| commit | 26bcfdd46ee56055b61b6e8f23f0ff57626a95a7 | [log] [tgz] |
|---|---|---|
| author | Amin Hassani <ahassani@google.com> | Sat Sep 30 00:54:15 2017 |
| committer | chrome-bot <chrome-bot@chromium.org> | Tue Oct 17 20:02:53 2017 |
| tree | 71a0bb21196d7d08f240d6b3a2599f5145a5e3cf | |
| parent | 92f667a14a8183e0efcc98a2ed347830dce71710 [diff] |
puffin: Use empty puff writer
There was a piece of code (Puffer.Puff) that was only being used in
puffdiff but it was also being shipped with puffpatch too. That code
figures out the size of the puff by puffing into a buffer, There was two
problem with that. First, the code shouldn't have been mixed with the
client code, and second, it needs retry of the Puffer.PuffDeflate to do
the puffing again if the buffer size was small. This patch fixes that
problem by removing that function and adding checks in the
Puffer.PuffDeflate to not check for boundary or write into the buffer if
the given buffer size was nullptr. This way we can create a PuffWriter
with null buffer that can count the number of bytes needed for a puff
buffer. Along with, all PuffDeflate and HuffDeflate functions based on
the byte array buffer where removed and equivalent functions based on
BitReader/BitWriter/PuffReader/PuffWriter were made public.
Additionally this CL, adds a new function for finding the location of
Puffs using the aforementioned functionality in the utils.cc (which will
only be in used in puffdiff).
Furthermore, this CL fixes a long undiscovered bug, for when the length
of the literals was exactly 127. The PuffWriter would write a wrong
value to the output and this would cause problem. The unittests for this
bug was also added. Since this bug was in PuffWriter.cc and most of the
changes are in PuffWriter.cc this was a good candidate for fixing this
bug.
BUG=chromium:768505
TEST=unittests pass; brillo_update_payload {generate|verify} pass;
Change-Id: Ie5eb12dc637623b8f3ed08709590a323d9f830f8
Reviewed-on: https://chromium-review.googlesource.com/703680
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>
Source code for Puffin: A utility for deterministic DEFLATE recompression.
TODO(ahassani): Describe the directory structure and how-tos.
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_.