view mercurial/pure/osutil.py @ 44237:b4057d001760

merge: when rename was made on both sides, use ancestor as merge base

When both sides of a merge have renamed a file to the same place, we
would treat that as a "both created" action in merge.py. That means
that we'd use an empty diffbase. It seems better to use the copy
source as diffbase. That can be done by simply dropping code that
prevented us from doing that. I think I did it that way in
57203e0210f8 (copies: calculate mergecopies() based on pathcopies(),
2019-04-11) only to preserve the existing behavior. I also suspect it
was just an accident that it behaved that way before that commit.

Note that until fa9ad1da2e77 (merge: start using the per-side copy
dicts, 2020-01-23), it was non-deterministic (depending on iteration
order of the `allsources` set in `copies._fullcopytracing()`) which
source was used in the affected test case in test-rename-merge1.t. We
could easily have fixed that by sorting them, but now we can instead
detect the case (the TODO added in the previous patch).

Differential Revision: https://phab.mercurial-scm.org/D7974

# osutil.py - pure Python version of osutil.c
#
#  Copyright 2009 Matt Mackall <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import, division

import ctypes
import ctypes.util
import os
import socket
import stat as statmod

from ..pycompat import getattr
from .. import (
    encoding,
    pycompat,
)


def _mode_to_kind(mode):
    if statmod.S_ISREG(mode):
        return statmod.S_IFREG
    if statmod.S_ISDIR(mode):
        return statmod.S_IFDIR
    if statmod.S_ISLNK(mode):
        return statmod.S_IFLNK
    if statmod.S_ISBLK(mode):
        return statmod.S_IFBLK
    if statmod.S_ISCHR(mode):
        return statmod.S_IFCHR
    if statmod.S_ISFIFO(mode):
        return statmod.S_IFIFO
    if statmod.S_ISSOCK(mode):
        return statmod.S_IFSOCK
    return mode


def listdir(path, stat=False, skip=None):
    '''listdir(path, stat=False) -> list_of_tuples

    Return a sorted list containing information about the entries
    in the directory.

    If stat is True, each element is a 3-tuple:

      (name, type, stat object)

    Otherwise, each element is a 2-tuple:

      (name, type)
    '''
    result = []
    prefix = path
    if not prefix.endswith(pycompat.ossep):
        prefix += pycompat.ossep
    names = os.listdir(path)
    names.sort()
    for fn in names:
        st = os.lstat(prefix + fn)
        if fn == skip and statmod.S_ISDIR(st.st_mode):
            return []
        if stat:
            result.append((fn, _mode_to_kind(st.st_mode), st))
        else:
            result.append((fn, _mode_to_kind(st.st_mode)))
    return result


if not pycompat.iswindows:
    posixfile = open

    _SCM_RIGHTS = 0x01
    _socklen_t = ctypes.c_uint

    if pycompat.sysplatform.startswith(b'linux'):
        # socket.h says "the type should be socklen_t but the definition of
        # the kernel is incompatible with this."
        _cmsg_len_t = ctypes.c_size_t
        _msg_controllen_t = ctypes.c_size_t
        _msg_iovlen_t = ctypes.c_size_t
    else:
        _cmsg_len_t = _socklen_t
        _msg_controllen_t = _socklen_t
        _msg_iovlen_t = ctypes.c_int

    class _iovec(ctypes.Structure):
        _fields_ = [
            (u'iov_base', ctypes.c_void_p),
            (u'iov_len', ctypes.c_size_t),
        ]

    class _msghdr(ctypes.Structure):
        _fields_ = [
            (u'msg_name', ctypes.c_void_p),
            (u'msg_namelen', _socklen_t),
            (u'msg_iov', ctypes.POINTER(_iovec)),
            (u'msg_iovlen', _msg_iovlen_t),
            (u'msg_control', ctypes.c_void_p),
            (u'msg_controllen', _msg_controllen_t),
            (u'msg_flags', ctypes.c_int),
        ]

    class _cmsghdr(ctypes.Structure):
        _fields_ = [
            (u'cmsg_len', _cmsg_len_t),
            (u'cmsg_level', ctypes.c_int),
            (u'cmsg_type', ctypes.c_int),
            (u'cmsg_data', ctypes.c_ubyte * 0),
        ]

    _libc = ctypes.CDLL(ctypes.util.find_library(u'c'), use_errno=True)
    _recvmsg = getattr(_libc, 'recvmsg', None)
    if _recvmsg:
        _recvmsg.restype = getattr(ctypes, 'c_ssize_t', ctypes.c_long)
        _recvmsg.argtypes = (
            ctypes.c_int,
            ctypes.POINTER(_msghdr),
            ctypes.c_int,
        )
    else:
        # recvmsg isn't always provided by libc; such systems are unsupported
        def _recvmsg(sockfd, msg, flags):
            raise NotImplementedError(b'unsupported platform')

    def _CMSG_FIRSTHDR(msgh):
        if msgh.msg_controllen < ctypes.sizeof(_cmsghdr):
            return
        cmsgptr = ctypes.cast(msgh.msg_control, ctypes.POINTER(_cmsghdr))
        return cmsgptr.contents

    # The pure version is less portable than the native version because the
    # handling of socket ancillary data heavily depends on C preprocessor.
    # Also, some length fields are wrongly typed in Linux kernel.
    def recvfds(sockfd):
        """receive list of file descriptors via socket"""
        dummy = (ctypes.c_ubyte * 1)()
        iov = _iovec(ctypes.cast(dummy, ctypes.c_void_p), ctypes.sizeof(dummy))
        cbuf = ctypes.create_string_buffer(256)
        msgh = _msghdr(
            None,
            0,
            ctypes.pointer(iov),
            1,
            ctypes.cast(cbuf, ctypes.c_void_p),
            ctypes.sizeof(cbuf),
            0,
        )
        r = _recvmsg(sockfd, ctypes.byref(msgh), 0)
        if r < 0:
            e = ctypes.get_errno()
            raise OSError(e, os.strerror(e))
        # assumes that the first cmsg has fds because it isn't easy to write
        # portable CMSG_NXTHDR() with ctypes.
        cmsg = _CMSG_FIRSTHDR(msgh)
        if not cmsg:
            return []
        if (
            cmsg.cmsg_level != socket.SOL_SOCKET
            or cmsg.cmsg_type != _SCM_RIGHTS
        ):
            return []
        rfds = ctypes.cast(cmsg.cmsg_data, ctypes.POINTER(ctypes.c_int))
        rfdscount = (
            cmsg.cmsg_len - _cmsghdr.cmsg_data.offset
        ) // ctypes.sizeof(ctypes.c_int)
        return [rfds[i] for i in pycompat.xrange(rfdscount)]


else:
    import msvcrt

    _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

    # 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 flags
    _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

    def _raiseioerror(name):
        err = ctypes.WinError()
        raise IOError(
            err.errno, '%s: %s' % (encoding.strfromlocal(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=b'r', bufsize=-1):
            if b'b' in mode:
                flags = _O_BINARY
            else:
                flags = _O_TEXT

            m0 = mode[0:1]
            if m0 == b'r' and b'+' 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 == b'r':
                creation = _OPEN_EXISTING
            elif m0 == b'w':
                creation = _CREATE_ALWAYS
            elif m0 == b'a':
                creation = _OPEN_ALWAYS
                flags |= _O_APPEND
            else:
                raise ValueError("invalid mode: %s" % pycompat.sysstr(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)

            fd = msvcrt.open_osfhandle(fh, flags)
            if fd == -1:
                _kernel32.CloseHandle(fh)
                _raiseioerror(name)

            f = os.fdopen(fd, pycompat.sysstr(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)

        def __enter__(self):
            self._file.__enter__()
            return self

        def __exit__(self, exc_type, exc_value, exc_tb):
            return self._file.__exit__(exc_type, exc_value, exc_tb)