cabal-version: 3.0 name: git-phoenix version: 0.0.1 synopsis: Recover Git repositories from disk recovery tool output (photorec) description: This is a command line tool for recovery Git repositories after accidental removal or file system failure. == Motivation #motivation# The tool is started as a practical attempt to retrieve a few unpublished repositories from an EXT4 disk, with hundreds of other repos including very big ones (nixpkgs, Linux kernel, GHC), played a role of haystack here. EXT4 has tools, such as extundelete and ext4magic, but they didn’t succeed in that case. So I switched to more primitive tool (photorec), producing independent files with arbitrary names, based on magic headers and other content heuristics, specific to particular format, and luck that files take sequencial disk blocks. The tool did the job, but requried magic tuning, because by default GIT object files are skipped. Rescued git files usually were bigger than compressed content and had trailing trash bytes. == Getting input with photorec #getting-input-with-photorec# git-phoenix need input produced by photorec or similar tool. To make photorec recognize the zlib file format put following config into @~\/.photorec.sig@ on livecd. I used system-rescue distributive. > go1 0 0x7801 > go2 0 0x78DA > go3 0 0x789C Launch photorec without arguments - it has ncurses terminal UI. photorec output looks like: > $ tree /paranoid-no-brutforce-nonexpert-nocorrupted-zlib/ > |-- recup_dir.1 > | |-- f0305926.go1 > | |-- f0378540.go1 > | |-- f0421825.go1 > ... > |-- recup_dir.1055 > ... > |-- f167043017.go1 > `-- f167043025.go1 > $ == Building #building# The easiest way to build the project is to use nix. > $ nix-build > $ ./result/bin/git-phoenix --help == git-phoenix recovery steps #git-phoenix-recovery-steps# git-phoenix sunny day scenario assumes execution of several commands to get GIT repo from photorec output. === Step 1. Building uber repo #step-1.-building-uber-repo# Uber repo is a folder with structure equal to @.git\/objects@ but instead of regular files symlinks point to files in photorec structure. > $ git-phoenix uber -o uber -i /paranoid-no-brutforce-nonexpert-nocorrupted-zlib/ > Duration: 45.71s > Found: 423254 > Speed: 9260.03 files per second > Maximum number of SHA collisions: 17 > $ Uber command picks valid GIT objects and mitigates SHA collisions, which is pretty common in this situation. === Step 2. Discovery HEAD commit #step-2.-discovery-head-commit# This step is optional if you managed to recover reflog by simply grepping commit comment just pick the latest hash from there. Command prints SHAs of consistent commit chains i.e. ending with a commit without parent. > $ git-phoenix heads -a '^John' -u uber > 7768eed9387ff 1970-01-01 00:00 John Doe Big Bang Arbitrary commit can be filter in uber repo too: > $ git-phoenix search --days-before 0 --days-after 9 -a '^John' -u uber > 7768eed9387ff 1970-01-01 00:00 John Doe Big Bang === Step 3. Real GIT repo extraction #step-3.-real-git-repo-extraction# Uber repo should contain all required files, but it is not a valid GIT repo. GIT thoroughly checks object files and complains about any trailing trash. Extraction creates GIT repo with master branch referring specified commit, chopping off trailing trash and disambiguating SHAs. > $ git-phoenix extract -g my-foo -u uber -s 7768eed9387ff > $ git -C my-foo reset > $ git -C my-foo checkout . > $ echo Woo-Hah == Development environment #development-environment# == Building #building-1# HLS should be available inside dev env. > $ nix-shell > $ emacs src/Data/Git/Phoenix.hs & > $ cabal build > $ cabal test == Static linking #static-linking# Static is not enabled by default, because GitHub CI job times out. > nix-build --arg staticBuild true homepage: http://github.com/yaitskov/git-phoenix license: BSD-3-Clause author: Daniil Iaitskov maintainer: dyaitskov@gmail.com copyright: Daniil Iaitkov 2025 category: System build-type: Simple bug-reports: https://github.com/yaitskov/git-phoenix/issues extra-doc-files: changelog.md tested-with: GHC == 9.12.2 source-repository head type: git location: https://github.com/yaitskov/git-phoenix.git common base default-language: GHC2024 ghc-options: -Wall default-extensions: DefaultSignatures NoImplicitPrelude OverloadedStrings TemplateHaskell build-depends: base >=4.7 && < 5 , bytestring >= 0.12.1 && < 1 , directory < 2 , optparse-applicative < 1 , relude >= 1.2.2 && < 2 , tagged < 1 , unliftio < 1 library import: base hs-source-dirs: src exposed-modules: Data.Git.Phoenix Data.Git.Phoenix.App Data.Git.Phoenix.CmdArgs Data.Git.Phoenix.CmdRun Data.Git.Phoenix.Commit Data.Git.Phoenix.CommitSearch Data.Git.Phoenix.Extraction Data.Git.Phoenix.HeadsDiscovery Data.Git.Phoenix.Io Data.Git.Phoenix.Object Data.Git.Phoenix.Prelude Data.Git.Phoenix.Pretty Data.Git.Phoenix.Repo Data.Git.Phoenix.Sha Data.Git.Phoenix.ShaCollision Data.Git.Phoenix.Tree Data.Git.Phoenix.Uber other-modules: Paths_git_phoenix autogen-modules: Paths_git_phoenix build-depends: , base < 5 , binary < 1 , conduit < 2 , containers < 1 , cryptohash-sha1 < 1 , deepseq < 2 , extra < 2 , filepath < 2 , lens < 6 , memory < 1 , pretty-hex < 2 , regex-tdfa < 2 , template-haskell < 3 , time < 2 , trace-embrace >= 1.2.0 && < 2 , wl-pprint-text < 2 , word8 < 1 , zlib < 1 test-suite test import: base type: exitcode-stdio-1.0 main-is: Driver.hs other-modules: Data.Git.Phoenix.Test Data.Git.Phoenix.Test.UberCommitSearch Data.Git.Phoenix.Test.UberExtract Data.Git.Phoenix.Test.UberHeadsDiscovery Discovery hs-source-dirs: test ghc-options: -Wall -rtsopts -threaded -main-is Driver build-depends: , git-phoenix , QuickCheck , tasty , tasty-discover , tasty-hunit , tasty-quickcheck , time executable git-phoenix import: base ghc-options: -Wall -threaded -with-rtsopts=-N main-is: GitPhoenix.hs hs-source-dirs: app build-depends: , git-phoenix