[PATCH 0/5] Reintroduce writev(3p)

Hi,

this patch series reintroduces the writev(3p) wrapper. This wrapper was originally introduced as part of Git 2.54 [1], but was ejected due to issues on NonStop [2].

This patch series here revives the effort with a couple of fixes on top:

  - It picks Dscho's fix for CMake [3].

  - It picks a fix for NonStop [4] and polishes it a bit.

  - It adapts one more site to demonstrate that its usefulness is not
    limited to a single callsite, only.

Furthermore, I have included benchmarks now that demonstrate the benefits to make this series a bit more appealing. Ultimately, I'd be fine if we say we rather don't want to go this way though. I merely wanted to tie some loose ends that I left dangling.

That, and it's nice to not work on pluggable object databases once in a while.

Thanks!

Patrick

[1]: <20260227-pks-upload-pack-write-contention-v1-0-7166fe255704@pks.im> [2]: <028901dcc859$d2419470$76c4bd50$@nexbridge.com> [3]: <pull.2078.git.1775206502134.gitgitgadget@gmail.com> [4]: <20260409-b4-pks-writev-max-io-size-v1-1-81730e8f35df@pks.im>

---
Patrick Steinhardt (5):
      compat/posix: introduce writev(3p) wrapper
      wrapper: introduce writev(3p) wrappers
      wrapper: properly handle MAX_IO_SIZE in writev(3p)
      sideband: use writev(3p) to send pktlines
      fast-import: use writev(3p) to send cat-blob responses

 Makefile                            |  4 ++
 builtin/fast-import.c               | 18 +++++++--
 compat/posix.h                      | 14 +++++++
 compat/writev.c                     | 44 +++++++++++++++++++++
 config.mak.uname                    |  2 +
 contrib/buildsystems/CMakeLists.txt |  6 ++-
 meson.build                         |  1 +
 sideband.c                          | 14 +++++--
 wrapper.c                           | 78 +++++++++++++++++++++++++++++++++++++
 wrapper.h                           | 10 +++++
 write-or-die.c                      |  8 ++++
 write-or-die.h                      |  1 +
 12 files changed, 193 insertions(+), 7 deletions(-)

--- base-commit: 55526a18268bbc1ddaf8a6b7850c33d984eac9e9 change-id: 20260714-pks-reintroduce-writev-2d8f7e52eee9