Git hook to prevent unformatted code from being committed (#3502)

* Git hook to prevent unformatted code from being committed

* Hook must be activated by running `git config core.hooksPath
  scripts/githooks` from repo root (this is now automatically done in
  the `setup_software` script)

* [pre-commit.ci lite] apply automatic fixes

* Re-add requirements_lock.txt

* Use pre-push hook instead of pre-commit hook

* Add explanatory comments in bash scripts

* Add mac support for pre-commit hook

---------

Co-authored-by: Apeiros-46B <Apeiros-46B@users.noreply.github.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: Apeiros-46B

.gitignore

@@ -150,6 +150,9 @@ src/config
 # codespell dictionary
 scripts/dictionary/
 
+# marker files for pre-commit and pre-push hooks to check if staged files have been formatted
+scripts/.format_markers/
+
 # clangd for nvim lsp
 src/.clangd
 

environment_setup/setup_software.sh

@@ -18,6 +18,8 @@
 CURR_DIR=$(dirname -- "$(readlink -f -- "$BASH_SOURCE")")
 cd "$CURR_DIR" || exit
 
+git config core.hooksPath "$CURR_DIR/../scripts/githooks"
+
 source util.sh
 
 g_arch=$(uname -m)  # Global variable. No function should use this name.

scripts/githooks/pre-commit

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+# From the list of files on stdin (separated by newline), return formattable files to stdout
+filter_formattable_files() {
+    grep -E '\.(h|cpp|c|cc|hpp|tpp|proto|py|md|yml)$|/BUILD$'
+}
+
+# Output the modification time of a file (or 0 if nonexistent)
+get_mtime() {
+    case "$(uname -s)" in
+        Darwin*)
+            stat -f %m "$1" 2> /dev/null || echo 0
+            ;;
+        *)
+            # No one will run this on BSD or other Unixes, so this should be fine
+            stat -c %Y "$1" 2> /dev/null || echo 0
+            ;;
+    esac
+}
+
+# Find repo root, marker for the current branch, and marker mtime (0 if marker does not exist)
+toplevel="$(git rev-parse --show-toplevel)"
+marker="$toplevel/scripts/.format_markers/$(git rev-parse --abbrev-ref HEAD)"
+mtime=$(get_mtime "$marker")
+
+git diff --staged --name-only | filter_formattable_files | while read -r file; do
+    # Compare marker mtime with file mtime
+    if [ $mtime -lt $(get_mtime "$toplevel/$file") ]; then
+        # The file was modified AFTER formatting. Remove the marker to tell the pre-push hook
+        # that this commit introduces unformatted code.
+        rm -f "$marker" 2> /dev/null
+        echo "Warning: Code is unformatted."
+        break
+    fi
+done

scripts/githooks/pre-push

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+# Prompt user for confirmation at a [y/N] prompt and return 0 when user responds "yes" or "y"
+confirm() {
+    read -r -p "$1 [y/N] " response < /dev/tty
+    case "$response" in
+        [yY][eE][sS]|[yY])
+            return 0
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+}
+
+scriptsdir="$(git rev-parse --show-toplevel)/scripts"
+
+# If marker for current branch does not exist
+if ! [ -f "$scriptsdir/.format_markers/$(git rev-parse --abbrev-ref HEAD)" ]; then
+    echo "Warning: Code is unformatted. Please run $scriptsdir/lint_and_format.sh."
+    if confirm 'Continue without formatting?'; then
+        echo "Continuing push anyway."
+        exit 0
+    else
+        echo "Aborting push."
+        exit 1
+    fi
+fi

scripts/lint_and_format.sh

@@ -149,4 +149,10 @@ run_eof_new_line
 run_git_diff_check
 run_ansible_lint
 
+# Update markers, telling Git hooks that formatting has been done
+# (Per-branch, so switching branches doesn't confuse the hooks)
+branch="$(git rev-parse --abbrev-ref HEAD)"
+mkdir -p "$CURR_DIR/.format_markers/$(dirname "$branch")"
+touch "$CURR_DIR/.format_markers/${branch}"
+
 exit 0