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Initial commit. First version of Features documentation.

This initial commit only contains some documentation.
release-1.5.4.branch
Vreixo Formoso 14 years ago
commit
8adafdea11
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      doc/devel/README

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FEATURES
========
Contents:
2.0 Operations on image tree
2.1 ECMA-119
2.2 Rock Ridge
2.3 Joliet
2.4 El-Torito
2.5 UDF
2.6 HFS/HFS+
2.7 Others
===============================================================================
2.0 Operations on image tree
-----------------------------
Basic:
- We HAVE TO Support addition of directories
- From filesystem
- From filesystem recursively
- New on image
- We HAVE TO support addition of files
- From local filesystem
- From previous/ms images
- We HAVE TO support addition of other POSIX file types
- From filesystem
- New on image
- Types: symlinks, block/char devices, fifos, sockets...
- We HAVE TO support modification of file names on image
- We HAVE TO support modification of POSIX attributes:
- Uid/Gid
- Permissions (we DON'T HAVE TO support full mode modification,
as we don't want a dir to be changed to a reg file!!)
- Timestamps
- We HAVE TO support deletion of nodes.
- We HAVE TO support iteration of directory tree.
- We WANT TO support direct getting (without iteration) of the number of
nodes in a directory.
Extras:
- We WANT TO support on-the-fly modification of file contents, to
allow things like compression and encryption.
Notes: many operations will need RR extensions to be actually reflected on
the image.
===============================================================================
2.1 ECMA-119
------------
Support for ECMA-119 (ISO-9660) specification.
2.1.1 Creation
--------------
We HAVE TO support creation of new images.
General:
- We HAVE TO support single volume images
- We DON'T NEED TO support multiple volume images.
It seems multiple volume images are not used.
- We HAVE TO support bootable volumes (see 2.4 in this doc)
Conformance:
- We HAVE TO support Level 1 restrictions (ECMA-119 10.1)
- We HAVE TO support Level 2 restrictions (ECMA-119 10.2)
Single Section files have a theoric size limit of 4GB (data length
is a 32-bit number, see ECMA-119 9.1.4). However I think I have
read that only files up to 2GB are supported.
- We MAY support full Level 3 (ECMA-119 10.3)
Multiple file sections are useful to support files higher than
level 2 limit. However, it seems it's a feature not supported in
most O.S. nowadays, so it's not very useful.
- We DON'T WANT TO support files recording in interleaved mode
(ECMA-119 6.4.3)
It seems a feature that it's not used.
- We DON'T WANT TO support associated files (ECMA-119 6.5.4)
What is that? Is it used?
- We DON'T WANT TO support Volume Partitions (ECMA-119 8.6)
What is that? Is it used?
- We DON'T WANT TO support extended attribute records (ECMA-119 9.5)
It seems an unused feature. RR is a better alternative.
- We DON'T NEED TO support file versions other than 1.
Restrictions:
- We HAVE TO provide a way to relax iso restrictions related to
filenames, allowing:
- Higher filename length, up to 37 chars (ECMA-119 7.5.1/7.6.3)
- Omit version number (ECMA-119 7.5.1)
- Directory hierarchy deeper than 8 levels / 255 path length
(ECMA-119 6.8.2.1)
- More characters in filenames, not only d-characters
2.2.2 Reading
-------------
General
- We HAVE TO support the reading of iso images
- We DON'T NEED TO support reading of features we don't support in
creation (see 2.2.1 above)
- We HAVE TO support reading arbitray file contents inside image
2.2.3 Modification/growing
--------------------------
General
- We HAVE TO support creation of new images from the contents of
an existing image
- We HAVE TO support multissession images
- We HAVE TO support growing of images
===============================================================================
2.2 Rock Ridge
--------------
- We HAVE TO support ALL Rock Ridge features, with these exceptions:
- We DON'T NEED TO support SF System User Entry (RRIP 4.1.7), used to
encode sparse files.
- We MIGHT support BACKUP timestamp (RRIP 4.1.6)
- We HAVE TO support any charset in RR filenames, and not only POSIX portable
filename character set (RRIP 3.4.1). Namely, UTF-8 SHOULD BE the default for
RR filenames.
- We MIGHT support Linux specific ZF extension, to allow transparent
compression.
===============================================================================
2.3 Joliet
----------
- We HAVE TO support ALL Joliet features, with these exceptions:
- We DON'T KNOW what to do with UCS-2 conformance level 1 and 2 (scape
sequences '%\@' and '%\C'). What's this???????
- We DON'T KNOW what to do with CD-XA extensions.
===============================================================================
2.4 El-Torito
-------------
- We HAVE TO El-Torito standard with a single boot image.
- We MAY support multiple boot images and boot entry selection.
- El Torito standard is not very clear about how to do that.
- We HAVE TO support both emulation and not emulation mode.
- We HAVE TO support 80x86 platform. We MAY support Power PC and Mac platforms.
- We HAVE TO provide improved support for isolinux boot images, namely patching
features.
- We HAVE TO support El-Torito in ms images.
===============================================================================
2.5 UDF
-------
===============================================================================
2.6 HFS/HFS+
------------
===============================================================================
2.7 Others
----------
- We HAVE TO support sorting of file contents on image
- We HAVE TO support inode caching to prevent the same file to be written
several times into the image
- We DON'T NEED TO support TRANS.TBL files
- We DON'T NEED TO support padding of images
- Padding should be part of the burning process

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Index
=====
1. Overview
2. Features
3. Design
4. Implementation
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