Bazel: pkg_tar does not respect strip_prefix when output is in workspace root

[jasonchoimtt]

Repro:

touch WORKSPACE
cat > BUILD <<EOD
load("@bazel_tools//tools/build_defs/pkg:pkg.bzl", "pkg_tar")

pkg_tar(
    name = "repro",
    files = ["a/b/c.sh"],
    strip_prefix = "a/b",
)
EOD
mkdir -p a/b
touch a/b/c.sh
bazel build :repro
tar -tf bazel-bin/repro.tar

I believe the particular line is here:

https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/pkg/path.bzl#L51

else:  # Relative to a sub-directory
  return _short_path_dirname(out) + "/" + data_path

which fails to account for the fact that _short_path_dirname may return "". As a result, the returned data_path incorrectly includes a /.

[zhexuany]

@jasonchoimtt I could not reproduce the bug. The version I used is 0.3.1. It build project you provided correctly.

[jasonchoimtt]

Sorry, I should have elaborated more. I expect the tarball to contain:

./
./c.sh

since I strip_prefix a/b.

But instead it produces a tarball with (I'm on 0.3.0):

./
./a/
./a/b/
./a/b/c.sh

Can you reproduce this? If not, I can test on 0.3.1 later to verify.

[zhexuany]

The output I have is

tar -tf bazel-bin/repro.tar   
./
./a/
./a/b/
./a/b/c.sh

I missed some info. I think I reproduced the bug you have.

[jasonchoimtt]

That shows the problem I am reporting. If I am not mistaken, the intended behavior of strip_prefix = "a/b" is that it should remove a/b and so put c.sh at the root of the tarball. But as shown above this does not happen.

Am I right or did I misinterpret the documentation?

[zhexuany]

You are absolutely right. I read too fast and missed some key info. If you provide strip_prefix, it should behave like you expecting. But Bazel did not.

[zhexuany]

@jasonchoimtt I just fixed it. I am preparing pull request now. Hopefully, my changes can be merged into mater in near future. :)

[jasonchoimtt]

Thank you! Free to close this issue. :)

[zhexuany]

@hermione521 Could you close this issue, I do not have the access to close it.