Implement save, share image from archive

app/src/main/cpp/fdutils.c

@@ -0,0 +1,16 @@
+#include <jni.h>
+
+JNIEXPORT jint JNICALL
+Java_com_hippo_Native_getFd(JNIEnv *env, jclass clazz, jobject fileDescriptor) {
+    jint fd = -1;
+    jclass fdClass = (*env)->FindClass(env, "java/io/FileDescriptor");
+
+    if (fdClass != NULL) {
+        jfieldID fdClassDescriptorFieldID = (*env)->GetFieldID(env, fdClass, "descriptor", "I");
+        if (fdClassDescriptorFieldID != NULL && fileDescriptor != NULL) {
+            fd = (*env)->GetIntField(env, fileDescriptor, fdClassDescriptorFieldID);
+        }
+    }
+
+    return fd;
+}