mirror of https://github.com/python/cpython
101 lines
3.2 KiB
Python
101 lines
3.2 KiB
Python
import os
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import unittest
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import platform
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from test.test_support import TESTFN
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def can_symlink():
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# cache the result in can_symlink.prev_val
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prev_val = getattr(can_symlink, 'prev_val', None)
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if prev_val is not None:
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return prev_val
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symlink_path = TESTFN + "can_symlink"
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try:
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symlink(TESTFN, symlink_path)
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can = True
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except (OSError, NotImplementedError, AttributeError):
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can = False
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else:
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os.remove(symlink_path)
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can_symlink.prev_val = can
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return can
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def skip_unless_symlink(test):
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"""Skip decorator for tests that require functional symlink"""
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ok = can_symlink()
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msg = "Requires functional symlink implementation"
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return test if ok else unittest.skip(msg)(test)
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def _symlink_win32(target, link, target_is_directory=False):
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"""
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Ctypes symlink implementation since Python doesn't support
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symlinks in windows yet. Borrowed from jaraco.windows project.
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"""
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import ctypes.wintypes
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CreateSymbolicLink = ctypes.windll.kernel32.CreateSymbolicLinkW
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CreateSymbolicLink.argtypes = (
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ctypes.wintypes.LPWSTR,
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ctypes.wintypes.LPWSTR,
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ctypes.wintypes.DWORD,
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)
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CreateSymbolicLink.restype = ctypes.wintypes.BOOLEAN
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def format_system_message(errno):
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"""
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Call FormatMessage with a system error number to retrieve
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the descriptive error message.
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"""
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# first some flags used by FormatMessageW
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ALLOCATE_BUFFER = 0x100
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ARGUMENT_ARRAY = 0x2000
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FROM_HMODULE = 0x800
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FROM_STRING = 0x400
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FROM_SYSTEM = 0x1000
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IGNORE_INSERTS = 0x200
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# Let FormatMessageW allocate the buffer (we'll free it below)
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# Also, let it know we want a system error message.
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flags = ALLOCATE_BUFFER | FROM_SYSTEM
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source = None
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message_id = errno
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language_id = 0
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result_buffer = ctypes.wintypes.LPWSTR()
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buffer_size = 0
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arguments = None
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bytes = ctypes.windll.kernel32.FormatMessageW(
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flags,
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source,
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message_id,
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language_id,
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ctypes.byref(result_buffer),
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buffer_size,
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arguments,
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)
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# note the following will cause an infinite loop if GetLastError
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# repeatedly returns an error that cannot be formatted, although
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# this should not happen.
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handle_nonzero_success(bytes)
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message = result_buffer.value
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ctypes.windll.kernel32.LocalFree(result_buffer)
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return message
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def handle_nonzero_success(result):
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if result == 0:
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value = ctypes.windll.kernel32.GetLastError()
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strerror = format_system_message(value)
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raise WindowsError(value, strerror)
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target_is_directory = target_is_directory or os.path.isdir(target)
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handle_nonzero_success(CreateSymbolicLink(link, target, target_is_directory))
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symlink = os.symlink if hasattr(os, 'symlink') else (
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_symlink_win32 if platform.system() == 'Windows' else None
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)
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def remove_symlink(name):
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# On Windows, to remove a directory symlink, one must use rmdir
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try:
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os.rmdir(name)
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except OSError:
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os.remove(name)
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