Binary delta encoding tools.
Project description
About
Binary delta encoding in Python 3 and C.
Based on http://www.daemonology.net/bsdiff/, with the following differences:
BZ2, LZMA, Zstandard, heatshrink or CRLE compression.
Linear patch file access pattern to allow streaming and less RAM usage.
SA-IS instead of qsufsort.
Variable length size fields.
Incremental apply patch implemented in C, suitable for memory constrained embedded devices.
Optional experimental data format aware algorithm for potentially smaller patches. I don’t recommend anyone to use this functionality as the gain is small in relation to memory usage and code complexity!
There is a risk this functionality uses patent https://patents.google.com/patent/EP1988455B1/en. Anyway, this patent expires in August 2019 as I understand it.
Supported data formats:
ARM Cortex-M4
AArch64
Project homepage: https://github.com/eerimoq/detools
Documentation: http://detools.readthedocs.org/en/latest
Installation
pip install detools
Statistics
“LZMA ref.” is the target binary compressed with lzma --best.
The percentages are calculated as “patch size” / “to size”. Lower is better.
Update |
To size |
LZMA ref. |
LZMA |
heatshrink |
CRLE |
---|---|---|---|---|---|
upy v1.9.4 -> v1.10 |
615388 |
59.8 % |
11.7 % |
15.7 % |
26.2 % |
python 3.5 -> 3.6 |
4568920 |
30.7 % |
31.8 % |
- |
- |
foo old -> new |
2780 |
69.5 % |
4.5 % |
4.5 % |
6.8 % |
Example usage
Examples in C are found in src/c.
Command line tool
The create patch subcommand
Create a patch foo.patch from tests/files/foo/old to tests/files/foo/new.
$ detools create_patch tests/files/foo/old tests/files/foo/new foo.patch
Successfully created patch 'foo.patch'!
$ ls -l foo.patch
-rw-rw-r-- 1 erik erik 127 Mar 1 19:18 foo.patch
Create the same patch as above, but without compression.
$ detools create_patch --compression none \
tests/files/foo/old tests/files/foo/new foo-no-compression.patch
Successfully created patch 'foo-no-compression.patch'!
$ ls -l foo-no-compression.patch
-rw-rw-r-- 1 erik erik 2792 Mar 1 19:18 foo-no-compression.patch
Create an in-place patch foo-in-place.patch.
$ detools create_patch --type in-place --memory-size 3000 --segment-size 500 \
tests/files/foo/old tests/files/foo/new foo-in-place.patch
Successfully created patch 'foo-in-place.patch'!
$ ls -l foo-in-place.patch
-rw-rw-r-- 1 erik erik 672 Mar 16 08:49 foo-in-place.patch
Create a bsdiff patch foo-bsdiff.patch, compatible with the original bsdiff program.
$ detools create_patch --type bsdiff \
tests/files/foo/old tests/files/foo/new foo-bsdiff.patch
Successfully created patch 'foo-bsdiff.patch'!
$ ls -l foo-bsdiff.patch
-rw-rw-r-- 1 erik erik 261 Apr 22 18:20 foo-bsdiff.patch
The apply patch subcommand
Apply the patch foo.patch to tests/files/foo/old to create foo.new.
$ detools apply_patch tests/files/foo/old foo.patch foo.new
$ ls -l foo.new
-rw-rw-r-- 1 erik erik 2780 Mar 1 19:18 foo.new
The in-place apply patch subcommand
Apply the in-place patch foo-in-place.patch to foo.mem.
$ cp tests/files/foo/old foo.mem
$ detools apply_patch_in_place foo.mem foo-in-place.patch
$ ls -l foo.mem
-rwxrwxr-x 1 erik erik 2780 Mar 16 08:51 foo.mem
The bsdiff apply patch subcommand
Apply the patch foo-bsdiff.patch to tests/files/foo/old to create foo.new.
$ detools apply_patch_bsdiff tests/files/foo/old foo-bsdiff.patch foo.new
$ ls -l foo.new
-rw-rw-r-- 1 erik erik 2780 Mar 1 19:18 foo.new
The patch info subcommand
Print information about the patch foo.patch.
$ detools patch_info foo.patch
Type: normal
Patch size: 127 bytes
To size: 2.71 KiB
Patch/to ratio: 4.6 % (lower is better)
Diff/extra ratio: 9828.6 % (higher is better)
Size/data ratio: 0.3 % (lower is better)
Compression: lzma
Number of diffs: 2
Total diff size: 2.69 KiB
Average diff size: 1.34 KiB
Median diff size: 1.34 KiB
Number of extras: 2
Total extra size: 28 bytes
Average extra size: 14 bytes
Median extra size: 14 bytes
Contributing
Fork the repository.
Install prerequisites.
pip install -r requirements.txt
Implement the new feature or bug fix.
Implement test case(s) to ensure that future changes do not break legacy.
Run the tests.
make test
Create a pull request.
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