libsqfs: Expose the directory reader cache query function

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

2 files changed, 43 insertions, 18 deletions

diff --git a/include/sqfs/dir_reader.h b/include/sqfs/dir_reader.h
index 11f7ae0..ceac22b 100644
--- a/include/sqfs/dir_reader.h
+++ b/include/sqfs/dir_reader.h
@@ -253,6 +253,26 @@ SQFS_API int sqfs_dir_reader_get_inode(sqfs_dir_reader_t *rd, sqfs_u64 ref,
 SQFS_API int sqfs_dir_reader_get_root_inode(sqfs_dir_reader_t *rd,
 					    sqfs_inode_generic_t **inode);
 
+/**
+ * @brief Try to lookup a cached inode number
+ *
+ * @memberof sqfs_dir_reader_t
+ *
+ * If the inode reader was created with the @ref SQFS_DIR_READER_DOT_ENTRIES
+ * flag, it maintains an internal cache of all directory inodes that it has
+ * seen while traversing the filesystem. The cache maps inode numbers to
+ * inode references. This is used to lookup the parent inode of directory.
+ * This function can be used to query the cache directly.
+ *
+ * @param rd A pointer to a directory reader.
+ * @param inode An inode number.
+ * @param ref Retrns an inode reference on success.
+ *
+ * @return Zero on success, @ref SQFS_ERROR_NO_ENTRY if the inode is unknown
+ */
+SQFS_API int sqfs_dir_reader_resolve_inum(sqfs_dir_reader_t *rd,
+					  sqfs_u32 inode, sqfs_u64 *ref);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/sqfs/src/dir_reader.c b/lib/sqfs/src/dir_reader.c
index 042b93a..6920a7d 100644
--- a/lib/sqfs/src/dir_reader.c
+++ b/lib/sqfs/src/dir_reader.c
@@ -63,21 +63,6 @@ static int dcache_add(sqfs_dir_reader_t *rd,
 	return rbtree_insert(&rd->dcache, &inum, &ref);
 }
 
-static int dcache_find(sqfs_dir_reader_t *rd, sqfs_u32 inode, sqfs_u64 *ref)
-{
-	rbtree_node_t *node;
-
-	if (!(rd->flags & SQFS_DIR_READER_DOT_ENTRIES))
-		return SQFS_ERROR_NO_ENTRY;
-
-	node = rbtree_lookup(&rd->dcache, &inode);
-	if (node == NULL)
-		return SQFS_ERROR_NO_ENTRY;
-
-	*ref = *((sqfs_u64 *)rbtree_node_value(node));
-	return 0;
-}
-
 static void dir_reader_destroy(sqfs_object_t *obj)
 {
 	sqfs_dir_reader_t *rd = (sqfs_dir_reader_t *)obj;
@@ -208,12 +193,15 @@ int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
 			parent = inode->data.dir.parent_inode;
 		}
 
-		if (dcache_find(rd, inode->base.inode_number, &state->dir_ref))
-			return SQFS_ERROR_NO_ENTRY;
+		ret = sqfs_dir_reader_resolve_inum(rd, inode->base.inode_number,
+						   &state->dir_ref);
+		if (ret)
+			return ret;
 
 		if (state->dir_ref == rd->super.root_inode_ref) {
 			state->parent_ref = state->dir_ref;
-		} else if (dcache_find(rd, parent, &state->parent_ref)) {
+		} else if (sqfs_dir_reader_resolve_inum(rd, parent,
+							&state->parent_ref)) {
 			return SQFS_ERROR_NO_ENTRY;
 		}
 
@@ -291,3 +279,20 @@ int sqfs_dir_reader_get_root_inode(sqfs_dir_reader_t *rd,
 {
 	return sqfs_dir_reader_get_inode(rd, rd->super.root_inode_ref, inode);
 }
+
+int sqfs_dir_reader_resolve_inum(sqfs_dir_reader_t *rd,
+				 sqfs_u32 inode, sqfs_u64 *ref)
+{
+	rbtree_node_t *node;
+
+	*ref = 0;
+	if (!(rd->flags & SQFS_DIR_READER_DOT_ENTRIES))
+		return SQFS_ERROR_NO_ENTRY;
+
+	node = rbtree_lookup(&rd->dcache, &inode);
+	if (node == NULL)
+		return SQFS_ERROR_NO_ENTRY;
+
+	*ref = *((sqfs_u64 *)rbtree_node_value(node));
+	return 0;
+}