Fix rustls-platform-verifier initialization (#155)

## 🎟️ Tracking

<!-- Paste the link to the Jira or GitHub issue or otherwise describe /
point to where this change is coming from. -->

## 📔 Objective

Update rustls-platform-verifier initialization on Android to support
being manually loaded using `System.loadLibrary()`. This bypasses the
need to dynamically load `JNI_GetCreatedJavaVMs`, which is not available
for APIs <31.

I've still left the original code that calls `JNI_GetCreatedJavaVMs` as
a fallback, but once the Android APP is on minAPI >31, we should just
statically call `JNI_GetCreatedJavaVMs` using
`jni::sys::JNI_GetCreatedJavaVMs`.

## ⏰ Reminders before review

- Contributor guidelines followed
- All formatters and local linters executed and passed
- Written new unit and / or integration tests where applicable
- Protected functional changes with optionality (feature flags)
- Used internationalization (i18n) for all UI strings
- CI builds passed
- Communicated to DevOps any deployment requirements
- Updated any necessary documentation (Confluence, contributing docs) or
informed the documentation
  team

## 🦮 Reviewer guidelines

<!-- Suggested interactions but feel free to use (or not) as you desire!
-->

- 👍 (`:+1:`) or similar for great changes
- 📝 (`:memo:`) or ℹ️ (`:information_source:`) for notes or general info
- ❓ (`:question:`) for questions
- 🤔 (`:thinking:`) or 💭 (`:thought_balloon:`) for more open inquiry
that's not quite a confirmed
  issue and could potentially benefit from discussion
- 🎨 (`:art:`) for suggestions / improvements
- ❌ (`:x:`) or ⚠️ (`:warning:`) for more significant problems or
concerns needing attention
- 🌱 (`:seedling:`) or ♻️ (`:recycle:`) for future improvements or
indications of technical debt
- ⛏ (`:pick:`) for minor or nitpick changes

Author: dani-garcia

crates/bitwarden-uniffi/kotlin/app/src/main/java/com/bitwarden/myapplication/MainActivity.kt

@@ -89,6 +89,12 @@ class MainActivity : FragmentActivity() {
 
     private var accessToken = ""
 
+    companion object {
+        init {
+            System.loadLibrary("bitwarden_uniffi");
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         biometric = Biometric(this)

crates/bitwarden-uniffi/kotlin/publish-local.sh

@@ -12,7 +12,7 @@ cross build -p bitwarden-uniffi --release --target=aarch64-linux-android
 mv $SDK_REPO_ROOT/target/aarch64-linux-android/release/libbitwarden_uniffi.so ./sdk/src/main/jniLibs/arm64-v8a/libbitwarden_uniffi.so
 
 # Build other archs
-if [ $1 = "all" ]; then
+if [ "$1" = "all" ]; then
     echo "Building for all architectures"
 
     cross build -p bitwarden-uniffi --release --target=armv7-linux-androideabi

crates/bitwarden-uniffi/src/android_support.rs

@@ -1,22 +1,43 @@
-use std::error::Error;
+use std::{error::Error, sync::OnceLock};
 
 use jni::sys::{jint, jsize, JavaVM};
 
-pub fn init() {
-    static ANDROID_INIT: std::sync::Once = std::sync::Once::new();
+pub static JAVA_VM: OnceLock<jni::JavaVM> = OnceLock::new();
+
+// This function is called when the Android app calls `System.loadLibrary("bitwarden_uniffi")`
+// Important: This function must be named `JNI_OnLoad` or otherwise it won't be called
+#[allow(non_snake_case)]
+#[no_mangle]
+pub extern "system" fn JNI_OnLoad(vm_ptr: jni::JavaVM, _reserved: *mut std::ffi::c_void) -> jint {
+    log::info!("JNI_OnLoad initializing");
+    JAVA_VM.get_or_init(|| vm_ptr);
+    jni::sys::JNI_VERSION_1_6
+}
 
+pub fn init() {
     fn init_inner() -> Result<(), Box<dyn Error>> {
-        let jvm = java_vm()?;
+        let jvm = match JAVA_VM.get() {
+            Some(jvm) => {
+                log::info!("JavaVM already initialized");
+                jvm
+            }
+            None => {
+                log::info!("JavaVM not initialized, initializing now");
+                let jvm = java_vm()?;
+                JAVA_VM.get_or_init(|| jvm)
+            }
+        };
+
         let mut env = jvm.attach_current_thread_permanently()?;
+        log::info!("Initializing Android verifier");
         init_verifier(&mut env)?;
+        log::info!("SDK Android support initialized");
         Ok(())
     }
 
-    ANDROID_INIT.call_once(|| {
-        if let Err(e) = init_inner() {
-            log::error!("Failed to initialize Android support: {}", e);
-        }
-    });
+    if let Err(e) = init_inner() {
+        log::error!("Failed to initialize Android support: {:#?}", e);
+    }
 }
 
 type JniGetCreatedJavaVms =

crates/bitwarden-uniffi/src/lib.rs

@@ -107,6 +107,8 @@ fn init_logger() {
 
     #[cfg(target_os = "android")]
     android_logger::init_once(
-        android_logger::Config::default().with_max_level(uniffi::deps::log::LevelFilter::Info),
+        android_logger::Config::default()
+            .with_tag("com.bitwarden.sdk")
+            .with_max_level(uniffi::deps::log::LevelFilter::Info),
     );
 }