Prior to this change, connection errors such as "Connection refused"
etc, are caught either by some error condition being detected by
the eventhandler thread and that error condition being propagated
to the Dart thread, or by the first read or write after a
"successful" connection failing with an error.
However, posix documentation for non-blocking sockets recommends
either checking getsockopt(SO_ERROR), or calling connect() a
second time following the first write event on a socket after
the first connect call returns EINPROGRESS.
On Fuchsia, this check is mandatory because errors like
"Connection refused" are neither signaled on the socket's
underlying OS handle, nor indicated by error returns from
read() and write().
This change adds the check, which is optional on other platforms,
but mandatory on Fuchsia, to the Dart socket connection loop
after the first write signal is asserted.
Change-Id: I8aeea4665913f79e8138bdd830676ae43066a959
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104263
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Zach Anderson <zra@google.com>
Zach Anderson
d4d9f0afaa