JNI WARNING: input is not valid Modified UTF-8: illegal start byte 0xfe

灰太狼 2022-01-15 12:39 153阅读 0赞

W/dalvikvm( 1473):              in Landroid/media/MediaScanner;.processFile (Ljava/lang/String;Ljava/lang/String;Landroid/media/MediaScannerClient;)V (NewStringUTF)  
I/dalvikvm( 1473): "MediaScannerService" prio=5 tid=10 NATIVE  
I/dalvikvm( 1473):   | group="main" sCount=0 dsCount=0 s=N obj=0x45f1ea18 self=0x22f0d0  
I/dalvikvm( 1473):   | sysTid=1647 nice=11 sched=3/0 cgrp=unknown handle=2229456  
I/dalvikvm( 1473):   at android.media.MediaScanner.processFile(Native Method)  
I/dalvikvm( 1473):   at android.media.MediaScanner.access$500(MediaScanner.java:103)

这个就是蛋疼的地方，

造成该问题的原因是没有通过虚拟机的checkjni检查。代码在dalvik/vm/CheckJni.c

/\*  
 \* Verify that "bytes" points to valid "modified UTF-8" data.  
 \*/  
static void checkUtfString(JNIEnv\* env, const char\* bytes, bool nullOk,  
    const char\* func)  
\{  
    const char\* origBytes = bytes;

if (bytes == NULL) \{  
        if (!nullOk) \{  
            LOGW("JNI WARNING: unexpectedly null UTF string/n");  
            goto fail;  
        \}

return;  
    \}

while (\*bytes != '/0') \{  
        u1 utf8 = \*(bytes++);  
        // Switch on the high four bits.  
        switch (utf8 >> 4) \{  
            case 0x00:  
            case 0x01:  
            case 0x02:  
            case 0x03:  
            case 0x04:  
            case 0x05:  
            case 0x06:  
            case 0x07: \{  
                // Bit pattern 0xxx. No need for any extra bytes.  
                break;  
            \}  
            case 0x08:  
            case 0x09:  
            case 0x0a:  
            case 0x0b:  
            case 0x0f: \{  
                /\*  
                 \* Bit pattern 10xx or 1111, which are illegal start bytes.  
                 \* Note: 1111 is valid for normal UTF-8, but not the  
                 \* modified UTF-8 used here.  
                 \*/  
                LOGW("JNI WARNING: illegal start byte 0x%x/n", utf8);  
                goto fail;  
            \}  
            case 0x0e: \{  
                // Bit pattern 1110, so there are two additional bytes.  
                utf8 = \*(bytes++);  
                if ((utf8 & 0xc0) != 0x80) \{  
                    LOGW("JNI WARNING: illegal continuation byte 0x%x/n", utf8);  
                    goto fail;  
                \}  
                // Fall through to take care of the final byte.  
            \}  
            case 0x0c:  
            case 0x0d: \{  
                // Bit pattern 110x, so there is one additional byte.  
                utf8 = \*(bytes++);  
                if ((utf8 & 0xc0) != 0x80) \{  
                    LOGW("JNI WARNING: illegal continuation byte 0x%x/n", utf8);  
                    goto fail;  
                \}  
                break;  
            \}  
        \}  
    \}

return;

fail:  
    LOGW("             string: '%s'/n", origBytes);  
    showLocation(dvmGetCurrentJNIMethod(), func);  
    abortMaybe();  
\}

解决方法：

是否进行checkjni检查是由ro.kernel.android.checkjni决定。

在eng版本中ro.kernel.android.checkjni=1.而在user, userdebug版本不做检查

In build/core/main.mk

user\_variant := $(filter user userdebug,$(TARGET\_BUILD\_VARIANT))  
enable\_target\_debugging := true  
tags\_to\_install :=  
ifneq (,$(user\_variant))

...

ro.kernel.android.checkjni=0

else

...

ro.kernel.android.checkjni=1

note: 遇到了一次这个问题，kernel层上传的字符窜格式是S8, 长层接收转换时出错。