From 3e6740247afd3bf18fa282452f4b5c7fc03f065f Mon Sep 17 00:00:00 2001
From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Thu, 26 Oct 2023 09:25:16 -0400
Subject: [PATCH] tools/format-cpp: accept optional starting directory

This patch makes `tools/format-cpp` accept an optional starting
directory (instead of the root directory of the project) as its first
argument:

    $ pwd
    /home/dboucher/Mes Logiciels/babeltrace/src/plugins/ctf

    $ ../../../tools/format-cpp .
    clang-format -i /home/eepp/dev/babeltrace/src/plugins/ctf/fs-src/fs.cpp
    clang-format -i /home/eepp/dev/babeltrace/src/plugins/ctf/fs-src/file.cpp
    clang-format -i /home/eepp/dev/babeltrace/src/plugins/ctf/fs-src/query.cpp
    ...
    clang-format -i /home/eepp/dev/babeltrace/src/plugins/ctf/lttng-live/metadata.hpp
    clang-format -i /home/eepp/dev/babeltrace/src/plugins/ctf/lttng-live/data-stream.hpp

Using realpath(1) to transform the starting directory because find(1)
will only consider file names relative to its starting point, therefore
if the starting point is `.` (and the CWD is `src/cpp-common`),
`*/src/cpp-common/optional.hpp` and so on don't match anything and the
script will format files to be excluded.

Using `-path` instead of `-wholename` which is more precise and also
seems more portable.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I46219035e9b815dffe9200bb924478e4a7b02a04
Reviewed-on: https://review.lttng.org/c/babeltrace/+/11145
---
 CONTRIBUTING.adoc |  8 +++++++-
 tools/format-cpp  | 47 +++++++++++++++++++++++++++++++++++------------
 2 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/CONTRIBUTING.adoc b/CONTRIBUTING.adoc
index 23808c04..d5241ff4 100644
--- a/CONTRIBUTING.adoc
+++ b/CONTRIBUTING.adoc
@@ -1683,11 +1683,17 @@ To automatically format all the project's {cpp} files, run:
 $ ./tools/format-cpp
 ----
 
+Pass a directory path to only format the {cpp} files it contains:
+
+----
+$ ./tools/format-cpp ./src/cli
+----
+
 Use the `FORMATTER` environment variable to override the default
 formatter (`clang-format{nbsp}-i`):
 
 ----
-$ FORMATTER='clang-format-10 -i' ./tools/format-cpp
+$ FORMATTER='my-clang-format-15 -i' ./tools/format-cpp
 ----
 
 ==== Naming
diff --git a/tools/format-cpp b/tools/format-cpp
index dfc4bbd5..8094f135 100755
--- a/tools/format-cpp
+++ b/tools/format-cpp
@@ -2,12 +2,22 @@
 #
 # SPDX-License-Identifier: GPL-2.0-only
 #
-# Copyright (C) 2020-2022 Philippe Proulx <pproulx@efficios.com>
+# Copyright (C) 2020-2023 Philippe Proulx <pproulx@efficios.com>
 
 expected_formatter_major_version=15
 
-# Runs the formatter, making sure it's the expected version.
+# Runs the formatter, returning 1 if it's not the expected version.
+#
+# Argument 1:
+#     Starting directory.
+#
+# Remaining arguments:
+#     Formatter command.
 format_cpp() {
+	local root_dir=$1
+
+	shift
+
 	local formatter=("$@")
 	local version
 
@@ -28,19 +38,19 @@ format_cpp() {
 		return 1
 	fi
 
-	local root_dir
-
-	root_dir="$(dirname "${BASH_SOURCE[0]}")/.."
-
-	# Using xargs to fail as soon as the formatter fails (`-exec`
+	# Using xargs(1) to fail as soon as the formatter fails (`-exec`
 	# won't stop if its subprocess fails).
-	find "$root_dir" \( -name '*.cpp' -o -name '*.hpp' \) \
-		! -wholename '*/cpp-common/optional.hpp' \
-		! -wholename '*/cpp-common/string_view.hpp' \
-		! -wholename '*/cpp-common/nlohmann/json.hpp' \
+	#
+	# We want an absolute starting directory because find(1) excludes
+	# files in specific subdirectories.
+	find "$(realpath "$root_dir")" \( -name '*.cpp' -o -name '*.hpp' \) \
+		! -path '*/src/cpp-common/optional.hpp' \
+		! -path '*/src/cpp-common/string_view.hpp' \
+		! -path '*/src/cpp-common/nlohmann/json.hpp' \
 		-print0 | xargs -P"$(nproc)" -n1 -t -0 "${formatter[@]}"
 }
 
+# Choose formatter
 if [[ -n "$FORMATTER" ]]; then
 	# Try using environment-provided formatter
 	read -ra formatter <<< "$FORMATTER"
@@ -52,5 +62,18 @@ else
 	formatter=(clang-format -i)
 fi
 
+# Choose root directory
+if (($# == 1)); then
+	root_dir=$1
+
+	if [[ ! -d "$root_dir" ]]; then
+		echo "\`$root_dir\`: expecting an existing directory." >& 2
+		exit 1
+	fi
+else
+	# Default: root of the project, processing all C++ files
+	root_dir="$(dirname "${BASH_SOURCE[0]}")/.."
+fi
+
 # Try to format files
-format_cpp "${formatter[@]}"
+format_cpp "$root_dir" "${formatter[@]}"
-- 
2.34.1