Make permission errors more human readable (#66492)
Summary:
`_mkdir_p` feels like a remnant of Python-2 era, add `exist_ok` argument and re-raise OSError to make it more human readable.
After the change attempt to build PyTorch in a folder that does not have write permissions will result in:
```
% python3.6 setup.py develop
Building wheel torch-1.10.0a0+git9509e8a
-- Building version 1.10.0a0+git9509e8a
Traceback (most recent call last):
File "/Users/nshulga/git/pytorch-worktree/tools/setup_helpers/cmake.py", line 21, in _mkdir_p
os.makedirs(d, exist_ok=True)
File "/opt/homebrew/Cellar/python36/3.6.2+_254.20170915/Frameworks/Python.framework/Versions/3.6/lib/python3.6/os.py", line 220, in makedirs
mkdir(name, mode)
PermissionError: [Errno 13] Permission denied: 'build'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "setup.py", line 895, in <module>
build_deps()
File "setup.py", line 370, in build_deps
cmake=cmake)
File "/Users/nshulga/git/pytorch-worktree/tools/build_pytorch_libs.py", line 63, in build_caffe2
rerun_cmake)
File "/Users/nshulga/git/pytorch-worktree/tools/setup_helpers/cmake.py", line 225, in generate
_mkdir_p(self.build_dir)
File "/Users/nshulga/git/pytorch-worktree/tools/setup_helpers/cmake.py", line 23, in _mkdir_p
raise RuntimeError(f"Failed to create folder {os.path.abspath(d)}: {e.strerror}") from e
RuntimeError: Failed to create folder /Users/nshulga/git/pytorch-worktree/build: Permission denied
```
Fixes https://github.com/pytorch/pytorch/issues/65920
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66492
Reviewed By: seemethere
Differential Revision: D31578820
Pulled By: malfet
fbshipit-source-id: afe8240983100ac0a26cc540376b9dd71b1b53af
