mercurial/win32.py

win32: add comment about WinError

Prevent reintroducing the bug that was added in e34106fa0dc3 (and fixed with
a2285e2fc949).

# 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.

import ctypes, errno, os, subprocess, random

_kernel32 = ctypes.windll.kernel32
_advapi32 = ctypes.windll.advapi32
_user32 = ctypes.windll.user32

_BOOL = ctypes.c_long
_WORD = ctypes.c_ushort
_DWORD = ctypes.c_ulong
_UINT = ctypes.c_uint
_LONG = ctypes.c_long
_LPCSTR = _LPSTR = ctypes.c_char_p
_HANDLE = ctypes.c_void_p
_HWND = _HANDLE

_INVALID_HANDLE_VALUE = _HANDLE(-1).value

# GetLastError
_ERROR_SUCCESS = 0
_ERROR_NO_MORE_FILES = 18
_ERROR_INVALID_PARAMETER = 87
_ERROR_INSUFFICIENT_BUFFER = 122

# WPARAM is defined as UINT_PTR (unsigned type)
# LPARAM is defined as LONG_PTR (signed type)
if ctypes.sizeof(ctypes.c_long) == ctypes.sizeof(ctypes.c_void_p):
    _WPARAM = ctypes.c_ulong
    _LPARAM = ctypes.c_long
elif ctypes.sizeof(ctypes.c_longlong) == ctypes.sizeof(ctypes.c_void_p):
    _WPARAM = ctypes.c_ulonglong
    _LPARAM = ctypes.c_longlong

class _FILETIME(ctypes.Structure):
    _fields_ = [('dwLowDateTime', _DWORD),
                ('dwHighDateTime', _DWORD)]

class _BY_HANDLE_FILE_INFORMATION(ctypes.Structure):
    _fields_ = [('dwFileAttributes', _DWORD),
                ('ftCreationTime', _FILETIME),
                ('ftLastAccessTime', _FILETIME),
                ('ftLastWriteTime', _FILETIME),
                ('dwVolumeSerialNumber', _DWORD),
                ('nFileSizeHigh', _DWORD),
                ('nFileSizeLow', _DWORD),
                ('nNumberOfLinks', _DWORD),
                ('nFileIndexHigh', _DWORD),
                ('nFileIndexLow', _DWORD)]

# CreateFile
_FILE_SHARE_READ = 0x00000001
_FILE_SHARE_WRITE = 0x00000002
_FILE_SHARE_DELETE = 0x00000004

_OPEN_EXISTING = 3

_FILE_FLAG_BACKUP_SEMANTICS = 0x02000000

# SetFileAttributes
_FILE_ATTRIBUTE_NORMAL = 0x80
_FILE_ATTRIBUTE_NOT_CONTENT_INDEXED = 0x2000

# Process Security and Access Rights
_PROCESS_QUERY_INFORMATION = 0x0400

# GetExitCodeProcess
_STILL_ACTIVE = 259

class _STARTUPINFO(ctypes.Structure):
    _fields_ = [('cb', _DWORD),
                ('lpReserved', _LPSTR),
                ('lpDesktop', _LPSTR),
                ('lpTitle', _LPSTR),
                ('dwX', _DWORD),
                ('dwY', _DWORD),
                ('dwXSize', _DWORD),
                ('dwYSize', _DWORD),
                ('dwXCountChars', _DWORD),
                ('dwYCountChars', _DWORD),
                ('dwFillAttribute', _DWORD),
                ('dwFlags', _DWORD),
                ('wShowWindow', _WORD),
                ('cbReserved2', _WORD),
                ('lpReserved2', ctypes.c_char_p),
                ('hStdInput', _HANDLE),
                ('hStdOutput', _HANDLE),
                ('hStdError', _HANDLE)]

class _PROCESS_INFORMATION(ctypes.Structure):
    _fields_ = [('hProcess', _HANDLE),
                ('hThread', _HANDLE),
                ('dwProcessId', _DWORD),
                ('dwThreadId', _DWORD)]

_CREATE_NO_WINDOW = 0x08000000
_SW_HIDE = 0

class _COORD(ctypes.Structure):
    _fields_ = [('X', ctypes.c_short),
                ('Y', ctypes.c_short)]

class _SMALL_RECT(ctypes.Structure):
    _fields_ = [('Left', ctypes.c_short),
                ('Top', ctypes.c_short),
                ('Right', ctypes.c_short),
                ('Bottom', ctypes.c_short)]

class _CONSOLE_SCREEN_BUFFER_INFO(ctypes.Structure):
    _fields_ = [('dwSize', _COORD),
                ('dwCursorPosition', _COORD),
                ('wAttributes', _WORD),
                ('srWindow', _SMALL_RECT),
                ('dwMaximumWindowSize', _COORD)]

_STD_ERROR_HANDLE = _DWORD(-12).value

# CreateToolhelp32Snapshot, Process32First, Process32Next
_TH32CS_SNAPPROCESS = 0x00000002
_MAX_PATH = 260

class _tagPROCESSENTRY32(ctypes.Structure):
    _fields_ = [('dwsize', _DWORD),
                ('cntUsage', _DWORD),
                ('th32ProcessID', _DWORD),
                ('th32DefaultHeapID', ctypes.c_void_p),
                ('th32ModuleID', _DWORD),
                ('cntThreads', _DWORD),
                ('th32ParentProcessID', _DWORD),
                ('pcPriClassBase', _LONG),
                ('dwFlags', _DWORD),
                ('szExeFile', ctypes.c_char * _MAX_PATH)]

    def __init__(self):
        super(_tagPROCESSENTRY32, self).__init__()
        self.dwsize = ctypes.sizeof(self)


# 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

_kernel32.GetFileInformationByHandle.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.GetFileInformationByHandle.restype = _BOOL

_kernel32.CloseHandle.argtypes = [_HANDLE]
_kernel32.CloseHandle.restype = _BOOL

try:
    _kernel32.CreateHardLinkA.argtypes = [_LPCSTR, _LPCSTR, ctypes.c_void_p]
    _kernel32.CreateHardLinkA.restype = _BOOL
except AttributeError:
    pass

_kernel32.SetFileAttributesA.argtypes = [_LPCSTR, _DWORD]
_kernel32.SetFileAttributesA.restype = _BOOL

_kernel32.OpenProcess.argtypes = [_DWORD, _BOOL, _DWORD]
_kernel32.OpenProcess.restype = _HANDLE

_kernel32.GetExitCodeProcess.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.GetExitCodeProcess.restype = _BOOL

_kernel32.GetLastError.argtypes = []
_kernel32.GetLastError.restype = _DWORD

_kernel32.GetModuleFileNameA.argtypes = [_HANDLE, ctypes.c_void_p, _DWORD]
_kernel32.GetModuleFileNameA.restype = _DWORD

_kernel32.CreateProcessA.argtypes = [_LPCSTR, _LPCSTR, ctypes.c_void_p,
    ctypes.c_void_p, _BOOL, _DWORD, ctypes.c_void_p, _LPCSTR, ctypes.c_void_p,
    ctypes.c_void_p]
_kernel32.CreateProcessA.restype = _BOOL

_kernel32.ExitProcess.argtypes = [_UINT]
_kernel32.ExitProcess.restype = None

_kernel32.GetCurrentProcessId.argtypes = []
_kernel32.GetCurrentProcessId.restype = _DWORD

_SIGNAL_HANDLER = ctypes.WINFUNCTYPE(_BOOL, _DWORD)
_kernel32.SetConsoleCtrlHandler.argtypes = [_SIGNAL_HANDLER, _BOOL]
_kernel32.SetConsoleCtrlHandler.restype = _BOOL

_kernel32.GetStdHandle.argtypes = [_DWORD]
_kernel32.GetStdHandle.restype = _HANDLE

_kernel32.GetConsoleScreenBufferInfo.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.GetConsoleScreenBufferInfo.restype = _BOOL

_advapi32.GetUserNameA.argtypes = [ctypes.c_void_p, ctypes.c_void_p]
_advapi32.GetUserNameA.restype = _BOOL

_user32.GetWindowThreadProcessId.argtypes = [_HANDLE, ctypes.c_void_p]
_user32.GetWindowThreadProcessId.restype = _DWORD

_user32.ShowWindow.argtypes = [_HANDLE, ctypes.c_int]
_user32.ShowWindow.restype = _BOOL

_WNDENUMPROC = ctypes.WINFUNCTYPE(_BOOL, _HWND, _LPARAM)
_user32.EnumWindows.argtypes = [_WNDENUMPROC, _LPARAM]
_user32.EnumWindows.restype = _BOOL

_kernel32.CreateToolhelp32Snapshot.argtypes = [_DWORD, _DWORD]
_kernel32.CreateToolhelp32Snapshot.restype = _BOOL

_kernel32.Process32First.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.Process32First.restype = _BOOL

_kernel32.Process32Next.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.Process32Next.restype = _BOOL

def _raiseoserror(name):
    err = ctypes.WinError()
    raise OSError(err.errno, '%s: %s' % (name, err.strerror))

def _getfileinfo(name):
    fh = _kernel32.CreateFileA(name, 0,
            _FILE_SHARE_READ | _FILE_SHARE_WRITE | _FILE_SHARE_DELETE,
            None, _OPEN_EXISTING, _FILE_FLAG_BACKUP_SEMANTICS, None)
    if fh == _INVALID_HANDLE_VALUE:
        _raiseoserror(name)
    try:
        fi = _BY_HANDLE_FILE_INFORMATION()
        if not _kernel32.GetFileInformationByHandle(fh, ctypes.byref(fi)):
            _raiseoserror(name)
        return fi
    finally:
        _kernel32.CloseHandle(fh)

def oslink(src, dst):
    try:
        if not _kernel32.CreateHardLinkA(dst, src, None):
            _raiseoserror(src)
    except AttributeError: # Wine doesn't support this function
        _raiseoserror(src)

def nlinks(name):
    '''return number of hardlinks for the given file'''
    return _getfileinfo(name).nNumberOfLinks

def samefile(path1, path2):
    '''Returns whether path1 and path2 refer to the same file or directory.'''
    res1 = _getfileinfo(path1)
    res2 = _getfileinfo(path2)
    return (res1.dwVolumeSerialNumber == res2.dwVolumeSerialNumber
        and res1.nFileIndexHigh == res2.nFileIndexHigh
        and res1.nFileIndexLow == res2.nFileIndexLow)

def samedevice(path1, path2):
    '''Returns whether path1 and path2 are on the same device.'''
    res1 = _getfileinfo(path1)
    res2 = _getfileinfo(path2)
    return res1.dwVolumeSerialNumber == res2.dwVolumeSerialNumber

def testpid(pid):
    '''return True if pid is still running or unable to
    determine, False otherwise'''
    h = _kernel32.OpenProcess(_PROCESS_QUERY_INFORMATION, False, pid)
    if h:
        try:
            status = _DWORD()
            if _kernel32.GetExitCodeProcess(h, ctypes.byref(status)):
                return status.value == _STILL_ACTIVE
        finally:
            _kernel32.CloseHandle(h)
    return _kernel32.GetLastError() != _ERROR_INVALID_PARAMETER

def executablepath():
    '''return full path of hg.exe'''
    size = 600
    buf = ctypes.create_string_buffer(size + 1)
    len = _kernel32.GetModuleFileNameA(None, ctypes.byref(buf), size)
    if len == 0:
        raise ctypes.WinError() # Note: WinError is a function
    elif len == size:
        raise ctypes.WinError(_ERROR_INSUFFICIENT_BUFFER)
    return buf.value

def getuser():
    '''return name of current user'''
    size = _DWORD(300)
    buf = ctypes.create_string_buffer(size.value + 1)
    if not _advapi32.GetUserNameA(ctypes.byref(buf), ctypes.byref(size)):
        raise ctypes.WinError()
    return buf.value

_signalhandler = []

def setsignalhandler():
    '''Register a termination handler for console events including
    CTRL+C. python signal handlers do not work well with socket
    operations.
    '''
    def handler(event):
        _kernel32.ExitProcess(1)

    if _signalhandler:
        return # already registered
    h = _SIGNAL_HANDLER(handler)
    _signalhandler.append(h) # needed to prevent garbage collection
    if not _kernel32.SetConsoleCtrlHandler(h, True):
        raise ctypes.WinError()

def hidewindow():

    def callback(hwnd, pid):
        wpid = _DWORD()
        _user32.GetWindowThreadProcessId(hwnd, ctypes.byref(wpid))
        if pid == wpid.value:
            _user32.ShowWindow(hwnd, _SW_HIDE)
            return False # stop enumerating windows
        return True

    pid = _kernel32.GetCurrentProcessId()
    _user32.EnumWindows(_WNDENUMPROC(callback), pid)

def termwidth():
    # cmd.exe does not handle CR like a unix console, the CR is
    # counted in the line length. On 80 columns consoles, if 80
    # characters are written, the following CR won't apply on the
    # current line but on the new one. Keep room for it.
    width = 79
    # Query stderr to avoid problems with redirections
    screenbuf = _kernel32.GetStdHandle(
                  _STD_ERROR_HANDLE) # don't close the handle returned
    if screenbuf is None or screenbuf == _INVALID_HANDLE_VALUE:
        return width
    csbi = _CONSOLE_SCREEN_BUFFER_INFO()
    if not _kernel32.GetConsoleScreenBufferInfo(
                        screenbuf, ctypes.byref(csbi)):
        return width
    width = csbi.srWindow.Right - csbi.srWindow.Left
    return width

def _1stchild(pid):
    '''return the 1st found child of the given pid

    None is returned when no child is found'''
    pe = _tagPROCESSENTRY32()

    # create handle to list all processes
    ph = _kernel32.CreateToolhelp32Snapshot(_TH32CS_SNAPPROCESS, 0)
    if ph == _INVALID_HANDLE_VALUE:
        raise ctypes.WinError()
    try:
        r = _kernel32.Process32First(ph, ctypes.byref(pe))
        # loop over all processes
        while r:
            if pe.th32ParentProcessID == pid:
                # return first child found
                return pe.th32ProcessID
            r = _kernel32.Process32Next(ph, ctypes.byref(pe))
    finally:
        _kernel32.CloseHandle(ph)
    if _kernel32.GetLastError() != _ERROR_NO_MORE_FILES:
        raise ctypes.WinError()
    return None # no child found

class _tochildpid(int): # pid is _DWORD, which always matches in an int
    '''helper for spawndetached, returns the child pid on conversion to string

    Does not resolve the child pid immediately because the child may not yet be
    started.
    '''
    def childpid(self):
        '''returns the child pid of the first found child of the process
        with this pid'''
        return _1stchild(self)
    def __str__(self):
        # run when the pid is written to the file
        ppid = self.childpid()
        if ppid is None:
            # race, child has exited since check
            # fall back to this pid. Its process will also have disappeared,
            # raising the same error type later as when the child pid would
            # be returned.
            return " %d" % self
        return str(ppid)

def spawndetached(args):
    # No standard library function really spawns a fully detached
    # process under win32 because they allocate pipes or other objects
    # to handle standard streams communications. Passing these objects
    # to the child process requires handle inheritance to be enabled
    # which makes really detached processes impossible.
    si = _STARTUPINFO()
    si.cb = ctypes.sizeof(_STARTUPINFO)

    pi = _PROCESS_INFORMATION()

    env = ''
    for k in os.environ:
        env += "%s=%s\0" % (k, os.environ[k])
    if not env:
        env = '\0'
    env += '\0'

    args = subprocess.list2cmdline(args)
    # Not running the command in shell mode makes Python 2.6 hang when
    # writing to hgweb output socket.
    comspec = os.environ.get("COMSPEC", "cmd.exe")
    args = comspec + " /c " + args

    res = _kernel32.CreateProcessA(
        None, args, None, None, False, _CREATE_NO_WINDOW,
        env, os.getcwd(), ctypes.byref(si), ctypes.byref(pi))
    if not res:
        raise ctypes.WinError()

    # _tochildpid because the process is the child of COMSPEC
    return _tochildpid(pi.dwProcessId)

def unlink(f):
    '''try to implement POSIX' unlink semantics on Windows'''

    if os.path.isdir(f):
        # use EPERM because it is POSIX prescribed value, even though
        # unlink(2) on directories returns EISDIR on Linux
        raise IOError(errno.EPERM,
                      "Unlinking directory not permitted: '%s'" % f)

    # POSIX allows to unlink and rename open files. Windows has serious
    # problems with doing that:
    # - Calling os.unlink (or os.rename) on a file f fails if f or any
    #   hardlinked copy of f has been opened with Python's open(). There is no
    #   way such a file can be deleted or renamed on Windows (other than
    #   scheduling the delete or rename for the next reboot).
    # - Calling os.unlink on a file that has been opened with Mercurial's
    #   posixfile (or comparable methods) will delay the actual deletion of
    #   the file for as long as the file is held open. The filename is blocked
    #   during that time and cannot be used for recreating a new file under
    #   that same name ("zombie file"). Directories containing such zombie files
    #   cannot be removed or moved.
    # A file that has been opened with posixfile can be renamed, so we rename
    # f to a random temporary name before calling os.unlink on it. This allows
    # callers to recreate f immediately while having other readers do their
    # implicit zombie filename blocking on a temporary name.

    for tries in xrange(10):
        temp = '%s-%08x' % (f, random.randint(0, 0xffffffff))
        try:
            os.rename(f, temp)  # raises OSError EEXIST if temp exists
            break
        except OSError, e:
            if e.errno != errno.EEXIST:
                raise
    else:
        raise IOError(errno.EEXIST, "No usable temporary filename found")

    try:
        os.unlink(temp)
    except OSError:
        # The unlink might have failed because the READONLY attribute may heave
        # been set on the original file. Rename works fine with READONLY set,
        # but not os.unlink. Reset all attributes and try again.
        _kernel32.SetFileAttributesA(temp, _FILE_ATTRIBUTE_NORMAL)
        try:
            os.unlink(temp)
        except OSError:
            # The unlink might have failed due to some very rude AV-Scanners.
            # Leaking a tempfile is the lesser evil than aborting here and
            # leaving some potentially serious inconsistencies.
            pass

def makedir(path, notindexed):
    os.mkdir(path)
    if notindexed:
        _kernel32.SetFileAttributesA(path, _FILE_ATTRIBUTE_NOT_CONTENT_INDEXED)