Switch to a new installer approach using a path manipulation helper

Fixes #11089 - cleanup PATH on MSI uninstall
Additionally fixes scenarios where the path can be overwritten by setx
Also removes the console flash, since the helper is built as a silent gui
Helper executable can be rerun by user to repair PATHs broken by other tools
Utilizes executable location instead of passed parameters to remove delicate escaping requirements

[NO NEW TESTS NEEDED]

Signed-off-by: Jason T. Greene <jason.greene@redhat.com>

1 files changed, 184 insertions, 0 deletions

diff --git a/cmd/winpath/main.go b/cmd/winpath/main.go
new file mode 100644
index 000000000..494d1cf3c
--- /dev/null
+++ b/cmd/winpath/main.go
@@ -0,0 +1,184 @@
+//go:build windows
+// +build windows
+
+package main
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+type operation int
+
+const (
+	HWND_BROADCAST             = 0xFFFF
+	WM_SETTINGCHANGE           = 0x001A
+	SMTO_ABORTIFHUNG           = 0x0002
+	ERR_BAD_ARGS               = 0x000A
+	OPERATION_FAILED           = 0x06AC
+	Environment                = "Environment"
+	Add              operation = iota
+	Remove
+	NotSpecified
+)
+
+func main() {
+	op := NotSpecified
+	if len(os.Args) >= 2 {
+		switch os.Args[1] {
+		case "add":
+			op = Add
+		case "remove":
+			op = Remove
+		}
+	}
+
+	// Stay silent since ran from an installer
+	if op == NotSpecified {
+		alert("Usage: " + filepath.Base(os.Args[0]) + " [add|remove]\n\nThis utility adds or removes the podman directory to the Windows Path.")
+		os.Exit(ERR_BAD_ARGS)
+	}
+
+	if err := modify(op); err != nil {
+		os.Exit(OPERATION_FAILED)
+	}
+}
+
+func modify(op operation) error {
+	exe, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	exe, err = filepath.EvalSymlinks(exe)
+	if err != nil {
+		return err
+	}
+	target := filepath.Dir(exe)
+
+	if op == Remove {
+		return removePathFromRegistry(target)
+	}
+
+	return addPathToRegistry(target)
+}
+
+// Appends a directory to the Windows Path stored in the registry
+func addPathToRegistry(dir string) error {
+	k, _, err := registry.CreateKey(registry.CURRENT_USER, Environment, registry.WRITE|registry.READ)
+	if err != nil {
+		return err
+	}
+
+	defer k.Close()
+
+	existing, typ, err := k.GetStringValue("Path")
+	if err != nil {
+		return err
+	}
+
+	// Is this directory already on the windows path?
+	for _, element := range strings.Split(existing, ";") {
+		if strings.EqualFold(element, dir) {
+			// Path already added
+			return nil
+		}
+	}
+
+	// If the existing path is empty we don't want to start with a delimiter
+	if len(existing) > 0 {
+		existing += ";"
+	}
+
+	existing += dir
+
+	// It's important to preserve the registry key type so that it will be interpreted correctly
+	// EXPAND = evaluate variables in the expression, e.g. %PATH% should be expanded to the system path
+	// STRING = treat the contents as a string literal
+	if typ == registry.EXPAND_SZ {
+		err = k.SetExpandStringValue("Path", existing)
+	} else {
+		err = k.SetStringValue("Path", existing)
+	}
+
+	if err == nil {
+		broadcastEnvironmentChange()
+	}
+
+	return err
+}
+
+// Removes all occurences of a directory path from the Windows path stored in the registry
+func removePathFromRegistry(path string) error {
+	k, err := registry.OpenKey(registry.CURRENT_USER, Environment, registry.READ|registry.WRITE)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			// Nothing to cleanup, the Environment registry key does not exist.
+			return nil
+		}
+		return err
+	}
+
+	defer k.Close()
+
+	existing, typ, err := k.GetStringValue("Path")
+	if err != nil {
+		return err
+	}
+
+	var elements []string
+	for _, element := range strings.Split(existing, ";") {
+		if strings.EqualFold(element, path) {
+			continue
+		}
+		elements = append(elements, element)
+	}
+
+	newPath := strings.Join(elements, ";")
+	// Preserve value type (see corresponding comment above)
+	if typ == registry.EXPAND_SZ {
+		err = k.SetExpandStringValue("Path", newPath)
+	} else {
+		err = k.SetStringValue("Path", newPath)
+	}
+
+	if err == nil {
+		broadcastEnvironmentChange()
+	}
+
+	return err
+}
+
+// Sends a notification message to all top level windows informing them the environmental setings have changed.
+// Applications such as the Windows command prompt and powershell will know to stop caching stale values on
+// subsequent restarts. Since applications block the sender when receiving a message, we set a 3 second timeout
+func broadcastEnvironmentChange() {
+	env, _ := syscall.UTF16PtrFromString(Environment)
+	user32 := syscall.NewLazyDLL("user32")
+	proc := user32.NewProc("SendMessageTimeoutW")
+	millis := 3000
+	_, _, _ = proc.Call(HWND_BROADCAST, WM_SETTINGCHANGE, 0, uintptr(unsafe.Pointer(env)), SMTO_ABORTIFHUNG, uintptr(millis), 0)
+}
+
+// Creates an "error" style pop-up window
+func alert(caption string) int {
+	// Error box style
+	format := 0x10
+
+	user32 := syscall.NewLazyDLL("user32.dll")
+	captionPtr, _ := syscall.UTF16PtrFromString(caption)
+	titlePtr, _ := syscall.UTF16PtrFromString("winpath")
+	ret, _, _ := user32.NewProc("MessageBoxW").Call(
+		uintptr(0),
+		uintptr(unsafe.Pointer(captionPtr)),
+		uintptr(unsafe.Pointer(titlePtr)),
+		uintptr(format))
+
+	return int(ret)
+}