Windows: Workaround for long paths (#23)

By using the short path version of a file, we can
manage to move long paths to the trash.

Limitations:
1/ If the final short path is longer than what
    `SHFileOperationW` can handle, it will fail
2/ Still not able to trash long path from another
    drive, ie: trying to delete C:\temp\foo.txt
    while the script is running from D:\trash.py

send2trash/plat_win.py

@@ -7,15 +7,19 @@
 from __future__ import unicode_literals
 
 from ctypes import (windll, Structure, byref, c_uint,
-                    create_unicode_buffer, sizeof, addressof)
+                    create_unicode_buffer, addressof)
 from ctypes.wintypes import HWND, UINT, LPCWSTR, BOOL
 import os.path as op
 
 from .compat import text_type
 
+kernel32 = windll.kernel32
+GetShortPathNameW = kernel32.GetShortPathNameW
+
 shell32 = windll.shell32
 SHFileOperationW = shell32.SHFileOperationW
 
+
 class SHFILEOPSTRUCTW(Structure):
     _fields_ = [
         ("hwnd", HWND),
@@ -28,6 +32,7 @@ class SHFILEOPSTRUCTW(Structure):
         ("lpszProgressTitle", LPCWSTR),
         ]
 
+
 FO_MOVE = 1
 FO_COPY = 2
 FO_DELETE = 3
@@ -39,11 +44,22 @@ FOF_NOCONFIRMATION = 16
 FOF_ALLOWUNDO = 64
 FOF_NOERRORUI = 1024
 
+
+def get_short_path_name(long_name):
+    if not long_name.startswith('\\\\?\\'):
+        long_name = '\\\\?\\' + long_name
+    buf_size = GetShortPathNameW(long_name, None, 0)
+    output = create_unicode_buffer(buf_size)
+    GetShortPathNameW(long_name, output, buf_size)
+    return output.value[4:]  # Remove '\\?\' for SHFileOperationW
+
+
 def send2trash(path):
     if not isinstance(path, text_type):
         path = text_type(path, 'mbcs')
     if not op.isabs(path):
         path = op.abspath(path)
+    path = get_short_path_name(path)
     fileop = SHFILEOPSTRUCTW()
     fileop.hwnd = 0
     fileop.wFunc = FO_DELETE
@@ -51,7 +67,7 @@ def send2trash(path):
     # Starting in python 3.6.3 it is no longer possible to use:
     # LPCWSTR(path + '\0') directly as embedded null characters are no longer
     # allowed in strings
-    # Workaround 
+    # Workaround
     #  - create buffer of c_wchar[] (LPCWSTR is based on this type)
     #  - buffer is two c_wchar characters longer (double null terminator)
     #  - cast the address of the buffer to a LPCWSTR

tests/test_plat_win.py

@@ -0,0 +1,46 @@
+# coding: utf-8
+import os
+import sys
+import unittest
+from os import path as op
+from tempfile import gettempdir
+
+from send2trash import send2trash as s2t
+
+
+@unittest.skipIf(sys.platform != 'win32', 'Windows only')
+class TestLongPath(unittest.TestCase):
+    def setUp(self):
+        filename = 'A' * 100
+        self.dirname = '\\\\?\\' + os.path.join(gettempdir(), filename)
+        self.file = os.path.join(
+            self.dirname,
+            filename,
+            filename,  # From there, the path is not trashable from Explorer
+            filename,
+            filename + '.txt')
+        self._create_tree(self.file)
+
+    def tearDown(self):
+        try:
+            os.remove(self.dirname)
+        except OSError:
+            pass
+
+    def _create_tree(self, path):
+        dirname = os.path.dirname(path)
+        if not os.path.isdir(dirname):
+            os.makedirs(dirname)
+        with open(path, 'w') as writer:
+            writer.write('Looong filename!')
+
+    def test_trash_file(self):
+        s2t(self.file)
+        self.assertFalse(op.exists(self.file))
+
+    @unittest.skipIf(
+        op.splitdrive(os.getcwd())[0] != op.splitdrive(gettempdir())[0],
+        'Cannot trash long path from other drive')
+    def test_trash_folder(self):
+        s2t(self.dirname)
+        self.assertFalse(op.exists(self.dirname))