bsdiff4 Library

Warnings

• gotcha All input data (old, new, and diff) for `bsdiff4.diff` and `bsdiff4.patch` functions must be `bytes` objects, not strings. Passing strings will result in `TypeError`.
  Fix: Ensure all string data is encoded to bytes (e.g., `my_string.encode('utf-8')`) before passing it to bsdiff4 functions.
• gotcha For very large files, `bsdiff4` can be memory intensive, as it often loads entire files or significant portions into memory during diffing and patching operations. Monitor memory usage for performance-critical applications.
  Fix: Consider processing data in smaller chunks if feasible, or ensure sufficient RAM is available for operations on large files. The `file_diff` and `file_patch` functions might manage memory slightly better by handling file streams, but the core algorithm still requires memory proportional to the input size.
• gotcha The `bsdiff4` library implements the `bsdiff4` format, which is a specific version of the bsdiff algorithm. Diffs generated by this library may not be compatible with other bsdiff implementations (e.g., bsdiff3, or other variations) if they use a different format version.
  Fix: When exchanging diffs with other systems or languages, ensure that all parties are using a `bsdiff4` compatible implementation to avoid parsing errors or incorrect patches.
• gotcha On some systems, particularly those without pre-built binary wheels available on PyPI (e.g., specific Linux distributions, older macOS versions, or Windows without development tools), `pip install bsdiff4` might fail due to the need for a C compiler to build its native extensions.
  Fix: Install the necessary build tools and C compiler for your operating system (e.g., `build-essential` on Debian/Ubuntu, Xcode Command Line Tools on macOS, Visual C++ Build Tools on Windows) or use an environment with pre-built wheels.

Install

• pip install bsdiff4 Install latest version

Imports

• diff

  import bsdiff4
  # bsdiff4.diff(...)

• patch

  import bsdiff4
  # bsdiff4.patch(...)

• file_diff

  import bsdiff4
  # bsdiff4.file_diff(...)

• file_patch

  import bsdiff4
  # bsdiff4.file_patch(...)

Quickstart

This quickstart demonstrates how to use `bsdiff4` to generate and apply binary differences for both `bytes` objects in memory and actual files on disk. It shows how to compute a `diff` from old and new data, and then apply that `diff` to the old data to reconstruct the new data.

import bsdiff4
import os

# Example with bytes
old_data = b"This is the old data string."
new_data = b"This is the new and updated data string."

# Generate a binary diff
diff_data = bsdiff4.diff(old_data, new_data)
print(f"Diff data length: {len(diff_data)} bytes")

# Apply the patch to get back the new data
patched_data = bsdiff4.patch(old_data, diff_data)
assert patched_data == new_data
print(f"Patched data (bytes): {patched_data.decode('utf-8')}\n")

# Example with files
file_old = 'old_file.txt'
file_new = 'new_file.txt'
file_diff = 'diff.bin'
file_patched = 'patched_file.txt'

with open(file_old, 'wb') as f:
    f.write(old_data)
with open(file_new, 'wb') as f:
    f.write(new_data)

# Generate diff between files
bsdiff4.file_diff(file_old, file_new, file_diff)
print(f"File diff created: {file_diff}")

# Apply patch to recreate new file
bsdiff4.file_patch(file_old, file_patched, file_diff)

with open(file_patched, 'rb') as f:
    recreated_data = f.read()
assert recreated_data == new_data
print(f"Patched file created: {file_patched} (content matches new_file.txt)")

# Clean up generated files
os.remove(file_old)
os.remove(file_new)
os.remove(file_diff)
os.remove(file_patched)