Allow symlinks in the build backend

crates/uv-build-backend/src/lib.rs

@@ -9,12 +9,12 @@ pub use settings::{BuildBackendSettings, WheelDataIncludes};
 pub use source_dist::{build_source_dist, list_source_dist};
 pub use wheel::{build_editable, build_wheel, list_wheel, metadata};
 
-use std::fs::FileType;
 use std::io;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use thiserror::Error;
 use tracing::debug;
+use walkdir::DirEntry;
 
 use uv_fs::Simplified;
 use uv_globfilter::PortableGlobError;
@@ -54,8 +54,6 @@ pub enum Error {
         #[source]
         err: walkdir::Error,
     },
-    #[error("Unsupported file type {:?}: `{}`", _1, _0.user_display())]
-    UnsupportedFileType(PathBuf, FileType),
     #[error("Failed to write wheel zip archive")]
     Zip(#[from] zip::result::ZipError),
     #[error("Failed to write RECORD file")]
@@ -86,6 +84,16 @@ trait DirectoryWriter {
     /// Files added through the method are considered generated when listing included files.
     fn write_bytes(&mut self, path: &str, bytes: &[u8]) -> Result<(), Error>;
 
+    /// Add the file or directory to the path.
+    fn write_dir_entry(&mut self, entry: &DirEntry, target_path: &str) -> Result<(), Error> {
+        if entry.file_type().is_dir() {
+            self.write_directory(target_path)?;
+        } else {
+            self.write_file(target_path, entry.path())?;
+        }
+        Ok(())
+    }
+
     /// Add a local file.
     fn write_file(&mut self, path: &str, file: &Path) -> Result<(), Error>;
 

crates/uv-build-backend/src/source_dist.rs

@@ -250,32 +250,16 @@ fn write_source_dist(
             .expect("walkdir starts with root");
 
         if !include_matcher.match_path(relative) || exclude_matcher.is_match(relative) {
-            trace!("Excluding: `{}`", relative.user_display());
+            trace!("Excluding from sdist: `{}`", relative.user_display());
             continue;
         }
 
-        debug!("Including {}", relative.user_display());
-        if entry.file_type().is_dir() {
-            writer.write_directory(
-                &Path::new(&top_level)
-                    .join(relative)
-                    .portable_display()
-                    .to_string(),
-            )?;
-        } else if entry.file_type().is_file() {
-            writer.write_file(
-                &Path::new(&top_level)
-                    .join(relative)
-                    .portable_display()
-                    .to_string(),
-                entry.path(),
-            )?;
-        } else {
-            return Err(Error::UnsupportedFileType(
-                relative.to_path_buf(),
-                entry.file_type(),
-            ));
-        }
+        let entry_path = Path::new(&top_level)
+            .join(relative)
+            .portable_display()
+            .to_string();
+        debug!("Adding to sdist: {}", relative.user_display());
+        writer.write_dir_entry(&entry, &entry_path)?;
     }
     debug!("Visited {files_visited} files for source dist build");
 

crates/uv-build-backend/src/wheel.rs

@@ -164,29 +164,18 @@ fn write_wheel(
             .path()
             .strip_prefix(source_tree)
             .expect("walkdir starts with root");
-        let wheel_path = entry
+        let entry_path = entry
             .path()
             .strip_prefix(&src_root)
             .expect("walkdir starts with root");
         if exclude_matcher.is_match(match_path) {
             trace!("Excluding from module: `{}`", match_path.user_display());
             continue;
         }
-        let wheel_path = wheel_path.portable_display().to_string();
 
-        debug!("Adding to wheel: `{wheel_path}`");
-
-        if entry.file_type().is_dir() {
-            wheel_writer.write_directory(&wheel_path)?;
-        } else if entry.file_type().is_file() {
-            wheel_writer.write_file(&wheel_path, entry.path())?;
-        } else {
-            // TODO(konsti): We may want to support symlinks, there is support for installing them.
-            return Err(Error::UnsupportedFileType(
-                entry.path().to_path_buf(),
-                entry.file_type(),
-            ));
-        }
+        let entry_path = entry_path.portable_display().to_string();
+        debug!("Adding to wheel: {entry_path}");
+        wheel_writer.write_dir_entry(&entry, &entry_path)?;
     }
     debug!("Visited {files_visited} files for wheel build");
 
@@ -519,23 +508,12 @@ fn wheel_subdir_from_globs(
             continue;
         }
 
-        let relative_licenses = Path::new(target)
+        let license_path = Path::new(target)
             .join(relative)
             .portable_display()
             .to_string();
-
-        if entry.file_type().is_dir() {
-            wheel_writer.write_directory(&relative_licenses)?;
-        } else if entry.file_type().is_file() {
-            debug!("Adding {} file: `{}`", globs_field, relative.user_display());
-            wheel_writer.write_file(&relative_licenses, entry.path())?;
-        } else {
-            // TODO(konsti): We may want to support symlinks, there is support for installing them.
-            return Err(Error::UnsupportedFileType(
-                entry.path().to_path_buf(),
-                entry.file_type(),
-            ));
-        }
+        debug!("Adding for {}: `{}`", globs_field, relative.user_display());
+        wheel_writer.write_dir_entry(&entry, &license_path)?;
     }
     Ok(())
 }

crates/uv/tests/it/build_backend.rs

@@ -768,3 +768,93 @@ fn complex_namespace_packages() -> Result<()> {
     );
     Ok(())
 }
+
+/// Test that a symlinked file (here: license) gets included.
+#[test]
+#[cfg(unix)]
+fn symlinked_file() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let project = context.temp_dir.child("project");
+    context
+        .init()
+        .arg("--preview")
+        .arg("--build-backend")
+        .arg("uv")
+        .arg(project.path())
+        .assert()
+        .success();
+
+    project.child("pyproject.toml").write_str(indoc! {r#"
+        [project]
+        name = "project"
+        version = "1.0.0"
+        license-files = ["LICENSE"]
+
+        [build-system]
+        requires = ["uv_build>=0.5.15,<10000"]
+        build-backend = "uv_build"
+        "#
+    })?;
+
+    let license_file = context.temp_dir.child("LICENSE");
+    let license_symlink = project.child("LICENSE");
+
+    let license_text = "Project license";
+    license_file.write_str(license_text)?;
+    fs_err::os::unix::fs::symlink(license_file.path(), license_symlink.path())?;
+
+    uv_snapshot!(context
+        .build_backend()
+        .arg("build-sdist")
+        .arg(context.temp_dir.path())
+        .current_dir(project.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    project-1.0.0.tar.gz
+
+    ----- stderr -----
+    ");
+
+    uv_snapshot!(context
+        .build_backend()
+        .arg("build-wheel")
+        .arg(context.temp_dir.path())
+        .current_dir(project.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    project-1.0.0-py3-none-any.whl
+
+    ----- stderr -----
+    ");
+
+    uv_snapshot!(context.filters(), context.pip_install().arg("project-1.0.0-py3-none-any.whl"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + project==1.0.0 (from file://[TEMP_DIR]/project-1.0.0-py3-none-any.whl)
+    ");
+
+    // Check that we included the actual license text and not a broken symlink.
+    let installed_license = context
+        .site_packages()
+        .join("project-1.0.0.dist-info")
+        .join("licenses")
+        .join("LICENSE");
+    assert!(
+        fs_err::symlink_metadata(&installed_license)?
+            .file_type()
+            .is_file()
+    );
+    let license = fs_err::read_to_string(&installed_license)?;
+    assert_eq!(license, license_text);
+
+    Ok(())
+}