support metamodule, remove built-in overlayfs mount

Co-authored-by: weishu <twsxtd@gmail.com>
Co-authored-by: YuKongA <70465933+YuKongA@users.noreply.github.com>
Co-authored-by: Ylarod <me@ylarod.cn>

userspace/meta-overlayfs/build.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+set -e
+
+# Configuration
+VERSION=$(grep '^version' Cargo.toml | head -1 | sed 's/.*"\(.*\)".*/\1/')
+OUTPUT_DIR="target"
+METAMODULE_DIR="metamodule"
+MODULE_OUTPUT_DIR="$OUTPUT_DIR/module"
+
+echo "=========================================="
+echo "Building meta-overlayfs v${VERSION}"
+echo "=========================================="
+
+# Detect build tool
+if command -v cross >/dev/null 2>&1; then
+    BUILD_TOOL="cross"
+    echo "Using cross for compilation"
+else
+    BUILD_TOOL="cargo-ndk"
+    echo "Using cargo ndk for compilation"
+    if ! command -v cargo-ndk >/dev/null 2>&1; then
+        echo "Error: Neither cross nor cargo-ndk found!"
+        echo "Please install one of them:"
+        echo "  - cross: cargo install cross"
+        echo "  - cargo-ndk: cargo install cargo-ndk"
+        exit 1
+    fi
+fi
+
+# Clean output directory
+echo "Cleaning output directory..."
+rm -rf "$OUTPUT_DIR"
+mkdir -p "$MODULE_OUTPUT_DIR"
+
+# Build for multiple architectures
+echo ""
+echo "Building for aarch64-linux-android..."
+if [ "$BUILD_TOOL" = "cross" ]; then
+    cross build --release --target aarch64-linux-android
+else
+    cargo ndk build -t arm64-v8a --release
+fi
+
+echo ""
+echo "Building for x86_64-linux-android..."
+if [ "$BUILD_TOOL" = "cross" ]; then
+    cross build --release --target x86_64-linux-android
+else
+    cargo ndk build -t x86_64 --release
+fi
+
+# Copy binaries
+echo ""
+echo "Copying binaries..."
+cp target/aarch64-linux-android/release/meta-overlayfs \
+   "$MODULE_OUTPUT_DIR/meta-overlayfs-aarch64"
+cp target/x86_64-linux-android/release/meta-overlayfs \
+   "$MODULE_OUTPUT_DIR/meta-overlayfs-x86_64"
+
+# Copy metamodule files
+echo "Copying metamodule files..."
+cp "$METAMODULE_DIR"/module.prop "$MODULE_OUTPUT_DIR/"
+cp "$METAMODULE_DIR"/*.sh "$MODULE_OUTPUT_DIR/"
+
+# Set permissions
+echo "Setting permissions..."
+chmod 755 "$MODULE_OUTPUT_DIR"/*.sh
+chmod 755 "$MODULE_OUTPUT_DIR"/meta-overlayfs-*
+
+# Display binary sizes
+echo ""
+echo "Binary sizes:"
+echo "  aarch64: $(du -h "$MODULE_OUTPUT_DIR"/meta-overlayfs-aarch64 | awk '{print $1}')"
+echo "  x86_64:  $(du -h "$MODULE_OUTPUT_DIR"/meta-overlayfs-x86_64 | awk '{print $1}')"
+
+# Package
+echo ""
+echo "Packaging..."
+cd "$MODULE_OUTPUT_DIR"
+ZIP_NAME="meta-overlayfs-v${VERSION}.zip"
+zip -r "../$ZIP_NAME" .
+cd ../..
+
+echo ""
+echo "=========================================="
+echo "Build completed successfully!"
+echo "Output: $OUTPUT_DIR/$ZIP_NAME"
+echo "=========================================="
+echo ""
+echo "To install:"
+echo "  adb push $OUTPUT_DIR/$ZIP_NAME /sdcard/"
+echo "  adb shell su -c 'ksud module install /sdcard/$ZIP_NAME'"