Disallow reading object data from Parcels with non-object reads
The check added to each non-object reads adds an overhead. If the
objects (binders and file descriptors) were written to the Parcel in
sequential order then check adds a small O(1) overhead to each read,
plus an O(N) overhead to the first read (to verify the N objects were
added in order).
If the objects were written out of order (as in by jumping around the Parcel
with setDataPosition and writing Binder, DON'T DO THIS!!) (writing non
objects out of order is fine), the first read is forced to sort the objects
in the internal bookkeeping. Based on the assumption non sequential writes
are infrequent and overall Parcels are probably mostly sorted, insertion
sort was used. Worst case sorts will add an O(N^2) overhead to the first
non object read from the Parcel.
Test: run cts -m CtsOsTestCases -t android.os.cts.ParcelTest
Bug: 29833520
Change-Id: Id0119caf530023fe8b61be6d15f5b6a9c49c08df
Merged-In: I82de8eb5f5eb56f869542d5358e96884c24301b2
(cherry picked from commit f784183c17a4985b9703ac22d063ad4ef8b9090f)
2 files changed
