puffin: Add ExtentStream

We need some sort of extent stream for the update payload tests in
update_engine. These scripts are run as a part of canary builds. This CL
adds a new class ExtentStream that is only used in main.cc for applying
patches. This class should not be shipped to the client devices as part
of puffpatch nor it needs to be in puffdiff.

BUG=chromium:768461
TEST=unittest pass;

Change-Id: Ic482be8e9b6b7e7f12f5f796de1d96d57275097b
Reviewed-on: https://chromium-review.googlesource.com/714453
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
6 files changed
tree: 64e756065a5a38bca2d17ffa854cc8a24eaf665c
  1. LICENSE
  2. Makefile
  3. OWNERS
  4. PRESUBMIT.cfg
  5. README.md
  6. libpuffdiff.pc
  7. libpuffpatch.pc
  8. puffin.gyp
  9. src/
README.md

Puffin

Source code for Puffin: A utility for deterministic DEFLATE recompression.

TODO(ahassani): Describe the directory structure and how-tos.

Glossary

  • Alphabet A value that occurs in the input stream. It can be either a literal:[0..255], and end of block sign [256], a length[257..285], or a distance [0..29].

  • Huffman code A variable length code representing the Huffman encoded of an alphabet. Huffman codes can be created uniquely using Huffman code length array.

  • Huffman code array An array which an array index identifies a Huffman code and the array element in that index represents the corresponding alphabet. Throughout the code, Huffman code arrays are identified by vectors with postfix hcodes_.

  • Huffman reverse code array An array which an array index identifies an alphabet and the array element in that index contains the Huffman code of the alphabet. Throughout the code, The Huffman reverse code arrays are identified by vectors with postfix rcodes_.

  • Huffman code length The number of bits in a Huffman code.

  • Huffman code length array An array of Huffman code lengths with the array index as the alphabet. Throughout the code, Huffman code length arrays are identified by vectors with postfix lens_.