It looks to me like there's been a bug in the MSG_WAITALL support for AF_INET and AF_LOCAL sockets ever since that support was first introduced 13 years ago in commit 023a2fa7. If I'm right, MSG_WAITALL has never worked.
This patch fixes it. I'll push it in a few days if no one sees anything wrong with it. In a followup email I'll show how I tested it. Ken Brown (1): Cygwin: AF_INET and AF_LOCAL: recv_internal: fix MSG_WAITALL support winsup/cygwin/fhandler_socket_inet.cc | 2 +- winsup/cygwin/fhandler_socket_local.cc | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) -- 2.28.0