simplecache

The simplecache package provides support for reading Chromium simple cache v6 or v7.

Learn more: http://www.chromium.org/developers/design-documents/network-stack/disk-cache/very-simple-backend

See the example_test.go for an example of how to read an image from cache in testdata.

This project also includes a tool to read the cache from command line, read this README.

Short cache format

The simple cache contains different files:

Fake index file format (index)

Real index file format (the-real-index)

Overview:

• File header
• Last write reason (starting v7)
• Index table
• Last modified

File header

The index file header (struct indexHeader) is 36 bytes in size and consists of:

Index table

The index table is an array of entries. An entry (struct indexEntry) is 24 bytes in size and consists of:

Data stream file format (#####_0)

Overview:

• File header
• URL
• Data stream (stream 1)
• Stream EOF
• HTTP headers (stream 0)
• (optionally) the SHA256 of the URL
• Stream EOF

File header

The index file header (struct entryHeader) is 20 bytes in size and consists of:

Stream EOF

The separator (struct entryEOF) contains information about the stream above. It is 20 bytes in size and consists of:

Flag

Data stream file format (#####_1)

Overview:

• File header
• URL
• Data stream (stream 2)
• Stream EOF

Data stream file format (#####_s)

Overview:

• File header
• many of the following:
  • Range header
  • Range data stream

File header

The index file header (struct entryHeader) is 20 bytes in size and consists of:

Range header

The range header (struct sparseRangeHeader) contains information about the following range stream. It is 28 bytes in size and consists of: