1. ansh462's Avatar
    Android application in java having permission issues when accessing sysfs entry.

    FileOutputStream fos = new FileOutputStream("/sys/class/shift_reg/shift_reg/value");
    byte mybyte = 1;
    } catch ( Exception e) {
    Log.d(TAG, "Failed in writing to Shift Register"); <------- I am always getting this exception.
    1) Have tried putting 'setenforce 0'. Does't work. Even though enforce level is permissive.

    2) Do I have to access using JNI way: ( android-app -> jni -> driver )

    3) I have set file permission as 0777 for the sysfs node file.

    Dmesg Error message:

    [ 417.176302] type=1400 audit(418.589:63): avc: denied { write } for pid=3164 comm="com.android.cam" name="value" dev="sysfs" ino=9749 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:sysfs:s0 tclass=file permissive=1
    ps -Z

    u:r:untrusted_app:s0 u0_a67 4360 333
    04-03-2017 11:04 AM
  2. BayK's Avatar
    This file is exposed by the kernel, it is not a physical file in the file system.
    For you need to check you kernel doc to verify if it is writable.

    Did you try to write to /sys/class/shift_reg/shift_reg/value from Adb? Does it work?
    04-13-2017 04:22 PM

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