mirror of
https://github.com/Stone-Red-Code/dvc.git
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Ruslan Kuprieiev
874aceccf8
`os.link` is broken across platforms when dealing with symlinks. See https://bugs.python.org/issue41355 for more info.
135 lines
3.7 KiB
Python
135 lines
3.7 KiB
Python
import errno
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import logging
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import os
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import platform
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import stat
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import sys
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logger = logging.getLogger(__name__)
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if os.name == "nt" and sys.version_info < (3, 8):
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# NOTE: using backports for `os.path.realpath`
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# See https://bugs.python.org/issue9949 for more info.
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# pylint: disable=import-error, no-name-in-module
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from jaraco.windows.filesystem.backports import realpath as _realpath
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def realpath(path):
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return _realpath(os.fspath(path))
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else:
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realpath = os.path.realpath
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class System:
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@staticmethod
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def hardlink(source, link_name):
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# NOTE: we should really be using `os.link()` here with
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# `follow_symlinks=True`, but unfortunately the implementation is
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# buggy across platforms, so until it is fixed, we just dereference
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# the symlink ourselves here.
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#
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# See https://bugs.python.org/issue41355 for more info.
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st = os.lstat(source)
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if stat.S_ISLNK(st.st_mode):
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src = realpath(source)
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else:
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src = source
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os.link(src, link_name)
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@staticmethod
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def symlink(source, link_name):
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os.symlink(source, link_name)
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@staticmethod
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def _reflink_darwin(src, dst):
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import ctypes
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def _cdll(name):
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return ctypes.CDLL(name, use_errno=True)
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LIBC = "libc.dylib"
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LIBC_FALLBACK = "/usr/lib/libSystem.dylib"
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try:
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clib = _cdll(LIBC)
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except OSError as exc:
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logger.debug(
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"unable to access '{}' (errno '{}'). "
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"Falling back to '{}'.".format(LIBC, exc.errno, LIBC_FALLBACK)
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)
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if exc.errno != errno.ENOENT:
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raise
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# NOTE: trying to bypass System Integrity Protection (SIP)
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clib = _cdll(LIBC_FALLBACK)
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if not hasattr(clib, "clonefile"):
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raise OSError(
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errno.ENOTSUP,
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"'clonefile' not supported by the standard library",
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)
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clonefile = clib.clonefile
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clonefile.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_int]
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clonefile.restype = ctypes.c_int
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ret = clonefile(
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ctypes.c_char_p(os.fsencode(src)),
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ctypes.c_char_p(os.fsencode(dst)),
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ctypes.c_int(0),
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)
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if ret:
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err = ctypes.get_errno()
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msg = os.strerror(err)
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raise OSError(err, msg)
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@staticmethod
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def _reflink_linux(src, dst):
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import fcntl # pylint: disable=import-error
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from funcy import suppress
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FICLONE = 0x40049409
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try:
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with open(src, "rb") as s, open(dst, "wb+") as d:
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fcntl.ioctl(d.fileno(), FICLONE, s.fileno())
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except OSError:
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with suppress(OSError):
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os.unlink(dst)
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raise
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@staticmethod
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def reflink(source, link_name):
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from dvc.utils.fs import umask
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source, link_name = os.fspath(source), os.fspath(link_name)
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system = platform.system()
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if system == "Darwin":
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System._reflink_darwin(source, link_name)
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elif system == "Linux":
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System._reflink_linux(source, link_name)
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else:
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raise OSError(
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errno.ENOTSUP,
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f"reflink is not supported on '{system}'",
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)
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# NOTE: reflink has a new inode, but has the same mode as the src,
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# so we need to chmod it to look like a normal copy.
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os.chmod(link_name, 0o666 & ~umask)
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@staticmethod
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def inode(path):
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return os.lstat(path).st_ino
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@staticmethod
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def is_symlink(path):
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return os.path.islink(path)
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@staticmethod
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def is_hardlink(path):
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return os.stat(path).st_nlink > 1
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