[build-check] scripts: add check_build script

[Norbert Manthey]

This script performs build testing, by building several configurations
several times. The script is introduced to improve the consistency of
testing changes in the kernel configuration.

This version build randconfig 10 times, as well as allyesconfig,
allnoconfig and allmodconfig. Depending on the used machine and system
setup, the script might take a while to finish.

The script logs all the used config files, as well as the output of the
build commands to a log directory "build_check_logs", so that this data
can be retrieved after running the script.

Signed-off-by: Norbert Manthey <nmanthey@xxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
 scripts/check_build.sh | 136 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100755 scripts/check_build.sh

diff --git a/scripts/check_build.sh b/scripts/check_build.sh
new file mode 100755
index 0000000..a100d99
--- /dev/null
+++ b/scripts/check_build.sh
@@ -0,0 +1,136 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Check whether kernel changes compile with multiple configurations.
+# Configurations that fail for the current commit are tested on an upstream
+# commit, and failures are ignored in case the configuration fails on the
+# upstream commit as well.
+#
+# Usage:
+# ./scripts/check_build.sh [upstream-commit]
+#
+# Example:
+# ./scripts/check_build.sh origin/master
+
+# Fail early on error or uninitialized values
+set -e -u
+
+# Write all files to this directory
+declare -r LOG_DIR=build_check_logs
+
+# Gather all configurations we should build, in form of make targets
+collect_configurations ()
+{
+	local CONFIGS="randconfig allyesconfig allnoconfig allmodconfig"
+	local -i I=0
+
+	while [ "$I" -le 8 ]; do I=$((I+1)); CONFIGS+=" randconfig"; done
+
+	echo "$CONFIGS"
+}
+
+# Build the kernel with the current configuration, return the status, log to $1
+build ()
+{
+	local -r LOG_FILE="$1"
+	local -i STATUS=0
+
+	make clean -j $(nproc) &> /dev/null
+	make -j $(nproc) &>> "$LOG_FILE" || STATUS=$?
+
+	echo "build status: $STATUS" >> "$LOG_FILE"
+	echo "[$SECONDS] build status: $STATUS"
+	return "$STATUS"
+}
+
+# Check whether we're executing from a clean repository, and proper location
+check_environment()
+{
+	local -r UPSTREAM_COMMIT="$1"
+
+	if [ ! -x scripts/check_build.sh ]; then
+		echo "error: please execute script from repository root!"
+		exit 1
+	fi
+
+	if ! git diff-index --quiet HEAD --; then
+		echo "error: please commit or stash your local changes!"
+		exit 1
+	fi
+
+	if ! git cat-file -e "$UPSTREAM_COMMIT" &> /dev/null; then
+		echo "error: upstream commit $UPSTREAM_COMMIT does not exist!"
+		exit 1
+	fi
+}
+
+TEST_COMMIT=$(git rev-parse --short HEAD)
+
+LAST_TAG=$(git describe --abbrev=0)
+DEFAULT_UPSTREAM="origin/master"
+[ -z "$LAST_TAG" ] || DEFAULT_UPSTREAM="$LAST_TAG"
+UPSTREAM_COMMIT="${1:-$DEFAULT_UPSTREAM}"
+
+# Before starting, check call location and git environment
+check_environment "$UPSTREAM_COMMIT"
+
+# Collect status, as well as failing configuration file names
+declare -i OVERALL_STATUS=0
+mkdir -p "$LOG_DIR"
+BRANCH_FAILS=""
+UPSTREAM_FAILS=""
+
+# Build multiple configurations
+declare -i COUNT=0
+declare -r CONFIGS=$(collect_configurations)
+echo "[$SECONDS] Check commit $TEST_COMMIT with upstream reference $UPSTREAM_COMMIT"
+for config in $CONFIGS
+do
+	COUNT=$((COUNT+1))
+	echo "[$SECONDS] build $config as build nr $COUNT"
+	LOG_FILE=$LOG_DIR/build-"$COUNT"-"$config".log
+
+	# Prepare configuration, and memorize it
+	STATUS=0
+	make "$config" &> "$LOG_FILE" || STATUS=$?
+	cp .config $LOG_DIR/config-"$COUNT"-"$config"
+
+	# Try to build with current configuration
+	build "$LOG_FILE" || STATUS=$?
+
+	# Evaluate build failure
+	if [ "$STATUS" -ne 0 ]
+	then
+		cp .config "$LOG_DIR"/config-failing-branch-"$COUNT"-"$config"
+		echo "[$SECONDS] check whether current configuration fails upstream as well ..."
+		echo "[$SECONDS] go back in time to commit $UPSTREAM_COMMIT"
+
+		# Check whether upstream commit builds
+		git checkout "$UPSTREAM_COMMIT" &>> "$LOG_FILE"
+		UPSTREAM_STATUS=0
+		build "$LOG_FILE" || UPSTREAM_STATUS=$?
+		git checkout "$TEST_COMMIT" &>> "$LOG_FILE"
+
+		if [ "$UPSTREAM_STATUS" -ne 0 ]
+		then
+			echo "[$SECONDS] upstream build fails as well, ignore failure"
+			cp .config "$LOG_DIR"/config-failing-upstream-"$COUNT"-"$config"
+			UPSTREAM_FAILS+=" config-$COUNT-$config"
+		else
+			echo "[$SECONDS] upstream build succeeds, while branch build fails"
+			BRANCH_FAILS+=" config-$COUNT-$config"
+			OVERALL_STATUS=1
+		fi
+
+		echo "[$SECONDS] jump back to commit under test, $TEST_COMMIT"
+	fi
+done
+
+# Print summary, and exit with status of local changes
+echo "Finished after $SECONDS seconds"
+echo "Found upstream failures: $UPSTREAM_FAILS"
+echo "Found branch failures: $BRANCH_FAILS"
+echo "Collected configurations and logs can be found in $LOG_DIR"
+
+# Exit 0, if no build fails, or the upstream commit always fails as well
+exit $OVERALL_STATUS
-- 
2.7.4

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