Native Crash on Android 4.3 when calling Picture.writeToStream ()

Question

In Android 4.3, regression was introduced. Code that used to work in previous versions of Android now causes its own crash, which terminates the process.

A crash occurs when drawing an image larger than 32 kb into the canvas, which is recorded by the Picture object, which, in turn, is written to the stream through writeToStream() .

Skia crashes when trying to write a string (which I believe is the Uri of the image object).

 I/DEBUG(122): #00 pc 0001e3bc /system/lib/libc.so (strlen+72) I/DEBUG(122): #01 pc 000d9858 /system/lib/libskia.so (SkWriter32::writeString(char const*, unsigned int)+256) I/DEBUG(122): #02 pc 00113d68 /system/lib/libskia.so (SkImageRef_ashmem::flatten(SkFlattenableWriteBuffer&) const+44) 

The following program shows how to reproduce this problem. All that is needed is a layout with a button that has the identifier 'button'.

  public class MainActivity extends Activity { static final String IMAGE_FILE = Environment.getExternalStorageDirectory() + "/test.jpg"; static final String SKIA_FILE = Environment.getExternalStorageDirectory() + "/test.skia"; private static Bitmap loadBitmap(final String filename) { Bitmap bitmap = null; FileInputStream is; try { is = new FileInputStream(filename); final BitmapFactory.Options options = new BitmapFactory.Options(); options.inInputShareable = true; options.inPurgeable = true; bitmap = BitmapFactory.decodeFileDescriptor(is.getFD(), null, options); is.close(); } catch (final FileNotFoundException e) { e.printStackTrace(); } catch (final IOException ex) { ex.printStackTrace(); } return bitmap; } @Override protected void onCreate(final Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final Button button = (Button) findViewById(R.id.button); button.setOnClickListener(new OnClickListener() { @Override public void onClick(final View v) { final Runnable runnable = new Runnable() { @Override public void run() { // Create a Canvas and begin recording final Picture picture = new Picture(); final Canvas canvas = picture.beginRecording(1024, 1024); // De-compress an image from file final Bitmap bitmap = loadBitmap(IMAGE_FILE); // If present draw the image to the canvas and end // recording if (bitmap != null) { canvas.drawBitmap(bitmap, new Matrix(), null); } picture.endRecording(); // Write out the Picture object to a Skia File. FileOutputStream os; try { os = new FileOutputStream(SKIA_FILE); picture.writeToStream(os); os.close(); } catch (final FileNotFoundException e) { e.printStackTrace(); } catch (final IOException ex) { ex.printStackTrace(); } } }; new Thread(runnable).start(); } }); } } 

The two lines setting BitmapFactory.Options are needed to get the Skia anti-aliasing code to write image data (otherwise the images are emitted).

 options.inInputShareable = true; options.inPurgeable = true; 

I am aware that the Picture writeToStream() and createFromStream() methods are deprecated, but I did not expect this to cause a stability problem.

I need to write a Picture object as I want to transfer it from the main application to the service process. I cannot use the recommended workaround in the documentation that says “draw image into bitmap” for the following reasons:

• The desired image resolution is unknown during recording.
• The Picture object must be scaled using the matrix after restoration.
• Saving to a very high resolution bitmap is inefficient in terms of memory and processing time.

Does anyone know a job that allows you to write images to a stream without causing this failure?

Answer 1

I would add this as a comment, but I do not have enough reputation ...

A devastating change in Skia is a change to SkImageRef_ashmem.cpp :

https://code.google.com/p/skia/source/detail?r=4980

The smoothing method used to check for a null URI and writes 0 to the output stream if uri was null. Passing null to SkFlattenableWriteBuffer::writeString() crashes in strlen() .