view mercurial/win32.py @ 12938:bf826c0b9537 stable

opener: check hardlink count reporting (issue1866)

The Linux CIFS kernel driver (even in 2.6.36) suffers from a hardlink
count blindness bug (lstat() returning 1 in st_nlink when it is expected
to return >1), which causes repository corruption if Mercurial running
on Linux pushes or commits to a hardlinked repository stored on a Windows
share, if that share is mounted using the CIFS driver.

This patch works around issue1866 and improves the workaround done in
50523b4407f6 to fix issue761, by teaching the opener to lazily execute a
runtime check (new function checknlink) to see if the hardlink count
reported by nlinks() can be trusted.

Since nlinks() is also known to return varying count values (1 or >1)
depending on whether the file is open or not and depending on what client
and server software combination is being used for accessing and serving
the Windows share, we deliberately open the file before calling nlinks() in
order to have a stable precondition. Trying to depend on the precondition
"file closed" would be fragile, as the file could have been opened very
easily somewhere else in the program.

# win32.py - utility functions that use win32 API
#
# Copyright 2005-2009 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.

"""Utility functions that use win32 API.

Mark Hammond's win32all package allows better functionality on
Windows. This module overrides definitions in util.py. If not
available, import of this module will fail, and generic code will be
used.
"""

import win32api

import errno, os, sys, pywintypes, win32con, win32file, win32process
import winerror, win32gui, win32console
import osutil, encoding
from win32com.shell import shell, shellcon

def os_link(src, dst):
    try:
        win32file.CreateHardLink(dst, src)
    except pywintypes.error:
        raise OSError(errno.EINVAL, 'target implements hardlinks improperly')
    except NotImplementedError: # Another fake error win Win98
        raise OSError(errno.EINVAL, 'Hardlinking not supported')

def _getfileinfo(pathname):
    """Return number of hardlinks for the given file."""
    try:
        fh = win32file.CreateFile(pathname,
            win32file.GENERIC_READ, win32file.FILE_SHARE_READ,
            None, win32file.OPEN_EXISTING, 0, None)
    except pywintypes.error:
        raise OSError(errno.ENOENT, 'The system cannot find the file specified')
    try:
        return win32file.GetFileInformationByHandle(fh)
    finally:
        fh.Close()

def nlinks(pathname):
    """Return number of hardlinks for the given file."""
    return _getfileinfo(pathname)[7]

def samefile(fpath1, fpath2):
    """Returns whether fpath1 and fpath2 refer to the same file. This is only
    guaranteed to work for files, not directories."""
    res1 = _getfileinfo(fpath1)
    res2 = _getfileinfo(fpath2)
    # Index 4 is the volume serial number, and 8 and 9 contain the file ID
    return res1[4] == res2[4] and res1[8] == res2[8] and res1[9] == res2[9]

def samedevice(fpath1, fpath2):
    """Returns whether fpath1 and fpath2 are on the same device. This is only
    guaranteed to work for files, not directories."""
    res1 = _getfileinfo(fpath1)
    res2 = _getfileinfo(fpath2)
    return res1[4] == res2[4]

def testpid(pid):
    '''return True if pid is still running or unable to
    determine, False otherwise'''
    try:
        handle = win32api.OpenProcess(
            win32con.PROCESS_QUERY_INFORMATION, False, pid)
        if handle:
            status = win32process.GetExitCodeProcess(handle)
            return status == win32con.STILL_ACTIVE
    except pywintypes.error, details:
        return details[0] != winerror.ERROR_INVALID_PARAMETER
    return True

def lookup_reg(key, valname=None, scope=None):
    ''' Look up a key/value name in the Windows registry.

    valname: value name. If unspecified, the default value for the key
    is used.
    scope: optionally specify scope for registry lookup, this can be
    a sequence of scopes to look up in order. Default (CURRENT_USER,
    LOCAL_MACHINE).
    '''
    try:
        from _winreg import HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, \
            QueryValueEx, OpenKey
    except ImportError:
        return None

    if scope is None:
        scope = (HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE)
    elif not isinstance(scope, (list, tuple)):
        scope = (scope,)
    for s in scope:
        try:
            val = QueryValueEx(OpenKey(s, key), valname)[0]
            # never let a Unicode string escape into the wild
            return encoding.tolocal(val.encode('UTF-8'))
        except EnvironmentError:
            pass

def system_rcpath_win32():
    '''return default os-specific hgrc search path'''
    proc = win32api.GetCurrentProcess()
    try:
        # This will fail on windows < NT
        filename = win32process.GetModuleFileNameEx(proc, 0)
    except:
        filename = win32api.GetModuleFileName(0)
    # Use mercurial.ini found in directory with hg.exe
    progrc = os.path.join(os.path.dirname(filename), 'mercurial.ini')
    if os.path.isfile(progrc):
        return [progrc]
    # Use hgrc.d found in directory with hg.exe
    progrcd = os.path.join(os.path.dirname(filename), 'hgrc.d')
    if os.path.isdir(progrcd):
        rcpath = []
        for f, kind in osutil.listdir(progrcd):
            if f.endswith('.rc'):
                rcpath.append(os.path.join(progrcd, f))
        return rcpath
    # else look for a system rcpath in the registry
    try:
        value = win32api.RegQueryValue(
                win32con.HKEY_LOCAL_MACHINE, 'SOFTWARE\\Mercurial')
        rcpath = []
        for p in value.split(os.pathsep):
            if p.lower().endswith('mercurial.ini'):
                rcpath.append(p)
            elif os.path.isdir(p):
                for f, kind in osutil.listdir(p):
                    if f.endswith('.rc'):
                        rcpath.append(os.path.join(p, f))
        return rcpath
    except pywintypes.error:
        return []

def user_rcpath_win32():
    '''return os-specific hgrc search path to the user dir'''
    userdir = os.path.expanduser('~')
    if sys.getwindowsversion()[3] != 2 and userdir == '~':
        # We are on win < nt: fetch the APPDATA directory location and use
        # the parent directory as the user home dir.
        appdir = shell.SHGetPathFromIDList(
            shell.SHGetSpecialFolderLocation(0, shellcon.CSIDL_APPDATA))
        userdir = os.path.dirname(appdir)
    return [os.path.join(userdir, 'mercurial.ini'),
            os.path.join(userdir, '.hgrc')]

def getuser():
    '''return name of current user'''
    return win32api.GetUserName()

def set_signal_handler_win32():
    """Register a termination handler for console events including
    CTRL+C. python signal handlers do not work well with socket
    operations.
    """
    def handler(event):
        win32process.ExitProcess(1)
    win32api.SetConsoleCtrlHandler(handler)

def hidewindow():
    def callback(*args, **kwargs):
        hwnd, pid = args
        wpid = win32process.GetWindowThreadProcessId(hwnd)[1]
        if pid == wpid:
            win32gui.ShowWindow(hwnd, win32con.SW_HIDE)

    pid =  win32process.GetCurrentProcessId()
    win32gui.EnumWindows(callback, pid)

def termwidth():
    try:
        # Query stderr to avoid problems with redirections
        screenbuf = win32console.GetStdHandle(win32console.STD_ERROR_HANDLE)
        try:
            window = screenbuf.GetConsoleScreenBufferInfo()['Window']
            width = window.Right - window.Left
            return width
        finally:
            screenbuf.Detach()
    except pywintypes.error:
        return 79