Binary delta encoding in Python 3 and C.

Based on http://www.daemonology.net/bsdiff/, with the following differences:

• BZ2, LZ4, 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.

• Normal or in-place (resumable) updates.

• 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

pip install detools

"LZMA ref." is the target binary compressed with lzma --best.

The percentages are calculated as "patch size" / "to size". Lower is better.

Examples in C are found in src/c.

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

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

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

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

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

1. Fork the repository.

2. Install prerequisites.

   pip install -r requirements.txt
   

3. Implement the new feature or bug fix.

4. Implement test case(s) to ensure that future changes do not break legacy.

5. Run the tests.

   make test
   

6. Create a pull request.