node-hdiffpatch

Create patch buffer with origin buffer with HDiffPatch

Patch compatible with HDiffPatch -SD

Installation

npm install node-hdiffpatch
# or
bun add node-hdiffpatch

Prebuilt binaries are bundled for: darwin-arm64, darwin-x64, linux-x64, linux-arm64 (glibc), and win32-x64. Other platforms are not supported by the published package.

Development

Clone with submodules, then build and test:

git clone --recursive https://github.com/reactnativecn/node-hdiffpatch.git
cd node-hdiffpatch
bun install --ignore-scripts
bun run prebuild   # builds prebuilds/<platform>-<arch>/ for the current machine
bun run test       # run tests under Node
bun run test:bun   # run the same tests under the Bun runtime

Usage

diff(originBuf, newBuf)

Compare two buffers and return a new hdiffpatch patch as return value.

diffSingleStream(oldPath, newPath, outDiffPath[, cb])

Create a single-format (same wire format as diff()) patch by streaming file paths with block matching — generation memory stays O(match block) regardless of input size (100MB inputs use ~30MB RSS). The output applies with patch(), patchSingleStream(), and any existing HDiffPatch single-format apply side, so legacy clients need no changes. Patch size is larger than the in-memory diff() for the same inputs; prefer diff() when memory allows. In sync mode returns outDiffPath; async callback signature is (err, outDiffPath).

diffWindow(oldPath, newPath, outDiffPath[, windowSize][, cb])

Create a single-format (same wire format as diff()) patch using window mode: big covers come from streaming block matching, then residuals are refined with suffix-string matching inside a sliding window (2MB) over the old data. Match quality is close to the in-memory diff() while generation memory stays at the streaming tier — usually a much smaller patch than diffSingleStream() for the same inputs. The output applies with patch(), patchSingleStream(), and any existing single-format apply side. In sync mode returns outDiffPath; async callback signature is (err, outDiffPath). windowSize is the sliding-window byte size over the old data (default 2MB); a larger window catches longer-distance content moves at roughly linear additional memory.

patchSingleStream(oldPath, diffPath, outNewPath[, cb])

Apply a single-compressed hpatch payload created by diff or diffSingleStream from files. This is the file-level apply path for the normal in-memory diff format. In sync mode returns outNewPath. In async mode, callback signature is (err, outNewPath).

diffStream(oldPath, newPath, outDiffPath[, cb])

Create diff file by streaming file paths (low memory). In sync mode returns outDiffPath. In async mode, callback signature is (err, outDiffPath). The diff format is the streaming compressed format; use patchStream to apply it.

patchStream(oldPath, diffPath, outNewPath[, cb])

Apply diff file to old file and write new file by streaming. In sync mode returns outNewPath. In async mode, callback signature is (err, outNewPath).

CLI

After install, you can run:

hdp diff <oldFile> <newFile> <outDiff>
hdp patch <oldFile> <diffFile> <outNew>

Note: hdp patch auto-detects the diff format by its header, so it can apply both streaming diffs created by hdp diff and single-compressed diffs created by the in-memory diff() / streaming diffSingleStream() APIs.

License

MIT. The prebuilt binaries statically include HDiffPatch (MIT) and the LZMA SDK (public domain).