[RFC PATCH 0/3] posix_spawn improvements

[Jeremy Drake]

An idea I proposed on cygwin-devel that I intended to look at for 3.7, and
which came up again with rustc having dll base conflicts, I started
looking at optimizing posix_spawn to use spawn instead of fork/exec where
it's already more-or-less possible.  I did add the ability to redirect
stderr in ch_spawn.worker, as was already done for stdin and stdout, since
that was used by rust and apparently by llvm.  I have not handled any of
the spawnattr flags or (f)chdir, but it feels like they shouldn't be too
horribly difficult to deal with (particularly chdir since CreateProcessW
can take a current directory parameter).

The ugliness of this is that I had to copy/paste some structs from
newlib/libc/posix/posix_spawn.c to access the file actions.

Jeremy Drake (3):
  Cygwin: allow redirecting stderr in ch_spawn
  Cygwin: hook posix_spawn/posix_spawnp
  Cygwin: add fast-path for posix_spawn(p)

 winsup/cygwin/cygwin.din                  |   4 +-
 winsup/cygwin/dcrt0.cc                    |   2 +
 winsup/cygwin/local_includes/child_info.h |   6 +-
 winsup/cygwin/spawn.cc                    | 167 +++++++++++++++++++++-
 4 files changed, 172 insertions(+), 7 deletions(-)

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2.49.0.windows.1