Crash When Attempting to Open Read-Only Content in Read-Write Mode

[commonsguy]

On Amaze 3.2.1, if another app starts an ACTION_VIEW Intent for text/plain and a valid Uri pointing to read-only content, TextReader crashes:

java.lang.SecurityException: Permission Denial: writing android.support.v4.content.FileProvider uri content://com.commonsware.myapplication.provider/Download/hello_world.txt from pid=592, uid=10170 requires the provider be exported, or grantUriPermission()
   at android.os.Parcel.readException(Parcel.java:2004)
   at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:183)
   at android.database.DatabaseUtils.readExceptionWithFileNotFoundExceptionFromParcel(DatabaseUtils.java:146)
   at android.content.ContentProviderProxy.openAssetFile(ContentProviderNative.java:625)
   at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:1265)
   at android.content.ContentResolver.openFileDescriptor(ContentResolver.java:1100)
   at android.content.ContentResolver.openFileDescriptor(ContentResolver.java:1054)
   at com.amaze.filemanager.activities.TextReader.getInputStream(TextReader.java:685)
   at com.amaze.filemanager.activities.TextReader.access$400(TextReader.java:92)
   at com.amaze.filemanager.activities.TextReader$4.run(TextReader.java:461)

That comes from this code segment. I think that your algorithm is fine, but you need to check for SecurityException in addition to FileNotFoundException, and try the read-only access in both cases.

The attached sample project reproduces the problem. It is nearly the same as the one from issue #1014, except that this one fixes the null Uri problem that triggered that earlier crash. Like the first one, it requires a hello_world.txt file in the Download/ directory of external storage.

MyApplication-20180211b.zip

This can be reproduced on Android 8.1 at minimum, though I suspect that it will yield similar results on other modern versions of Android.