crash when using SpassFingerprint.RegisteredFingerprintName

[seligam]

hi

I am using Xamarin studio 5.9.3, Xamarin Android support 22.2.0.0 (if it is important)

when I call SpassFingerprint.RegisteredFingerprintName on Samsung Galaxy S6 application crashes immediately with this error log

I/FPMS_SamsungFingerprintProxyFactory( 6043): getFingerprintIndexList FP_PROXY FINISH (1ms) RESULT: [I@2f0fbcaa
I/PersonaManagerService( 3691): getParentId() for 0
F/art     (26346): sart/runtime/check_jni.cc:65] JNI DETECTED ERROR IN APPLICATION: not an array: android.util.SparseArray
F/art     (26346): sart/runtime/check_jni.cc:65]     in call to GetArrayLength
F/art     (26346): sart/runtime/check_jni.cc:65]     from java.lang.Object md5bc232938925bcb871197f46a495ecf2e.FingerPrintEvaluate.n_doInBackground(java.lang.Object[])
F/art     (26346): sart/runtime/check_jni.cc:65] "AsyncTask #4" prio=5 tid=20 Runnable
F/art     (26346): sart/runtime/check_jni.cc:65]   | group="main" sCount=0 dsCount=0 obj=0x12dcb520 self=0xf4b7d800
F/art     (26346): sart/runtime/check_jni.cc:65]   | sysTid=27068 nice=10 cgrp=bg_non_interactive sched=0/0 handle=0xdc846480
F/art     (26346): sart/runtime/check_jni.cc:65]   | state=R schedstat=( 0 0 0 ) utm=1 stm=0 core=3 HZ=100
F/art     (26346): sart/runtime/check_jni.cc:65]   | stack=0xda9d4000-0xda9d6000 stackSize=1036KB
F/art     (26346): sart/runtime/check_jni.cc:65]   | held mutexes= "mutator lock"(shared held)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #00 pc 00004e64  /system/lib/libbacktrace_libc++.so (UnwindCurrent::Unwind(unsigned int, ucontext*)+23)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #01 pc 00003665  /system/lib/libbacktrace_libc++.so (Backtrace::Unwind(unsigned int, ucontext*)+8)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #02 pc 0025f37d  /system/lib/libart.so (art::DumpNativeStack(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, int, char const*, art::mirror::ArtMethod*)+84)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #03 pc 00241a2f  /system/lib/libart.so (art::Thread::Dump(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) const+158)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #04 pc 000b3933  /system/lib/libart.so (art::JniAbort(char const*, char const*)+610)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #05 pc 000b4059  /system/lib/libart.so (art::JniAbortF(char const*, char const*, ...)+68)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #06 pc 001d1159  /system/lib/libart.so (art::JNI::GetArrayLength(_JNIEnv*, _jarray*)+660)
F/art     (26346): sart/runtime/check_jni.cc:65]   native: #07 pc 00004624   (???)
F/art     (26346): sart/runtime/check_jni.cc:65]   at md5bc232938925bcb871197f46a495ecf2e.FingerPrintEvaluate.n_doInBackground(Native method)
F/art     (26346): sart/runtime/check_jni.cc:65]   at md5bc232938925bcb871197f46a495ecf2e.FingerPrintEvaluate.doInBackground(FingerPrintEvaluate.java:33)
F/art     (26346): sart/runtime/check_jni.cc:65]   at android.os.AsyncTask$2.call(AsyncTask.java:292)
F/art     (26346): sart/runtime/check_jni.cc:65]   at java.util.concurrent.FutureTask.run(FutureTask.java:237)
F/art     (26346): sart/runtime/check_jni.cc:65]   at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
F/art     (26346): sart/runtime/check_jni.cc:65]   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
F/art     (26346): sart/runtime/check_jni.cc:65]   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
F/art     (26346): sart/runtime/check_jni.cc:65]   at java.lang.Thread.run(Thread.java:818)

it happens on

sparseArray.ToArray<string>()

there is no crash when i replaced

return new List<string> (sparseArray.ToArray<string> ());

with

List<string> l=new List<string> ();
for(int i = 0; i < sparseArray.Size(); i++) {
    int key = sparseArray.KeyAt(i);
    string s = (string)sparseArray.Get(key);
    l.Add (s);
}
return l;

same this is also in RegisteredFingerprintUniqueId

btw I don't know where this SparseArray.ToArray came from, there is no such method in android documentation. Maybe it is something added by Xamarin and it is their implementation which is buggy.

[seligam]

at the end i changed these 2 functions to return SparseArray which is then processed in application.
conversion to IList moved indexes so index returned by IdentifiedFingerprintIndex was pointing to wrong name/uid. Probably it would be enough just to subtract 1 from returned index, but i think working with native structure is safer

so in final version

return new List<string> (sparseArray.ToArray<string> ());

is replaced with

return sparseArray;