1.6.5

[platform/upstream/dbus.git] / NEWS

D-Bus 1.6.6 (UNRELEASED)
==

...

D-Bus 1.6.4 (2012-07-18)
==

• Detect that users are "at the console" correctly when configured with
  a non-default path such as --enable-console-auth-dir=/run/console
  (fd.o #51521, Dave Reisner)

• Remove an incorrect assertion from DBusTransport (fd.o #51657,
  Simon McVittie)

• Make --enable-developer default to "no" (regression in 1.6.2;
  fd.o #51657, Simon McVittie)

• Windows-specific:
  · Launch dbus-daemon correctly if its path contains a space
    (fd.o #49450, Wolfgang Baron)

D-Bus 1.6.2 (2012-06-27)
==

The "Ice Cabbage" release.

• Change how we create /var/lib/dbus so it works under Automake >= 1.11.4
  (fd.o #51406, Simon McVittie)

• Don't return from dbus_pending_call_set_notify with a lock held on OOM
  (fd.o #51032, Simon McVittie)

• Disconnect "developer mode" (assertions, verbose mode etc.) from
  Automake maintainer mode. D-Bus developers should now configure with
  --enable-developer. Automake maintainer mode is now on by default;
  distributions can disable it with --disable-maintainer-mode.
  (fd.o #34671, Simon McVittie)

• Automatically define DBUS_STATIC_BUILD in static-only Autotools builds,
  fixing linking when targeting Windows (fd.o #33973; william, Simon McVittie)

• Unix-specific:
  · Check for libpthread under CMake on Unix (fd.o #47237, Simon McVittie)

D-Bus 1.6.0 (2012-06-05)
==

The “soul of this machine has improved” release.

This version starts a new stable branch of D-Bus: only bug fixes will
be accepted into 1.6.x. Other changes will now go to the 1.7.x branch.

Summary of changes since 1.4.x:

• New requirements
  · PTHREAD_MUTEX_RECURSIVE on Unix
  · compiler support for 64-bit integers (int64_t or equivalent)

• D-Bus Specification v0.19

• New dbus-daemon features
  · <allow own_prefix="com.example.Service"/> rules allow the service to
    own names like com.example.Service.Instance3
  · optional systemd integration when checking at_console policies
  · --nopidfile option, mainly for use by systemd
  · path_namespace and arg0namespace may appear in match rules
  · eavesdropping is disabled unless the match rule contains eavesdrop=true

• New public API
  · functions to validate various string types (dbus_validate_path() etc.)
  · dbus_type_is_valid()
  · DBusBasicValue, a union of every basic type

• Bug fixes
  · removed an unsafe reimplementation of recursive mutexes
  · dbus-daemon no longer busy-loops if it has far too many file descriptors
  · dbus-daemon.exe --print-address works on Windows
  · all the other bug fixes from 1.4.20

• Other major implementation changes
  · on Linux, dbus-daemon uses epoll if supported, for better scalability
  · dbus_threads_init() ignores its argument and behaves like
    dbus_threads_init_default() instead
  · removed the per-connection link cache, improving dbus-daemon performance

• Developer features
  · optional Valgrind instrumentation (--with-valgrind)
  · optional Stats interface on the dbus-daemon (--enable-stats)
  · optionally abort whenever malloc() fails (--enable-embedded-tests
    and export DBUS_MALLOC_CANNOT_FAIL=1)

Changes since 1.5.12:

• Be more careful about monotonic time vs. real time, fixing DBUS_COOKIE_SHA1
  spec-compliance (fd.o #48580, David Zeuthen)

• Don't use install(1) within the source/build trees, fixing the build as
  non-root when using OpenBSD install(1) (fd.o #48217, Antoine Jacoutot)

• Add missing commas in some tcp and nonce-tcp addresses, and remove
  an unused duplicate copy of the nonce-tcp transport in Windows builds
  (fd.o #45896, Simon McVittie)

D-Bus 1.5.12 (2012-03-27)
==

The “Big Book of Science” release.

• Add public API to validate various string types:
  dbus_validate_path(), dbus_validate_interface(), dbus_validate_member(),
  dbus_validate_error_name(), dbus_validate_bus_name(), dbus_validate_utf8()
  (fd.o #39549, Simon McVittie)

• Turn DBusBasicValue into public API so bindings don't need to invent their
  own "union of everything" type (fd.o #11191, Simon McVittie)

• Enumerate data files included in the build rather than using find(1)
  (fd.o #33840, Simon McVittie)

• Add support for policy rules like <allow own_prefix="com.example.Service"/>
  in dbus-daemon (fd.o #46273, Alban Crequy)

• Windows-specific:
  · make dbus-daemon.exe --print-address (and --print-pid) work again
    on Win32, but not on WinCE (fd.o #46049, Simon McVittie)
  · fix duplicate case value when compiling against mingw-w64
    (fd.o #47321, Andoni Morales Alastruey)

D-Bus 1.5.10 (2012-02-21)
==

The "fire in Delerium" release.

On Unix platforms, PTHREAD_MUTEX_RECURSIVE (as specified in POSIX 2008 Base
and SUSv2) is now required.

• D-Bus Specification 0.19:
  · Formally define unique connection names and well-known bus names,
    and document best practices for interface, bus, member and error names,
    and object paths (fd.o #37095, Simon McVittie)
  · Document the search path for session and system services on Unix, and
    where they should be installed by build systems (fd.o #21620, fd.o #35306;
    Simon McVittie)
  · Document the systemd transport (fd.o #35232, Lennart Poettering)

• Make dbus_threads_init() use the same built-in threading implementation
  as dbus_threads_init_default(); the user-specified primitives that it
  takes as a parameter are now ignored (fd.o #43744, Simon McVittie)

• Allow all configured auth mechanisms, not just one (fd.o #45106,
  Pavel Strashkin)

• Improve cmake build system (Ralf Habacker):
  · simplify XML parser dependencies (fd.o #41027)
  · generate build timestamp (fd.o #41029)
  · only create batch files on Windows
  · fix option and cache syntax
  · add help-options target
  · share dbus-arch-deps.h.in with autotools rather than having our
    own version (fd.o #41033)

• Build tests successfully with older GLib, as found in e.g. Debian 6
  (fd.o #41219, Simon McVittie)

• Avoid use of deprecated GThread API (fd.o #44413, Martin Pitt)

• Build documentation correctly if man2html doesn't support filenames on
  its command-line (fd.o #43875, Jack Nagel)

• Improve test coverage. To get even more coverage, run the tests with
  DBUS_TEST_SLOW=1 (fd.o #38285, #42811; Simon McVittie)

• Reduce the size of the shared library by moving functionality only used
  by dbus-daemon, tests etc. into their internal library and deleting
  unused code (fd.o #34976, #39759; Simon McVittie)

• Add dbus-daemon --nopidfile option, overriding the configuration, for
  setups where the default configuration must include <pidfile/> to avoid
  breaking traditional init, but the pid file is in fact unnecessary; use
  it under systemd to improve startup time a bit (fd.o #45520,
  Lennart Poettering)

• Optionally (if configured --with-valgrind) add instrumentation to debug
  libdbus and associated tools more meaningfully under Valgrind
  (fd.o #37286, Simon McVittie)

• Improve the dbus-send(1) man page (fd.o #14005, Simon McVittie)

• Make dbus-protocol.h compatible with C++11 (fd.o #46147, Marc Mutz)

• If tests are enabled and DBUS_MALLOC_CANNOT_FAIL is set in the environment,
  abort on failure to malloc() (like GLib does), to turn runaway memory leaks
  into a debuggable core-dump if a resource limit is applied (fd.o #41048,
  Simon McVittie)

• Don't crash if realloc() returns NULL in a debug build (fd.o #41048,
  Simon McVittie)

• Unix-specific:
  · Replace our broken reimplementation of recursive mutexes, which has
    been broken since 2006, with an ordinary pthreads recursive mutex
    (fd.o #43744; Sigmund Augdal, Simon McVittie)
  · Use epoll(7) for a more efficient main loop in Linux; equivalent patches
    welcomed for other OSs' equivalents like kqueue, /dev/poll, or Solaris
    event ports (fd.o #33337; Simon McVittie, Ralf Habacker)
  · When running under systemd, use it instead of ConsoleKit to check
    whether to apply at_console policies (fd.o #39609, Lennart Poettering)
  · Avoid a highly unlikely fd leak (fd.o #29881, Simon McVittie)
  · Don't close invalid fd -1 if getaddrinfo fails (fd.o #37258, eXeC001er)
  · Don't touch ~/.dbus and ~/.dbus-keyrings when running 'make installcheck'
    (fd.o #41218, Simon McVittie)
  · Stop pretending we respect XDG_DATA_DIRS for system services: the launch
    helper doesn't obey environment variables to avoid privilege escalation
    attacks, so make the system bus follow the same rules
    (fd.o #21620, Simon McVittie)

• Windows-specific:
  · Find the dbus-daemon executable next to the shared library (fd.o #41558;
    Jesper Dam, Ralf Habacker)
  · Remove the faulty implementation of _dbus_condvar_wake_all (fd.o #44609,
    Simon McVittie)

D-Bus 1.5.8 (2011-09-21)
==

The "cross-metering" release.

In addition to dead code removal and refactoring, this release contains all
of the bugfixes from 1.4.16.

• Clean up dead code, and make more warnings fatal in development builds
  (fd.o #39231, fd.o #41012; Simon McVittie)

• If full test coverage is requested via --enable-tests, strictly require
  Python, pygobject and dbus-python, which are required by some tests; if not,
  and Python is missing, skip those tests rather than failing
  (fd.o #37847, Simon McVittie)

• When using cmake, provide the same version-info API in the installed headers
  as for autotools (DBUS_VERSION, etc.) (fd.o #40905, Ralf Habacker)

• Add a regression test for fd.o #38005 (fd.o #39836, Simon McVittie)

• Make "NOCONFIGURE=1 ./autogen.sh" not run configure (Colin Walters)

• Add _DBUS_STATIC_ASSERT and use it to check invariants (fd.o #39636,
  Simon McVittie)

• Fix duplicates in authors list (Ralf Habacker)

• Fix broken links from dbus-tutorial.html if $(htmldir) != $(docdir)
  (fd.o #39879, Chris Mayo)

• Fix a small memory leak, and a failure to report errors, when updating
  a service file entry for activation (fd.o #39230, Simon McVittie)

• Unix-specific:
  · Clean up (non-abstract) Unix sockets on bus daemon exit (fd.o #38656;
    Brian Cameron, Simon McVittie)
  · On systems that use libcap-ng but not systemd, drop supplemental groups
    when switching to the daemon user (Red Hat #726953, Steve Grubb)
  · Make the cmake build work again on GNU platforms (fd.o #29228,
    Simon McVittie)
  · Fix compilation on non-C99 systems that have inttypes.h but not stdint.h,
    like Solaris (fd.o #40313, Dagobert Michelsen)
  · Define CMSG_ALIGN, CMSG_LEN, CMSG_SPACE on Solaris < 10
    (fd.o #40235, Simon McVittie)
  · Cope with Unixes that don't have LOG_PERROR, like Solaris 10
    (fd.o #39987, Simon McVittie)
  · Cope with platforms whose vsnprintf violates both POSIX and C99, like
    Tru64, IRIX and HP-UX (fd.o #11668, Simon McVittie)

• Windows-specific:
  · Fix compilation on MSVC, which doesn't understand "inline" with its
    C99 meaning (fd.o #40000; Ralf Habacker, Simon McVittie)
  · Fix misuse of GPid in test/dbus-daemon.c (fd.o #40003, Simon McVittie)
  · Fix cross-compilation to Windows with Automake (fd.o #40003, Simon McVittie)

D-Bus 1.5.6 (2011-07-29)
==

The "weird, gravy-like aftertaste" release.

In addition to new features and refactoring, this release contains all of the
bugfixes from 1.4.14.

Potentially incompatible (Bustle and similar debugging tools will need
changes to work as intended):

• Do not allow match rules to "eavesdrop" (receive messages intended for a
  different recipient) by mistake: eavesdroppers must now opt-in to this
  behaviour by putting "eavesdrop='true'" in the match rule, which will
  not have any practical effect on buses where eavesdropping is not allowed
  (fd.o #37890, Cosimo Alfarano)

Other changes:

• D-Bus Specification version 0.18 (fd.o #37890, fd.o #39450, fd.o #38252;
  Cosimo Alfarano, Simon McVittie)
  · add the "eavesdrop" keyword to match rules
  · define eavesdropping, unicast messages and broadcast messages
  · stop claiming that match rules are needed to match unicast messages to you
  · promote the type system to be a top-level section

• Use DBUS_ERROR_OBJECT_PATH_IN_USE if dbus_connection_try_register_object_path
  or dbus_connection_try_register_fallback fails, not ...ADDRESS_IN_USE,
  and simplify object-path registration (fd.o #38874, Jiří Klimeš)

• Consistently use atomic operations on everything that is ever manipulated
  via atomic ops, as was done for changes to DBusConnection's refcount in
  1.4.12 (fd.o #38005, Simon McVittie)

• Fix a file descriptor leak when connecting to a TCP socket (fd.o #37258,
  Simon McVittie)

• Make "make check" in a clean tree work, by not running tests until
  test data has been set up (fd.o #34405, Simon McVittie)

• The dbus-daemon no longer busy-loops if it has a very large number of file
  descriptors (fd.o #23194, Simon McVittie)

• Refactor message flow through dispatching to avoid locking violations if
  the bus daemon's message limit is hit; remove the per-connection link cache,
  which was meant to improve performance, but now reduces it (fd.o #34393,
  Simon McVittie)

• Some cmake fixes (Ralf Habacker)

• Remove dead code, mainly from DBusString (fd.o #38570, fd.o #39610;
  Simon McVittie, Lennart Poettering)

• Stop storing two extra byte order indicators in each D-Bus message
  (fd.o #38287, Simon McVittie)

• Add an optional Stats interface which can be used to get statistics from
  a running dbus-daemon if enabled at configure time with --enable-stats
  (fd.o #34040, Simon McVittie)

• Fix various typos (fd.o #27227, fd.o #38284; Sascha Silbe, Simon McVittie)

• Documentation (fd.o #36156, Simon McVittie):
  · let xsltproc be overridden as usual: ./configure XSLTPROC=myxsltproc
  · install more documentation automatically, including man2html output
  · put dbus.devhelp in the right place (it must go in ${htmldir})

• Unix-specific:
  · look for system services in /lib/dbus-1/system-services in addition to all
    the other well-known locations; note that this should always be /lib,
    even on platforms where shared libraries on the root FS would go in /lib64,
    /lib/x86_64-linux-gnu or similar (fd.o #35229, Lennart Poettering)
  · opt-in to fd passing on Solaris (fd.o #33465, Simon McVittie)

• Windows-specific (Ralf Habacker):
  · fix use of a mutex for autolaunch server detection
  · don't crash on malloc failure in _dbus_printf_string_upper_bound

D-Bus 1.5.4 (2011-06-10)
==

Security (local denial of service):

• Byte-swap foreign-endian messages correctly, preventing a long-standing
  local DoS if foreign-endian messages are relayed through the dbus-daemon
  (backporters: this is git commit c3223ba6c401ba81df1305851312a47c485e6cd7)
  (CVE-2011-2200, fd.o #38120, Debian #629938; Simon McVittie)

New things:

• The constant to use for an infinite timeout now has a name,
  DBUS_TIMEOUT_INFINITE. It is numerically equivalent to 0x7fffffff (INT32_MAX)
  which can be used for source compatibility with older versions of libdbus.

• If GLib and DBus-GLib are already installed, more tests will be built,
  providing better coverage. The new tests can also be installed via
      ./configure --enable-installed-tests
  for system integration testing, if required. (fd.o #34570, Simon McVittie)

Changes:

• Consistently use atomic operations for the DBusConnection's refcount,
  fixing potential threading problems (fd.o #38005, Simon McVittie)

• Don't use -Wl,--gc-sections by default: in practice the size decrease is
  small (300KiB on x86-64) and it frequently doesn't work in unusual
  toolchains. To optimize for minimum installed size, you should benchmark
  various possibilities for CFLAGS and LDFLAGS, and set the best flags for
  your particular toolchain at configure time. (fd.o #33466, Simon McVittie)

• Use #!/bin/sh for run-with-tmp-session-bus.sh, making it work on *BSD
  (fd.o #35880, Timothy Redaelli)

• Use ln -fs to set up dbus for systemd, which should fix reinstallation
  when not using a DESTDIR (fd.o #37870, Simon McVittie)

• Windows-specific changes:
  · don't try to build dbus-daemon-launch-helper (fd.o #37838, Mark Brand)

D-Bus 1.5.2 (2011-06-01)
==

The "Boar Hunter" release.

Notes for distributors:

  This version of D-Bus no longer uses -fPIE by default. Distributions wishing
  to harden the dbus-daemon and dbus-launch-helper can re-enable this if their
  toolchain supports it reliably, via something like:

    ./configure CFLAGS=-fPIE LDFLAGS="-pie -Wl,-z,relro"

  or by using distribution-specific wrappers such as Debian's hardening-wrapper.

Changes:

  • D-Bus Specification v0.17
    · Reserve the extra characters used in signatures by GVariant
      (fd.o #34529, Simon McVittie)
    · Define the ObjectManager interface (fd.o #34869, David Zeuthen)
  • Don't force -fPIE: distributions and libtool know better than we do whether
    it's desirable (fd.o #16621, fd.o #27215; Simon McVittie)
  • Allow --disable-gc-sections, in case your toolchain offers the
    -ffunction-sections, -fdata-sections and -Wl,--gc-sections options
    but they're broken, as seen on Solaris (fd.o #33466, Simon McVittie)
  • Install dbus-daemon and dbus-daemon-launch-helper in a more normal way
    (fd.o #14512; Simon McVittie, loosely based on a patch from Luca Barbato)
  • Ensure that maintainers upload documentation with the right permissions
    (fd.o #36130, Simon McVittie)
  • Don't force users of libdbus to be linked against -lpthread, -lrt
    (fd.o #32827, Simon McVittie)
  • Log system-bus activation information to syslog (fd.o #35705,
    Colin Walters)
  • Log messages dropped due to quotas to syslog (fd.o #35358,
    Simon McVittie)
  • Make the nonce-tcp transport work on Unix (fd.o #34569, Simon McVittie)
  • On Unix, if /var/lib/dbus/machine-id cannot be read, try /etc/machine-id
    (fd.o #35228, Lennart Poettering)
  • In the regression tests, don't report fds as "leaked" if they were open
    on startup (fd.o #35173, Simon McVittie)
  • Make dbus-monitor bail out if asked to monitor more than one bus,
    rather than silently using the last one (fd.o #26548, Will Thompson)
  • Clarify documentation (fd.o #35182, Simon McVittie)
  • Clean up minor dead code and some incorrect error handling
    (fd.o #33128, fd.o #29881; Simon McVittie)
  • Check that compiler options are supported before using them (fd.o #19681,
    Simon McVittie)
  • Windows:
    • Remove obsolete workaround for winioctl.h (fd.o #35083, Ralf Habacker)

D-Bus 1.5.0 (2011-04-11)
==

The "you never know when you need to tow something from your giant
flying shark" release.

  • D-Bus Specification v0.16
    · Add support for path_namespace and arg0namespace in match rules
      (fd.o #24317, #34870; Will Thompson, David Zeuthen, Simon McVittie)
    · Make argNpath support object paths, not just object-path-like strings,
      and document it better (fd.o #31818, Will Thompson)
  • Let the bus daemon implement more than one interface (fd.o #33757,
    Simon McVittie)
  • Optimize _dbus_string_replace_len to reduce waste (fd.o #21261,
    Roberto Guido)
  • Require user intervention to compile with missing 64-bit support
    (fd.o #35114, Simon McVittie)
  • Add dbus_type_is_valid as public API (fd.o #20496, Simon McVittie)
  • Raise UnknownObject instead of UnknownMethod for calls to methods on
    paths that are not part of the object tree, and UnknownInterface for calls
    to unknown interfaces in the bus daemon (fd.o #34527, Lennart Poettering)

D-Bus 1.4.8 (2011-04-08)
==

The "It's like the beginning of a lobster" release.

  • Rename configure.in to configure.ac, and update it to modern conventions
    (fd.o #32245; Javier Jardón, Simon McVittie)
  • Correctly give XDG_DATA_HOME priority over XDG_DATA_DIRS (fd.o #34496,
    Anders Kaseorg)
  • Prevent X11 autolaunching if $DISPLAY is unset or empty, and add
    --disable-x11-autolaunch configure option to prevent it altogether
    in embedded environments (fd.o #19997, NB#219964; Simon McVittie)
  • Install the documentation, and an index for Devhelp (fd.o #13495,
    Debian #454142; Simon McVittie, Matthias Clasen)
  • If checks are not disabled, check validity of string-like types and
    booleans when sending them (fd.o #16338, NB#223152; Simon McVittie)
  • Add UnknownObject, UnknownInterface, UnknownProperty and PropertyReadOnly
    errors to dbus-shared.h (fd.o #34527, Lennart Poettering)
  • Break up a huge conditional in config-parser so gcov can produce coverage
    data (fd.o #10887, Simon McVittie)
  • List which parts of the Desktop Entry specification are applicable to
    .service files (fd.o #19159, Sven Herzberg)
  • Don't suppress service activation if two services have the same Exec=
    (fd.o #35750, Colin Walters)
  • Windows:
    · Avoid the name ELEMENT_TYPE due to namespace-pollution from winioctl.h
      (Andre Heinecke)
    · Include _dbus_path_is_absolute in libdbus on Windows, fixing compilation
      (fd.o #32805, Mark Brand)

D-Bus 1.4.6 (2010-02-17)
==

The "1, 2, miss a few, 99, 100" release.

  • Remove unfinished changes intended to support GTest-based tests,
    which were mistakenly included in 1.4.4

D-Bus 1.4.4 (2010-02-17)
==

  • Switch back to using even micro versions for stable releases; 1.4.1
    should have been called 1.4.2, so skip that version number
  • Don't leave bad file descriptors being watched when spawning processes,
    which could result in a busy-loop (fd.o #32992, NB#200248; possibly
    also LP#656134, LP#680444, LP#713157)
  • Check for MSG_NOSIGNAL correctly
  • Fix failure to detect abstract socket support (fd.o #29895)
  • Make _dbus_system_logv actually exit with DBUS_SYSTEM_LOG_FATAL
    (fd.o #32262, NB#180486)
  • Improve some error code paths (fd.o #29981, fd.o #32264, fd.o #32262,
    fd.o #33128, fd.o #33277, fd.o #33126, NB#180486)
  • Avoid possible symlink attacks in /tmp during compilation (fd.o #32854)
  • Tidy up dead code (fd.o #25306, fd.o #33128, fd.o #34292, NB#180486)
  • Improve gcc malloc annotations (fd.o #32710)
  • If the system bus is launched via systemd, protect it from the OOM killer
  • Documentation improvements (fd.o #11190)
  • Avoid readdir_r, which is difficult to use correctly (fd.o #8284,
    fd.o #15922, LP#241619)
  • Cope with invalid files in session.d, system.d (fd.o #19186,
    Debian #230231)
  • Don't distribute generated files that embed our builddir (fd.o #30285,
    fd.o #34292)
  • Raise the system bus's fd limit to be sufficient for its configuration
    (fd.o #33474, LP#381063)
  • Fix syslog string processing
  • Ignore -Waddress
  • Remove broken gcov parsing code and --enable-gcov, and replace them
    with lcov HTML reports and --enable-compiler-coverage (fd.o #10887)
  • Windows:
    · avoid live-lock in Windows CE due to unfair condition variables
  • OpenBSD:
    · support credentials-passing (fd.o #32542)
  • Solaris:
    · opt-in to thread safety (fd.o #33464)

D-Bus 1.4.1 (20 December 2010)
==

 • Fix for CVE-2010-4352: sending messages with excessively-nested variants can
   crash the bus. The existing restriction to 64-levels of nesting previously
   only applied to the static type signature; now it also applies to dynamic
   nesting using variants. Thanks to Rémi Denis-Courmont for discoving this
   issue.
 • OS X portability fixes, including launchd support.
 • Windows autolaunch improvements.
 • Various bug fixes.

D-Bus 1.4.0 (6 Sep 2010)
==
 - systemd hookup

D-Bus 1.3.1 (23 June 2010)
==
 - New standardized PropertiesChanged signal in the properties interface
 - Various portability fixes, in particular to Windows platforms
 - Support forking bus services, for compatibility

D-Bus 1.3.0 (29 July 2009)
==
 - ability for dbus-send to send to any bus (--address)
 - file descriptor passing on Unix socket transports
 - use of GCC atomic intrinsics for better processor support
   (requires -march=i486 or above for x86 compilation)
 - thread-safe FD_CLOEXEC setting on recent Linux kernels (2.6.24-27 and up)
   and glibc (2.9 for pipe2 and 2.10 for accept4)
 - feature negotiation in the bus daemon