[PATCH 2 of 2 chg-port] osutil: implement pure version of recvfds() for PyPy

FUJIWARA Katsunori foozy at lares.dti.ne.jp
Wed Dec 23 10:30:40 CST 2015


At Sat, 19 Dec 2015 12:17:37 +0900,
Yuya Nishihara wrote:
> 
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1450363989 -32400
> #      Thu Dec 17 23:53:09 2015 +0900
> # Node ID 9726608c61dd53832c821d8bb9ce15b8aa268466
> # Parent  076525f412e74c913f72ff52034aa7ea046af74b
> osutil: implement pure version of recvfds() for PyPy
> 
> This is less portable than the C version, but PyPy can't load CPython
> extensions. So for now, this will be used on PyPy.
> 
> I've tested it on Linux amd64 and Mac OS X.
> 
> diff --git a/mercurial/pure/osutil.py b/mercurial/pure/osutil.py
> --- a/mercurial/pure/osutil.py
> +++ b/mercurial/pure/osutil.py
> @@ -7,8 +7,12 @@
>  
>  from __future__ import absolute_import
>  
> +import ctypes
> +import ctypes.util
>  import os
> +import socket
>  import stat as statmod
> +import sys
>  
>  def _mode_to_kind(mode):
>      if statmod.S_ISREG(mode):
> @@ -59,8 +63,87 @@ def listdir(path, stat=False, skip=None)
>  
>  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_ = [
> +            ('iov_base', ctypes.c_void_p),
> +            ('iov_len', ctypes.c_size_t),
> +        ]
> +
> +    class _msghdr(ctypes.Structure):
> +        _fields_ = [
> +            ('msg_name', ctypes.c_void_p),
> +            ('msg_namelen', _socklen_t),
> +            ('msg_iov', ctypes.POINTER(_iovec)),
> +            ('msg_iovlen', _msg_iovlen_t),
> +            ('msg_control', ctypes.c_void_p),
> +            ('msg_controllen', _msg_controllen_t),
> +            ('msg_flags', ctypes.c_int),
> +        ]
> +
> +    class _cmsghdr(ctypes.Structure):
> +        _fields_ = [
> +            ('cmsg_len', _cmsg_len_t),
> +            ('cmsg_level', ctypes.c_int),
> +            ('cmsg_type', ctypes.c_int),
> +            ('cmsg_data', ctypes.c_ubyte * 0),
> +        ]
> +
> +    _libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
> +    _recvmsg = _libc.recvmsg
> +    _recvmsg.restype = ctypes.c_ssize_t

This change doesn't work with Python 2.6.x, because ctypes.c_ssize_t
was introduced by 2.7. Loading osutil itself is aborted.

Even if Mercurial itself will be built without pure python modules,
"hg id -i" before building *.o in setup.py requires pure version of
osutil module.


> +    _recvmsg.argtypes = (ctypes.c_int, ctypes.POINTER(_msghdr), ctypes.c_int)
> +
> +    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 ctypes
>      import msvcrt
>  
>      _kernel32 = ctypes.windll.kernel32
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> Mercurial-devel at selenic.com
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----------------------------------------------------------------------
[FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp


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