Add script to automate BoringSSL rebuilds.

BUILDING.md

@@ -62,6 +62,8 @@ cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE \
 ninja
 ```
 
+You can also use the `rebuild_boringssl.sh` script (see below) to automate this process.
+
 ##### Building on macOS.
 When building Conscrypt on macOS it will build libraries for both x86 and ARM, and so BoringSSL
 must also be build for each of these.
@@ -90,6 +92,7 @@ cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE \
 ninja
 ```
 
+You can also use the `rebuild_boringssl.sh` script (see below) to automate this process.
 
 ##### Building on Windows
 This assumes that you have Microsoft Visual Studio 2017 installed along
@@ -117,6 +120,26 @@ ninja
 
 32-bit mode is no longer supported.
 
+If running `bash`, you can use the `rebuild_boringssl` script (see below)
+to automate this process.
+
+##### rebuild_boringssl.sh script
+
+The script `scripts/rebuild_boringssl.sh` will build or rebuild BoringSSL
+with the correct configuration for the current host architecture.
+
+When run with no arguments, the script assumes that `BORINGSSL_HOME` is set
+correctly and will re-run `cmake` and `ninja` with the correct arguments.
+
+The following arguments can be used to modify its behaviour:
+
+* `--clone` May only be used if `BORINGSSL_HOME` is set but does not
+yet exist.  Will clone BoringSSL from Github and build it.
+
+* `--clean` Delete the current build directly and rebuild from scratch.
+* `--pull` or `--update` Updates the source tree to the latest revision and
+then builds. Note will not clean old builds unless `--clean` is also specified.
+
 Coverage
 --------
 To see coverage numbers, run the tests and then execute the jacocoTestReport rule

scripts/rebuild_boringssl.sh

@@ -0,0 +1,122 @@
+#! /bin/bash
+#
+#  Copyright (C) 2025 The Android Open Source Project
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+# Rebuilds BoringSSL from scratch for supported architectures,
+# optionally performing a `git pull` first to update it.
+
+
+UPSTREAM="https://github.com/google/boringssl.git"
+MAIN="main"
+
+fail() {
+        echo "*** FAILED: " $@
+        exit 1
+}
+
+usage() {
+    cat <<EOF
+Usage: $0 [OPTIONS]
+
+--clone   Clone BoringSSL git repository if not already present
+--update  Resync from upstream before building
+--clean   Clean before building
+
+EOF
+    exit 0
+}
+
+test "$BORINGSSL_HOME" || fail "Please set BORINGSSL_HOME."
+
+
+CLONE=
+UPDATE=
+CLEAN=
+while [ "$1" ]; do
+    case "$1" in
+        --clone)
+            CLONE=true
+            ;;
+
+        --update | --pull)
+            UPDATE=true
+            ;;
+
+        --clean | --fresh)
+            CLEAN=true
+            ;;
+
+        *)
+            usage
+            95
+            ;;
+    esac
+    shift
+done
+
+if [ "$CLONE" ]; then
+    echo "Cloning BoringSSL from ${UPSTREAM}."
+
+    test -d "$BORINGSSL_HOME" && fail "$BORINGSSL_HOME already exists"
+    PARENT="$(dirname $BORINGSSL_HOME)"
+    cd "$PARENT" || fail "Cannot access parent directory $PARENT"
+    git clone "$UPSTREAM" "$BORINGSSL_HOME" || fail "Unable to clone BoringSSL"
+    UPDATE=
+    CLEAN=true
+fi
+
+cd "$BORINGSSL_HOME" || fail "Cannot access $BORINGSSL_HOME"
+
+if [ "$UPDATE" ]; then
+    echo "Updating BoringSSL."
+    git checkout "$MAIN"
+    git pull
+fi
+
+run_cmake() {
+    local BUILD_DIR="${BORINGSSL_HOME}/$1"
+    local EXTRA_CMAKE_FLAGS="$2"
+
+    if [ "$CLEAN" ]; then
+        echo "Removing $BUILD_DIR"
+        rm -rf "$BUILD_DIR"
+    fi
+    mkdir -p "$BUILD_DIR" || fail "Unable to create $BUILD_DIR"
+    cd "$BUILD_DIR" || fail "Unable to access $BUILD_DIR"
+    echo "Running cmake."
+    cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE -DCMAKE_BUILD_TYPE=Release $EXTRA_CMAKE_FLAGS \
+          -GNinja .. || fail "cmake failed."
+    echo "Building BoringSSL in ${BUILD_DIR}."
+    ninja
+}
+
+case "$(uname -s)" in
+    Darwin)
+        run_cmake build.x86 "-DCMAKE_ASM_FLAGS=-Wa,--noexecstack -DCMAKE_OSX_ARCHITECTURES=x86_64"
+        run_cmake build.arm "-DCMAKE_ASM_FLAGS=-Wa,--noexecstack -DCMAKE_OSX_ARCHITECTURES=arm64"
+        ;;
+
+    Linux)
+        run_cmake build64 "-DCMAKE_ASM_FLAGS=-Wa,--noexecstack"
+        ;;
+
+    MINGW64*)
+        run_cmake build64 "-DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded"
+        ;;
+
+    *)
+        fail "Please follow the manual build instructions."
+        ;;
+esac