1 files changed, 91 insertions, 0 deletions
diff --git a/fs/squashfs/sqfs_dir.c b/fs/squashfs/sqfs_dir.c
new file mode 100644
index 0000000..5f7660a
--- /dev/null
+++ b/fs/squashfs/sqfs_dir.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/byteorder/little_endian.h>
+#include <linux/byteorder/generic.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+bool sqfs_is_dir(u16 type)
+{
+	return type == SQFS_DIR_TYPE || type == SQFS_LDIR_TYPE;
+}
+
+/*
+ * Receives a pointer (void *) to a position in the inode table containing the
+ * directory's inode. Returns directory inode offset into the directory table.
+ * m_list contains each metadata block's position, and m_count is the number of
+ * elements of m_list. Those metadata blocks come from the compressed directory
+ * table.
+ */
+int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count)
+{
+	struct squashfs_base_inode *base = dir_i;
+	struct squashfs_ldir_inode *ldir;
+	struct squashfs_dir_inode *dir;
+	u32 start_block;
+	u16 offset;
+	int j;
+
+	switch (get_unaligned_le16(&base->inode_type)) {
+	case SQFS_DIR_TYPE:
+		dir = (struct squashfs_dir_inode *)base;
+		start_block = get_unaligned_le32(&dir->start_block);
+		offset = get_unaligned_le16(&dir->offset);
+		break;
+	case SQFS_LDIR_TYPE:
+		ldir = (struct squashfs_ldir_inode *)base;
+		start_block = get_unaligned_le32(&ldir->start_block);
+		offset = get_unaligned_le16(&ldir->offset);
+		break;
+	default:
+		printf("Error: this is not a directory.\n");
+		return -EINVAL;
+	}
+
+	for (j = 0; j < m_count; j++) {
+		if (m_list[j] == start_block)
+			return (++j * SQFS_METADATA_BLOCK_SIZE) + offset;
+	}
+
+	if (start_block == 0)
+		return offset;
+
+	printf("Error: invalid inode reference to directory table.\n");
+
+	return -EINVAL;
+}
+
+bool sqfs_is_empty_dir(void *dir_i)
+{
+	struct squashfs_base_inode *base = dir_i;
+	struct squashfs_ldir_inode *ldir;
+	struct squashfs_dir_inode *dir;
+	u32 file_size;
+
+	switch (get_unaligned_le16(&base->inode_type)) {
+	case SQFS_DIR_TYPE:
+		dir = (struct squashfs_dir_inode *)base;
+		file_size = get_unaligned_le16(&dir->file_size);
+		break;
+	case SQFS_LDIR_TYPE:
+		ldir = (struct squashfs_ldir_inode *)base;
+		file_size = get_unaligned_le16(&ldir->file_size);
+		break;
+	default:
+		printf("Error: this is not a directory.\n");
+		return false;
+	}
+
+	return file_size == SQFS_EMPTY_FILE_SIZE;
+}