Add basic setup for precommit (#749) (#764)

* Add basic setup for precommit

* Update README.md with instructions on installing precommit hooks

---------
Co-authored-by: Illia Silin <98187287+illsilin@users.noreply.github.com>
Co-authored-by: Bartlomiej Wroblewski <bwroblewski10@gmail.com>

.pre-commit-config.yaml

+repos:
+-   repo: local
+    hooks:
+    -   id: clang-format
+        name: clang-format
+        entry: clang-format-10 -i --style=file
+        language: system
+        types_or: [c++, inc]
+    -   id: copyright-year-checker
+        name: copyright-year-checker
+        entry: script/check_copyright_year.sh
+        verbose: false
+        language: script
+        types: [c++]

README.md

@@ -109,6 +109,24 @@ make install
 
 Instructions for using CK as a pre-built kernel library are under [client_example](/client_example)
 
+## Contributing
+
+When you contribute to Composable Kernel, make sure to run `clang-format` on all the changed files. We highly recommend using git hooks that are managed by the `pre-commit` framework. To install hooks, run:
+
+```bash
+sudo script/install_precommit.sh
+```
+
+This way, `pre-commit` will add the appropriate hooks to your local repository and automatically run `clang-format` (and possibly additional checks) before any commit is created.
+
+If you need to uninstall hooks from the repository, you can do so by running the following command:
+
+```bash
+script/uninstall_precommit.sh
+```
+
+If for any reason, you need to temporarily disable precommit hooks, you can add the `--no-verify` option to the `git commit` command.
+
 ## Caveat
 ### Kernel Timing and Verification
 

script/check_copyright_year.sh

+#!/bin/bash
+
+current_year=$(date +%Y)
+exit_code=0
+
+for file in $@; do
+    if grep -q "Copyright (c)" $file
+    then
+        if ! grep -q "Copyright (c).*$current_year" $file
+        then
+            echo "ERROR: File $file has a copyright notice without the current year ($current_year)."
+            exit_code=1
+        fi
+    fi
+done
+
+exit $exit_code

script/install_precommit.sh

+#!/bin/bash
+
+run_and_check() {
+    "$@"
+    status=$?
+    if [ $status -ne 0 ]; then
+        echo "Error with \"$@\": Exited with status $status"
+        exit $status
+    fi
+    return $status
+}
+
+echo "I: Installing tools required for pre-commit checks..."
+run_and_check apt install clang-format-10
+
+echo "I: Installing pre-commit itself..."
+run_and_check pip3 install pre-commit
+run_and_check pre-commit install
+
+echo "I: Installation successful."

script/uninstall_precommit.sh

+pre-commit uninstall