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builtins.fetchGit: Fix build when fetching a git worktree

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Worktrees[1] are a feature of git which allow you to check out a ref in
a different directory.

While playing around with flakes I realized that git repositories in a
worktree checkout break when trying to build a flake:

```
$ git worktree add ../nixpkgs-flakes nixpkgs-flakes
$ cd ../nixpkgs-flakes
$ nix build .#hello
error: opening directory '/home/ma27/Projects/nixpkgs-flakes/.git/refs/heads': Not a directory
```

This issue has been fixed by determining with `git rev-parse --git-common-dir`
where the actual `.git` directory is.

Please note that this issue only exists on the `flakes` branch, fetching
worktree checkouts with Nix master seems to work fine.

[1] https://git-scm.com/docs/git-worktree
This commit is contained in:
Maximilian Bosch 2019-11-15 13:04:42 +01:00
parent 144bb3ef7d
commit c169ea5904
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GPG key ID: 091DBF4D1FC46B8E
2 changed files with 18 additions and 1 deletions
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11
src/libstore/fetchers/git.cc
View file

@ -217,7 +217,16 @@ struct GitInput : Input
/* Check whether this repo has any commits. There are
probably better ways to do this. */
bool haveCommits = !readDirectory(actualUrl + "/.git/refs/heads").empty();
auto gitDir = actualUrl + "/.git";
auto commonGitDir = chomp(runProgram(
"git",
true,
{ "-C", actualUrl, "rev-parse", "--git-common-dir" }
));
if (commonGitDir != ".git")
gitDir = commonGitDir;
bool haveCommits = !readDirectory(gitDir + "/refs/heads").empty();
try {
if (haveCommits) {

8
tests/fetchGit.sh
View file

@ -25,8 +25,16 @@ rev1=$(git -C $repo rev-parse HEAD)
echo world > $repo/hello
git -C $repo commit -m 'Bla2' -a
git -C $repo worktree add $TEST_ROOT/worktree
echo hello >> $TEST_ROOT/worktree/hello
rev2=$(git -C $repo rev-parse HEAD)
# Fetch a worktree
unset _NIX_FORCE_HTTP
path0=$(nix eval --impure --raw --expr "(builtins.fetchGit file://$TEST_ROOT/worktree).outPath")
export _NIX_FORCE_HTTP=1
[[ $(tail -n 1 $path0/hello) = "hello" ]]
# Fetch the default branch.
path=$(nix eval --impure --raw --expr "(builtins.fetchGit file://$repo).outPath")
[[ $(cat $path/hello) = world ]]