check.sh

#!/usr/bin/env bash

###############################################################################
#                                entrypoint.sh                                #
###############################################################################
# USAGE: ./entrypoint.sh [<path>] [<fallback style>]
#
# Checks all C/C++/Protobuf files (.h, .H, .hpp, .hh, .h++, .hxx and .c, .C,
# .cpp, .cc, .c++, .cxx, .proto) in the provided GitHub repository path
# (arg1) for conforming to clang-format. If no path is provided or provided path
# is not a directory, all C/C++/Protobuf files are checked. If any files are
# incorrectly formatted, the script lists them and exits with 1.
#
# Define your own formatting rules in a .clang-format file at your repository
# root. Otherwise, the provided style guide (arg2) is used as a fallback.

# format_diff function
# Accepts a filepath argument. The filepath passed to this function must point
# to a C/C++/Protobuf file.
format_diff() {
	local filepath="$1"
	# Invoke clang-format with dry run and formatting error output
	if [[ $CLANG_FORMAT_VERSION -gt "9" ]]; then
		local_format="$(docker run -i -v "$(pwd)":"$(pwd)" -w "$(pwd)" --rm ghcr.io/jidicula/clang-format:"$CLANG_FORMAT_VERSION" -n --Werror --style=file --fallback-style="$FALLBACK_STYLE" "${filepath}")"
	else # Versions below 9 don't have dry run
		formatted="$(docker run -i -v "$(pwd)":"$(pwd)" -w "$(pwd)" --rm ghcr.io/jidicula/clang-format:"$CLANG_FORMAT_VERSION" --style=file --fallback-style="$FALLBACK_STYLE" "${filepath}")"
		local_format="$(diff -q <(cat "${filepath}") <(echo "${formatted}"))"
	fi

	local format_status="$?"
	if [[ ${format_status} -ne 0 ]]; then
		# Append Markdown-bulleted monospaced filepath of failing file to
		# summary file.
		echo "* \`$filepath\`" >>failing-files.txt

		echo "Failed on file: $filepath" >&2
		echo "$local_format" >&2
		exit_code=1 # flip the global exit code
		return "${format_status}"
	fi
	return 0
}

CLANG_FORMAT_VERSION="$1"
CHECK_PATH="$2"
FALLBACK_STYLE="$3"
EXCLUDE_REGEX="$4"

# Set the regex to an empty string regex if nothing was provided
if [ -z "$EXCLUDE_REGEX" ]; then
	EXCLUDE_REGEX="^$"
fi

cd "$GITHUB_WORKSPACE" || exit 2

if [[ ! -d $CHECK_PATH ]]; then
	echo "Not a directory in the workspace, fallback to all files." >&2
	CHECK_PATH="."
fi

# initialize exit code
exit_code=0

# All files improperly formatted will be printed to the output.
# find all C/C++/Protobuf files:
#   h, H, hpp, hh, h++, hxx
#   c, C, cpp, cc, c++, cxx
#   ino, pde
#   proto
src_files=$(find "$CHECK_PATH" -name .git -prune -o -regextype posix-egrep -regex '^.*\.((((c|C)(c|pp|xx|\+\+)?$)|((h|H)h?(pp|xx|\+\+)?$))|(ino|pde)|(proto))$' -print)

# check formatting in each source file
for file in $src_files; do
	# Only check formatting if the path doesn't match the regex
	if ! [[ ${file} =~ $EXCLUDE_REGEX ]]; then
		format_diff "${file}"
	fi
done

# global exit code is flipped to nonzero if any invocation of `format_diff` has
# a formatting difference.
exit "$exit_code"