elfi.py

#!/usr/bin/env python3
import os
import shutil
import sys
from itertools import filterfalse

#TODO
# - logging instead of printing
# - tests
# - actually make directory changes
# - filters to exclude certain files
# - tar and compress option

def diff_walk(base, backup):
    base = os.path.abspath(base)
    backup = os.path.abspath(backup)

    if not os.path.exists(base):
        raise IOError('File not found: {}'.format(base))

    if not os.path.isdir(base):
        print('Warning: base path not a directory, changing to base directory')
        base = os.path.dirname(base)

    os.makedirs(backup, exist_ok=True)

    add_list = []
    remove_list = []
    update_list = []

    #walk base root to find difference between dir trees
    for base_path, dirs, files in os.walk(base):
        rel_path = os.path.join(get_rel_path(base, base_path), '')
        backup_path = os.path.join(backup, rel_path)

        if not os.path.exists(backup_path):
            add_list.append(rel_path)
            continue

        backup_listing = os.listdir(backup_path)
        base_listing = dirs + files

        for direntry in files:
            if not direntry in backup_listing:
                add_list.append(os.path.join(rel_path, direntry))

        for direntry in backup_listing:
            rel_direntry = os.path.join(rel_path, direntry)
            base_direntry = os.path.join(base_path, direntry)
            backup_direntry = os.path.join(backup_path, direntry)
            if os.path.isdir(backup_direntry):
                rel_direntry = os.path.join(rel_direntry, '')

            if not direntry in base_listing:
                remove_list.append(rel_direntry)
            elif newer(base_direntry, backup_direntry):
                if not os.path.isdir(base_direntry):
                    update_list.append(rel_direntry)
            elif newer(backup_direntry, base_direntry):
                print('Warning: backup file newer than original:')
                print('    {}'.format(os.path.join(rel_path, direntry)))

    add_set = build_backup_path_set(add_list)
    remove_set = build_backup_path_set(remove_list)
    update_set = build_backup_path_set(update_list)

    return (add_set, remove_set, update_set)

def do_backup(base, backup, add_set, remove_set, update_set):
    for item in add_set | update_set:
        base_path = os.path.join(base, item)
        copy_to_backup(base, backup, item)

    for item in remove_set:
        remove_from_backup(backup, item)

def build_backup_path_set(paths):
    """Build a set of paths that excludes all files belew any directory.

    E.g. would exclude hello/world.txt if hello/ is in paths
    """
    path_set = set(paths)
    for path in paths:
        exclude_subtree = set(filterfalse(lambda p: p.startswith(path), paths))
        exclude_subtree.add(path)
        path_set &= exclude_subtree
    return path_set

def get_rel_path(base, path):
    path = path[len(base):]
    if path.startswith(os.path.sep):
        path = path[1:]
    return path

#TODO symbolic link copying and testing
def copy_to_backup(base, backup, relpath):
    base_path = os.path.join(base, relpath)
    backup_path = os.path.join(backup, relpath)
    if os.path.isfile(base_path):
        shutil.copy2(base_path, backup_path)
    elif os.path.isdir(base_path):
        shutil.copytree(base_path, backup_path)
    else:
        print('Warning: copying {} not supported.'.format(base_path))

#TODO symbolic link removal and testing
def remove_from_backup(backup, relpath):
    backup_path = os.path.join(backup, relpath)
    if os.path.isfile(backup_path):
        os.remove(backup_path)
    elif os.path.isdir(backup_path) and not os.path.islink(backup_path):
        shutil.rmtree(backup_path)
    else:
        print('Warning: removing {} not supported.'.format(backup_path))

def newer(path1, path2):
    return int(os.path.getmtime(path1)) > int(os.path.getmtime(path2))

def print_diff_walk(add_set, remove_set, update_set):
    """Prints the changes detected by diff_walk()."""
    print('To be added to backup:')
    for item in sorted(add_set):
        print('    {}'.format(item))
    print('To be removed from backup:')
    for item in sorted(remove_set):
        print('    {}'.format(item))
    print('To be updated in backup:')
    for item in sorted(update_set):
        print('    {}'.format(item))

def print_walk(base):
    """Prints the result of walking starting at the path argument."""
    for path, dirs, files in os.walk(base):
        path = path[len(basepath):] + os.path.sep
        print(path)
        print('dirs:\t{}'.format(dirs))
        print('files:\t{}'.format(files))
        print()

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print('usage: elfi.py base_path backup_path')
        exit(1)
    base = sys.argv[1]
    backup = sys.argv[2]
    print_diff_walk(*diff_walk(base, backup))
    exit(0)