1 files changed, 104 insertions, 0 deletions
diff --git a/lib/ext2fs/check_desc.c b/lib/ext2fs/check_desc.c
new file mode 100644
index 0000000..3e3fa94
--- /dev/null
+++ b/lib/ext2fs/check_desc.c
@@ -0,0 +1,104 @@
+/*
+ * check_desc.c --- Check the group descriptors of an ext2 filesystem
+ *
+ * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Library
+ * General Public License, version 2.
+ * %End-Header%
+ */
+
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include <fcntl.h>
+#include <time.h>
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+/*
+ * This routine sanity checks the group descriptors
+ */
+errcode_t ext2fs_check_desc(ext2_filsys fs)
+{
+	ext2fs_block_bitmap bmap;
+	errcode_t retval;
+	dgrp_t i;
+	blk64_t first_block = fs->super->s_first_data_block;
+	blk64_t last_block = ext2fs_blocks_count(fs->super)-1;
+	blk64_t blk, b;
+	unsigned int j;
+
+	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
+
+	if (EXT2_DESC_SIZE(fs->super) & (EXT2_DESC_SIZE(fs->super) - 1))
+		return EXT2_ET_BAD_DESC_SIZE;
+
+	retval = ext2fs_allocate_subcluster_bitmap(fs, "check_desc map", &bmap);
+	if (retval)
+		return retval;
+
+	for (i = 0; i < fs->group_desc_count; i++)
+		ext2fs_reserve_super_and_bgd(fs, i, bmap);
+
+	for (i = 0; i < fs->group_desc_count; i++) {
+		if (!ext2fs_has_feature_flex_bg(fs->super)) {
+			first_block = ext2fs_group_first_block2(fs, i);
+			last_block = ext2fs_group_last_block2(fs, i);
+		}
+
+		/*
+		 * Check to make sure the block bitmap for group is sane
+		 */
+		blk = ext2fs_block_bitmap_loc(fs, i);
+		if (blk < first_block || blk > last_block ||
+		    ext2fs_test_block_bitmap2(bmap, blk)) {
+			retval = EXT2_ET_GDESC_BAD_BLOCK_MAP;
+			goto errout;
+		}
+		ext2fs_mark_block_bitmap2(bmap, blk);
+
+		/*
+		 * Check to make sure the inode bitmap for group is sane
+		 */
+		blk = ext2fs_inode_bitmap_loc(fs, i);
+		if (blk < first_block || blk > last_block ||
+		    ext2fs_test_block_bitmap2(bmap, blk)) {
+			retval = EXT2_ET_GDESC_BAD_INODE_MAP;
+			goto errout;
+		}
+		ext2fs_mark_block_bitmap2(bmap, blk);
+
+		/*
+		 * Check to make sure the inode table for group is sane
+		 */
+		blk = ext2fs_inode_table_loc(fs, i);
+		if (blk < first_block ||
+		    ((blk + fs->inode_blocks_per_group - 1) > last_block)) {
+			retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
+			goto errout;
+		}
+		for (j = 0, b = blk; j < fs->inode_blocks_per_group;
+		     j++, b++) {
+			if (ext2fs_test_block_bitmap2(bmap, b)) {
+				retval = EXT2_ET_GDESC_BAD_INODE_TABLE;
+				goto errout;
+			}
+			ext2fs_mark_block_bitmap2(bmap, b);
+		}
+	}
+errout:
+	ext2fs_free_block_bitmap(bmap);
+	return retval;
+}