[PATCH v2 3/5] xenstore: add explicit memory context parameter to read_node()

[Juergen Gross <jgross@suse.com>]

Add a parameter to xenstored read_node() function to explicitly
specify the memory context to be used for allocations. This will make
it easier to avoid memory leaks by using a context which is freed
soon.

When calling read_node() select a sensible memory context for the new
parameter by preferring a temporary one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 tools/xenstore/xenstored_core.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 9448ee8..e5c74f4 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -398,7 +398,8 @@ bool is_child(const char *child, const char *parent)
 }
 
 /* If it fails, returns NULL and sets errno. */
-static struct node *read_node(struct connection *conn, const char *name)
+static struct node *read_node(struct connection *conn, const void *mem,
+			      const char *name)
 {
 	TDB_DATA key, data;
 	uint32_t *p;
@@ -419,7 +420,7 @@ static struct node *read_node(struct connection *conn, const char *name)
 		return NULL;
 	}
 
-	node = talloc(name, struct node);
+	node = talloc(mem, struct node);
 	node->name = talloc_strdup(node, name);
 	node->parent = NULL;
 	node->tdb = tdb_context(conn);
@@ -522,7 +523,7 @@ static enum xs_perm_type ask_parents(struct connection *conn, const char *name)
 
 	do {
 		name = get_parent(name, name);
-		node = read_node(conn, name);
+		node = read_node(conn, name, name);
 		if (node)
 			break;
 	} while (!streq(name, "/"));
@@ -563,7 +564,7 @@ struct node *get_node(struct connection *conn,
 		errno = EINVAL;
 		return NULL;
 	}
-	node = read_node(conn, name);
+	node = read_node(conn, name, name);
 	/* If we don't have permission, we don't have node. */
 	if (node) {
 		if ((perm_for_conn(conn, node->perms, node->num_perms) & perm)
@@ -819,7 +820,7 @@ static struct node *construct_node(struct connection *conn, const char *name)
 	char *children, *parentname = get_parent(name, name);
 
 	/* If parent doesn't exist, create it. */
-	parent = read_node(conn, parentname);
+	parent = read_node(conn, parentname, parentname);
 	if (!parent)
 		parent = construct_node(conn, parentname);
 	if (!parent)
@@ -984,7 +985,7 @@ static void delete_node(struct connection *conn, struct node *node)
 	for (i = 0; i < node->childlen; i += strlen(node->children+i) + 1) {
 		struct node *child;
 
-		child = read_node(conn, 
+		child = read_node(conn, node,
 				  talloc_asprintf(node, "%s/%s", node->name,
 						  node->children + i));
 		if (child) {
@@ -1036,7 +1037,7 @@ static int _rm(struct connection *conn, struct node *node, const char *name)
 	/* Delete from parent first, then if we crash, the worst that can
 	   happen is the child will continue to take up space, but will
 	   otherwise be unreachable. */
-	struct node *parent = read_node(conn, get_parent(name, name));
+	struct node *parent = read_node(conn, name, get_parent(name, name));
 	if (!parent) {
 		send_error(conn, EINVAL);
 		return 0;
@@ -1055,7 +1056,7 @@ static int _rm(struct connection *conn, struct node *node, const char *name)
 static void internal_rm(const char *name)
 {
 	char *tname = talloc_strdup(NULL, name);
-	struct node *node = read_node(NULL, tname);
+	struct node *node = read_node(NULL, tname, tname);
 	if (node)
 		_rm(NULL, node, tname);
 	talloc_free(node);
@@ -1073,7 +1074,7 @@ static void do_rm(struct connection *conn, struct buffered_data *in)
 	if (!node) {
 		/* Didn't exist already?  Fine, if parent exists. */
 		if (errno == ENOENT) {
-			node = read_node(conn, get_parent(in, name));
+			node = read_node(conn, in, get_parent(in, name));
 			if (node) {
 				send_ack(conn, XS_RM);
 				return;
@@ -1604,7 +1605,7 @@ static void remember_string(struct hashtable *hash, const char *str)
  */
 static void check_store_(const char *name, struct hashtable *reachable)
 {
-	struct node *node = read_node(NULL, name);
+	struct node *node = read_node(NULL, name, name);
 
 	if (node) {
 		size_t i = 0;
@@ -1618,7 +1619,8 @@ static void check_store_(const char *name, struct hashtable *reachable)
 			size_t childlen = strlen(node->children + i);
 			char * childname = child_name(node->name,
 						      node->children + i);
-			struct node *childnode = read_node(NULL, childname);
+			struct node *childnode = read_node(NULL, childname,
+							   childname);
 			
 			if (childnode) {
 				if (hashtable_search(children, childname)) {
-- 
2.6.6


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