scons: Update automatic hook install for pre-commit

This replaces the old hooks with the pre-commit check. If Python
pre-commit has not been installed an error is thrown asking the user to
install the requirements via pip.

Change-Id: I2d42f42624e10d38d0da39b473f0363db128ce1c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/62553
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

site_scons/site_tools/git.py

@@ -38,17 +38,21 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+from asyncio import subprocess
 import os
 import sys
+import subprocess
 
 import gem5_scons.util
 import SCons.Script
 
 git_style_message = """
-You're missing the gem5 style or commit message hook. These hooks help
-to ensure that your code follows gem5's style rules on git commit.
-This script will now install the hook in your .git/hooks/ directory.
-Press enter to continue, or ctrl-c to abort: """
+You're missing the pre-commit/commit-msg hooks. These hook help to ensure your
+code follows gem5's style rules on git commit and your commit messages follow
+our commit message requirements. This script will now install these hooks in
+your .git/hooks/ directory.
+Press enter to continue, or ctrl-c to abort:
+"""
 
 
 def install_style_hooks(env):
@@ -68,42 +72,6 @@ def install_style_hooks(env):
         hook = git_hooks.File(hook_name)
         return hook.exists()
 
-    def hook_install(hook_name, script):
-        hook = git_hooks.File(hook_name)
-        if hook.exists():
-            print(
-                "Warning: Can't install %s, hook already exists." % hook_name
-            )
-            return
-
-        if hook.islink():
-            print("Warning: Removing broken symlink for hook %s." % hook_name)
-            os.unlink(hook.get_abspath())
-
-        if not git_hooks.exists():
-            os.mkdir(git_hooks.get_abspath())
-            git_hooks.clear()
-
-        abs_symlink_hooks = git_hooks.islink() and os.path.isabs(
-            os.readlink(git_hooks.get_abspath())
-        )
-
-        # Use a relative symlink if the hooks live in the source directory,
-        # and the hooks directory is not a symlink to an absolute path.
-        if hook.is_under(env.Dir("#")) and not abs_symlink_hooks:
-            script_path = os.path.relpath(
-                os.path.realpath(script.get_abspath()),
-                os.path.realpath(hook.Dir(".").get_abspath()),
-            )
-        else:
-            script_path = script.get_abspath()
-
-        try:
-            os.symlink(script_path, hook.get_abspath())
-        except:
-            print("Error updating git %s hook" % hook_name)
-            raise
-
     if hook_exists("pre-commit") and hook_exists("commit-msg"):
         return
 
@@ -117,11 +85,9 @@ def install_style_hooks(env):
             print("Input exception, exiting scons.\n")
             sys.exit(1)
 
-    git_style_script = env.Dir("#util").File("git-pre-commit.py")
-    git_msg_script = env.Dir("#ext").File("git-commit-msg")
+    pre_commit_install = env.Dir("#util").File("pre-commit-install.sh")
 
-    hook_install("pre-commit", git_style_script)
-    hook_install("commit-msg", git_msg_script)
+    subprocess.call(str(pre_commit_install), shell=True)
 
 
 def generate(env):

util/pre-commit-install.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+
+# Copyright (c) 2022 The Regents of the University of California
+# All Rights Reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met: redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer;
+# redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+set -e
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+GEM5_ROOT="${DIR}/.."
+
+cd ${GEM5_ROOT}
+
+if ! command -v pre-commit &> /dev/null
+then
+    echo "Cannot find 'pre-commit'. Please ensure all Python requirements are "
+    echo "installed. This can be done via `pip install -r requirements.txt`."
+    exit 1
+fi
+
+pre-commit install -t pre-commit -t commit-msg