Add script to automate BoringSSL rebuilds.

BUILDING.md

@@ -22,11 +22,7 @@ Conscrypt requires that you have __Java__, __BoringSSL__ and the __Android SDK__
 described below.
 
 #### Java
-The build uses a version of Gradle which requires a __Java 11__ JRE to run, however to ensure 
-backward compatibility Conscrypt itself is compiled with a __Java 8__ JDK using Gradle's
-recent Java toolchain support.  At the least, you will need to install __Java 11__ to run 
-Gradle, but if you do not also have __Java 8__ then depending on the OS, Gradle will
-try and install it automatically.
+The build uses a version of Gradle which requires a __Java 11__ JDK.
 
 #### Android SDK
 [Download and install](https://developer.android.com/studio/install.html) the latest Android SDK
@@ -62,9 +58,11 @@ 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.
+must also be built for each of these.
 
 To build the x86_64 version:
 ```bash
@@ -90,22 +88,34 @@ 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
-with both the Windows 8.1 and 10 SDKs and that your machine is capable of
-compiling 64-bit.
+This assumes that you have
+[Git for Windows](https://gitforwindows.org/) and
+[Microsoft Visual Studio 2022](https://visualstudio.microsoft.com/downloads/)
+installed.
+
+You'll also need `nasm`, `cmake` and `ninja` which can be usefully
+managed via a package tool such as
+[Chocolatey](https://chocolatey.org/).
+
+Like Visual Studio 2017, Visual Studio 2022 provides a batch file
+to set up the correct environment for the compiler which can be invoked
+as follows (assuming a default installation):
+```bat
+call "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliary\Build\vcvarsall.bat" x86_amd64
+```
 
-Unlike earlier versions, Visual Studio 2017 doesn't appear to set an
-environment variable to simplify building from the command line. The
-instructions below assume the default installation of the community
-edition. To use another edition or a non-standard install path, you'll
-need to modify the paths below as appropriate.
+However, Visual Studio 2022 also sets up a _Developer Command Prompt_
+in Windows Terminal which provides a simpler way of getting the
+correct compiler environment, defaulting to 64-bit mode.
 
-To build in 64-bit mode, set up with this command line:
+After either method, you can run Git for Windows' `bash` to get a
+more UNIX like environment with a working compiler.
 
+To build BoringSSL in 64-bit mode from a Command Prompt:
 ```bat
-call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat" x86_amd64
 mkdir build64
 cd build64
 cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ^
@@ -115,7 +125,27 @@ cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ^
 ninja
 ```
 
-32-bit mode is no longer supported.
+32-bit mode is no longer supported on Windows.
+
+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 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
 --------

openjdk/build.gradle

@@ -547,10 +547,13 @@ boolean isExecutableOnPath(executable) {
             return executable == name
         }
     }
-    for(String folder : System.getenv('PATH').split("" + File.pathSeparatorChar)) {
-        File[] files = file(folder).listFiles(filter)
-        if (files != null && files.size() > 0) {
-            return true
+    for (String folder : System.getenv('PATH').split("" + File.pathSeparatorChar)) {
+        // Ignore any empty PATH elements.
+        if (folder != '') {
+            File[] files = file(folder).listFiles(filter)
+            if (files != null && files.size() > 0) {
+                return true
+            }
         }
     }
     return false

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