274 lines
8.1 KiB
Go
274 lines
8.1 KiB
Go
/*
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* Minimalist Object Storage, (C) 2015 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package nimble
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import (
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"fmt"
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"net"
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"os"
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"os/exec"
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"strconv"
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"strings"
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"sync"
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"github.com/minio/minio/pkg/iodine"
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)
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// This package originally from https://github.com/facebookgo/grace
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//
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// Re-licensing with Apache License 2.0, with code modifications
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// This package provides a family of Listen functions that either open a
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// fresh connection or provide an inherited connection from when the process
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// was started. This behaves like their counterparts in the net pacakge, but
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// transparently provide support for graceful restarts without dropping
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// connections. This is provided in a systemd socket activation compatible form
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// to allow using socket activation.
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//
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const (
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// Used to indicate a graceful restart in the new process.
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envCountKey = "LISTEN_FDS" // similar to systemd SDS_LISTEN_FDS
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envCountKeyPrefix = envCountKey + "="
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)
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// In order to keep the working directory the same as when we started we record
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// it at startup.
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var originalWD, _ = os.Getwd()
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// nimbleNet provides the family of Listen functions and maintains the associated
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// state. Typically you will have only once instance of nimbleNet per application.
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type nimbleNet struct {
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inheritedListeners []net.Listener
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activeListeners []net.Listener
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mutex sync.Mutex
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inheritOnce sync.Once
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}
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// nimbleAddr simple wrapper over net.Addr interface to implement IsEqual()
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type nimbleAddr struct {
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net.Addr
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}
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// fileListener simple interface to extract file pointers from different types of net.Listener's
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type fileListener interface {
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File() (*os.File, error)
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}
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// getInheritedListeners - look for LISTEN_FDS in environment variables and populate listeners accordingly
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func (n *nimbleNet) getInheritedListeners() error {
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var retErr error
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n.inheritOnce.Do(func() {
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n.mutex.Lock()
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defer n.mutex.Unlock()
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countStr := os.Getenv(envCountKey)
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if countStr == "" {
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return
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}
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count, err := strconv.Atoi(countStr)
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if err != nil {
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retErr = fmt.Errorf("found invalid count value: %s=%s", envCountKey, countStr)
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return
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}
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fdStart := 3
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for i := fdStart; i < fdStart+count; i++ {
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file := os.NewFile(uintptr(i), "listener")
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l, err := net.FileListener(file)
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if err != nil {
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file.Close()
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retErr = fmt.Errorf("error inheriting socket fd %d: %s", i, err)
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return
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}
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if err := file.Close(); err != nil {
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retErr = fmt.Errorf("error closing inherited socket fd %d: %s", i, err)
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return
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}
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n.inheritedListeners = append(n.inheritedListeners, l)
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}
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})
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return iodine.New(retErr, nil)
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}
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// Listen announces on the local network address laddr. The network net must be
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// a stream-oriented network: "tcp", "tcp4", "tcp6", "unix" or "unixpacket". It
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// returns an inherited net.Listener for the matching network and address, or
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// creates a new one using net.Listen()
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func (n *nimbleNet) Listen(nett, laddr string) (net.Listener, error) {
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switch nett {
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default:
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return nil, net.UnknownNetworkError(nett)
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case "tcp", "tcp4", "tcp6":
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addr, err := net.ResolveTCPAddr(nett, laddr)
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if err != nil {
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return nil, iodine.New(err, nil)
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}
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return n.ListenTCP(nett, addr)
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case "unix", "unixpacket":
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addr, err := net.ResolveUnixAddr(nett, laddr)
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if err != nil {
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return nil, iodine.New(err, nil)
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}
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return n.ListenUnix(nett, addr)
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}
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}
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// ListenTCP announces on the local network address laddr. The network net must
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// be: "tcp", "tcp4" or "tcp6". It returns an inherited net.Listener for the
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// matching network and address, or creates a new one using net.ListenTCP.
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func (n *nimbleNet) ListenTCP(nett string, laddr *net.TCPAddr) (*net.TCPListener, error) {
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if err := n.getInheritedListeners(); err != nil {
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return nil, iodine.New(err, nil)
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}
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n.mutex.Lock()
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defer n.mutex.Unlock()
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// look for an inherited listener
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for i, l := range n.inheritedListeners {
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if l == nil { // we nil used inherited listeners
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continue
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}
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equal := nimbleAddr{l.Addr()}.IsEqual(laddr)
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if equal {
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n.inheritedListeners[i] = nil
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n.activeListeners = append(n.activeListeners, l)
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return l.(*net.TCPListener), nil
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}
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}
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// make a fresh listener
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l, err := net.ListenTCP(nett, laddr)
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if err != nil {
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return nil, iodine.New(err, nil)
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}
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n.activeListeners = append(n.activeListeners, l)
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return l, nil
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}
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// ListenUnix announces on the local network address laddr. The network net
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// must be a: "unix" or "unixpacket". It returns an inherited net.Listener for
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// the matching network and address, or creates a new one using net.ListenUnix.
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func (n *nimbleNet) ListenUnix(nett string, laddr *net.UnixAddr) (*net.UnixListener, error) {
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if err := n.getInheritedListeners(); err != nil {
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return nil, iodine.New(err, nil)
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}
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n.mutex.Lock()
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defer n.mutex.Unlock()
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// look for an inherited listener
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for i, l := range n.inheritedListeners {
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if l == nil { // we nil used inherited listeners
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continue
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}
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equal := nimbleAddr{l.Addr()}.IsEqual(laddr)
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if equal {
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n.inheritedListeners[i] = nil
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n.activeListeners = append(n.activeListeners, l)
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return l.(*net.UnixListener), nil
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}
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}
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// make a fresh listener
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l, err := net.ListenUnix(nett, laddr)
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if err != nil {
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return nil, iodine.New(err, nil)
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}
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n.activeListeners = append(n.activeListeners, l)
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return l, nil
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}
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// activeListeners returns a snapshot copy of the active listeners.
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func (n *nimbleNet) getActiveListeners() ([]net.Listener, error) {
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n.mutex.Lock()
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defer n.mutex.Unlock()
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ls := make([]net.Listener, len(n.activeListeners))
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copy(ls, n.activeListeners)
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return ls, nil
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}
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// IsEqual is synonymous with IP.IsEqual() method, here IsEqual matches net.Addr instead of net.IP
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func (n1 nimbleAddr) IsEqual(n2 net.Addr) bool {
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if n1.Network() != n2.Network() {
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return false
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}
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a1h, a1p, _ := net.SplitHostPort(n1.String())
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a2h, a2p, _ := net.SplitHostPort(n2.String())
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// Special cases since Addr() from net.Listener will
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// add frivolous [::] ipv6 for no ":[PORT]" style addresses
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if a1h == "::" && a2h == "" && a1p == a2p {
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return true
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}
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if a2h == "::" && a1h == "" && a1p == a2p {
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return true
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}
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if net.ParseIP(a1h).Equal(net.ParseIP(a2h)) && a1p == a2p {
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return true
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}
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return false
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}
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// StartProcess starts a new process passing it the active listeners. It
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// doesn't fork, but starts a new process using the same environment and
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// arguments as when it was originally started. This allows for a newly
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// deployed binary to be started. It returns the pid of the newly started
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// process when successful.
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func (n *nimbleNet) StartProcess() (int, error) {
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listeners, err := n.getActiveListeners()
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if err != nil {
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return 0, iodine.New(err, nil)
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}
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// Extract the fds from the listeners.
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files := make([]*os.File, len(listeners))
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for i, l := range listeners {
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files[i], err = l.(fileListener).File()
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if err != nil {
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return 0, iodine.New(err, nil)
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}
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defer files[i].Close()
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}
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// Use the original binary location. This works with symlinks such that if
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// the file it points to has been changed we will use the updated symlink.
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argv0, err := exec.LookPath(os.Args[0])
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if err != nil {
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return 0, iodine.New(err, nil)
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}
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// Pass on the environment and replace the old count key with the new one.
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var env []string
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for _, v := range os.Environ() {
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if !strings.HasPrefix(v, envCountKeyPrefix) {
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env = append(env, v)
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}
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}
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env = append(env, fmt.Sprintf("%s%d", envCountKeyPrefix, len(listeners)))
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allFiles := append([]*os.File{os.Stdin, os.Stdout, os.Stderr}, files...)
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process, err := os.StartProcess(argv0, os.Args, &os.ProcAttr{
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Dir: originalWD,
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Env: env,
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Files: allFiles,
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})
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if err != nil {
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return 0, iodine.New(err, nil)
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}
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return process.Pid, nil
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}
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