Small script to copy the difference between two folders to a new folder

diffFolders.py

#!/usr/bin/env python

import os
import os.path
import sys
import shutil

# Bugfixed version of makedirs
def makedirs(name, mode=0777):
    """makedirs(path [, mode=0777])

    Super-mkdir; create a leaf directory and all intermediate ones.
    Works like mkdir, except that any intermediate path segment (not
    just the rightmost) will be created if it does not exist.  This is
    recursive.

    """
    head, tail = os.path.split(name)
    if not tail:
        head, tail = os.path.split(head)
    if head and tail and not os.path.exists(head):
        try:
            makedirs(head, mode)
        except OSError, e:
            # be happy if someone already created the path
            if e.errno != errno.EEXIST:
                raise
        if tail == curdir:           # xxx/newdir/. exists if xxx/newdir exists
            return
    # Bugfix: Don't fail if directory exists
    if not os.path.exists(name):
        os.mkdir(name, mode)

os.makedirs = makedirs

class DiffFolders:
    def run(self, args):
        src1 = os.path.abspath( args[0] )
        src2 = os.path.abspath( args[1] )
        dest = os.path.abspath( args[2] )

        if not os.path.exists(src1):
            raise Exception('Missing source folder %s' % src1)
        if not os.path.exists(src2):
            raise Exception('Missing source folder %s' % src2)

        if os.path.exists(dest):
            print 'Deleting %s' % dest
            shutil.rmtree(dest)

        def ignore(folder, content):
            if folder.startswith(src1):
                prefix = src2
                relpath = os.path.relpath(folder, src1)
            else:
                prefix = src1
                relpath = os.path.relpath(folder, src2)

            result = []
            for entry in content:
                path = os.path.join(folder, entry)
                if os.path.isdir(path):
                    continue

                if not os.path.isfile(path):
                    raise Exception('Can only handle files: %s' % path)

                otherPath = os.path.join(prefix, relpath, entry)
                if os.path.exists(otherPath):
                    if not os.path.isfile(otherPath):
                        raise Exception('Expected two files:\n%s\n%s' % (path, otherPath))
                    
                    result.append( entry )
            
            return result

        shutil.copytree(src1, dest, ignore=ignore)
        shutil.copytree(src2, dest, ignore=ignore)

if __name__ == '__main__':
    DiffFolders().run(sys.argv[1:])