# whitequark/unfork

unfork(2) is the inverse of fork(2).    sort of.

Repository: https://github.com/whitequark/unfork
Canonical: https://ross.abutalabs.com/products/unfork
Language: C++
License: 0BSD
License Family: permissive
Last push: 2024-04-21T11:49:37+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 2500, "days_push": 864, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1488, forks 34 (observed 2026-08-28T04:04:52.165121+00:00)

## What it is
unfork(2) is a proof-of-concept Linux technique and library that joins two process address spaces into one, the inverse of fork(2), by combining userfaultfd with process_vm_readv to create copy-on-write mappings of another process's memory. It enables stealthy dynamic binary analysis and instrumentation of applications with built-in integrity checks, leaving no ptrace traces or signals.

## Use cases
- analyze a binary with anti-debugging protections without being detected
- instrument a running process by manipulating a private copy of its memory
- take a cheap snapshot of another application's address space to read, write, execute, and discard
- reverse engineer software that checks for ptrace or debugger attachment
- inspect and modify memory of a process running under the same uid

## When to choose
- you need to dynamically analyze or instrument a target with integrity checks that detect ptrace
- you want a copy-on-write view of another process's memory without signals or traces
- you are doing security research on Linux x86_64 or i386 and can build with patched musl-gcc

## When to avoid
- you need a production-ready or supported tool, since this is explicitly a proof of concept
- you need to share files or shared memory between the merged address spaces, which requires a kernel module
- you are not on Linux, or you cannot obtain ptrace privileges over the target process

## Facets
- artifact type: library
- maturity: experimental
- function: security, reverse-engineering, cryptography
- domain: security, reverse-engineering, operating-systems
- platform: cpp, c
- tags: ptrace, userfaultfd, process-injection, binary-analysis, proof-of-concept, memory-introspection, linux

## Member repositories
- whitequark/unfork (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:52.165121+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:33:46.750180+00:00, confidence not recorded.
  - readme: https://github.com/whitequark/unfork (fetched 2026-08-28T04:04:52.165121+00:00, sha 916ba788b274)
- Data as of 2026-08-30T08:39:29.467469+00:00.