autofs/autofs-5.1.7-make-tree-implementation-data-independent.patch

autofs-5.1.7 - make tree implementation data independent

From: Ian Kent <raven@themaw.net>

Generalise the tree implementation so that it's independent of the
data structure that's used.

Do this by refactoring it into core tree functions and functions
specific to the data structure to be used so that different data
structures can be used when needed by adding an implementation for
the data structure specific functions.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG        |    1 
 include/mounts.h |   29 +++++++++
 lib/mounts.c     |  174 ++++++++++++++++++++++++++++++++++--------------------
 3 files changed, 140 insertions(+), 64 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 0dae6761..74571570 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -31,6 +31,7 @@
 - add some multi-mount macros.
 - remove unused functions cache_dump_multi() and cache_dump_cache().
 - add a len field to struct autofs_point.
+- make tree implementation data independent.
 
 25/01/2021 autofs-5.1.7
 - make bind mounts propagation slave by default.
diff --git a/include/mounts.h b/include/mounts.h
index ac480c06..71d29566 100644
--- a/include/mounts.h
+++ b/include/mounts.h
@@ -51,10 +51,36 @@ extern const unsigned int t_indirect;
 extern const unsigned int t_direct;
 extern const unsigned int t_offset;
 
+struct mnt_list;
 struct mapent;
 
+struct tree_ops;
+
+struct tree_node {
+	struct tree_ops *ops;
+	struct tree_node *left;
+	struct tree_node *right;
+};
+#define INIT_TREE_NODE(ptr)	((ptr)->ops = NULL, (ptr)->left = NULL, (ptr)->right = NULL)
+
+#define MNT_LIST(n)		(container_of(n, struct mnt_list, node))
+#define MNT_LIST_NODE(ptr)	((struct tree_node *) &((struct mnt_list *) ptr)->node)
+
+typedef struct tree_node *(*tree_new_t) (void *ptr);
+typedef int  (*tree_cmp_t) (struct tree_node *n, void *ptr);
+typedef void (*tree_free_t) (struct tree_node *n);
+
+struct tree_ops {
+	tree_new_t new;
+	tree_cmp_t cmp;
+	tree_free_t free;
+};
+
+typedef int (*tree_work_fn_t) (struct tree_node *n, void *ptr);
+
 struct mnt_list {
 	char *mp;
+	size_t len;
 	unsigned int flags;
 
 	/* Hash of all mounts */
@@ -79,6 +105,9 @@ struct mnt_list {
 	unsigned int amd_cache_opts;
 	struct list_head amdmount;
 
+	/* Tree operations */
+	struct tree_node node;
+
 	/*
 	 * List operations ie. get_mnt_list.
 	 */
diff --git a/lib/mounts.c b/lib/mounts.c
index b478ecb4..a6d1c5a7 100644
--- a/lib/mounts.c
+++ b/lib/mounts.c
@@ -68,6 +68,17 @@ static pthread_mutex_t ext_mount_hash_mutex = PTHREAD_MUTEX_INITIALIZER;
 static DEFINE_HASHTABLE(mnts_hash, MNTS_HASH_BITS);
 static pthread_mutex_t mnts_hash_mutex = PTHREAD_MUTEX_INITIALIZER;
 
+static struct tree_node *tree_mnt_new(void *ptr);
+static int tree_mnt_cmp(struct tree_node *n, void *ptr);
+static void tree_mnt_free(struct tree_node *n);
+
+static struct tree_ops mnt_ops = {
+	.new = tree_mnt_new,
+	.cmp = tree_mnt_cmp,
+	.free = tree_mnt_free,
+};
+static struct tree_ops *tree_mnt_ops = &mnt_ops;
+
 unsigned int linux_version_code(void)
 {
 	struct utsname my_utsname;
@@ -904,6 +915,7 @@ static struct mnt_list *mnts_alloc_mount(const char *mp)
 		this = NULL;
 		goto done;
 	}
+	this->len = strlen(mp);
 
 	this->ref = 1;
 	INIT_HLIST_NODE(&this->hash);
@@ -912,6 +924,7 @@ static struct mnt_list *mnts_alloc_mount(const char *mp)
 	INIT_LIST_HEAD(&this->submount_work);
 	INIT_LIST_HEAD(&this->amdmount);
 	INIT_LIST_HEAD(&this->expire);
+	INIT_TREE_NODE(&this->node);
 done:
 	return this;
 }
@@ -1225,91 +1238,58 @@ done:
 	return has_mounted_mounts;
 }
 
-struct tree_node {
-	struct mnt_list *mnt;
-	struct tree_node *left;
-	struct tree_node *right;
-};
-
-static struct tree_node *tree_new(struct mnt_list *mnt)
+static inline struct tree_node *tree_root(struct tree_ops *ops, void *ptr)
 {
-	struct tree_node *n;
-
-	n = malloc(sizeof(struct tree_node));
-	if (!n)
-		return NULL;
-	memset(n, 0, sizeof(struct tree_node));
-	n->mnt = mnt;
-
-	return n;
-}
-
-static struct tree_node *tree_root(struct mnt_list *mnt)
-{
-	struct tree_node *n;
-
-	n = tree_new(mnt);
-	if (!n) {
-		error(LOGOPT_ANY, "failed to allcate tree root");
-		return NULL;
-	}
-
-	return n;
+	return ops->new(ptr);
 }
 
-static struct tree_node *tree_add_left(struct tree_node *n, struct mnt_list *mnt)
+static struct tree_node *tree_add_left(struct tree_node *n, void *ptr)
 {
 	struct tree_node *new;
 
-	new = tree_new(mnt);
-	if (!new) {
-		error(LOGOPT_ANY, "failed to allcate tree node");
-		return NULL;
-	}
+	new = n->ops->new(ptr);
 	n->left = new;
 
-	return n;
+	return new;
 }
 
-static struct tree_node *tree_add_right(struct tree_node *n, struct mnt_list *mnt)
+static struct tree_node *tree_add_right(struct tree_node *n, void *ptr)
 {
 	struct tree_node *new;
 
-	new = tree_new(mnt);
-	if (!new) {
-		error(LOGOPT_ANY, "failed to allcate tree node");
-		return NULL;
-	}
+	new = n->ops->new(ptr);
 	n->right = new;
 
-	return n;
+	return new;
 }
 
-static struct tree_node *tree_add_node(struct tree_node *root, struct mnt_list *mnt)
+static struct tree_node *tree_add_node(struct tree_node *root, void *ptr)
 {
 	struct tree_node *p, *q;
-	unsigned int mp_len;
-
-	mp_len = strlen(mnt->mp);
+	struct tree_ops *ops = root->ops;
+	int eq;
 
 	q = root;
 	p = root;
 
-	while (q && strcmp(mnt->mp, p->mnt->mp)) {
+	while (q) {
 		p = q;
-		if (mp_len < strlen(p->mnt->mp))
+		eq = ops->cmp(p, ptr);
+		if (!eq)
+			break;
+		if (eq < 0)
 			q = p->left;
 		else
 			q = p->right;
 	}
 
-	if (strcmp(mnt->mp, p->mnt->mp) == 0)
-		error(LOGOPT_ANY, "duplicate entry in mounts list");
+	if (!eq)
+		error(LOGOPT_ANY, "cannot add duplicate entry to tree");
 	else {
-		if (mp_len < strlen(p->mnt->mp))
-			return tree_add_left(p, mnt);
+		if (eq < 0)
+			return tree_add_left(p, ptr);
 		else
-			return tree_add_right(p, mnt);
+			return tree_add_right(p, ptr);
 	}
 
 	return NULL;
@@ -1317,26 +1297,92 @@ static struct tree_node *tree_add_node(struct tree_node *root, struct mnt_list *
 
 static void tree_free(struct tree_node *root)
 {
+	struct tree_ops *ops = root->ops;
+
 	if (root->right)
 		tree_free(root->right);
 	if (root->left)
 		tree_free(root->left);
-	free(root);
+	ops->free(root);
 }
 
-static void tree_traverse(struct tree_node *n, struct list_head *mnts)
+static int tree_traverse_inorder(struct tree_node *n, tree_work_fn_t work, void *ptr)
 {
-	if (n->right)
-		tree_traverse(n->right, mnts);
-	list_add_tail(&n->mnt->expire, mnts);
-	if (n->left)
-		tree_traverse(n->left, mnts);
+	int ret;
+
+	if (n->left) {
+		ret = tree_traverse_inorder(n->left, work, ptr);
+		if (!ret)
+			goto done;
+	}
+	ret = work(n, ptr);
+	if (!ret)
+		goto done;
+	if (n->right) {
+		ret = tree_traverse_inorder(n->right, work, ptr);
+		if (!ret)
+			goto done;
+	}
+done:
+	return ret;
+}
+
+static struct tree_node *tree_mnt_root(struct mnt_list *mnt)
+{
+	return tree_root(tree_mnt_ops, mnt);
+}
+
+static struct tree_node *tree_mnt_new(void *ptr)
+{
+	struct tree_node *n = MNT_LIST_NODE(ptr);
+
+	n->ops = tree_mnt_ops;
+	n->left = NULL;
+	n->right = NULL;
+
+	return n;
+}
+
+static int tree_mnt_cmp(struct tree_node *n, void *ptr)
+{
+	struct mnt_list *n_mnt = MNT_LIST(n);
+	size_t n_mnt_len = n_mnt->len;
+	struct mnt_list *mnt = ptr;
+	size_t mnt_len = mnt->len;
+	int eq;
+
+	eq = strcmp(mnt->mp, n_mnt->mp);
+	if (!eq)
+		return 0;
+	return (mnt_len < n_mnt_len) ? -1 : 1;
+}
+
+static void tree_mnt_free(struct tree_node *n)
+{
+	n->ops = NULL;
+	n->left = NULL;
+	n->right = NULL;
+}
+
+static int tree_mnt_expire_list_work(struct tree_node *n, void *ptr)
+{
+	struct mnt_list *mnt = MNT_LIST(n);
+	struct list_head *mnts = ptr;
+
+	/* The expire of the root offset of an offset tree is the same
+	 * as expiring the offset tree root itself (if theree is a root
+	 * offset).
+	 */
+	if (mnt->mp[mnt->len - 1] != '/')
+		list_add(&mnt->expire, mnts);
+
+	return 1;
 }
 
 void mnts_get_expire_list(struct list_head *mnts, struct autofs_point *ap)
 {
-	struct mnt_list *mnt;
 	struct tree_node *tree = NULL;
+	struct mnt_list *mnt;
 
 	mnts_hash_mutex_lock();
 	if (list_empty(&ap->mounts))
@@ -1351,7 +1397,7 @@ void mnts_get_expire_list(struct list_head *mnts, struct autofs_point *ap)
 		__mnts_get_mount(mnt);
 
 		if (!tree) {
-			tree = tree_root(mnt);
+			tree = tree_mnt_root(mnt);
 			if (!tree) {
 				error(LOGOPT_ANY, "failed to create expire tree root");
 				goto done;
@@ -1367,7 +1413,7 @@ void mnts_get_expire_list(struct list_head *mnts, struct autofs_point *ap)
 		}
 	}
 
-	tree_traverse(tree, mnts);
+	tree_traverse_inorder(tree, tree_mnt_expire_list_work, mnts);
 	tree_free(tree);
 done:
 	mnts_hash_mutex_unlock();