bug #33 Fix Symlink evaluation on Windows (tucksaun)

This PR was merged into the main branch.

Discussion
----------

Fix Symlink evaluation on Windows

Symlink evaluation is broken on Windows under certain circumstances (e.g., when using junctions - mounting a drive under a directory). See golang/go#40180 for more information.
This can break PHP discovery if the PHP installation is reachable using these kinds of links

This PR borrows code from golangci-lint, which encounters the same kind of issue.

Fixes #16
Superseeds #21

Commits
-------

a701f47 Fix Symlink evaluation on Windows

Author: fabpot

discovery.go

@@ -191,7 +191,7 @@ func (s *PHPStore) discoverPHPViaPHP(dir, binName string) *Version {
 	}
 	php = filepath.Clean(php)
 	var err error
-	php, err = filepath.EvalSymlinks(php)
+	php, err = evalSymlinks(php)
 	if err != nil {
 		s.log("  %s is not a valid symlink", php)
 		return nil
@@ -332,7 +332,7 @@ func (s *PHPStore) pathDirectories(configDir string) []string {
 	seen := make(map[string]bool)
 	for _, dir := range filepath.SplitList(path) {
 		dir = strings.Replace(dir, "%%USERPROFILE%%", user, 1)
-		edir, err := filepath.EvalSymlinks(dir)
+		edir, err := evalSymlinks(dir)
 		if err != nil {
 			continue
 		}

fsutils_others.go

@@ -0,0 +1,7 @@
+//go:build !windows
+
+package phpstore
+
+import "path/filepath"
+
+var evalSymlinks = filepath.EvalSymlinks

fsutils_windows.go

@@ -0,0 +1,39 @@
+package phpstore
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+// Taken from https://github.com/golangci/golangci-lint/blob/main/pkg/fsutils/fsutils_windows.go
+
+// This is a workaround for the behavior of [filepath.EvalSymlinks],
+// which fails with [syscall.ENOTDIR] if the specified path contains a junction on Windows.
+// Junctions can occur, for example, when a volume is mounted as a subdirectory inside another drive.
+// This can usually happen when using the Dev Drives feature and replacing existing directories.
+// See: https://github.com/golang/go/issues/40180
+//
+// Since [syscall.ENOTDIR] is only returned when calling [filepath.EvalSymlinks] on Windows
+// if part of the presented path is a junction and nothing before was a symlink,
+// we simply treat this as NOT symlink,
+// because a symlink over the junction makes no sense at all.
+func evalSymlinks(path string) (string, error) {
+	resolved, err := filepath.EvalSymlinks(path)
+	if err == nil {
+		return resolved, nil
+	}
+
+	if !errors.Is(err, syscall.ENOTDIR) {
+		return "", err
+	}
+
+	_, err = os.Stat(path)
+	if err != nil {
+		return "", err
+	}
+
+	// If exists, we make the path cleaned before being used
+	return filepath.Abs(path), nil
+}

store.go

@@ -238,7 +238,7 @@ func (s *PHPStore) loadVersions() {
 // addVersion ensures that all versions are unique in the store
 func (s *PHPStore) addVersion(version *Version) int {
 	idx, ok := s.seen[version.PHPPath]
-	sl, _ := filepath.EvalSymlinks(version.PHPPath)
+	sl, _ := evalSymlinks(version.PHPPath)
 	// double-check to see if that's not just a symlink to another existing version
 	if !ok && sl != "" {
 		idx, ok = s.seen[sl]

version.go

@@ -185,35 +185,35 @@ func (v *Version) setServer(fpm, cgi, phpconfig, phpize, phpdbg string) string {
 	msg := fmt.Sprintf("  Found PHP: %s", v.PHPPath)
 	fpm = filepath.Clean(fpm)
 	if _, err := os.Stat(fpm); err == nil {
-		if fpm, err := filepath.EvalSymlinks(fpm); err == nil {
+		if fpm, err := evalSymlinks(fpm); err == nil {
 			v.FPMPath = fpm
 			msg += fmt.Sprintf(", with FPM: %s", fpm)
 		}
 	}
 	cgi = filepath.Clean(cgi)
 	if _, err := os.Stat(cgi); err == nil {
-		if cgi, err := filepath.EvalSymlinks(cgi); err == nil {
+		if cgi, err := evalSymlinks(cgi); err == nil {
 			v.CGIPath = cgi
 			msg += fmt.Sprintf(", with CGI: %s", cgi)
 		}
 	}
 	phpconfig = filepath.Clean(phpconfig)
 	if _, err := os.Stat(phpconfig); err == nil {
-		if phpconfig, err := filepath.EvalSymlinks(phpconfig); err == nil {
+		if phpconfig, err := evalSymlinks(phpconfig); err == nil {
 			v.PHPConfigPath = phpconfig
 			msg += fmt.Sprintf(", with php-config: %s", phpconfig)
 		}
 	}
 	phpize = filepath.Clean(phpize)
 	if _, err := os.Stat(phpize); err == nil {
-		if phpize, err := filepath.EvalSymlinks(phpize); err == nil {
+		if phpize, err := evalSymlinks(phpize); err == nil {
 			v.PHPizePath = phpize
 			msg += fmt.Sprintf(", with phpize: %s", phpize)
 		}
 	}
 	phpdbg = filepath.Clean(phpdbg)
 	if _, err := os.Stat(phpdbg); err == nil {
-		if phpdbg, err := filepath.EvalSymlinks(phpdbg); err == nil {
+		if phpdbg, err := evalSymlinks(phpdbg); err == nil {
 			v.PHPdbgPath = phpdbg
 			msg += fmt.Sprintf(", with phpdbg: %s", phpdbg)
 		}