Fix regression for files without permissions.

[CharString]

Closes #398

[nicorikken]

Sorry for not looking into this sooner. Thanks for working on this.
I still get the stacktrace output. Am I doing something wrong?

$ ls -la tmp/test2.sh 
-rw-r--r-- 1 root root 49 nov  9 10:55 tmp/test2.sh

$ git log -n 1
commit 0e0e4668d14a98f155dc9b1c69e6234c2abb31a3 (HEAD -> issue_398, charstring/issue_398)
Author: Chris Wesseling <Chris.Wesseling@cwi.nl>
Date:   Fri Oct 1 17:04:15 2021 +0200

    Fix linting error and typo.

$ ./venv/bin/reuse --version
reuse 0.13.1.dev33+g0e0e466

$ ./venv/bin/reuse addheader -c 'mycorp' -l Apache-2.0 -y 2020 tmp/test2.sh
Traceback (most recent call last):
  File "./venv/bin/reuse", line 33, in <module>
    sys.exit(load_entry_point('reuse==0.13.1.dev33+g0e0e466', 'console_scripts', 'reuse')())
  File "/home/nico/Software/fsfe/reuse-tool/venv/lib/python3.8/site-packages/reuse/_main.py", line 256, in main
    return parsed_args.func(parsed_args, project, out)
  File "/home/nico/Software/fsfe/reuse-tool/venv/lib/python3.8/site-packages/reuse/header.py", line 605, in run
    result += _add_header_to_file(
  File "/home/nico/Software/fsfe/reuse-tool/venv/lib/python3.8/site-packages/reuse/header.py", line 436, in _add_header_to_file
    with path.open("w", encoding="utf-8", newline=line_ending) as fp:
  File "/usr/lib/python3.8/pathlib.py", line 1222, in open
    return io.open(self, mode, buffering, encoding, errors, newline,
  File "/usr/lib/python3.8/pathlib.py", line 1078, in _opener
    return self._accessor.open(self, flags, mode)
PermissionError: [Errno 13] Permission denied: 'tmp/test2.sh'

[mxmehl]

I cannot reproduce your error, @nicorikken. For me, the following happens which is what I think @CharString intended:

$ reuse --version
reuse 0.13.1.dev33+g0e0e466
$ echo foo > bar.md && chmod 444 bar.md
$ ls -l bar.md 
.r--r--r-- 4 max max  9 Nov 16:20 bar.md
$ reuse addheader -c 'mycorp' -l Apache-2.0 -y 2020 bar.md 
usage: reuse addheader [-h] [--copyright COPYRIGHT] [--license LICENSE] [--year YEAR]
                       [--style {applescript,aspx,bat,bibtex,c,css,f,handlebars,haskell,html,jinja,jsx,lisp,m4,ml,plantuml,python,rst,tex}]
                       [--copyright-style {spdx,spdx-symbol,string,string-c,string-symbol,symbol}]
                       [--template TEMPLATE] [--exclude-year] [--single-line] [--multi-line]
                       [--explicit-license] [--skip-unrecognised]
                       path [path ...]
reuse addheader: error: can't write to 'bar.md'
$ reuse addheader -c 'mycorp' -l Apache-2.0 -y 2020 --explicit-license bar.md
Successfully changed header of bar.md.license
$ cat bar.md.license
SPDX-FileCopyrightText: 2020 mycorp

SPDX-License-Identifier: Apache-2.0

Or am I missing something?

[nicorikken]

Hmm, I have to do some more debugging in my system them to pinpoint it.

[nicorikken]

Perhaps there was some state left from my own Python code. I did a clean clone in a separate directory and now it works:

.venv/bin/reuse addheader -c 'mycorp' -l Apache-2.0 -y 2020 tmp/script.sh 
usage: reuse addheader [-h] [--copyright COPYRIGHT] [--license LICENSE] [--year YEAR]
                       [--style {applescript,aspx,bat,bibtex,c,css,f,handlebars,haskell,html,jinja,jsx,lisp,m4,ml,plantuml,python,rst,tex}]
                       [--copyright-style {spdx,spdx-symbol,string,string-c,string-symbol,symbol}]
                       [--template TEMPLATE] [--exclude-year] [--single-line] [--multi-line]
                       [--explicit-license] [--skip-unrecognised]
                       path [path ...]
reuse addheader: error: can't write to 'tmp/script.sh'

Great!!

The code also looks good to me, so Max I approve.

[CharString]

@nicorikken No problem

[mxmehl]

Yay, happy that it worked out :)