use file to communicate from wheel build function (#94)

crates/rattler_installs_packages/src/wheel_builder.rs

@@ -396,6 +396,25 @@ impl<'db, 'i> WheelBuilder<'db, 'i> {
         let output = build_environment.run_command("WheelMetadata")?;
 
         if !output.status.success() {
+            if output.status.code() == Some(50) {
+                tracing::warn!("SDist build backend does not support metadata generation");
+                // build wheel instead
+                let wheel_file = self.build_wheel(sdist).await?;
+                let wheel = crate::wheel::Wheel::from_path(
+                    &wheel_file,
+                    &sdist.name().distribution.clone().into(),
+                )
+                .map_err(|e| {
+                    WheelBuildError::Error(format!(
+                        "Could not build wheel for metadata extraction: {}",
+                        e
+                    ))
+                })?;
+
+                return wheel.metadata().map_err(|e| {
+                    WheelBuildError::Error(format!("Could not parse wheel metadata: {}", e))
+                });
+            }
             let stdout = String::from_utf8_lossy(&output.stderr);
             return Err(WheelBuildError::Error(stdout.to_string()));
         }
@@ -423,8 +442,10 @@ impl<'db, 'i> WheelBuilder<'db, 'i> {
             return Err(WheelBuildError::Error(stdout.to_string()));
         }
 
-        let stdout = String::from_utf8_lossy(&output.stdout);
-        let wheel_file = PathBuf::from(stdout.trim());
+        let result =
+            std::fs::read_to_string(build_environment.work_dir.path().join("wheel_result"))?;
+        let wheel_file = PathBuf::from(result.trim());
+
         Ok(wheel_file)
     }
 }

crates/rattler_installs_packages/src/wheel_builder_frontend.py

@@ -80,26 +80,30 @@ def prepare_metadata_for_build_wheel(backend: ModuleType, work_dir: Path):
         # Write the path to the dist-info directory to a file
         result_file.write_text(result)
     else:
-        exit(123)
+        exit(50)
 
 def wheel_dirs(work_dir: Path):
     return work_dir / "wheel"
 
 def build_wheel(backend: ModuleType, work_dir: Path):
     """Take a folder with an SDist and build a wheel from it."""
     wheel_dir = wheel_dirs(work_dir)
+    result_file = work_dir / "wheel_result"
 
-    # TODO: maybe start reading this from the file again if it fails
-    metadata_dir = metadata_dirs(work_dir) / ".dist-info"
-    # Use the metadata directory if it exists, otherwise set this to None
+    # Use the metadata result if it exists, otherwise set this to None
+    metadata_result = work_dir / "metadata_result"
+    if metadata_result.exists():
+        metadata_dir = metadata_result.read_text().strip()
+    else:
+        metadata_dir = None
 
     wheel_dir.mkdir()
     wheel_basename = backend.build_wheel(
         str(wheel_dir),
-        metadata_directory=metadata_dir if metadata_dir.exists() else None,
+        metadata_directory=metadata_dir,
     )
 
-    print(str(wheel_dir / wheel_basename))
+    result_file.write_text(str(wheel_dir / wheel_basename))
 
 if __name__ == "__main__":
     work_dir, entry_point, goal = sys.argv[1:]