steffenfritz / bagit Goto Github PK

I recently discovered that the BagIt 1.0 specification requires that CR, LF, and % in file paths within manifest files are percent-encoded, and that there isn't a single BagIt implementation that does this correctly. Implementations either only encode CR and LF but not % or they encode nothing.

This implementation does not encode paths in the manifest, which means that it would fail to validate BagIt 1.0 bags that include file paths containing CR, LF, or %. Likewise, it would create bags that would fail BagIt 1.0 validation in the case that there are paths that naturally contain percent-encoded characters.

For example, let's say a bag contains the file data/file%0A1.txt. This file should be written to the manifest per the spec as data/file%250A1.txt. However, this implementation writes it as data/file%0A1.txt. This means, that when this implementation validates a properly constructed 1.0 bag it will look for the file data/file%250A1.txt which does not exist. Similarly, if another implementation that follows the spec attempts to validate a bag produced by this implementation, it would look for data/file\n1.txt, which does not exist.

It would seem desirable to me to move the ecosystem in the direction of properly implementing the 1.0 specification, while at the same acknowledging that there are a large number of 1.0 bags in existence that may then become invalid.

As such, it may be prudent to, when validating bags, fall back on a series of tests. You may want to first attempt to validate per the spec, and then, if a file cannot be found, attempt to locate it by either only decoding the CR and LF or leaving the path unchanged, ideally validating all of the files using the same method.

I have not examined fetch.txt implementations, but the same encoding requirements exist for paths in that file as well. This is potentially a thornier problem to address in a backward compatible way as it is unclear if the path data/file%250A1.txt is supposed to create data/file%250A1.txt (incorrect) or data/file%0A1.txt (correct).

Finally, I created a related ticket against the spec discussing this encoding problem, in particular how it breaks checksum utility compatibility.

What:
Add a command line flag that inserts a fetch.txt file into the bag.

Why:
BagIt allows the usage of a fetch.txt file that references remote resources.

Things to consider:
The referenced resources MUST be listed in all payload manifest files. So it is necessary to download all resources temporary and calculate all hashsums on creation time.

Describe the bug
Validation fails if there are more whitespaces between hashsum and file path. BagIt 1.0 allows more than one whitespaces.

To Reproduce

1. create bag
2. add additional whitespace between hashsum and filepath in manifest-algo.txt
3. Validation fails

"The purpose of the BagIt Profiles Specification is to allow creators and consumers of Bags to agree on optional components of the Bags they are exchanging. Details of the profile are instantiated in a JSON file that both the producing and consuming applications..."

https://github.com/bagit-profiles/bagit-profiles

The code base is three years old and needs some re-work.

BagIt 1.0 supports multiple manifest files for same payload or tagfiles with different hashing algorithms.

Add suport to create and validate

BagIt version 1.0 allows optional tagmanifest files

Describe the solution you'd like
Add a command line argument for creating at least one optional tagmanifest file

Replace standard library flag with spf13's flag package for POSIX/GNU-style --flags.