Set EM_PKG_CONFIG_PATH to correctly configure pkg-config (#52)

Closes #51

---------

CHANGELOG.md

@@ -5,13 +5,20 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.29.1]
 
 ### Added
 
 - Add `skip_emscripten_version_check` flag and SKIP_EMSCRIPTEN_VERSION_CHECK environment
   variable to skip emscripten version check.
   [#53](https://github.com/pyodide/pyodide-build/pull/53)
+- Set the `EM_PKG_CONFIG_PATH` environment variable used by emscripten/`pkg-config` to discover dependencies
+  [#52](https://github.com/pyodide/pyodide-build/pull/52)
+
+### Changed
+
+- Source tar files are now extracted with python's [data filter](https://docs.python.org/3/library/tarfile.html#tarfile.data_filter)
+  [#52](https://github.com/pyodide/pyodide-build/pull/52)
 
 - The `pyodide build` command will now raise an error if the local Python version has been changed,
   after the cross-build environment has been set up.

pyodide_build/buildpkg.py

@@ -10,7 +10,6 @@
 import shutil
 import subprocess
 import sys
-import warnings
 from collections.abc import Iterator
 from datetime import datetime
 from email.message import Message
@@ -356,12 +355,18 @@ def _download_and_extract(self) -> None:
             shutil.copy(tarballpath, self.src_dist_dir)
             return
 
-        with warnings.catch_warnings():
-            # Python 3.12-3.13 emits a DeprecationWarning when using shutil.unpack_archive without a filter,
-            # but filter doesn't work well for zip files, so we suppress the warning until we find a better solution.
-            # https://github.com/python/cpython/issues/112760
-            warnings.simplefilter("ignore")
-            shutil.unpack_archive(tarballpath, self.build_dir)
+        # Use a Python 3.14-like filter (see https://github.com/python/cpython/issues/112760)
+        # Can be removed once we use Python 3.14
+        # The "data" filter will reset ownership but preserve permissions and modification times
+        # Without it, permissions and modification times will be silently skipped if the uid/git
+        # is too large for the chown() call. This behavior can lead to "Permission denied" errors
+        # (missing x bit) or random strange `make` behavior (due to wrong mtime order) in the CI
+        # pipeline.
+        shutil.unpack_archive(
+            tarballpath,
+            self.build_dir,
+            filter=None if tarballpath.suffix == ".zip" else "data",
+        )
 
         extract_dir_name = self.source_metadata.extract_dir
         if extract_dir_name is None:
@@ -556,7 +561,11 @@ def _get_helper_vars(self) -> dict[str, str]:
             "DISTDIR": str(self.src_dist_dir),
             # TODO: rename this to something more compatible with Makefile or CMake conventions
             "WASM_LIBRARY_DIR": str(self.library_install_prefix),
-            # Using PKG_CONFIG_LIBDIR instead of PKG_CONFIG_PATH,
+            # Emscripten will use this variable to configure pkg-config in emconfigure
+            "EM_PKG_CONFIG_PATH": str(self.library_install_prefix / "lib/pkgconfig"),
+            # This variable is usually overwritten by emconfigure
+            # The value below will only be used if pkg-config is called without emconfigure
+            # We use PKG_CONFIG_LIBDIR instead of PKG_CONFIG_PATH,
             # so pkg-config will not look in the default system directories
             "PKG_CONFIG_LIBDIR": str(self.library_install_prefix / "lib/pkgconfig"),
         }

pyodide_build/tests/test_buildpkg.py

@@ -126,6 +126,9 @@ def test_get_helper_vars(tmp_path):
         tmp_path / "pkg_1" / "build" / "pkg_1-1.0.0" / "dist"
     )
     assert helper_vars["WASM_LIBRARY_DIR"] == str(tmp_path / ".libs")
+    assert helper_vars["EM_PKG_CONFIG_PATH"] == str(
+        tmp_path / ".libs" / "lib" / "pkgconfig"
+    )
     assert helper_vars["PKG_CONFIG_LIBDIR"] == str(
         tmp_path / ".libs" / "lib" / "pkgconfig"
     )