The original implementation of APK Signature Scheme v2 verification
mmapped the whole APK. This does not work on devices with limited
amount of contiguous free logical memory, especially on 32-bit
devices where logical address space is relatively small. For example,
a 500 MB APK is unlikely to mmap on a Nexus 6.
This commit fixes the issue by switching the verification strategy
to mmapping each individual 1 MB chunk of the APK, digesting it, and
then immediately munmapping. This is about 5-10% slower than mmapping
the whole APK in one go.
Bug: 27613575
Change-Id: I4167d5a7720c1bb87a0edad5d4f2607f7d554b56
0722ffcd06