java代码混淆后crash还原的代码行号不对

[lxzh]

我这里加了混淆，修改了一下测试用例testJavaCrash，但发现混淆后堆栈的代码行号不对。如下：
crash:trace

        ...
     Caused by: java.lang.RuntimeException: test java exception
        at a.l.a(XCrash.java:44)
        at xcrash.sample.MainActivity.testJavaCrashInMainThread_onClick(MainActivity.java:1)
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:3) 
        ...

这里面还原的几个行号都比较奇怪，如at a.l.a(XCrash.java:44)这个44行
apk
smali文件

[lxzh]

哦，了解了，这个行号是混淆后处理了的行号，这个44行号可以在a.l.smali文件可以找到crash的位置。
如：
crash发生在XCrash.java的51行:

     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.substring(int)' on a null object reference
        at a.l.a(XCrash.java:51)
        at xcrash.sample.MainActivity.testJavaCrashInMainThread_onClick(MainActivity.java:1)
        at java.lang.reflect.Method.invoke(Native Method) 

实际上是a.l.smali文件中.line51对应的代码：

    .line 51
    sget-object v0, La/l;->e:La/g;

    new-instance v2, Ljava/lang/StringBuilder;

    invoke-direct {v2}, Ljava/lang/StringBuilder;-><init>()V

    const-string v4, "testJavaCrash case:4 str="

    invoke-virtual {v2, v4}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

    invoke-virtual {p0, v1}, Ljava/lang/String;->substring(I)Ljava/lang/String;

    move-result-object p0

    invoke-virtual {v2, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

    invoke-virtual {v2}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;

    move-result-object p0

    invoke-interface {v0, v3, p0}, La/g;->b(Ljava/lang/String;Ljava/lang/String;)V

    goto :goto_0

对应的mapping文件：

    38:40:void testJavaCrash(boolean):885:887 -> a
    41:41:void testJavaCrash(boolean):892:892 -> a
    42:43:void testJavaCrash(boolean):898:899 -> a
    44:44:void testJavaCrash(boolean):901:901 -> a
    45:50:void testJavaCrash(boolean):922:927 -> a
    51:51:void testJavaCrash(boolean):919:919 -> a
    52:53:void testJavaCrash(boolean):914:915 -> a
    54:56:void testJavaCrash(boolean):907:909 -> a

因此这个51行就对应原文件的919行，原文件：

917            case 4:
918                String str = null;
919                logger.d(TAG, "testJavaCrash case:4 str=" + str.substring(3));
920                break;

刚好吻合

[lxzh]

但奇怪的是用retrace还原crash堆栈，并没有校正行号

     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.substring(int)' on a null object reference
        at xcrash.XCrash.void testJavaCrash(boolean)(XCrash.java:51)
        at xcrash.sample.MainActivity.void testJavaCrashInMainThread_onClick(android.view.View)(MainActivity.java:1)
        at java.lang.reflect.Method.invoke(Native Method)?

[caikelun]

xCrash 投递的 java 崩溃的 stacktrace 信息，是通过注册 jvm 标准的 Thread.setDefaultUncaughtExceptionHandler 获取的，并未对 stacktrace 信息做任何修改。