tree 2daec84a94b32259130eff16a18e9042cb3b8ebb
parent dcf9570d756aa74a2330406c13330c18c34e0db2
author Jiakai Zhang <jiakaiz@google.com> 1641491537 +0000
committer Treehugger Robot <treehugger-gerrit@google.com> 1641559591 +0000

Fix ReadMagicAndReset.

ReadMagicAndReset is a function that is supposed to read a uint32_t
from the beginning of a file. However, it cannot handle the case where
the file offset of the fd is non-zero. Specifically, when an fd is
passed from dex2oat, dex2oat has probably read that file, causing the
file offset to be non-zero. This CL fixes the problem by resetting the
file offest before reading from the fd. Ideally, we should use `pread`,
but `ReadMagicAndReset` is part of `libartbase`, which has to support
Windows build where `pread` is not supported.

This change fixes odrefresh, which invokes dex2oat with fds.

Bug: 213446666
Test: atest odsign_e2e_tests
Change-Id: Ib5dd8e2855a4f0a391afa5313cf3a2d12f1a3121