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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin dragonfly freebsd linux netbsd openbsd
package net
import (
"io"
"os"
"syscall"
"unsafe"
)
func (c *conn) writeBuffers(v *Buffers) (int64, error) {
if !c.ok() {
return 0, syscall.EINVAL
}
n, err := c.fd.writeBuffers(v)
if err != nil {
return n, &OpError{Op: "writev", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return n, nil
}
func (fd *netFD) writeBuffers(v *Buffers) (n int64, err error) {
if err := fd.writeLock(); err != nil {
return 0, err
}
defer fd.writeUnlock()
if err := fd.pd.prepareWrite(); err != nil {
return 0, err
}
var iovecs []syscall.Iovec
if fd.iovecs != nil {
iovecs = *fd.iovecs
}
// TODO: read from sysconf(_SC_IOV_MAX)? The Linux default is
// 1024 and this seems conservative enough for now. Darwin's
// UIO_MAXIOV also seems to be 1024.
maxVec := 1024
for len(*v) > 0 {
iovecs = iovecs[:0]
for _, chunk := range *v {
if len(chunk) == 0 {
continue
}
iovecs = append(iovecs, syscall.Iovec{Base: &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
}
}
if len(iovecs) == 0 {
break
}
fd.iovecs = &iovecs // cache
wrote, _, e0 := syscall.Syscall(syscall.SYS_WRITEV,
uintptr(fd.sysfd),
uintptr(unsafe.Pointer(&iovecs[0])),
uintptr(len(iovecs)))
if wrote == ^uintptr(0) {
wrote = 0
}
testHookDidWritev(int(wrote))
n += int64(wrote)
v.consume(int64(wrote))
if e0 == syscall.EAGAIN {
if err = fd.pd.waitWrite(); err == nil {
continue
}
} else if e0 != 0 {
err = syscall.Errno(e0)
}
if err != nil {
break
}
if n == 0 {
err = io.ErrUnexpectedEOF
break
}
}
if _, ok := err.(syscall.Errno); ok {
err = os.NewSyscallError("writev", err)
}
return n, err
}
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