pkgs/build-support/fetchgit/deterministic-git

   1 #!/bin/sh
   2
   3 # some git commands print to stdout, which would contaminate our JSON output
   4 clean_git(){
   5     git "$@" >&2
   6 }
   7
   8 # Remove all remote branches, remove tags not reachable from HEAD, do a full
   9 # repack and then garbage collect unreferenced objects.
  10 make_deterministic_repo(){
  11     local repo="$1"
  12
  13     # run in sub-shell to not touch current working directory
  14     (
  15     cd "$repo"
  16     # Remove files that contain timestamps or otherwise have non-deterministic
  17     # properties.
  18     rm -rf .git/logs/ .git/hooks/ .git/index .git/FETCH_HEAD .git/ORIG_HEAD \
  19         .git/refs/remotes/origin/HEAD .git/config
  20
  21     # Remove all remote branches.
  22     git branch -r | while read -r branch; do
  23         clean_git branch -rD "$branch"
  24     done
  25
  26     # Remove tags not reachable from HEAD. If we're exactly on a tag, don't
  27     # delete it.
  28     maybe_tag=$(git tag --points-at HEAD)
  29     git tag --contains HEAD | while read -r tag; do
  30         if [ "$tag" != "$maybe_tag" ]; then
  31             clean_git tag -d "$tag"
  32         fi
  33     done
  34
  35     # Do a full repack. Must run single-threaded, or else we lose determinism.
  36     clean_git config pack.threads 1
  37     clean_git repack -A -d -f
  38     rm -f .git/config
  39
  40     # Garbage collect unreferenced objects.
  41     # Note: --keep-largest-pack prevents non-deterministic ordering of packs
  42     #   listed in .git/objects/info/packs by only using a single pack
  43     clean_git gc --prune=all --keep-largest-pack
  44     )
  45 }