https://github.com/znerol/py-idlk

idlk lock filename generator
https://github.com/znerol/py-idlk

Last synced: about 1 year ago
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idlk lock filename generator

• Host: GitHub
• URL: https://github.com/znerol/py-idlk
• Owner: znerol
• License: mit
• Created: 2015-06-09T18:10:25.000Z (almost 11 years ago)
• Default Branch: master
• Last Pushed: 2016-02-23T08:46:26.000Z (over 10 years ago)
• Last Synced: 2025-02-27T08:01:31.525Z (over 1 year ago)
• Language: Python
• Size: 10.7 KB
• Stars: 2
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

          
# Python idlk

[![Build Status](https://travis-ci.org/znerol/py-idlk.svg?branch=master)](https://travis-ci.org/znerol/py-idlk)

[![Coverage Status](https://coveralls.io/repos/github/znerol/py-idlk/badge.svg?branch=master)](https://coveralls.io/github/znerol/py-idlk?branch=master)

This is a proof-of-concept implementation of a lock filename generator for idlk

files used by a well known desktop publishing suite.

## Usage

```

    from idlk import idlk

    lockname = idlk(u'My Layout File.INDD')

    # lockname == u'~my layout file~q7e)nv.idlk'

    lockname = idlk(u'My Text.icml')

    # lockname == u'~my text~7h5m7u.idlk'

```

## Technical details

The names of the lockfiles are derived from a given file name with the

following steps:

1. Apply NFC unicode normalization.

2. Convert the complete filename to lower case.

3. Switch to Mac Roman encoding.

4. Generate a 32bit hash value over the whole file name and encode it using a

   custom base41 encoding scheme.

5. Remove extension from the prepared file name, shorten it further to 18

   characters if necessary.

6. Generate the idlk file name using the following pattern:

   ~shortened-lowercase-basename[1..18]~hash[6].idlk

Note: Even though the hash-function is rather primitive, there is no way of

directly deriving the original document name for a given idlk name.

### Hash function

The hash function is a very simple shift-add function. The only tricky/weird

thing is a final modulo with the magic number `0xFFFEECED`.

### Base41 encoding

Base41 produces a case insensitive string containing digits `0-9`, characters

`a-z` and the 5 additional characters `-`, `_`, `(`, `)` and `$`.

## Caveats

The algorithm has been deduced after observing the behavior of the original

software. It currently only works with file names which are completely mappable

to the Mac Roman encoding.

## License

All code and documentation is released under the MIT license.