Fix hardlinks in tar unpacking (#11221)

In astral-sh/tokio-tar#2, we accidentally
changed the `target_base` from the target base to the parent of the
file. This would cause hardlink unpacking to fail.

Example: A hardlink at `hardlinked-0.1.0/pyproject.toml` pointing to
`hardlinked-0.1.0/pyproject.toml.real` would try pointing to
`hardlinked-0.1.0/hardlinked-0.1.0/pyproject.toml.real` instead and fail
the unpacking.

The actual fix is in astral-tokio-tar, on the uv side there are only tests.

Fixes #11213

Author: konstin

Cargo.lock

@@ -73,7 +73,7 @@ uv-workspace = { path = "crates/uv-workspace" }
 anstream = { version = "0.6.15" }
 anyhow = { version = "1.0.89" }
 arcstr = { version = "1.2.0" }
-astral-tokio-tar = { git = "https://github.com/astral-sh/tokio-tar", rev = "ba2b140f27d081c463335f0d68b5f8df8e6c845e" }
+astral-tokio-tar = { git = "https://github.com/astral-sh/tokio-tar", rev = "efeaea927c7a40ee66121de2e1bebfd5d7a4a602" }
 async-channel = { version = "2.3.1" }
 async-compression = { version = "0.4.12", features = ["bzip2", "gzip", "xz", "zstd"] }
 async-trait = { version = "0.1.82" }

Cargo.toml

@@ -1746,3 +1746,80 @@ fn build_version_mismatch() -> Result<()> {
     "###);
     Ok(())
 }
+
+#[cfg(unix)] // Symlinks aren't universally available on windows.
+#[test]
+fn build_with_symlink() -> Result<()> {
+    let context = TestContext::new("3.12");
+    context
+        .temp_dir
+        .child("pyproject.toml.real")
+        .write_str(indoc! {r#"
+            [project]
+            name = "softlinked"
+            version = "0.1.0"
+            requires-python = ">=3.12"
+
+            [build-system]
+            requires = ["hatchling"]
+            build-backend = "hatchling.build"
+    "#})?;
+    std::os::unix::fs::symlink(
+        context.temp_dir.child("pyproject.toml.real"),
+        context.temp_dir.child("pyproject.toml"),
+    )?;
+    context
+        .temp_dir
+        .child("src/softlinked/__init__.py")
+        .touch()?;
+    uv_snapshot!(context.filters(), context.build(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Building source distribution...
+    Building wheel from source distribution...
+    Successfully built dist/softlinked-0.1.0.tar.gz
+    Successfully built dist/softlinked-0.1.0-py3-none-any.whl
+    "###);
+    Ok(())
+}
+
+#[test]
+fn build_with_hardlink() -> Result<()> {
+    let context = TestContext::new("3.12");
+    context
+        .temp_dir
+        .child("pyproject.toml.real")
+        .write_str(indoc! {r#"
+            [project]
+            name = "hardlinked"
+            version = "0.1.0"
+            requires-python = ">=3.12"
+
+            [build-system]
+            requires = ["hatchling"]
+            build-backend = "hatchling.build"
+    "#})?;
+    fs_err::hard_link(
+        context.temp_dir.child("pyproject.toml.real"),
+        context.temp_dir.child("pyproject.toml"),
+    )?;
+    context
+        .temp_dir
+        .child("src/hardlinked/__init__.py")
+        .touch()?;
+    uv_snapshot!(context.filters(), context.build(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Building source distribution...
+    Building wheel from source distribution...
+    Successfully built dist/hardlinked-0.1.0.tar.gz
+    Successfully built dist/hardlinked-0.1.0-py3-none-any.whl
+    "###);
+    Ok(())
+}