}
	defer out.Close()

	// Try fallocate first.
	for {
		err = out.fallocate(1 << 10)
		if errors.Is(err, errors.ErrUnsupported) || err == errNoFallocate { // The underlying file system may not support fallocate
			t.Skip("fallocate is not supported")
		}
		if err == syscall.EINTR {
			continue // try again
		}
		if err != nil {
			t.Fatalf("fallocate failed: %v", err)
		}
		break
	}

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

package ld

import "syscall"

func (out *OutBuf) fallocate(size uint64) error {
	return syscall.Fallocate(int(out.f.Fd()), 0, 0, int64(size))

func (out *OutBuf) Mmap(filesize uint64) (err error) {
	oldlen := len(out.buf)
	if oldlen != 0 {
		out.munmap()
	}

	for {
		if err = out.fallocate(filesize); err != syscall.EINTR {
			break
		}
	}
	if err != nil {
		// Some file systems do not support fallocate. We ignore that error as linking
		// can still take place, but you might SIGBUS when you write to the mmapped
		// area.

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

//go:build !darwin && !(freebsd && go1.21) && !linux

package ld

func (out *OutBuf) fallocate(size uint64) error {
	return errNoFallocate

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

//go:build freebsd && go1.21

package ld

import (
	"internal/syscall/unix"
	"syscall"
)

func (out *OutBuf) fallocate(size uint64) error {
	err := unix.PosixFallocate(int(out.f.Fd()), 0, int64(size))
	// ZFS on FreeBSD does not support posix_fallocate and returns EINVAL in that case.
	if err == syscall.EINVAL {
		return errNoFallocate
	}

func (out *OutBuf) fallocate(size uint64) error {
	stat, err := out.f.Stat()
	if err != nil {
		return err
	}
	// F_PEOFPOSMODE allocates from the end of the file, so we want the size difference.
	// Apparently, it uses the end of the allocation, instead of the logical end of the
	// file.
	cursize := uint64(stat.Sys().(*syscall.Stat_t).Blocks * 512) // allocated size
	if size <= cursize {
		return nil
	}

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

package ld

import (
	"cmd/internal/sys"
	"cmd/link/internal/loader"
	"encoding/binary"
	"errors"
	"log"
	"os"
)

// If fallocate is not supported on this platform, return this error. The error
// is ignored where needed, and OutBuf writes to heap memory.
var errNoFallocate = errors.New("operation not supported")

const outbufMode = 0775

	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

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

func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
	_, _, e1 := Syscall6(SYS_FALLOCATE, uintptr(fd), uintptr(mode), uintptr(off), uintptr(off>>32), uintptr(len), uintptr(len>>32))
	if e1 != 0 {
		err = errnoErr(e1)
	}

	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

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

func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
	_, _, e1 := Syscall6(SYS_FALLOCATE, uintptr(fd), uintptr(mode), uintptr(off), uintptr(len), 0, 0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

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

func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
	_, _, e1 := Syscall6(SYS_FALLOCATE, uintptr(fd), uintptr(mode), uintptr(off), uintptr(len), 0, 0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}