(conn, vec[0]);
 	list_for_each_entry(watch, &conn->watches, list) {
@@ -199,10 +189,10 @@ void do_unwatch(struct connection *conn, struct buffered_data *in)
 			talloc_free(watch);
 			domain_watch_dec(conn);
 			send_ack(conn, XS_UNWATCH);
-			return;
+			return 0;
 		}
 	}
-	send_error(conn, ENOENT);
+	return ENOENT;
 }
 
 void conn_delete_all_watches(struct connection *conn)
diff --git a/tools/xenstore/xenstored_watch.h b/tools/xenstore/xenstored_watch.h
index 8ed1ddef612e..546a5c30f056 100644
--- a/tools/xenstore/xenstored_watch.h
+++ b/tools/xenstore/xenstored_watch.h
@@ -21,8 +21,8 @@
 
 #include "xenstored_core.h"
 
-void do_watch(struct connection *conn, struct buffered_data *in);
-void do_unwatch(struct connection *conn, struct buffered_data *in);
+int do_watch(struct connection *conn, struct buffered_data *in);
+int do_unwatch(struct connection *conn, struct buffered_data *in);
 
 /* Fire all watches: recurse means all the children are affected (ie. rm). */
 void fire_watches(struct connection *conn, void *tmp, const char *name,
-- 
2.25.4