Canonicalize now de-shorten paths on Windows

Author: cmaglie

paths.go

@@ -561,5 +561,8 @@ func (p *Path) Canonical() *Path {
 	if absPath, err := canonical.Abs(); err == nil {
 		canonical = absPath
 	}
+	if c, err := canonicalize(canonical.path); c != "" && err == nil {
+		canonical.path = c
+	}
 	return canonical
 }

paths_others.go

@@ -0,0 +1,37 @@
+//
+// This file is part of PathsHelper library.
+//
+// Copyright 2025 Arduino AG (http://www.arduino.cc/)
+//
+// PathsHelper library is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+//
+// As a special exception, you may use this file as part of a free software
+// library without restriction.  Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License.  This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+//
+
+//go:build !windows
+
+package paths
+
+func canonicalize(string) (string, error) {
+	// On non-Windows platforms, the path is already in a canonical form.
+	return "", nil
+}

paths_windows.go

@@ -0,0 +1,51 @@
+//
+// This file is part of PathsHelper library.
+//
+// Copyright 2025 Arduino AG (http://www.arduino.cc/)
+//
+// PathsHelper library is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+//
+// As a special exception, you may use this file as part of a free software
+// library without restriction.  Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License.  This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+//
+
+package paths
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/windows"
+)
+
+func canonicalize(inPath string) (string, error) {
+	var buf [4096]uint16
+	data := &buf[0]
+	n, err := windows.GetLongPathName(windows.StringToUTF16Ptr(inPath), &buf[0], uint32(len(buf)))
+	if n >= uint32(len(buf)) {
+		buf2 := make([]uint16, n+1)
+		data = &buf2[0]
+		_, err = windows.GetLongPathName(windows.StringToUTF16Ptr(inPath), &buf2[0], uint32(len(buf2)))
+	}
+	if err != nil {
+		return "", fmt.Errorf("getting long path name: %w", err)
+	}
+	return windows.UTF16PtrToString(data), err
+}