// not a suitable use for a Pool, since the overhead does not amortize well in
// that scenario. It is more efficient to have such objects implement their own
// free list.
//
// A Pool must not be copied after first use.
//
// In the terminology of [the Go memory model], a call to Put(x) “synchronizes before”
// a call to [Pool.Get] returning that same value x.
// Similarly, a call to New returning x “synchronizes before”

	}
	vs := []struct {
		call           string
		fn             func() error
		filter, expect string
	}{
		{call: "Setegid(1)", fn: func() error { return syscall.Setegid(1) }, filter: "Gid:", expect: "\t0\t1\t0\t1"},
		{call: "Setegid(0)", fn: func() error { return syscall.Setegid(0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},

	}

	// Unblock any I/O.  Once it all unblocks and returns,
	// so that it cannot be referring to fd.sysfd anymore,
	// the final decref will close fd.sysfd. This should happen
	// fairly quickly, since all the I/O is non-blocking, and any
	// attempts to block in the pollDesc will return errClosing(fd.isFile).
	fd.pd.evict()

	// The call to decref will call destroy if there are no other
	// references.

import (
	"context"
	"errors"
)

// A Stream is a two-way stream.
// All responses *must* be read by the caller.
// If the call is canceled through the context,
// the appropriate error will be returned.
type Stream struct {
	// responses from the remote server.
	// Channel will be closed after error or when remote closes.
	// All responses *must* be read by the caller until either an error is returned or the channel is closed.

	// Announce we are entering a system call
	// so that the scheduler knows to create another
	// M to run goroutines while we are in the
	// foreign code.
	//
	// The call to asmcgocall is guaranteed not to
	// grow the stack and does not allocate memory,
	// so it is safe to call while "in a system call", outside
	// the $GOMAXPROCS accounting.
	//
	// fn may call back into Go code, in which case we'll exit the

// routed to an IPv6 socket - two separate sockets are required if
// both address families are to be supported.
// See inet6(4) for details.

type ipStackCapabilities struct {
	sync.Once             // guards following
	ipv4Enabled           bool
	ipv6Enabled           bool
	ipv4MappedIPv6Enabled bool
}

var ipStackCaps ipStackCapabilities

// supportsIPv4 reports whether the platform supports IPv4 networking

   * cancelled, cancellation will be propagated to {@code delegate}. Additionally, any call to
   * {@code setFuture} after any cancellation will propagate cancellation to the supplied {@code
   * Future}.
   *
   * <p>Note that, even if the supplied future is cancelled and it causes this future to complete,

   * cancelled, cancellation will be propagated to {@code delegate}. Additionally, any call to
   * {@code setFuture} after any cancellation will propagate cancellation to the supplied {@code
   * Future}.
   *
   * <p>Note that, even if the supplied future is cancelled and it causes this future to complete,

        | ((source[offset + 3] & 0xFF) << 24);
  }

  /**
   * Indicates that the loading of Unsafe was successful and the load and store operations will be
   * very efficient. May be useful for calling code to fall back on an alternative implementation
   * that is slower than Unsafe.get/store but faster than the pure-Java mask-and-shift.
   */
  static boolean usingUnsafe() {

	if islibrary || isarchive {
		return
	}

	// If we are dying because of a signal caught on an already idle thread,
	// freezetheworld will cause all running threads to block.
	// And runtime will essentially enter into deadlock state,
	// except that there is a thread that will call exit soon.
	if panicking.Load() > 0 {
		return
	}

	// If we are not running under cgo, but we have an extra M then account