directory names rendered to empty string raise exception or overwrite parent directories

[dusktreader]

• Cookiecutter version: 1.7.2
• Template project url: n/a
• Python version: 3.8.7
• Operating System: Ubuntu 20.04 (via WSL)

Description:

If you have a directory whose template resolve to an empty string, it will do one of two bad things:

1. If you are running normally, it will give an error about the directory already existing
2. If you run with overwrite-if-exists, bad stuff happens culminating in a permission denied error

This is happening, because the render_and_create_dir method joins the generate path with its parent to produce a new one. If the generated path is empty, the resulting path is the same as its parent. This behavior is clearly undesirable.

I think an empty directory name (and filename) for that matter should be omitted entirely, perhaps with a warning

What I've run:

$ cat dump.txt
$ tree
.
├── cookiecutter.json
└── {{cookiecutter.project_name}}
    ├── README.md
    └── {{cookiecutter.foolish}}
        └── BOOM.md

2 directories, 3 files

$ cat cookiecutter.json
{
    "project_name": "boom-test",
    "foolish": ""
}

$ cookiecutter --output-dir=.. .
project_name [boom-test]:
foolish []:
Error: "/home/dusktreader/boom-test" directory already exists

$ cookiecutter --output-dir=.. . -f
project_name [boom-test]:
foolish []:
Traceback (most recent call last):
  File "/home/dusktreader/.pyenv/versions/3.8.7/bin/cookiecutter", line 8, in <module>
    sys.exit(main())
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/cookiecutter/cli.py", line 140, in main
    cookiecutter(
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/cookiecutter/main.py", line 101, in cookiecutter
    result = generate_files(
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/cookiecutter/generate.py", line 352, in generate_files
    generate_file(
  File "/home/dusktreader/.pyenv/versions/3.8.7/lib/python3.8/site-packages/cookiecutter/generate.py", line 179, in generate_file
    with io.open(outfile, 'w', encoding='utf-8') as fh:
PermissionError: [Errno 13] Permission denied: '/BOOM.md'

[simobasso]

Nice @dusktreader good catch!

The permission denied is because cookiecutter wanna write BOOM.md on the root.

I'll try to look into the issue.

Thanks.