commit b5d98ad5e673d50ffffe296e97f86e78aae109b6
author Kousik Kumar <48490842+gkousik@users.noreply.github.com> Wed Mar 23 16:14:36 2022 -0400
committer GitHub <noreply@github.com> Wed Mar 23 16:14:36 2022 -0400
tree 918c12fe8e2a4ecbb24b13c7b24b17c5da77822a
parent ed923fee5a60fcf01f4532de3fb45c52f02c4ba9

Always set file modified time after writing to a file (#414)

Two problems:
1. We are incorrectly writing to a file if the destination file has more
   content than the source file during copying.
2. We aren't updating the timestamp of the file when the destiination
   file has zero bytes.

Both these would be fixed by just setting the file open mode to
os.O_TRUNC which would truncate the file if it already exists.

Test:
1. Unit tests
2. Tested in Android build with:
```
rm -f out/reproxy* && touch frameworks/opt/net/voip/src/java/com/android/server/sip/SipWakeupTimer.java && RBE_v=3 RBE_instance="projects/foundry-x-experiments/instances/default-instance" RBE_use_unified_cas_ops=false RBE_use_batches=false RBE_METALAVA=true m out/soong/.intermediates/frameworks/base/api-stubs-docs-non-updatable/android_common/metalava/check_last_released_api.timestamp
```

and confirmed that `restat` warnings were no longer popping up during
rebuilds.