feat(android): add httpPost bridge for mod.postLog log sends

Android ships no curl and the JNI bridge was GET-only, so mod.postLog
failed there with 'no POST transport on this platform' (HostShell.lua).
Add the mirror of httpDownload: GameActivity.httpPost (https-only,
hand-followed redirects re-POSTing the body, one-way), the JNI bridge
with the same old-APK-skew tolerance, the love.system.httpPost binding,
and the HostShell arm that rides it when curl is absent. The body
crosses the JNI as raw bytes (jbyteArray) so a log ring with arbitrary
UTF-8 cannot corrupt through modified-UTF-8 jstring conversion.

mobile/android/love/src/jni/love/src/common/android.cpp

@@ -325,6 +325,55 @@ bool httpDownload(const char *url, const char *destPath, const char *userAgent,
 	return result;
 }
 
+bool httpPost(const char *url, const char *body, int bodyLen, const char *contentType, const char *userAgent)
+{
+	if (url == nullptr || body == nullptr || bodyLen < 0)
+		return false;
+
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	// Same resolution rule as httpDownload: the activity's own class via
+	// SDL_AndroidGetActivity, never FindClass -- this bridge is called off
+	// the main thread (love.thread workers), whose class loader cannot see
+	// app classes.
+	jobject activityObj = (jobject) SDL_AndroidGetActivity();
+	if (activityObj == nullptr)
+		return false;
+	jclass activity = env->GetObjectClass(activityObj);
+	env->DeleteLocalRef(activityObj);
+
+	// Old APK / new liblove skew: report "no transport" the same way a
+	// missing curl does, instead of aborting on a missing method (#597).
+	jmethodID method = env->GetStaticMethodID(activity, "httpPost",
+		"(Ljava/lang/String;[BLjava/lang/String;Ljava/lang/String;)Z");
+	if (method == nullptr)
+	{
+		env->ExceptionClear();
+		env->DeleteLocalRef(activity);
+		return false;
+	}
+
+	jstring jurl = env->NewStringUTF(url);
+	// raw bytes across the bridge: a log ring can carry arbitrary UTF-8,
+	// and a jstring would run it through modified UTF-8
+	jbyteArray jbody = env->NewByteArray(bodyLen);
+	if (jbody != nullptr)
+		env->SetByteArrayRegion(jbody, 0, bodyLen, (const jbyte*) body);
+	jstring jct = contentType != nullptr ? env->NewStringUTF(contentType) : nullptr;
+	jstring jua = userAgent != nullptr ? env->NewStringUTF(userAgent) : nullptr;
+
+	jboolean result = env->CallStaticBooleanMethod(activity, method, jurl, jbody, jct, jua);
+
+	env->DeleteLocalRef(jurl);
+	if (jbody != nullptr)
+		env->DeleteLocalRef(jbody);
+	if (jct != nullptr)
+		env->DeleteLocalRef(jct);
+	if (jua != nullptr)
+		env->DeleteLocalRef(jua);
+	env->DeleteLocalRef(activity);
+	return result;
+}
+
 /*
  * TLS sockets. Same resolution rule as httpDownload above -- the activity's
  * own class, never FindClass -- and the same tolerance for an old APK: a

mobile/android/love/src/jni/love/src/common/android.h

@@ -98,6 +98,14 @@ bool restartApp();
  **/
 bool httpDownload(const char *url, const char *destPath, const char *userAgent, const char *accept);
 
+/**
+ * Blocking HTTPS POST of a raw byte body (GameActivity.httpPost). The
+ * mirror of httpDownload for mod.postLog log sends, which need POST and
+ * have no curl on Android. contentType / userAgent may be null. Returns
+ * whether the server accepted the send (2xx).
+ **/
+bool httpPost(const char *url, const char *body, int bodyLen, const char *contentType, const char *userAgent);
+
 /**
  * TLS client sockets (GameActivity.tls*, implemented by TlsSocket.java).
  * LuaSocket, which is what LOVE ships, does TCP only, so wss:// is otherwise

mobile/android/love/src/jni/love/src/modules/system/System.cpp

@@ -259,6 +259,21 @@ bool System::httpDownload(const char *url, const char *destPath,
 #endif
 }
 
+bool System::httpPost(const char *url, const char *body, int bodyLen,
+	const char *contentType, const char *userAgent) const
+{
+#ifdef LOVE_ANDROID
+	return love::android::httpPost(url, body, bodyLen, contentType, userAgent);
+#else
+	LOVE_UNUSED(url);
+	LOVE_UNUSED(body);
+	LOVE_UNUSED(bodyLen);
+	LOVE_UNUSED(contentType);
+	LOVE_UNUSED(userAgent);
+	return false;
+#endif
+}
+
 int System::tlsOpen(const char *host, int port) const
 {
 #ifdef LOVE_ANDROID

mobile/android/love/src/jni/love/src/modules/system/System.h

@@ -151,6 +151,14 @@ public:
 	virtual bool httpDownload(const char *url, const char *destPath,
 		const char *userAgent = nullptr, const char *accept = nullptr) const;
 
+	/**
+	 * Blocking HTTPS POST of a raw byte body (Android only; false
+	 * elsewhere). The mirror of httpDownload for mod.postLog log sends,
+	 * which need POST and have no curl on Android (#597).
+	 **/
+	virtual bool httpPost(const char *url, const char *body, int bodyLen,
+		const char *contentType = nullptr, const char *userAgent = nullptr) const;
+
 	/**
 	 * TLS client sockets (Android only; every call fails elsewhere, where
 	 * LuaSec or another provider is the answer). Non-blocking by contract:

mobile/android/love/src/jni/love/src/modules/system/wrap_System.cpp

@@ -139,6 +139,17 @@ int w_httpDownload(lua_State *L)
 	return 1;
 }
 
+int w_httpPost(lua_State *L)
+{
+	const char *url = luaL_checkstring(L, 1);
+	size_t bodyLen = 0;
+	const char *body = luaL_checklstring(L, 2, &bodyLen);
+	const char *ct = luaL_optstring(L, 3, nullptr);
+	const char *ua = luaL_optstring(L, 4, nullptr);
+	luax_pushboolean(L, instance()->httpPost(url, body, (int) bodyLen, ct, ua));
+	return 1;
+}
+
 int w_hasBackgroundMusic(lua_State *L)
 {
 	lua_pushboolean(L, instance()->hasBackgroundMusic());
@@ -233,6 +244,7 @@ static const luaL_Reg functions[] =
 	{ "syncHealthSteps", w_syncHealthSteps },
 	{ "restartApp", w_restartApp },
 	{ "httpDownload", w_httpDownload },
+	{ "httpPost", w_httpPost },
 	{ "tlsOpen", w_tlsOpen },
 	{ "tlsStatus", w_tlsStatus },
 	{ "tlsSend", w_tlsSend },