return n, err
}

//sys	preadv(fd int, iovs []Iovec, off int64) (n int, err error)

func Preadv(fd int, iovs [][]byte, off int64) (n int, err error) {
	iovecs := bytes2iovec(iovs)
	n, err = preadv(fd, iovecs, off)
	return n, err
}

//sys	writev(fd int, iovs []Iovec) (n int, err error)

func Writev(fd int, iovs [][]byte) (n int, err error) {
	iovecs := bytes2iovec(iovs)
	n, err = writev(fd, iovecs)

	var err error
	for len(*v) > 0 {
		iovecs = iovecs[:0]
		for _, chunk := range *v {
			if len(chunk) == 0 {
				continue
			}
			iovecs = append(iovecs, newIovecWithBase(&chunk[0]))
			if fd.IsStream && len(chunk) > 1<<30 {
				iovecs[len(iovecs)-1].SetLen(1 << 30)
				break // continue chunk on next writev
			}
			iovecs[len(iovecs)-1].SetLen(len(chunk))
			if len(iovecs) == maxVec {
				break
			}
		}

package poll

import (
	"syscall"
	"unsafe"
)

func writev(fd int, iovecs []syscall.Iovec) (uintptr, error) {
	var (
		r uintptr
		e syscall.Errno
	)
	for {
		r, _, e = syscall.Syscall(syscall.SYS_WRITEV, uintptr(fd), uintptr(unsafe.Pointer(&iovecs[0])), uintptr(len(iovecs)))
		if e != syscall.EINTR {
			break
		}
	}
	if e != 0 {
		return r, e
	}
	return r, nil

}

func Readv(fd int, iovs [][]byte) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	n, err = readv(fd, iovecs)
	readvRacedetect(iovecs, n, err)
	return n, err
}

func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	lo, hi := offs2lohi(offset)

//go:build aix || darwin || (openbsd && !mips64) || solaris

package poll

import (
	"syscall"
	_ "unsafe" // for go:linkname
)

//go:linkname writev syscall.writev

// license that can be found in the LICENSE file.

//go:build unix || (js && wasm)

package poll

import "syscall"

type SysFile struct {
	// Writev cache.
	iovecs *[]syscall.Iovec
}

func (s *SysFile) init() {}

func (s *SysFile) destroy(fd int) error {
	// We don't use ignoringEINTR here because POSIX does not define
	// whether the descriptor is closed if close returns EINTR.

}

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func writev(fd int, iovecs []Iovec) (n uintptr, err error) {
	var _p0 *Iovec
	if len(iovecs) > 0 {
		_p0 = &iovecs[0]
	}
	r0, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&libc_writev)), 3, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(len(iovecs)), 0, 0, 0)
	n = uintptr(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

//sys	Umask(newmask int) (oldmask int)
//sys	Unlink(path string) (err error)
//sys	Unmount(path string, flags int) (err error)
//sys	write(fd int, p []byte) (n int, err error)
//sys	writev(fd int, iovecs []Iovec) (n uintptr, err error)
//sys	mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
//sys	munmap(addr uintptr, length uintptr) (err error)

func writev(fd int, iovecs []Iovec) (n uintptr, err error) {
	var _p0 unsafe.Pointer
	if len(iovecs) > 0 {
		_p0 = unsafe.Pointer(&iovecs[0])
	} else {
		_p0 = unsafe.Pointer(&_zero)
	}
	r0, _, e1 := syscallX(abi.FuncPCABI0(libc_writev_trampoline), uintptr(fd), uintptr(_p0), uintptr(len(iovecs)))
	n = uintptr(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}

}

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func writev(fd int, iovecs []Iovec) (n uintptr, err error) {
	var _p0 *Iovec
	if len(iovecs) > 0 {
		_p0 = &iovecs[0]
	}
	r0, _, e1 := syscall6(uintptr(unsafe.Pointer(&libc_writev)), 3, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(len(iovecs)), 0, 0, 0)
	n = uintptr(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}