view mercurial/pure/osutil.py @ 29765:19578bb84731

extensions: add unwrapfunction to undo wrapfunction

Before this patch, we don't have a safe way to undo a wrapfunction because
other extensions may wrap the same function and calling setattr will undo
them accidentally.

This patch adds an "unwrapfunction" to address the issue. It removes the
wrapper from the wrapper chain, and re-wraps everything, which is not the
most efficient but short and easy to understand. We can revisit the code
if we have perf issues with long chains.

The "undo" feature is useful in cases like wrapping a function just in a
scope. Like, having a "select" command to interactively (using arrow keys)
select content from some output (ex. smartlog). It could wrap "ui.label" to
extract interesting texts just in the "select" command.

# 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

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

from . import policy
modulepolicy = policy.policy
policynocffi = policy.policynocffi

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 listdirpure(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(os.sep):
        prefix += os.sep
    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

ffi = None
if modulepolicy not in policynocffi and sys.platform == 'darwin':
    try:
        from _osutil_cffi import ffi, lib
    except ImportError:
        if modulepolicy == 'cffi': # strict cffi import
            raise

if sys.platform == 'darwin' and ffi is not None:
    listdir_batch_size = 4096
    # tweakable number, only affects performance, which chunks
    # of bytes do we get back from getattrlistbulk

    attrkinds = [None] * 20 # we need the max no for enum VXXX, 20 is plenty

    attrkinds[lib.VREG] = statmod.S_IFREG
    attrkinds[lib.VDIR] = statmod.S_IFDIR
    attrkinds[lib.VLNK] = statmod.S_IFLNK
    attrkinds[lib.VBLK] = statmod.S_IFBLK
    attrkinds[lib.VCHR] = statmod.S_IFCHR
    attrkinds[lib.VFIFO] = statmod.S_IFIFO
    attrkinds[lib.VSOCK] = statmod.S_IFSOCK

    class stat_res(object):
        def __init__(self, st_mode, st_mtime, st_size):
            self.st_mode = st_mode
            self.st_mtime = st_mtime
            self.st_size = st_size

    tv_sec_ofs = ffi.offsetof("struct timespec", "tv_sec")
    buf = ffi.new("char[]", listdir_batch_size)

    def listdirinternal(dfd, req, stat, skip):
        ret = []
        while True:
            r = lib.getattrlistbulk(dfd, req, buf, listdir_batch_size, 0)
            if r == 0:
                break
            if r == -1:
                raise OSError(ffi.errno, os.strerror(ffi.errno))
            cur = ffi.cast("val_attrs_t*", buf)
            for i in range(r):
                lgt = cur.length
                assert lgt == ffi.cast('uint32_t*', cur)[0]
                ofs = cur.name_info.attr_dataoffset
                str_lgt = cur.name_info.attr_length
                base_ofs = ffi.offsetof('val_attrs_t', 'name_info')
                name = str(ffi.buffer(ffi.cast("char*", cur) + base_ofs + ofs,
                           str_lgt - 1))
                tp = attrkinds[cur.obj_type]
                if name == "." or name == "..":
                    continue
                if skip == name and tp == statmod.S_ISDIR:
                    return []
                if stat:
                    mtime = cur.time.tv_sec
                    mode = (cur.accessmask & ~lib.S_IFMT)| tp
                    ret.append((name, tp, stat_res(st_mode=mode, st_mtime=mtime,
                                st_size=cur.datalength)))
                else:
                    ret.append((name, tp))
                cur += lgt
        return ret

    def listdir(path, stat=False, skip=None):
        req = ffi.new("struct attrlist*")
        req.bitmapcount = lib.ATTR_BIT_MAP_COUNT
        req.commonattr = (lib.ATTR_CMN_RETURNED_ATTRS |
                          lib.ATTR_CMN_NAME |
                          lib.ATTR_CMN_OBJTYPE |
                          lib.ATTR_CMN_ACCESSMASK |
                          lib.ATTR_CMN_MODTIME)
        req.fileattr = lib.ATTR_FILE_DATALENGTH
        dfd = lib.open(path, lib.O_RDONLY, 0)
        if dfd == -1:
            raise OSError(ffi.errno, os.strerror(ffi.errno))

        try:
            ret = listdirinternal(dfd, req, stat, skip)
        finally:
            try:
                lib.close(dfd)
            except BaseException:
                pass # we ignore all the errors from closing, not
                # much we can do about that
        return ret
else:
    listdir = listdirpure

if os.name != 'nt':
    posixfile = open

    _SCM_RIGHTS = 0x01
    _socklen_t = ctypes.c_uint

    if sys.platform == 'linux2':
        # 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('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 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' % (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='r', bufsize=-1):
            if 'b' in mode:
                flags = _O_BINARY
            else:
                flags = _O_TEXT

            m0 = mode[0]
            if m0 == 'r' and '+' 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 == 'r':
                creation = _OPEN_EXISTING
            elif m0 == 'w':
                creation = _CREATE_ALWAYS
            elif m0 == 'a':
                creation = _OPEN_ALWAYS
                flags |= _O_APPEND
            else:
                raise ValueError("invalid mode: %s" % 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, 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):
            return self._file.__enter__()

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