Move classes used by scripts to their own module

Those classes are used by wrapper scripts and we should not have to
import the rest of mesonlib, build.py, and all their dependencies for
that.

This renames mesonlib/ directory to utils/ and add a mesonlib.py module
that imports everything from utils/ to not have to change `import
mesonlib` everywhere. It allows to import utils.core without importing
the rest of mesonlib.

1 files changed, 39 insertions, 0 deletions

diff --git a/mesonbuild/utils/posix.py b/mesonbuild/utils/posix.py
new file mode 100644
index 0000000..67f9a44
--- /dev/null
+++ b/mesonbuild/utils/posix.py
@@ -0,0 +1,39 @@
+# SPDX-license-identifier: Apache-2.0
+# Copyright 2012-2021 The Meson development team
+# Copyright © 2021 Intel Corporation
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Posix specific implementations of mesonlib functionality."""
+
+import fcntl
+import typing as T
+
+from .universal import MesonException
+from .platform import BuildDirLock as BuildDirLockBase
+
+__all__ = ['BuildDirLock']
+
+class BuildDirLock(BuildDirLockBase):
+
+    def __enter__(self) -> None:
+        self.lockfile = open(self.lockfilename, 'w', encoding='utf-8')
+        try:
+            fcntl.flock(self.lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        except (BlockingIOError, PermissionError):
+            self.lockfile.close()
+            raise MesonException('Some other Meson process is already using this build directory. Exiting.')
+
+    def __exit__(self, *args: T.Any) -> None:
+        fcntl.flock(self.lockfile, fcntl.LOCK_UN)
+        self.lockfile.close()