1299454 - Round Off Ambient Light Sensor event.value

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Data Providers, defect)

Description

[Lukasz]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36

Steps to reproduce:

User-Agent: Mozilla/5.0 (Android 6.0.1; Mobile; rv:49.0) Gecko/49.0 Firefox/49.0

I entered a web site registering devicelight events.



Actual results:

The event.value readout is too verbose:

75.2131500244140625 lx  
435.8228149414062500 lx  
548.1655883789062500 lx  
13 lx 



Expected results:

The event.value readout should be rounded:

75 lx  
435 lx  
548 lx  
13 lx 

Providing too verbose, non-rounded illuminance values can potentially open unexpected issues related to fingerprinting, tracking and data leaks (possibly similarly to http://lukaszolejnik.com/battery.pdf, but potentially more directly). It is also not necessary from a physical point of view. Please also see https://bugzilla.mozilla.org/show_bug.cgi?id=1124127

Comment 1

[Joseph Lorenzo Hall]

This comes after the over-precision of the BatteryStatus API returns in Mobile Firefox. (Bug: 1124127)

It would be great if FF mobile had a systematic way of assessing whether sensor API returns are overly-precise.

Comment 2

[Dylan Roeh (:droeh) (he/him)]

Attachment: Round Device Light Value

I can't actually reproduce this on a Nexus 6 running Android N (the values are already rounded to integers for me), but it's an easy enough fix regardless. This patch just rounds the event value before creating the DeviceLightEvent.

Comment 3

[James Willcox (:snorp) ([e-mail]) (he/him)]

I don't know if integer precision is still too much or not. Seems like it probably is, but this is a start.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/f41a22a14e0d
Round event value before creating a DeviceLightEvent. r=snorp

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/f41a22a14e0d