]> git.rkrishnan.org Git - tahoe-lafs/tahoe-lafs.git/blobdiff - src/allmydata/util/fileutil.py
Improved error handling and cosmetics for ctypes calls on Windows.
[tahoe-lafs/tahoe-lafs.git] / src / allmydata / util / fileutil.py
index 7add35cb41a968c2952c17e159b00eca149cde00..152cae0bb82860844dbbb77fe567a54d74332352 100644 (file)
@@ -4,6 +4,11 @@ Futz with files like a pro.
 
 import sys, exceptions, os, stat, tempfile, time, binascii
 
+if sys.platform == "win32":
+    from ctypes import WINFUNCTYPE, WinError, windll, POINTER, byref, c_ulonglong, \
+        create_unicode_buffer, get_last_error
+    from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPWSTR
+
 from twisted.python import log
 
 from pycryptopp.cipher.aes import AES
@@ -87,34 +92,6 @@ class ReopenableNamedTemporaryFile:
     def shutdown(self):
         remove(self.name)
 
-class NamedTemporaryDirectory:
-    """
-    This calls tempfile.mkdtemp(), stores the name of the dir in
-    self.name, and rmrf's the dir when it gets garbage collected or
-    "shutdown()".
-    """
-    def __init__(self, cleanup=True, *args, **kwargs):
-        """ If cleanup, then the directory will be rmrf'ed when the object is shutdown. """
-        self.cleanup = cleanup
-        self.name = tempfile.mkdtemp(*args, **kwargs)
-
-    def __repr__(self):
-        return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
-
-    def __str__(self):
-        return self.__repr__()
-
-    def __del__(self):
-        try:
-            self.shutdown()
-        except:
-            import traceback
-            traceback.print_exc()
-
-    def shutdown(self):
-        if self.cleanup and hasattr(self, 'name'):
-            rm_dir(self.name)
-
 class EncryptedTemporaryFile:
     # not implemented: next, readline, readlines, xreadlines, writelines
 
@@ -224,12 +201,6 @@ def remove_if_possible(f):
     except:
         pass
 
-def open_or_create(fname, binarymode=True):
-    try:
-        return open(fname, binarymode and "r+b" or "r+")
-    except EnvironmentError:
-        return open(fname, binarymode and "w+b" or "w+")
-
 def du(basedir):
     size = 0
 
@@ -255,8 +226,8 @@ def write_atomically(target, contents, mode="b"):
         f.close()
     move_into_place(target+".tmp", target)
 
-def write(path, data):
-    wf = open(path, "wb")
+def write(path, data, mode="wb"):
+    wf = open(path, mode)
     try:
         wf.write(data)
     finally:
@@ -269,9 +240,11 @@ def read(path):
     finally:
         rf.close()
 
-def put_file(pathname, inf):
+def put_file(path, inf):
+    precondition_abspath(path)
+
     # TODO: create temporary file and move into place?
-    outf = open(os.path.expanduser(pathname), "wb")
+    outf = open(path, "wb")
     try:
         while True:
             data = inf.read(32768)
@@ -282,6 +255,20 @@ def put_file(pathname, inf):
         outf.close()
 
 
+def precondition_abspath(path):
+    if not isinstance(path, unicode):
+        raise AssertionError("an abspath must be a Unicode string")
+
+    if sys.platform == "win32":
+        # This intentionally doesn't view absolute paths starting with a drive specification, or
+        # paths relative to the current drive, as acceptable.
+        if not path.startswith("\\\\"):
+            raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
+    else:
+        # This intentionally doesn't view the path '~' or paths starting with '~/' as acceptable.
+        if not os.path.isabs(path):
+            raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
+
 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
 # with some simplifications.
@@ -292,49 +279,150 @@ try:
 except ImportError:
     pass
 
-def abspath_expanduser_unicode(path):
-    """Return the absolute version of a path."""
-    assert isinstance(path, unicode), path
+def abspath_expanduser_unicode(path, base=None):
+    """
+    Return the absolute version of a path. If 'base' is given and 'path' is relative,
+    the path will be expanded relative to 'base'.
+    'path' must be a Unicode string. 'base', if given, must be a Unicode string
+    corresponding to an absolute path as returned by a previous call to
+    abspath_expanduser_unicode.
+    """
+    if not isinstance(path, unicode):
+        raise AssertionError("paths must be Unicode strings")
+    if base is not None:
+        precondition_abspath(base)
 
-    path = os.path.expanduser(path)
+    path = expanduser(path)
 
     if _getfullpathname:
-        # On Windows, os.path.isabs will return True for paths without a drive letter,
+        # On Windows, os.path.isabs will incorrectly return True
+        # for paths without a drive letter (that are not UNC paths),
         # e.g. "\\". See <http://bugs.python.org/issue1669539>.
         try:
-            path = _getfullpathname(path or u".")
+            if base is None:
+                path = _getfullpathname(path or u".")
+            else:
+                path = _getfullpathname(os.path.join(base, path))
         except OSError:
             pass
 
     if not os.path.isabs(path):
-        path = os.path.join(os.getcwdu(), path)
+        if base is None:
+            path = os.path.join(os.getcwdu(), path)
+        else:
+            path = os.path.join(base, path)
 
     # We won't hit <http://bugs.python.org/issue5827> because
     # there is always at least one Unicode path component.
-    return os.path.normpath(path)
+    path = os.path.normpath(path)
+
+    if sys.platform == "win32":
+        path = to_windows_long_path(path)
+
+    return path
+
+def to_windows_long_path(path):
+    # '/' is normally a perfectly valid path component separator in Windows.
+    # However, when using the "\\?\" syntax it is not recognized, so we
+    # replace it with '\' here.
+    path = path.replace(u"/", u"\\")
+
+    # Note that other normalizations such as removing '.' and '..' should
+    # be done outside this function.
+
+    if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
+        return path
+    elif path.startswith(u"\\\\"):
+        return u"\\\\?\\UNC\\" + path[2 :]
+    else:
+        return u"\\\\?\\" + path
 
 
 have_GetDiskFreeSpaceExW = False
 if sys.platform == "win32":
-    try:
-        from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_ulonglong
-        from ctypes.wintypes import BOOL, DWORD, LPCWSTR
+    # <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683188%28v=vs.85%29.aspx>
+    GetEnvironmentVariableW = WINFUNCTYPE(
+        DWORD,  LPCWSTR, LPWSTR, DWORD,
+        use_last_error=True
+    )(("GetEnvironmentVariableW", windll.kernel32))
 
+    try:
         # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
         PULARGE_INTEGER = POINTER(c_ulonglong)
 
         # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
-        GetDiskFreeSpaceExW = WINFUNCTYPE(BOOL, LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER)(
-            ("GetDiskFreeSpaceExW", windll.kernel32))
-
-        # <http://msdn.microsoft.com/en-us/library/ms679360%28v=VS.85%29.aspx>
-        GetLastError = WINFUNCTYPE(DWORD)(("GetLastError", windll.kernel32))
+        GetDiskFreeSpaceExW = WINFUNCTYPE(
+            BOOL,  LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER,
+            use_last_error=True
+        )(("GetDiskFreeSpaceExW", windll.kernel32))
 
         have_GetDiskFreeSpaceExW = True
     except Exception:
         import traceback
         traceback.print_exc()
 
+def expanduser(path):
+    # os.path.expanduser is hopelessly broken for Unicode paths on Windows (ticket #1674).
+    if sys.platform == "win32":
+        return windows_expanduser(path)
+    else:
+        return os.path.expanduser(path)
+
+def windows_expanduser(path):
+    if not path.startswith('~'):
+        return path
+
+    home_dir = windows_getenv(u'USERPROFILE')
+    if home_dir is None:
+        home_drive = windows_getenv(u'HOMEDRIVE')
+        home_path = windows_getenv(u'HOMEPATH')
+        if home_drive is None or home_path is None:
+            raise OSError("Could not find home directory: neither %USERPROFILE% nor (%HOMEDRIVE% and %HOMEPATH%) are set.")
+        home_dir = os.path.join(home_drive, home_path)
+
+    if path == '~':
+        return home_dir
+    elif path.startswith('~/') or path.startswith('~\\'):
+        return os.path.join(home_dir, path[2 :])
+    else:
+        return path
+
+# <https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382%28v=vs.85%29.aspx>
+ERROR_ENVVAR_NOT_FOUND = 203
+
+def windows_getenv(name):
+    # Based on <http://stackoverflow.com/questions/2608200/problems-with-umlauts-in-python-appdata-environvent-variable/2608368#2608368>,
+    # with improved error handling. Returns None if there is no enivronment variable of the given name.
+    if not isinstance(name, unicode):
+        raise AssertionError("name must be Unicode")
+
+    n = GetEnvironmentVariableW(name, None, 0)
+    # GetEnvironmentVariableW returns DWORD, so n cannot be negative.
+    if n == 0:
+        err = get_last_error()
+        if err == ERROR_ENVVAR_NOT_FOUND:
+            return None
+        raise OSError("WinError: %s\n attempting to read size of environment variable %r"
+                      % (WinError(err), name))
+    if n == 1:
+        # Avoid an ambiguity between a zero-length string and an error in the return value of the
+        # call to GetEnvironmentVariableW below.
+        return u""
+
+    buf = create_unicode_buffer(u'\0'*n)
+    retval = GetEnvironmentVariableW(name, buf, n)
+    if retval == 0:
+        err = get_last_error()
+        if err == ERROR_ENVVAR_NOT_FOUND:
+            return None
+        raise OSError("WinError: %s\n attempting to read environment variable %r"
+                      % (WinError(err), name))
+    if retval >= n:
+        raise OSError("Unexpected result %d (expected less than %d) from GetEnvironmentVariableW attempting to read environment variable %r"
+                      % (retval, n, name))
+
+    return buf.value
+
 def get_disk_stats(whichdir, reserved_space=0):
     """Return disk statistics for the storage disk, in the form of a dict
     with the following fields.
@@ -370,8 +458,8 @@ def get_disk_stats(whichdir, reserved_space=0):
                                                byref(n_total),
                                                byref(n_free_for_root))
         if retval == 0:
-            raise OSError("Windows error %d attempting to get disk statistics for %r"
-                          % (GetLastError(), whichdir))
+            raise OSError("WinError: %s\n attempting to get disk statistics for %r"
+                          % (WinError(get_last_error()), whichdir))
         free_for_nonroot = n_free_for_nonroot.value
         total            = n_total.value
         free_for_root    = n_free_for_root.value