Part-2

Write a program that will perform some of the basic tasks accomplished by a file integrity checker such as Tripwire.

In this first part of the assignment you will be dealing strictly with processing one file at a time in any operation in part 2 you will deal with directories).

The program should present the user with a menu of four choices:

1) Add a file to the integrity database,

2) Remove a file from the integrity database,

3) Check a file for changes, and

4) Quit.

Your integrity database should be maintained as a python dictionary with nested components. Between invocations of your program, the database should be stored in a file using the pickle module. You should establish a default name for your database, but allow the user to override this name by giving a new name as a command line argument. If the database already exists, read it in. If not, then create an empty new database.

The database should be represented by a nested dictionary structure that mirrors the tree-like nature of the file system. The top level dictionary represents the root directory. Its components are the files and directories contained in /, indexing by their name as a key. Any subdirectories should be represented by another dictionary, continuing recursively.

When adding a new file into the database a nested set of entries should be made in this structure (if they do not already exist) according to the full path name of the file (all filenames can be assumed to have absolute paths) by breaking it up into the directory names between slashes. The final entry for the file should be a computed checksum value based on the file contents as indicated below. It is an error if the indicated name does not represent a valid file.

Removing a file from the database means first deleting the entry at the lowest file level in the structure, and then if the containing dictionary becomes empty it should be deleted also, and so forth up the line until a non-empty dictionary is encountered. It is an error if you attempt to remove an entry that is not in the database.

Checking the integrity of a file means computing the checksum value of the specified file and comparing it against the value stored in the database and reporting the result. It is an error if the file doesn't exist on the system or in the database.

Part-2

1) Add a directory of files to the database. The user supplies the name of a directory. You should add a checksum entry for every file in the directory (not the directory itself), as well as recursively descend into any subdirectories, adding entries for files in them (but not themselves).

2) Delete a directory of files from the database. The user supplies the name of a directory. You should delete entries for all files contained in that directory, and any of its subdirectories.

3) Check the integrity of files in a directory. The user supplies the name of a directory. Each file contained in that directory, and recursively through its subdirectories, should have its checksum checked against the corresponding entry in the database, if it exists. All of the files which have been changed based on different checksums should be listed in sorted order. Any new files that are not currently in the database should be given in a separate sorted list. 

Add the ability to store a file's permissions along with the checksum value in the database. Every time an entry is made in the database, the permissions should also be stored. Add a command line option, -p, that if specified means that an integrity check is not just comparing the checksum values, but also comparing to see if the permission bits have changed.