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// +build !windows
/*
Copyright 2015 The Kubernetes Authors All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package redirfd
import (
"fmt"
"os"
"syscall"
)
type RedirectMode int
const (
Read RedirectMode = iota // open file for reading
Write // open file for writing, truncating if it exists
Update // open file for read & write
Append // open file for append, create if it does not exist
AppendExisting // open file for append, do not create if it does not already exist
WriteNew // open file for writing, creating it, failing if it already exists
)
// see https://github.com/skarnet/execline/blob/master/src/execline/redirfd.c
func (mode RedirectMode) Redirect(nonblock, changemode bool, fd FileDescriptor, name string) (*os.File, error) {
flags := 0
what := -1
switch mode {
case Read:
what = syscall.O_RDONLY
flags &= ^(syscall.O_APPEND | syscall.O_CREAT | syscall.O_TRUNC | syscall.O_EXCL)
case Write:
what = syscall.O_WRONLY
flags |= syscall.O_CREAT | syscall.O_TRUNC
flags &= ^(syscall.O_APPEND | syscall.O_EXCL)
case Update:
what = syscall.O_RDWR
flags &= ^(syscall.O_APPEND | syscall.O_CREAT | syscall.O_TRUNC | syscall.O_EXCL)
case Append:
what = syscall.O_WRONLY
flags |= syscall.O_CREAT | syscall.O_APPEND
flags &= ^(syscall.O_TRUNC | syscall.O_EXCL)
case AppendExisting:
what = syscall.O_WRONLY
flags |= syscall.O_APPEND
flags &= ^(syscall.O_CREAT | syscall.O_TRUNC | syscall.O_EXCL)
case WriteNew:
what = syscall.O_WRONLY
flags |= syscall.O_CREAT | syscall.O_EXCL
flags &= ^(syscall.O_APPEND | syscall.O_TRUNC)
default:
return nil, fmt.Errorf("unexpected mode %d", mode)
}
if nonblock {
flags |= syscall.O_NONBLOCK
}
flags |= what
fd2, e := open(name, flags, 0666)
if (what == syscall.O_WRONLY) && (e == syscall.ENXIO) {
// Opens file in read-only, non-blocking mode. Returns a valid fd number if it succeeds, or -1 (and sets errno) if it fails.
fdr, e2 := open(name, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
if e2 != nil {
return nil, &os.PathError{Op: "open_read", Path: name, Err: e2}
}
fd2, e = open(name, flags, 0666)
fd_close(fdr)
}
if e != nil {
return nil, &os.PathError{Op: "open", Path: name, Err: e}
}
if e = fd_move(fd, fd2); e != nil {
return nil, &os.PathError{Op: "fd_move", Path: name, Err: e}
}
if changemode {
if nonblock {
e = ndelay_off(fd)
} else {
e = ndelay_on(fd)
}
if e != nil {
return nil, &os.PathError{Op: "ndelay", Path: name, Err: e}
}
}
return os.NewFile(uintptr(fd2), name), nil
}
// proxy to return a FileDescriptor
func open(path string, openmode int, perm uint32) (FileDescriptor, error) {
fdint, err := syscall.Open(path, openmode, perm)
return FileDescriptor(fdint), err
}
// see https://github.com/skarnet/skalibs/blob/master/src/libstddjb/fd_move.c
func fd_move(to, from FileDescriptor) (err error) {
if to == from {
return
}
for {
_, _, e1 := syscall.RawSyscall(syscall.SYS_DUP2, uintptr(from), uintptr(to), 0)
if e1 != syscall.EINTR {
if e1 != 0 {
err = e1
}
break
}
}
if err != nil {
err = fd_close(from)
}
return
/*
do
r = dup2(from, to) ;
while ((r == -1) && (errno == EINTR)) ;
return (r == -1) ? -1 : fd_close(from) ;
*/
}
// see https://github.com/skarnet/skalibs/blob/master/src/libstddjb/fd_close.c
func fd_close(fd FileDescriptor) (err error) {
i := 0
var e error
for {
if e = syscall.Close(int(fd)); e != nil {
return nil
}
i++
if e != syscall.EINTR {
break
}
}
if e == syscall.EBADF && i > 1 {
return nil
}
return e
}
/*
int fd_close (int fd)
{
register unsigned int i = 0 ;
doit:
if (!close(fd)) return 0 ;
i++ ;
if (errno == EINTR) goto doit ;
return ((errno == EBADF) && (i > 1)) ? 0 : -1 ;
}
*/
// see https://github.com/skarnet/skalibs/blob/master/src/libstddjb/ndelay_on.c
func ndelay_on(fd FileDescriptor) error {
// 32-bit will likely break because it needs SYS_FCNTL64
got, _, e := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(syscall.F_GETFL), 0)
if e != 0 {
return e
}
_, _, e = syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(syscall.F_SETFL), uintptr(got|syscall.O_NONBLOCK))
if e != 0 {
return e
}
return nil
}
/*
int ndelay_on (int fd)
{
register int got = fcntl(fd, F_GETFL) ;
return (got == -1) ? -1 : fcntl(fd, F_SETFL, got | O_NONBLOCK) ;
}
*/
// see https://github.com/skarnet/skalibs/blob/master/src/libstddjb/ndelay_off.c
func ndelay_off(fd FileDescriptor) error {
// 32-bit will likely break because it needs SYS_FCNTL64
got, _, e := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(syscall.F_GETFL), 0)
if e != 0 {
return e
}
_, _, e = syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), uintptr(syscall.F_SETFL), uintptr(int(got) & ^syscall.O_NONBLOCK))
if e != 0 {
return e
}
return nil
}
/*
int ndelay_off (int fd)
{
register int got = fcntl(fd, F_GETFL) ;
return (got == -1) ? -1 : fcntl(fd, F_SETFL, got & ^O_NONBLOCK) ;
}
*/
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