From 5e0bec20c6359c92819510601b33265539135450 Mon Sep 17 00:00:00 2001
From: Jose Ignacio Lorenzo <74208929+joselo85@users.noreply.github.com>
Date: Wed, 19 Oct 2022 17:35:46 -0300
Subject: [PATCH] [CONSUL-519] Implement mkfifo Alternative (#84)

---
 command/connect/envoy/exec_unsupported.go |   4 +-
 command/connect/envoy/exec_windows.go     | 121 ++++++++++++++++++++++
 2 files changed, 123 insertions(+), 2 deletions(-)
 create mode 100644 command/connect/envoy/exec_windows.go

diff --git a/command/connect/envoy/exec_unsupported.go b/command/connect/envoy/exec_unsupported.go
index d22b4c8cdf23..4125a021e80b 100644
--- a/command/connect/envoy/exec_unsupported.go
+++ b/command/connect/envoy/exec_unsupported.go
@@ -1,5 +1,5 @@
-//go:build !linux && !darwin
-// +build !linux,!darwin
+//go:build !linux && !darwin && !windows
+// +build !linux,!darwin,!windows
 
 package envoy
 
diff --git a/command/connect/envoy/exec_windows.go b/command/connect/envoy/exec_windows.go
new file mode 100644
index 000000000000..e274c1b0b596
--- /dev/null
+++ b/command/connect/envoy/exec_windows.go
@@ -0,0 +1,121 @@
+//go:build windows
+// +build windows
+
+package envoy
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+
+	"path/filepath"
+	"strings"
+
+	"time"
+)
+
+// testSelfExecOverride is a way for the tests to no fork-bomb themselves by
+// self-executing the whole test suite for each case recursively. It's gross but
+// the least gross option I could think of.
+var testSelfExecOverride string
+
+func isHotRestartOption(s string) bool {
+	restartOpts := []string{
+		"--restart-epoch",
+		"--hot-restart-version",
+		"--drain-time-s",
+		"--parent-shutdown-time-s",
+	}
+	for _, opt := range restartOpts {
+		if s == opt {
+			return true
+		}
+		if strings.HasPrefix(s, opt+"=") {
+			return true
+		}
+	}
+	return false
+}
+
+func hasHotRestartOption(argSets ...[]string) bool {
+	for _, args := range argSets {
+		for _, opt := range args {
+			if isHotRestartOption(opt) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func makeBootstrapTemp(bootstrapJSON []byte) (string, error) {
+	tempFile := filepath.Join(os.TempDir(),
+		fmt.Sprintf("envoy-%x-bootstrap.json", time.Now().UnixNano()+int64(os.Getpid())))
+
+	f, err := os.Create(tempFile)
+	if err != nil {
+		return tempFile, err
+	}
+
+	defer f.Close()
+	f.Write(bootstrapJSON)
+	f.Sync()
+
+	// We can't wait for the process since we need to exec into Envoy before it
+	// will be able to complete so it will be remain as a zombie until Envoy is
+	// killed then will be reaped by the init process (pid 0). This is all a bit
+	// gross but the cleanest workaround I can think of for Envoy 1.10 not
+	// supporting /dev/fd/<fd> config paths any more. So we are done and leaving
+	// the child to run it's course without reaping it.
+	return tempFile, nil
+}
+
+func startProc(binary string, args []string) (p *os.Process, err error) {
+	if binary, err = exec.LookPath(binary); err == nil {
+		var procAttr os.ProcAttr
+		procAttr.Files = []*os.File{os.Stdin,
+			os.Stdout, os.Stderr}
+		p, err := os.StartProcess(binary, args, &procAttr)
+		if err == nil {
+			return p, nil
+		}
+	}
+	return nil, err
+}
+
+func execEnvoy(binary string, prefixArgs, suffixArgs []string, bootstrapJSON []byte) error {
+	tempFile, err := makeBootstrapTemp(bootstrapJSON)
+	if err != nil {
+		os.RemoveAll(tempFile)
+		return err
+	}
+	// We don't defer a cleanup since we are about to Exec into Envoy which means
+	// defer will never fire. The child process cleans up for us in the happy
+	// path.
+
+	// We default to disabling hot restart because it makes it easier to run
+	// multiple envoys locally for testing without them trying to share memory and
+	// unix sockets and complain about being different IDs. But if user is
+	// actually configuring hot-restart explicitly with the --restart-epoch option
+	// then don't disable it!
+	disableHotRestart := !hasHotRestartOption(prefixArgs, suffixArgs)
+
+	// First argument needs to be the executable name.
+	envoyArgs := []string{}
+	envoyArgs = append(envoyArgs, prefixArgs...)
+	if disableHotRestart {
+		envoyArgs = append(envoyArgs, "--disable-hot-restart")
+	}
+	envoyArgs = append(envoyArgs, suffixArgs...)
+	envoyArgs = append(envoyArgs, "--config-path", tempFile)
+
+	// Exec
+	if proc, err := startProc(binary, envoyArgs); err == nil {
+		proc.Wait()
+	} else if err != nil {
+		return errors.New("Failed to exec envoy: " + err.Error())
+	}
+
+	return nil
+}