pure: provide more correct implementation of posixfile for Windows
requires ctypes
Why is posixfile a class?
Because the implementation needs to use the Python library call os.fdopen [1],
which sets the 'name' attribute on the Python file object it creates to the
mostly meaningless string '<fdopen>', since file descriptors don't have a name.
But users of posixfile depend on the name attribute [2] being set to a proper
value, like Python's built-in 'open' function sets it on file objects.
Python file's name attribute is read-only, so we can't just assign to it after
the file object has alrady been created.
To solve this problem, we save the name of the file on a wrapper object,
and delegate the file function calls to the wrapped (private) file object
using __getattr__.
[1] http://docs.python.org/library/os.html#os.fdopen
[2] http://docs.python.org/library/stdtypes.html#file.name
--- a/mercurial/pure/osutil.py Mon May 23 20:35:10 2011 +0200
+++ b/mercurial/pure/osutil.py Wed May 18 09:12:27 2011 +0200
@@ -8,8 +8,6 @@
import os
import stat as statmod
-posixfile = open
-
def _mode_to_kind(mode):
if statmod.S_ISREG(mode):
return statmod.S_IFREG
@@ -57,3 +55,131 @@
result.append((fn, _mode_to_kind(st.st_mode)))
return result
+if os.name != 'nt':
+ posixfile = open
+else:
+ import ctypes, ctypes.util
+
+ _kernel32 = ctypes.windll.kernel32
+
+ _DWORD = ctypes.c_ulong
+ _LPCSTR = _LPSTR = ctypes.c_char_p
+ _HANDLE = ctypes.c_void_p
+
+ _INVALID_HANDLE_VALUE = _HANDLE(-1).value
+
+ def _crtname():
+ try:
+ # find_msvcrt was introduced in Python 2.6
+ return ctypes.util.find_msvcrt()
+ except AttributeError:
+ return 'msvcr80.dll' # CPython 2.5
+
+ _crt = ctypes.PyDLL(_crtname())
+
+ # CreateFile
+ _FILE_SHARE_READ = 0x00000001
+ _FILE_SHARE_WRITE = 0x00000002
+ _FILE_SHARE_DELETE = 0x00000004
+
+ _CREATE_ALWAYS = 2
+ _OPEN_EXISTING = 3
+ _OPEN_ALWAYS = 4
+
+ _GENERIC_READ = 0x80000000
+ _GENERIC_WRITE = 0x40000000
+
+ _FILE_ATTRIBUTE_NORMAL = 0x80
+
+ # _open_osfhandle
+ _O_RDONLY = 0x0000
+ _O_RDWR = 0x0002
+ _O_APPEND = 0x0008
+
+ _O_TEXT = 0x4000
+ _O_BINARY = 0x8000
+
+ # types of parameters of C functions used (required by pypy)
+
+ _kernel32.CreateFileA.argtypes = [_LPCSTR, _DWORD, _DWORD, ctypes.c_void_p,
+ _DWORD, _DWORD, _HANDLE]
+ _kernel32.CreateFileA.restype = _HANDLE
+
+ _crt._open_osfhandle.argtypes = [_HANDLE, ctypes.c_int]
+ _crt._open_osfhandle.restype = ctypes.c_int
+
+ def _raiseioerror(name):
+ err = ctypes.WinError()
+ raise IOError(err.errno, '%s: %s' % (name, err.strerror))
+
+ class posixfile(object):
+ '''a file object aiming for POSIX-like semantics
+
+ CPython's open() returns a file that was opened *without* setting the
+ _FILE_SHARE_DELETE flag, which causes rename and unlink to abort.
+ This even happens if any hardlinked copy of the file is in open state.
+ We set _FILE_SHARE_DELETE here, so files opened with posixfile can be
+ renamed and deleted while they are held open.
+ Note that if a file opened with posixfile is unlinked, the file
+ remains but cannot be opened again or be recreated under the same name,
+ until all reading processes have closed the file.'''
+
+ def __init__(self, name, mode='r', bufsize=-1):
+ if 'b' in mode:
+ flags = _O_BINARY
+ else:
+ flags = _O_TEXT
+
+ m0 = mode[0]
+ if m0 == 'r' and not '+' in mode:
+ flags |= _O_RDONLY
+ access = _GENERIC_READ
+ else:
+ # work around http://support.microsoft.com/kb/899149 and
+ # set _O_RDWR for 'w' and 'a', even if mode has no '+'
+ flags |= _O_RDWR
+ access = _GENERIC_READ | _GENERIC_WRITE
+
+ if m0 == 'r':
+ creation = _OPEN_EXISTING
+ elif m0 == 'w':
+ creation = _CREATE_ALWAYS
+ elif m0 == 'a':
+ creation = _OPEN_ALWAYS
+ flags |= _O_APPEND
+ else:
+ raise ValueError("invalid mode: %s" % mode)
+
+ fh = _kernel32.CreateFileA(name, access,
+ _FILE_SHARE_READ | _FILE_SHARE_WRITE | _FILE_SHARE_DELETE,
+ None, creation, _FILE_ATTRIBUTE_NORMAL, None)
+ if fh == _INVALID_HANDLE_VALUE:
+ _raiseioerror(name)
+
+ # for CPython we must use the same CRT as Python uses,
+ # or the os.fdopen call below will abort with
+ # "OSError: [Errno 9] Bad file descriptor"
+ fd = _crt._open_osfhandle(fh, flags)
+ if fd == -1:
+ _kernel32.CloseHandle(fh)
+ _raiseioerror(name)
+
+ f = os.fdopen(fd, mode, bufsize)
+ # unfortunately, f.name is '<fdopen>' at this point -- so we store
+ # the name on this wrapper. We cannot just assign to f.name,
+ # because that attribute is read-only.
+ object.__setattr__(self, 'name', name)
+ object.__setattr__(self, '_file', f)
+
+ def __iter__(self):
+ return self._file
+
+ def __getattr__(self, name):
+ return getattr(self._file, name)
+
+ def __setattr__(self, name, value):
+ '''mimics the read-only attributes of Python file objects
+ by raising 'TypeError: readonly attribute' if someone tries:
+ f = posixfile('foo.txt')
+ f.name = 'bla' '''
+ return self._file.__setattr__(name, value)