osutil: do not abort loading pure module just because libc has no recvmsg()

On Solaris, recvmsg() is provided by libsocket.so. We could try hard to look
for the library which provides 'recvmsg' symbol, but it would make little sense
now since recvfds() won't work anyway on Solaris. So this patch just disables
_recvmsg() on such platforms.

Thanks to FUJIWARA Katsunori for spotting this problem.

mercurial/pure/osutil.py

@@ -1,262 +1,268 b''
 # 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
 
 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(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
 
 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 = 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)
+        _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)