From 8f32f1724fce55699a7a9675390c1c2b292190a4 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@datawire.io>
Date: Wed, 14 Aug 2019 21:51:23 -0400
Subject: Unify notify.go and notify_nonlinux.go a bit

---
 sd_daemon/notify.go | 95 ++++-------------------------------------------------
 1 file changed, 7 insertions(+), 88 deletions(-)

(limited to 'sd_daemon/notify.go')

diff --git a/sd_daemon/notify.go b/sd_daemon/notify.go
index 917e2d4..9591613 100644
--- a/sd_daemon/notify.go
+++ b/sd_daemon/notify.go
@@ -3,7 +3,7 @@
 //
 // Copyright 2013, 2015 Docker, Inc.
 // Copyright 2014 CoreOS, Inc.
-// Copyright 2015-2018 Luke Shumaker
+// Copyright 2015-2019 Luke Shumaker
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -17,16 +17,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build linux
-
 package sd_daemon
 
 import (
-	"bytes"
-	"net"
 	"os"
-
-	"golang.org/x/sys/unix"
 )
 
 // Notification is a message to be sent to the service manager about
@@ -36,6 +30,11 @@ type Notification struct {
 	// If PID <= 0, or if the current process does not have
 	// privileges to send messages on behalf of other processes,
 	// then the message is simply sent from the current process.
+	//
+	// BUG(lukeshu): Spoofing the PID is not implemented on
+	// non-Linux kernels.  If you are knowledgable about how to do
+	// this on other kernels, please let me know at
+	// <lukeshu@lukeshu.com>!
 	PID int
 
 	// State should contain a newline-separated list of variable
@@ -75,85 +74,5 @@ type Notification struct {
 // support both service managers that support these notifications and
 // those that do not.
 func (msg Notification) Send(unsetEnv bool) error {
-	if unsetEnv {
-		defer func() { _ = os.Unsetenv("NOTIFY_SOCKET") }()
-	}
-
-	socketAddr := &net.UnixAddr{
-		Name: os.Getenv("NOTIFY_SOCKET"),
-		Net:  "unixgram",
-	}
-
-	if socketAddr.Name == "" {
-		return ErrDisabled
-	}
-
-	conn, err := socketUnixgram(socketAddr.Name)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = conn.Close() }()
-
-	var cmsgs [][]byte
-
-	if len(msg.Files) > 0 {
-		fds := make([]int, len(msg.Files))
-		for i := range msg.Files {
-			fds[i] = int(msg.Files[i].Fd())
-		}
-		cmsg := unix.UnixRights(fds...)
-		cmsgs = append(cmsgs, cmsg)
-	}
-
-	havePid := msg.PID > 0 && msg.PID != os.Getpid()
-	if havePid {
-		cmsg := unix.UnixCredentials(&unix.Ucred{
-			Pid: int32(msg.PID),
-			Uid: uint32(os.Getuid()),
-			Gid: uint32(os.Getgid()),
-		})
-		cmsgs = append(cmsgs, cmsg)
-	}
-
-	// If the 2nd argument is empty, this is equivalent to
-	//
-	//    conn, _ := net.DialUnix(socketAddr.Net, nil, socketAddr)
-	//    conn.Write([]byte(msg.State))
-	_, _, err = conn.WriteMsgUnix([]byte(msg.State), bytes.Join(cmsgs, nil), socketAddr)
-
-	if err != nil && havePid {
-		// Maybe it failed because we don't have privileges to
-		// spoof our pid; retry without spoofing the pid.
-		//
-		// I'm not too happy that we do this silently without
-		// notifying the caller, but that's what
-		// sd_pid_notify_with_fds does.
-		cmsgs = cmsgs[:len(cmsgs)-1]
-		_, _, err = conn.WriteMsgUnix([]byte(msg.State), bytes.Join(cmsgs, nil), socketAddr)
-	}
-
-	return err
-}
-
-// socketUnixgram wraps socket(2), but doesn't bind(2) or connect(2)
-// the socket to anything.  This is an ugly hack because none of the
-// functions in "net" actually allow you to get a AF_UNIX socket not
-// bound/connected to anything.
-//
-// At some point you begin to question if it is worth it to keep up
-// the high-level interface of "net", and messing around with FileConn
-// and UnixConn.  Maybe we just drop to using unix.Socket and
-// unix.SendmsgN directly.
-func socketUnixgram(name string) (*net.UnixConn, error) {
-	fd, err := unix.Socket(unix.AF_UNIX, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
-	if err != nil {
-		return nil, os.NewSyscallError("socket", err)
-	}
-	defer unix.Close(fd)
-	conn, err := net.FileConn(os.NewFile(uintptr(fd), name))
-	if err != nil {
-		return nil, err
-	}
-	unixConn := conn.(*net.UnixConn)
-	return unixConn, nil
+	return msg.send(unsetEnv)
 }
-- 
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