59 lines
2.1 KiB
Plaintext
59 lines
2.1 KiB
Plaintext
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===============================================================================
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ISO-9660 Level 3 Cookbook
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===============================================================================
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Creation date: 2008-Aug-17
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Author: Vreixo Formoso
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_______________________________________________________________________________
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Contents:
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1. References
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2. General
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3. OS Support
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4. Implementation
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-------------------------------------------------------------------------------
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1. References:
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ECMA-119 "Volume and File Structure of CDROM for Information Interchange"
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-------------------------------------------------------------------------------
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2. General
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In ECMA-119 standard, the size of a file section cannot be bigger than 4GB - 1,
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because the Data Length field of the Directory Record is just 32 bits (9.1.4).
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However, "each file shall consist of one or more File Sections" (6.5.1), and
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that way we can store files greater than 4GB in a ECMA-119 image. Such image,
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with multiple File Sections, is only supported at Level 3 (10.3), as Level 2
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(10.2) states that "each file shall consist of only one File Section".
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On disc, each file section is stored in a Extent (6.4.2), i.e. a set of
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contiguous Logical Blocks.
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-------------------------------------------------------------------------------
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3. OS Support
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Wikipedia states that "Microsoft Windows XP supports this, while Mac OS X
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(as of 10.4.8) does not handle this case properly. In the case of Mac OS X,
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the driver appears not to support file fragmentation at all (i.e. it only
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supports ISO 9660 Level 2 but not Level 3). Linux supports multiple extents.
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FreeBSD only shows and reads the last extent of a multi-extent file."
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-------------------------------------------------------------------------------
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4. Implementation
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Each File Section will have its own Directory Record (6.5.1). So, for files
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greater than 4 GB, we need to store several directory records, that will have
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the same File Identifier, and stored in the order of the File Sections they
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refer (9.3).
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All but the last Directory Record must have the Multi-Extent flag set (9.1.6)
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