bundling required python dependencies, to make it easier on Tails users

lib/werkzeug/posixemulation.py

@@ -0,0 +1,105 @@
+# -*- coding: utf-8 -*-
+r"""
+    werkzeug.posixemulation
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    Provides a POSIX emulation for some features that are relevant to
+    web applications.  The main purpose is to simplify support for
+    systems such as Windows NT that are not 100% POSIX compatible.
+
+    Currently this only implements a :func:`rename` function that
+    follows POSIX semantics.  Eg: if the target file already exists it
+    will be replaced without asking.
+
+    This module was introduced in 0.6.1 and is not a public interface.
+    It might become one in later versions of Werkzeug.
+
+    :copyright: (c) 2013 by the Werkzeug Team, see AUTHORS for more details.
+    :license: BSD, see LICENSE for more details.
+"""
+import sys
+import os
+import errno
+import time
+import random
+
+
+can_rename_open_file = False
+if os.name == 'nt': # pragma: no cover
+    _rename = lambda src, dst: False
+    _rename_atomic = lambda src, dst: False
+
+    try:
+        import ctypes
+
+        _MOVEFILE_REPLACE_EXISTING = 0x1
+        _MOVEFILE_WRITE_THROUGH = 0x8
+        _MoveFileEx = ctypes.windll.kernel32.MoveFileExW
+
+        def _rename(src, dst):
+            if not isinstance(src, unicode):
+                src = unicode(src, sys.getfilesystemencoding())
+            if not isinstance(dst, unicode):
+                dst = unicode(dst, sys.getfilesystemencoding())
+            if _rename_atomic(src, dst):
+                return True
+            retry = 0
+            rv = False
+            while not rv and retry < 100:
+                rv = _MoveFileEx(src, dst, _MOVEFILE_REPLACE_EXISTING |
+                                           _MOVEFILE_WRITE_THROUGH)
+                if not rv:
+                    time.sleep(0.001)
+                    retry += 1
+            return rv
+
+        # new in Vista and Windows Server 2008
+        _CreateTransaction = ctypes.windll.ktmw32.CreateTransaction
+        _CommitTransaction = ctypes.windll.ktmw32.CommitTransaction
+        _MoveFileTransacted = ctypes.windll.kernel32.MoveFileTransactedW
+        _CloseHandle = ctypes.windll.kernel32.CloseHandle
+        can_rename_open_file = True
+
+        def _rename_atomic(src, dst):
+            ta = _CreateTransaction(None, 0, 0, 0, 0, 1000, 'Werkzeug rename')
+            if ta == -1:
+                return False
+            try:
+                retry = 0
+                rv = False
+                while not rv and retry < 100:
+                    rv = _MoveFileTransacted(src, dst, None, None,
+                                             _MOVEFILE_REPLACE_EXISTING |
+                                             _MOVEFILE_WRITE_THROUGH, ta)
+                    if rv:
+                        rv = _CommitTransaction(ta)
+                        break
+                    else:
+                        time.sleep(0.001)
+                        retry += 1
+                return rv
+            finally:
+                _CloseHandle(ta)
+    except Exception:
+        pass
+
+    def rename(src, dst):
+        # Try atomic or pseudo-atomic rename
+        if _rename(src, dst):
+            return
+        # Fall back to "move away and replace"
+        try:
+            os.rename(src, dst)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+            old = "%s-%08x" % (dst, random.randint(0, sys.maxint))
+            os.rename(dst, old)
+            os.rename(src, dst)
+            try:
+                os.unlink(old)
+            except Exception:
+                pass
+else:
+    rename = os.rename
+    can_rename_open_file = True