Commit ea5825b0 authored by Nick Patavalis's avatar Nick Patavalis Committed by Ian Lance Taylor

os: use poller when NewFile is called with a blocking descriptor.

If NewFile is called with a file descriptor that is already set to
non-blocking mode, it tries to return a pollable file (one for which
SetDeadline methods work) by adding the filedes to the poll/netpoll
mechanism. If called with a filedes in blocking mode, it returns a
non-pollable file, as it always did.

Fixes #22939
Updates #24331

Change-Id: Id54c8be1b83e6d35e14e76d7df0e57a9fd64e176
Reviewed-on: https://go-review.googlesource.com/100077
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: default avatarIan Lance Taylor <iant@golang.org>
parent ab48574b
......@@ -158,7 +158,7 @@ var pkgDeps = map[string][]string{
"internal/poll": {"L0", "internal/race", "syscall", "time", "unicode/utf16", "unicode/utf8", "internal/syscall/windows"},
"internal/testlog": {"L0"},
"os": {"L1", "os", "syscall", "time", "internal/poll", "internal/syscall/windows", "internal/testlog"},
"os": {"L1", "os", "syscall", "time", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/testlog"},
"path/filepath": {"L2", "os", "syscall", "internal/syscall/windows"},
"io/ioutil": {"L2", "os", "path/filepath", "time"},
"os/exec": {"L2", "os", "context", "path/filepath", "syscall"},
......
// Copyright 2018 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.
// This file is here just to make the go tool happy. It allows
// empty function declarations (no function body).
// It is used with "go:linkname".
// Copyright 2018 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 solaris
package unix
import (
"syscall"
_ "unsafe" // for go:linkname
)
//go:linkname syscall_fcntl syscall.fcntl
func syscall_fcntl(fd int, cmd int, arg int) (val int, err error)
func IsNonblock(fd int) (nonblocking bool, err error) {
flag, err := syscall_fcntl(fd, syscall.F_GETFL, 0)
if err != nil {
return false, err
}
return flag&syscall.O_NONBLOCK != 0, nil
}
// Copyright 2018 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.
package unix
func IsNonblock(fd int) (nonblocking bool, err error) {
return false, nil
}
......@@ -404,6 +404,12 @@ var testedAlreadyLeaked = false
// stdin, stdout, stderr, epoll/kqueue, maybe testlog
func basefds() uintptr {
n := os.Stderr.Fd() + 1
// The poll (epoll/kqueue) descriptor can be numerically
// either between stderr and the testlog-fd, or after
// testlog-fd.
if poll.PollDescriptor() == n {
n++
}
for _, arg := range os.Args {
if strings.HasPrefix(arg, "-test.testlogfile=") {
n++
......
......@@ -8,6 +8,7 @@ package os
import (
"internal/poll"
"internal/syscall/unix"
"runtime"
"syscall"
)
......@@ -74,9 +75,15 @@ func (f *File) Fd() uintptr {
// NewFile returns a new File with the given file descriptor and
// name. The returned value will be nil if fd is not a valid file
// descriptor.
// descriptor. On Unix systems, if the file descriptor is in
// non-blocking mode, NewFile will attempt to return a pollable File
// (one for which the SetDeadline methods work).
func NewFile(fd uintptr, name string) *File {
return newFile(fd, name, kindNewFile)
kind := kindNewFile
if nb, err := unix.IsNonblock(int(fd)); err == nil && nb {
kind = kindNonBlock
}
return newFile(fd, name, kind)
}
// newFileKind describes the kind of file to newFile.
......@@ -86,6 +93,7 @@ const (
kindNewFile newFileKind = iota
kindOpenFile
kindPipe
kindNonBlock
)
// newFile is like NewFile, but if called from OpenFile or Pipe
......@@ -109,11 +117,14 @@ func newFile(fd uintptr, name string, kind newFileKind) *File {
// Don't try to use kqueue with regular files on FreeBSD.
// It crashes the system unpredictably while running all.bash.
// Issue 19093.
// If the caller passed a non-blocking filedes (kindNonBlock),
// we assume they know what they are doing so we allow it to be
// used with kqueue.
if runtime.GOOS == "freebsd" && kind == kindOpenFile {
kind = kindNewFile
}
pollable := kind == kindOpenFile || kind == kindPipe
pollable := kind == kindOpenFile || kind == kindPipe || kind == kindNonBlock
if err := f.pfd.Init("file", pollable); err != nil {
// An error here indicates a failure to register
// with the netpoll system. That can happen for
......
......@@ -15,6 +15,7 @@ import (
"strings"
"syscall"
"testing"
"time"
)
func init() {
......@@ -224,3 +225,56 @@ func TestMkdirStickyUmask(t *testing.T) {
t.Errorf("unexpected mode %s", mode)
}
}
// See also issues: 22939, 24331
func newFileTest(t *testing.T, blocking bool) {
p := make([]int, 2)
if err := syscall.Pipe(p); err != nil {
t.Fatalf("pipe: %v", err)
}
defer syscall.Close(p[1])
// Set the the read-side to non-blocking.
if !blocking {
if err := syscall.SetNonblock(p[0], true); err != nil {
syscall.Close(p[0])
t.Fatalf("SetNonblock: %v", err)
}
}
// Convert it to a file.
file := NewFile(uintptr(p[0]), "notapipe")
if file == nil {
syscall.Close(p[0])
t.Fatalf("failed to convert fd to file!")
}
defer file.Close()
// Try to read with deadline (but don't block forever).
b := make([]byte, 1)
// Send something after 100ms.
timer := time.AfterFunc(100*time.Millisecond, func() { syscall.Write(p[1], []byte("a")) })
defer timer.Stop()
file.SetReadDeadline(time.Now().Add(10 * time.Millisecond))
_, err := file.Read(b)
if !blocking {
// We want it to fail with a timeout.
if !IsTimeout(err) {
t.Fatalf("No timeout reading from file: %v", err)
}
} else {
// We want it to succeed after 100ms
if err != nil {
t.Fatalf("Error reading from file: %v", err)
}
}
}
func TestNewFileBlock(t *testing.T) {
t.Parallel()
newFileTest(t, true)
}
func TestNewFileNonBlock(t *testing.T) {
t.Parallel()
newFileTest(t, false)
}
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