[roll] Roll fuchsia [starnix] Avoid `memchr` with unified aspaces

When reading C strings, Starnix read bytes from user-mode until it
observes a null (C string terminating) byte. When performing reads
without unified aspaces, Starnix will read a whole chunk of memory from
the user-mode process's VMO and then performs a `memchr` on the read
bytes to find the presence/location of the null byte.

However, the usercopy utilities that unified aspaces relies on will only
read bytes up until the null byte. With unified address spaces, there is
no need to perform a `memchr` to determine if the null-byte exists; only
the last read byte needs to be checked for the null-value.

This change refactors the `MemoryAccessor` implementation for
`MemoryManager` by only performing the `memchr` to find the null byte
when reading bytes directly from VMOs.

Original-Bug: b/276973344, b/303711008
Cq-Include-Trybots: luci.fuchsia.try:core.arm64-cxx20,core.x64-cxx20,core.x64-debug,core.arm64-debug
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/947792
Original-Revision: 93dc82c9b9033c829cb87e39eca4bef5a8372d71
GitOrigin-RevId: 2c8ef7ad8ad3cfa8331323c2436436cd4587e8a6
Change-Id: I66e121fa3b13fa78f40fab8696cfe80669b6c30c
1 file changed
tree: 5b450bb2986a79101f913e09f579d9bbe0ce63b5
  1. git-hooks/
  2. infra/
  3. third_party/
  4. cts
  5. firmware
  6. flower
  7. jiri.lock
  8. MILESTONE
  9. minimal
  10. prebuilts
  11. README.md
  12. stem
  13. test_durations
  14. toolchain
README.md

Integration

This repository contains Fuchsia's Global Integration manifest files.

Making changes

All changes should be made to the internal version of this repository. Our infrastructure automatically updates this version when the internal one changes.

Currently all changes must be made by a Google employee. Non-Google employees wishing to make a change can ask for assistance via the IRC channel #fuchsia on Freenode.

Obtaining the source

First install Jiri.

Next run:

$ jiri init
$ jiri import minimal https://fuchsia.googlesource.com/integration
$ jiri update

Third party

Third party projects should have their own subdirectory in ./third_party.