Fix potential 2**32-1 overflow problems by ext2fs_div_ceil()

[tools/e2fsprogs.git] / ext2ed / init.c

diff --git a/ext2ed/init.c b/ext2ed/init.c
index f89d893..7ab2e28 100644 (file)
--- a/ext2ed/init.c
+++ b/ext2ed/init.c
@@ -370,6 +370,13 @@ void add_user_command (struct struct_commands *ptr,char *name,char *description,
        ptr->callback [num]=callback;
 }
 
+static unsigned int div_ceil(unsigned int a, unsigned int b)
+{
+       if (!a)
+               return 0;
+       return ((a - 1) / b) + 1;
+}
+
 int set_file_system_info (void)
 
 {
@@ -415,8 +422,8 @@ int set_file_system_info (void)
                        file_system_info.first_group_desc_offset=2*EXT2_MIN_BLOCK_SIZE;
                else
                        file_system_info.first_group_desc_offset=file_system_info.block_size;
-               file_system_info.groups_count=( sb->s_blocks_count-sb->s_first_data_block+sb->s_blocks_per_group-1) /
-                                               sb->s_blocks_per_group;
+               file_system_info.groups_count = div_ceil(sb->s_blocks_count, 
+                                                sb->s_blocks_per_group);
        
                file_system_info.inodes_per_block=file_system_info.block_size/sizeof (struct ext2_inode);
                file_system_info.blocks_per_group=sb->s_inodes_per_group/file_system_info.inodes_per_block;