Hervé Boutemy <******@****.***> 1706543644 +0100

// splice wraps the splice system call. Since the current implementation
// only uses splice on sockets and pipes, the offset arguments are unused.
// splice returns int instead of int64, because callers never ask it to
// move more data in a single call than can fit in an int32.
func splice(out int, in int, max int, flags int) (int, error) {
	n, err := syscall.Splice(in, nil, out, nil, max, flags)
	return int(n), err
}

// mmap should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - modernc.org/memory
//   - github.com/ncruces/go-sqlite3
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//

Hervé Boutemy <******@****.***> 1706543644 +0100

Hervé Boutemy <******@****.***> 1711313751 +0100

Guillaume Nodet <******@****.***> 1712844394 +0200

Hervé Boutemy <******@****.***> 1706543644 +0100

	clientDown, serverDown := spawnTestSocketPair(t, "tcp")
	defer clientDown.Close()
	defer serverDown.Close()
	// If splice called poll.Splice here, we'd get err == syscall.EINVAL
	// and handled == false.  If poll.Splice gets an EINVAL on the first
	// try, it assumes the kernel it's running on doesn't support splice
	// for unix sockets and returns handled == false. This works for our

	// Streams benefit the most from the splice(2), non-streams are not even supported in old kernels
	// where splice(2) will just return EINVAL; newer kernels support non-streams like UDP, but I really
	// doubt that splice(2) could help non-streams, cuz they usually send small frames respectively
	// and one splice call would result in one frame.

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

package net

import (
	"internal/poll"
	"io"
)

var pollSplice = poll.Splice

// spliceFrom transfers data from r to c using the splice system call to minimize
// copies from and to userspace. c must be a TCP connection.
// Currently, spliceFrom is only enabled if r is a TCP or a stream-oriented Unix connection.
//