Preserve symlink contents in sdists

Wheels do not support symlinks (as they are ZIP files), but tarballs do.
For consistent results however, expand those symlinks to the files they
reference.

This is consistent with 0.16.0, and fixes this regression in 0.17.0.

mesonpy/__init__.py

@@ -14,6 +14,7 @@
 import argparse
 import collections
 import contextlib
+import copy
 import difflib
 import functools
 import importlib.machinery
@@ -854,6 +855,17 @@ def sdist(self, directory: Path) -> pathlib.Path:
 
         with tarfile.open(meson_dist_path, 'r:gz') as meson_dist, mesonpy._util.create_targz(sdist_path) as sdist:
             for member in meson_dist.getmembers():
+                # Wheels do not support links, though sdist tarballs could. For portability, reduce these to regular files.
+                if member.islnk() or member.issym():
+                    # Symlinks are relative to member directory, but hard links are relative to tarball root.
+                    path = member.name.rsplit('/', 1)[0] + '/' if member.issym() else ''
+                    orig = meson_dist.getmember(path + member.linkname)
+                    member = copy.copy(member)
+                    member.mode = orig.mode
+                    member.mtime = orig.mtime
+                    member.size = orig.size
+                    member.type = tarfile.REGTYPE
+
                 if member.isfile():
                     file = meson_dist.extractfile(member.name)
 

tests/packages/symlinks/meson.build

@@ -0,0 +1,12 @@
+# SPDX-FileCopyrightText: 2024 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+project('symlinks', version: '1.0.0')
+
+py = import('python').find_installation()
+
+install_subdir(
+  'subdir',
+  install_dir: py.get_install_dir(pure: false),
+)

tests/packages/symlinks/pyproject.toml

@@ -0,0 +1,7 @@
+# SPDX-FileCopyrightText: 2024 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+[build-system]
+build-backend = 'mesonpy'
+requires = ['meson-python']

tests/packages/symlinks/subdir/__init__.py

@@ -0,0 +1,3 @@
+# SPDX-FileCopyrightText: 2024 The meson-python developers
+#
+# SPDX-License-Identifier: MIT

tests/packages/symlinks/subdir/symlink.py

@@ -0,0 +1 @@
+test.py

tests/packages/symlinks/subdir/test.py

@@ -0,0 +1,3 @@
+# SPDX-FileCopyrightText: 2024 The meson-python developers
+#
+# SPDX-License-Identifier: MIT

tests/test_sdist.py

@@ -126,6 +126,33 @@ def test_contents_subdirs(sdist_subdirs):
     assert 0 not in mtimes
 
 
+def test_contents_symlinks(sdist_symlinks):
+    with tarfile.open(sdist_symlinks, 'r:gz') as sdist:
+        names = {member.name for member in sdist.getmembers()}
+        mtimes = {member.mtime for member in sdist.getmembers()}
+
+        orig_info = sdist.getmember('symlinks-1.0.0/subdir/test.py')
+        symlink_info = sdist.getmember('symlinks-1.0.0/subdir/symlink.py')
+        assert orig_info.mode == symlink_info.mode
+        assert orig_info.mtime == symlink_info.mtime
+        assert orig_info.size == symlink_info.size
+        orig = sdist.extractfile('symlinks-1.0.0/subdir/test.py')
+        symlink = sdist.extractfile('symlinks-1.0.0/subdir/symlink.py')
+        assert orig.read() == symlink.read()
+
+    assert names == {
+        'symlinks-1.0.0/PKG-INFO',
+        'symlinks-1.0.0/meson.build',
+        'symlinks-1.0.0/pyproject.toml',
+        'symlinks-1.0.0/subdir/__init__.py',
+        'symlinks-1.0.0/subdir/test.py',
+        'symlinks-1.0.0/subdir/symlink.py',
+    }
+
+    # All the archive members have a valid mtime.
+    assert 0 not in mtimes
+
+
 def test_contents_unstaged(package_pure, tmp_path):
     new = textwrap.dedent('''
         def bar():

tests/test_wheel.py

@@ -339,6 +339,23 @@ def test_install_subdir(wheel_install_subdir):
         }
 
 
+def test_install_symlink(wheel_symlinks):
+    artifact = wheel.wheelfile.WheelFile(wheel_symlinks)
+    # Handling of the exclude_files and exclude_directories requires
+    # Meson 1.1.0, see https://github.com/mesonbuild/meson/pull/11432.
+    # Run the test anyway to ensure that meson-python can produce a
+    # wheel also for older versions of Meson.
+    if MESON_VERSION >= (1, 1, 99):
+        assert wheel_contents(artifact) == {
+            'symlinks-1.0.0.dist-info/METADATA',
+            'symlinks-1.0.0.dist-info/RECORD',
+            'symlinks-1.0.0.dist-info/WHEEL',
+            'subdir/__init__.py',
+            'subdir/test.py',
+            'subdir/symlink.py',
+        }
+
+
 def test_vendored_meson(wheel_vendored_meson):
     # This test will error if the vendored meson.py wrapper script in
     # the test package isn't used.