// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements sysSocket for platforms that provide a fast path for
// setting SetNonblock and CloseOnExec, but don't necessarily support it.
// Support for SOCK_* flags as part of the type parameter was added to Oracle
// Solaris in the 11.4 release. Thus, on releases prior to 11.4, we fall back

//go:linkname rand
func rand() uint64 {
	// Note: We avoid acquirem here so that in the fast path
	// there is just a getg, an inlined c.Next, and a return.
	// The performance difference on a 16-core AMD is
	// 3.7ns/call this way versus 4.3ns/call with acquirem (+16%).
	mp := getg().m
	c := &mp.chacha8
	for {
		// Note: c.Next is marked nosplit,
		// so we don't need to use mp.locks
		// on the fast path, which is that the

		// MADV_FREE was added in Linux 4.5. Fall back on MADV_DONTNEED if it's
		// not supported.
		if madvise(v, n, _MADV_DONTNEED) == 0 {
			break
		}
		atomic.Store(&adviseUnused, madviseUnsupported)
		fallthrough
	case madviseUnsupported:
		// Since Linux 3.18, support for madvise is optional.
		// Fall back on mmap if it's not supported.
		// _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE will unmap all the

	}

	// If we can block until Wait4 will succeed immediately, do so.
	ready, err := p.blockUntilWaitable()
	if err != nil {
		return nil, err
	}
	if ready {
		// Mark the process done now, before the call to Wait4,
		// so that Process.pidSignal will not send a signal.
		p.pidDeactivate(statusDone)
		// Acquire a write lock on sigMu to wait for any
		// active call to the signal method to complete.
		p.sigMu.Lock()

		// Something wrong with socket(), fall back to checking the kernel version.
		major, minor := KernelVersion()
		if runtime.GOOS == "illumos" {
			return major > 5 || (major == 5 && minor >= 11) // minimal requirement is SunOS 5.11
		}
		return major > 11 || (major == 11 && minor >= 4)
	}
	return false
})

// SupportAccept4 tests whether accept4 system call is available.

// atomicwb performs a write barrier before an atomic pointer write.
// The caller should guard the call with "if writeBarrier.enabled".
//
// atomicwb should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - github.com/bytedance/gopkg
//   - github.com/songzhibin97/gkit
//
// Do not remove or change the type signature.

		return nil
	}

	// Splice will loop writing maxSpliceSize bytes from the source to the pipe,
	// and then write those bytes from the pipe to the destination.
	// Set the pipe buffer size to maxSpliceSize to optimize that.
	// Ignore errors here, as a smaller buffer size will work,
	// although it will require more system calls.
	unix.Fcntl(fds[0], syscall.F_SETPIPE_SZ, maxSpliceSize)

// 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”

	if (ret) {
		fprintf(stderr, "runtime/cgo: thread_get_state failed: %d\n", ret);
		abort();
	}

	// Bounce call to sigpanic through asm that makes it look like
	// we call sigpanic directly from the faulting code.
#ifdef __arm64__
	thread_state.ts_64.__x[1] = thread_state.ts_64.__lr;
	thread_state.ts_64.__x[2] = thread_state.ts_64.__pc;
	thread_state.ts_64.__pc = x_cgo_panicmem;
#else

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.